%0 Journal Article
%~ PubMed
%A Cheung, Florence Sg
%A Lovicu, Frank J
%A Reichardt, Juergen Kv
%T Current progress in using vitamin D and its analogs for cancer prevention and treatment.
%B Expert Review of Anticancer Therapy
%D 2012
%C United Kingdom
%I Expert Reviews Ltd.
%V 12
%N 6
%P 811-837
%@ 1744-8328
%X Vitamin D has long been known for its physiological role in mineral homeostasis through its actions on the intestines, kidneys, parathyroid glands and bone. However, recent observations of antiproliferative, prodifferentiating and antiangiogenic effects elicited by the bioactive form of vitamin D (1,25[OH](2)D(3)) in a broad range of cancers is less well understood. Here, we review the increasing epidemiological and experimental evidence that supports the development of 1,25(OH)(2)D(3) and vitamin D analogs as preventative and therapeutic anticancer agents. Furthermore, this review summarizes the preclinical and clinical studies of vitamin D and its analogs over the past decade, indicating the current problems of dose-limiting toxicity from hypercalcemia and large interpatient variability in pharmacokinetics. A better understanding of how genetic variants influence vitamin D status should not only improve cancer risk predictions, but also promote the development of vitamin D analogs with more specific actions to improve therapeutic outcomes.
%Z FOR Codes: 111204 111501


%0 Journal Article
%~ PubMed
%A Madakashira, Bhavani P
%A Kobrinski, Daniel A
%A Hancher, Andrew D
%A Arneman, Elizabeth C
%A Wagner, Brad D
%A Wang, Fen
%A Shin, Hailey
%A Lovicu, Frank J
%A Reneker, Lixing W
%A Robinson, Michael L
%T Frs2α enhances fibroblast growth factor-mediated survival and differentiation in lens development.
%B Development
%D 2012
%C United Kingdom
%I The Company of Biologists Ltd.
%V 139
%N 24
%P 4601-4612
%@ 1477-9129
%X 
%Z FOR Codes: 60103


%0 Journal Article
%~ PubMed
%A Shin, Eun Hye H
%A Basson, M Albert
%A Robinson, Michael L
%A McAvoy, John W
%A Lovicu, Frank J
%T Sprouty is a negative regulator of Transforming Growth Factor β-induced epithelial to mesenchymal transition and cataract.
%B Molecular Medicine
%D 2012
%C United States
%I The Feinstein Institute for Medical Research
%V 18
%N 1
%P 861-873
%@ 1528-3658
%X Fibrosis affects an extensive range of organs and is increasingly acknowledged as a major component of many chronic disorders. It is now well accepted that the elevated expression of certain inflammatory cell-derived cytokines, especially transforming growth factor beta (TGF??), is involved in the epithelial to mesenchymal transition (EMT) leading to the pathogenesis of a diverse range of fibrotic diseases. In lens, aberrant TGF??-signaling has been shown to induce EMT leading to cataract formation. Sproutys (Sprys) are negative feedback regulators of receptor tyrosine kinase (RTK)-signaling pathways in many vertebrate systems, and here we show that they are important in the murine lens for promoting the lens epithelial cell phenotype. Conditional deletion of Spry1 and Spry2 specifically from the lens leads to an aberrant increase in RTK-mediated ERK1/2 phosphorylation and surprisingly, elevated TGF??-related-signaling in lens epithelial cells, leading to an EMT and subsequent cataract formation. Conversely, increased Spry overexpression in lens cells has the ability to not only suppress TGF??-induced signaling, but also the accompanying EMT and cataract formation. Based on these findings, we propose that a better understanding of the relationship between Spry and TGF??-signaling, will prove beneficial not only in the etiology of lens pathology, but will serve to potentially treat other fibrotic-related diseases associated with TGF??-induced EMT.
%Z FOR Codes: 111301 110316 60111


%0 Journal Article
%~ PubMed
%A Sugiyama, Yuki
%A Lovicu, Frank J
%A McAvoy, John W
%T Planar cell polarity in the mammalian eye lens.
%B Organogenesis
%D 2011
%C United States
%I Landes Bioscience
%V 7
%N 3
%P 191-201
%@ 1555-8592
%X The major role of the eye lens is to transmit and focus images onto the retina. For this function, the lens needs to develop and maintain the correct shape, notably, the precise curvature and high-level order and organization of its elements. The lens is mainly comprised of highly elongated fiber cells with hexagonal cross-sectional profiles that facilitate regular packing. Collectively, they form concentrically arranged layers around the anterior-posterior polar axis, and their convex curvature contributes to the spheroidal shape of the lens. Although the lens has been a popular system for developmental studies, little is known about the mechanism(s) that underlies the development of its exquisite three-dimensional cellular architecture. In this review, we will describe our recent work, which shows how planar cell polarity (PCP) operates in lens and contributes to its morphogenesis. We believe that the lens will be a useful model system to study PCP in general and gain insights into mechanisms that generate high-level cellular order during development.
%Z FOR Codes: 60106 111301


%0 Journal Article
%~ PubMed
%A Kallifatidis, Georgios
%A Boros, Jessica
%A Shin, Eun Hye H
%A McAvoy, John W
%A Lovicu, Frank J
%T The fate of dividing cells during lens morphogenesis, differentiation and growth.
%B Experimental eye research
%D 2011
%C United Kingdom, United States
%I Academic Press
%V 92
%N 6
%P 502-11
%@ 0014-4835
%X Early in development, the ocular lens establishes its distinctive architecture, and this is maintained throughout life as the lens continues to grow. This growth is tightly regulated through the proliferation of the lens epithelial cells and their subsequent differentiation into specialized elongated fiber cells. Although much work has been carried out to define these patterns of growth, very little has been reported on the detailed fate and kinetics of lens cells during embryogenesis. Using BrdU-incorporation, the present study has attempted to follow the fate of lens cells that have undergone at least one round of DNA synthesis during the early stages of lens morphogenesis. Results from this work have confirmed that the rate of lens cell proliferation and new fiber cell differentiation progressively slows as the lens differentiates and grows. In addition, these studies have shown that early in lens development, not all DNA synthesis is restricted to the lens epithelium, with some elongating fiber cells retaining the ability to undergo DNA synthesis. Adopting this system we have also been able to place the initiation of secondary fiber cell differentiation in the mouse lens by E12.5, concomitant with the loss of the lens vesicle lumen by the elongating primary fiber cells. Overall, this study has allowed us to revisit some of the mechanisms involved in early lens development, has provided us with insights into the fate of cells during this rapid phase of murine lens growth, and has provided a novel method to study the rate of new fiber cell differentiation over a defined period of lens development and growth.
%Z FOR Codes: 111303


%0 Journal Article
%~ PubMed
%A Lovicu, F J
%A McAvoy, J W
%A de Iongh, R U
%T Understanding the role of growth factors in embryonic development: insights from the lens.
%B Royal Society of London. Philosophical Transactions B. Biological Sciences
%D 2011
%C United States
%I The Royal Society Publishing
%V 366
%N 1568
%P 1204-1218
%@ 1471-2970
%X Growth factors play key roles in influencing cell fate and behaviour during development. The epithelial cells and fibre cells that arise from the lens vesicle during lens morphogenesis are bathed by aqueous and vitreous, respectively. Vitreous has been shown to generate a high level of fibroblast growth factor (FGF) signalling that is required for secondary lens fibre differentiation. However, studies also show that FGF signalling is not sufficient and roles have been identified for transforming growth factor-?? and Wnt/Frizzled families in regulating aspects of fibre differentiation. In the case of the epithelium, key roles for Wnt/??-catenin and Notch signalling have been demonstrated in embryonic development, but it is not known if other factors are required for its formation and maintenance. This review provides an overview of current knowledge about growth factor regulation of differentiation and maintenance of lens cells. It also highlights areas that warrant future study.
%Z FOR Codes: 111303


%0 Journal Article
%~ Isi
%A West-Mays, J. A.
%A Pino, G.
%A Lovicu, F. J.
%T Development and use of the lens epithelial explant system to study lens differentiation and cataractogenesis
%B Progress in Retinal and Eye Research
%D 2010
%C United Kingdom
%I Pergamon
%V 29
%N 2
%P 135-143
%@ 1350-9462
%X 
%Z FOR Codes: 111303 60103


%0 Journal Article
%~ PubMed
%A Wang, Qian
%A McAvoy, John W
%A Lovicu, Frank J
%T Growth factor signaling in vitreous humour-induced lens fiber differentiation.
%B Investigative ophthalmology & visual science
%D 2010
%C United States
%I Association for Research in Vision and Ophthalmology
%V 51
%N 7
%P 3599-610
%@ 0146-0404
%X PURPOSE. Although some of the factors and signaling pathways that are involved in induction of fiber differentiation have been defined, such as FGF-mediated MAPK/ERK and PI3-K/Akt signaling, the factors in the vitreous that regulate this differentiation process in vivo have yet to be identified. The purpose of this study was to better understand the role of growth factors in vitreous that regulate this process by further characterizing the signaling pathways involved in lens fiber differentiation. METHODS. Rat lens epithelial explants were used to compare the ability of vitreous, IGF-1, PDGF-A, EGF, and FGF-2 to stimulate the phosphorylation of ERK1/2 and Akt leading to fiber differentiation, in the presence or absence of selective receptor tyrosine kinase (RTK) inhibitors. RESULTS. Similar to vitreous, FGF induced a sustained ERK1/2 signaling profile, unlike IGF, PDGF, and EGF, which induced a more transient (shorter) activation of ERK1/2. For Akt activation, IGF was the only factor that induced a profile similar to vitreous. IGF, PDGF, and EGF potentiated the effects of a low dose of FGF on lens fiber differentiation by extending the duration of ERK1/2 phosphorylation. In the presence of selective RTK inhibitors, although the sustained vitreous-induced ERK1/2 signaling profile and subsequent fiber differentiation was perturbed, the results also showed that, although prolonged ERK1/2 phosphorylation was necessary, it was not sufficient for fiber differentiation to proceed. CONCLUSIONS. These results are consistent with FGF''s being the key growth factor involved in vitreous-induced signaling leading to lens fiber differentiation; however, they also indicate that other vitreal growth factors such as IGF may be involved in fine-tuning ERK1/2- and Akt-phosphorylation to the level that is necessary for initiation and/or maintenance of lens fiber differentiation in vivo.
%Z FOR Codes: 60103


%0 Journal Article
%~ PubMed
%A Alibardi, Lorenzo
%A Lovicu, Frank J
%T Immunolocalization of FGF1 and FGF2 in the regenerating tail of the lizard Lampropholis guichenoti: Implications for FGFs as trophic factors in lizard tail regeneration.
%B Acta histochemica
%D 2010
%C Germany, United Stat
%I Urban und Fischer Verlag
%V 112
%N 5
%P 459-73
%@ 1618-0372
%X A role for fibroblast growth factors in stimulating limb and tail regeneration in amphibians has been shown; however, it is unknown whether these growth factors are also involved in the regeneration of the tail of lizard, an amniote model for studies on tissue regeneration. The presence of fibroblast growth factor-1 (FGF1) and -2 (FGF2) in the regenerating tail of the lizard Lampropholis guichenoti has been studied using immunofluorescence labeling. The study reveals that FGF2 is mainly localized in the wound and scaling epidermis, in differentiating muscles, in spinal ganglia, regenerating nerves and spinal cord. FGF1 is also present in the wound and differentiating epidermis, but is detectable at lower levels in the regenerating muscles and spinal cord. FGF1 is present in blastema cells, while FGF2 labeling is relatively low in these cells. Fibroblasts of the forming dermis are rich in FGF1 but not in FGF2. Developing blood vessels label for both FGF1 and FGF2 while the cartilaginous, bone and fat tissues are poorly labeled or unlabeled for FGFs. The present study suggests that most FGFs in the regenerating tail are located in the nervous system, in the epidermis and muscles, and these tissues most likely require these growth factors for their differentiation and growth. The present study suggests that FGFs produced in the regenerating epidermis, spinal cord and nerves can stimulate tail regeneration in lizards.
%Z FOR Codes: 110799


%0 Journal Article
%~ PubMed
%A Sugiyama, Yuki
%A Stump, Richard J W
%A Nguyen, Anke
%A Wen, Li
%A Chen, Yongjuan
%A Wang, Yanshu
%A Murdoch, Jennifer N
%A Lovicu, Frank J
%A McAvoy, John W
%T Secreted frizzled-related protein disrupts PCP in eye lens fiber cells that have polarised primary cilia.
%B Developmental biology
%D 2010
%C United States
%I Academic Press
%V 338
%N 2
%P 193-201
%@ 1095-564X
%X Planar cell polarity (PCP) signaling polarises cells along tissue axes. Although pathways involved are becoming better understood, outstanding issues include; (i) existence/identity of cues that orchestrate global polarisation in tissues, and (ii) the generality of the link between polarisation of primary cilia and asymmetric localisation of PCP proteins. Mammalian lenses are mainly comprised of epithelial-derived fiber cells. Concentrically arranged fibers are precisely aligned as they elongate along the anterior-posterior axis and orientate towards lens poles where they meet fibers from other segments to form characteristic sutures. We show that lens exhibits PCP, with each fiber cell having an apically situated cilium and in most cases this is polarised towards the anterior pole. Frizzled and other PCP proteins are also asymmetrically localised along the equatorial-anterior axis. Mutations in core PCP genes Van Gogh-like 2 and Celsr1 perturb oriented fiber alignment and suture formation. Suppression of the PCP pathway by overexpressing Sfrp2 shows that whilst local groups of fibers are often similarly oriented, they lack global orientation; consequently when local groups of fibers with different orientations meet they form multiple, small, ectopic suture-like configurations. This indicates that this extracellular inhibitor disrupts a global polarising signal that utilises a PCP-mediated mechanism to coordinate the global alignment and orientation of fibers to lens poles.
%Z FOR Codes: 60103 111303


%0 Journal Article
%~ PubMed
%A Newitt, Peter
%A Boros, Jessica
%A Madakashira, Bhavani P
%A Robinson, Michael L
%A Reneker, Lixing W
%A McAvoy, John W
%A Lovicu, Frank J
%T Sef is a negative regulator of fiber cell differentiation in the ocular lens.
%B Differentiation; research in biological diversity
%D 2010
%C United Kingdom, Unit
%I Elsevier Ltd
%V 80
%N 1
%P 53-67
%@ 1432-0436
%X Growth factor signaling, mediated via receptor tyrosine kinases (RTKs), needs to be tightly regulated in many developmental systems to ensure a physiologically appropriate biological outcome. At one level this regulation may involve spatially and temporally ordered patterns of expression of specific RTK signaling antagonists, such as Sef (similar expression to fgfs). Growth factors, notably FGFs, play important roles in development of the vertebrate ocular lens. FGF induces lens cell proliferation and differentiation at progressively higher concentrations and there is compelling evidence that a gradient of FGF signaling in the eye determines lens polarity and growth patterns. We have recently identified the presence of Sef in the lens, with strongest expression in the epithelial cells. Given the important role for FGFs in lens developmental biology, we employed transgenic mouse strategies to determine if Sef could be involved in regulating lens cell behaviour. Over-expressing Sef specifically in the lens of transgenic mice led to impaired lens and eye development that resulted in microphthalmia. Sef inhibited primary lens fiber cell elongation and differentiation, as well as increased apoptosis, consistent with a block in FGFR-mediated signaling during lens morphogenesis. These results are consistent with growth factor antagonists, such as Sef, being important negative regulators of growth factor signaling. Moreover, the lens provides a useful paradigm as to how opposing gradients of a growth factor and its antagonist could work together to determine and stabilise tissue patterning during development and growth.
%Z FOR Codes: 60111 111303


%0 Journal Article
%~ PubMed
%A Iyengar, Laxmi
%A Patkunanathan, Bramilla
%A McAvoy, John
%A Lovicu, Frank
%T Growth factors involved in aqueous humour-induced lens cell proliferation.
%B Growth factors (Chur, Switzerland)
%D 2009
%C United Kingdom
%I Informa Healthcare
%V 27
%N 1
%P 50-62
%@ 1029-2292
%X Lens epithelial cell proliferation is regulated by growth factors in the aqueous humour of the eye. Although the lens fibre cell-differentiating factors are well defined, the factors in aqueous that promote lens cell proliferation are not. Mitogens present in aqueous primarily signal through the MAPK/ERK and PI3-K/Akt pathways. By characterising the signalling pathways involved in lens cell proliferation, we aim to identify the factors in aqueous that regulate this process in vivo. Using rat lens epithelial explants, 5''-2''-bromo-deoxyuridine and H(3)-thymidine incorporation were used to compare the effects of aqueous, insulin-like growth factor (IGF-1), platelet-derived growth factor (PDGF-A), epidermal growth factor (EGF) and fibroblast growth factor (FGF-2) on lens cell proliferation. Western blotting was employed to characterise ERK1/2 and Akt signalling induced by these mitogens. The above assays were also repeated in the presence of selective receptor inhibitors. Similar to aqueous, FGF induced a sustained ERK1/2 signalling profile (up to 6 h), unlike IGF, PDGF and EGF that induced a transient activation of ERK1/2. In the presence of a FGF receptor (FGFR) inhibitor, the sustained aqueous-induced ERK1/2 signalling profile was perturbed, resembling the transient IGF-, PDGF- or EGF-induced profile. In the presence of other growth factor receptor inhibitors, aqueous maintained its sustained, 6 h, ERK1/2 signalling profile, although ERK1/2 phosphorylation at earlier time periods was reduced. No one-specific receptor inhibitor could block aqueous-induced lens cell proliferation; however, combinations of inhibitors could, providing FGFR signalling was blocked. Multiple growth factors are likely to regulate lens cell proliferation in vivo, with a key role for FGF in aqueous-induced signalling and lens cell proliferation.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Chong, C C W
%A Stump, R J W
%A Lovicu, F J
%A McAvoy, J W
%T TGFbeta promotes Wnt expression during cataract development.
%B Experimental eye research
%D 2009
%C United Kingdom
%I Academic Press
%V 88
%N 0
%P 307-13
%@ 0014-4835
%X TGFbeta induces lens epithelial cells to undergo epithelial mesenchymal transition (EMT) and many changes with characteristics of fibrosis including posterior capsular opacification (PCO). Consequently much effort is directed at trying to block the damaging effects of TGFbeta in the lens. To do this effectively it is important to know the key signaling pathways regulated by TGFbeta that lead to EMT and PCO. Given that Wnt signaling is involved in TGFbeta-induced EMT in other systems, this study set out to determine if Wnt signaling has a role in regulating this process in the lens. Using RT-PCR, in situ hybridization and immunolocalization this study clearly shows that Wnts 5a, 5b, 7b, 8a, 8b and their Frizzled receptors are upregulated in association with TGFbeta-induced EMT and cataract development. Both rat in vitro and mouse in vivo cataract models show similar profiles for the Wnt and Frizzled mRNAs and proteins that were assessed. Currently it is not clear if the canonical beta-catenin/TCF signaling pathway, or a non-canonical pathway, is activated in this context. Overall, the results from the current study indicate that Wnt signaling is involved in TGFbeta-induced EMT and development of fibrotic plaques in the lens.
%Z FOR Codes: 111301


%0 Book Section
%A Lovicu, Frank
%A McAvoy, Johnston
%T Epithelial explants and their application to study developmental processes in the lens
%B Animal Models in Eye Research
%D 2008
%C United States
%I Academic Press
%V 
%N 
%P 0
%@ 9786611766214
%E Tsonis, Panagiotis A
%X 
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A O'Connor, Michael D
%A Wederell, Elizabeth D
%A de Iongh, Robert
%A Lovicu, Frank J
%A McAvoy, John W
%T Generation of transparency and cellular organization in lens explants.
%B Experimental eye research
%D 2008
%C United Kingdom
%I Academic Press
%V 86
%N 5
%P 734-745
%@ 0014-4835
%X The lens grows via the proliferation and differentiation of lens epithelial cells into lens fibres. This differentiation process, thought to be controlled by factors present in the vitreous fluid, generates tightly-packed, parallel-aligned fibre cells that confer transparency to the lens. Using lens epithelial-cell explants we examined how explant orientation and growth factor treatment can affect cellular arrangement and explant transparency. Fibre cell differentiation was induced in lens explants by culturing cells with fibroblast growth factor (FGF) or bovine vitreous. Cell shape and arrangement was investigated using confocal microscopy, electron microscopy, immunofluorescence and in situ hybridization. Explant transparency was measured using light microscopy. Confocal microscopy demonstrated that explant orientation determined cellular arrangement, irrespective of the differentiation stimuli used. In explants where epithelial cells were confined between their normal basement membrane (the lens capsule) and the base of the culture dish, the cells became elongated, thin and parallel-aligned. In contrast, in explants cultured with cells directly exposed to the culture media the cells appeared to be shorter, globular and haphazardly arranged. FGF initiated the differentiation of most lens epithelial cells; however, abnormal cellular morphologies developed with subsequent culture of the cells. As a result, the transparency of these explants decreased with prolonged culture. Interestingly, explants cultured with vitreous (i) did not develop abnormal cellular morphologies, (ii) contained two distinct cell types (retained epithelial cells and newly differentiated fibre cells) and (iii) remained transparent throughout the lengthy culture period. In summary, we have developed a culture system that generates a transparent tissue with a cellular arrangement resembling that of the lens in vivo. We have shown that while FGF and vitreous initiate differentiation within this system, better maintenance of fibre cell integrity, more appropriate regulation of molecular events, and better maintenance of explant transparency was achieved in the presence of vitreous. This system offers an opportunity to further investigate the process of lens fibre cell differentiation as well as a means of better identifying the factors that contribute to the development of tissue transparency in vitro.
%Z FOR Codes: 111303


%0 Journal Article
%~ PubMed
%A Wang, Qian
%A Stump, Richard
%A McAvoy, John W
%A Lovicu, Frank J
%T MAPK/ERK1/2 and PI3-kinase signalling pathways are required for vitreous-induced lens fibre cell differentiation.
%B Experimental eye research
%D 2008
%C UK
%I Academic Press
%V 88
%N 0
%P 293-306
%@ 0014-4835
%X Lens epithelial cells withdraw from the cell cycle to differentiate into secondary fibre cells in response to vitreal factors. Fibroblast growth factor (FGF) in the vitreous has been shown to induce lens fibre differentiation in vivo and in vitro through the activation of defined intracellular signalling, namely via MAPK/ERK1/2 and PI3-K/Akt pathways. To better understand the role of these growth factor-activated signalling pathways in lens fibre differentiation, FGF- and vitreous-induced lens fibre differentiation was examined in primary rat lens epithelial cell explants. The induction of cell elongation and fibre specific beta- and gamma-crystallin expression in lens explants was accompanied by distinct phosphorylation profiles for ERK1/2 and Akt. Using selective inhibitors (U0126 and LY294002) in blocking studies, these pathways were shown to be required for different aspects of lens fibre differentiation. Furthermore, a short ''pulse'' treatment of explants with FGF showed that the activation of ERK1/2 over 24 h was not sufficient for the progression of lens fibre differentiation and that cyclic ERK1/2 phosphorylation was required throughout the extended differentiation process. In conclusion, these results support a key role for both ERK1/2 and PI3-kinase/Akt signalling pathways in FGF- and vitreous-induced lens fibre differentiation.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Chen, Yongjuan
%A Stump, Richard J W
%A Lovicu, Frank J
%A Shimono, Akihiko
%A McAvoy, John W
%T Wnt signaling is required for organization of the lens fiber cell cytoskeleton and development of lens three-dimensional architecture.
%B Developmental biology
%D 2008
%C 525 B ST, STE 1900, SAN DIEGO, USA, CA, 92101-449
%I Academic Press Inc Elsevier Science
%V 324
%N 1
%P 161-76
%@ 0012-1606
%X How an organ develops its characteristic shape is a major issue. This is particularly critical for the eye lens as its function depends on having appropriately ordered three-dimensional cellular architecture. Recent in vitro studies indicate that Wnt signaling plays key roles in regulating morphological events in FGF-induced fiber cell differentiation in the mammalian lens. To further investigate this the Wnt signaling antagonist, secreted frizzled-related protein 2 (Sfrp2), was overexpressed in lens fiber cells of transgenic mice. In these mice fiber cell elongation was attenuated and individual fibers exhibited irregular shapes and consequently did not align or pack regularly; microtubules, microfilaments and intermediate filaments were clearly disordered in these fibers. Furthermore, a striking feature of transgenic lenses was that fibers did not develop the convex curvature typically seen in normal lenses. This appears to be related to a lack of protrusive processes that are required for directed migratory activity at their apical and basal tips as well as for the formation of interlocking processes along their lateral margins. Components of the Wnt/Planar Cell Polarity (PCP) pathway were downregulated or inhibited. Taken together this supports a role for Wnt/PCP signaling in orchestrating the complex organization and dynamics of the fiber cell cytoskeleton.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Jamieson, Robyn V
%A Farrar, Nicola
%A Stewart, Katrina
%A Perveen, Rahat
%A Mihelec, Marija
%A Carette, Martin
%A Grigg, John R
%A McAvoy, John W
%A Lovicu, Frank J
%A Tam, Patrick P L
%A Scambler, Peter
%A Lloyd, I Christopher
%A Donnai, Dian
%A Black, Graeme C M
%T Characterization of a familial t(16;22) balanced translocation associated with congenital cataract leads to identification of a novel gene, TMEM114, expressed in the lens and disrupted by the translocation.
%B Human mutation
%D 2007
%C DIV JOHN WILEY & SON
%I Wiley-Liss
%V 28
%N 10
%P 968-977
%@ 1098-1004
%X Molecular characterization of chromosomal rearrangements is a powerful resource in identification of genes associated with monogenic disorders. We describe the molecular characterization of a balanced familial chromosomal translocation, t(16;22)(p13.3;q11.2), segregating with congenital lamellar cataract. This led to the discovery of a cluster of lens-derived expressed sequence tags (ESTs) close to the 16p13.3 breakpoint. This region harbors a locus associated with cataract and microphthalmia. Long-range PCR and 16p13.3 breakpoint sequencing identified genomic sequence in a human genome sequence gap, and allowed identification of a novel four-exon gene, designated TMEM114, which encodes a predicted protein of 223 amino acids. The breakpoint lies in the promoter region of TMEM114 and separates the gene from predicted eye-specific upstream transcription factor binding sites. There is sequence conservation among orthologs down to zebrafish. The protein is predicted to contain four transmembrane domains with homology to the lens intrinsic membrane protein, LIM2 (also known as MP20), in the PMP-22/EMP/MP20 family. TMEM114 mutation screening in 130 congenital cataract patients revealed missense mutations leading to the exchange of highly-conserved amino acids in the first extracellular domain of the protein (p.I35T, p.F106L) in two separate patients and their reportedly healthy sibling and mother, respectively. In the lens, Tmem114 shows expression in the lens epithelial cells extending into the transitional zone where early fiber differentiation occurs. Our findings implicate dysregulation of expression of this novel human gene, TMEM114, in mammalian cataract formation.
%Z FOR Codes: 111301


%0 Journal Article
%~ Isi
%A Sohaskey, ML
%A Lovicu, FJ
%A McAvoy, JW
%A Little, MH
%A Kolle, G
%A Wilkinson, L
%A Pennisi, DJ
%A Gillinder, K
%A Piper, MJ
%T Crim1(KST264/KST264) mice display a disruption of the Crim1 gene resulting in perinatal lethality with defects in multiple organ systems
%B DEVELOPMENTAL DYNAMICS
%D 2007
%C United States
%I John Wiley & Sons, Inc.
%V 236
%N 2
%P 502-511
%@ 1058-8388
%X 
%Z FOR Codes: 60803


%0 Journal Article
%~ PubMed
%A Iyengar, Laxmi
%A Wang, Qian
%A Rasko, John E J
%A McAvoy, John W
%A Lovicu, Frank J
%T Duration of ERK1/2 phosphorylation induced by FGF or ocular media determines lens cell fate.
%B Differentiation; Research in Biological Diversity
%D 2007
%C United Kingdom
%I Wiley-Blackwell Publishing Ltd.
%V 75
%N 7
%P 662-668
%@ 0301-4681
%X The ocular environment is important for the establishment and maintenance of lens growth patterns and polarity. In the anterior chamber of the eye, the aqueous humour regulates lens epithelial cell proliferation whereas in the posterior, the vitreous humour regulates the differentiation of the lens cells into fiber cells. Members of the fibroblast growth factor (FGF) growth factor family have been shown to induce lens epithelial cells to undergo cell division and differentiate into fibers, with a low dose of FGF able to induce cell proliferation (but not fiber differentiation), and higher doses required to induce fiber differentiation. Both these cellular events have been shown to be regulated by the MAPK/ERK1/2 signalling pathway. In the present study, to better understand the contribution of ERK1/2 signalling in regulating lens cell proliferation and differentiation, we characterized the ERK1/2 signalling profiles induced by different doses of FGF, and compared these to those induced by the different ocular media. Here, we show that FGF induced a dose-dependent sustained activation of ERK1/2, with both a high (fiber differentiating) dose of FGF and vitreous, stimulating and maintaining a prolonged (up to 18 hr) ERK1/2 phosphorylation profile. In contrast, a lower (proliferating) dose of FGF, and aqueous, stimulated ERK1/2 phosphorylation for only up to 6 hr. If we selectively reduce the 18 hr ERK1/2 phosphorylation profile induced by vitreous to 6 hr, by specifically blocking FGF receptor signalling, the vitreous now fails to induce lens fiber differentiation but retains the ability to induce lens cell proliferation. These findings not only provide insights into the important role that FGF plays in the different ocular media that bathe the lens, but enlighten us on some of the putative molecular mechanisms by which one specific growth factor, in this case FGF, can elicit a different cellular response in the same cell type.
%Z FOR Codes: 111303


%0 Journal Article
%~ Isi
%A Lovicu, FJ
%A Ziman, M
%A Thompson, JA
%T Pax7 and superior collicular polarity: insights from Pax6 (Sey) mutant mice
%B EXPERIMENTAL BRAIN RESEARCH
%D 2007
%C Germany
%I Springer
%V 178
%N 
%P 316-325
%@ 0014-4819
%X 
%Z FOR Codes: 110906


%0 Journal Article
%~ PubMed
%A Markus, M Andrea
%A Goy, Christine
%A Adams, David J
%A Lovicu, Frank J
%A Morris, Brian J
%T Renin Enhancer Is Crucial for Full Response in Renin Expression to an In Vivo Stimulus.
%B Hypertension
%D 2007
%C 530 WALNUT ST, PHILA
%I Lippincott Williams & Wilkins
%V 50
%N 
%P 933-8
%@ 1524-4563
%X We showed recently that deletion of a strong enhancer located 2.7 kb upstream of the renin gene in mice produces a strain with mild hypotension and salt-sensitivity. Here we set out to compare responses in renin expression in kidney and extrarenal tissues in these "REKO" mice. REKO and wild-type mice were placed on a low NaCl/enalapril regimen for 1 week, and then Ren-1(c) mRNA and renin enzyme activities were measured in tissues and plasma. In untreated REKO mice, renin and Ren-1(c) mRNA were reduced significantly in kidney, submandibular gland, adrenal, heart, and brain. In situ hybridization indicated a marked reduction in Ren-1(c) mRNA in juxtaglomerular cells and granular ducts of submandibular gland. After the chronic stimulus response in renal Ren-1(c) mRNA in REKO mice was blunted by 54% compared with wild-type mice, and was accompanied by almost complete exhaustion of renin stores. Response in plasma renin was blunted by 47%, this being mirrored in heart (54% decline), in which renin is derived mostly from the bloodstream. In adrenal a 55% reduction was seen. These data are consistent with inability of REKO mice to adequately replenish renal renin stores during chronic stimulation of renin secretion. In conclusion, the renin enhancer is critical for replenishment of renin stores and response in renin to a chronic in vivo stimulus.
%Z FOR Codes: 110105 111699


%0 Journal Article
%~ PubMed
%A Chen, Y
%A Stump, R J W
%A Lovicu, F J
%A McAvoy, J W
%T A role for Wnt/planar cell polarity signaling during lens fiber cell differentiation?
%B Seminars in cell & developmental biology
%D 2006
%C United Kingdom
%I Academic Press
%V 17
%N 
%P 712-25
%@ 1084-9521
%X Wnt signaling through frizzled (Fz) receptors plays key roles in just about every developmental system that has been studied. Several Wnt-Fz signaling pathways have been identified including the Wnt/planar cell polarity (PCP) pathway. PCP signaling is crucial for many developmental processes that require major cytoskeletal rearrangements. Downstream of Fz, PCP signaling is thought to involve the GTPases, Rho, Rac and Cdc42 and regulation of the JNK cascade. Here we report on the localization of these GTPases and JNK in the lens and assess their involvement in the cytoskeletal reorganisation that is a key element of FGF-induced lens fiber cell differentiation.
%Z FOR Codes: 111601


%0 Journal Article
%~ PubMed
%A Iyengar, Laxmi
%A Patkunanathan, Bramilla
%A Lynch, Oonagh T
%A McAvoy, John W
%A Rasko, John E J
%A Lovicu, Frank J
%T Aqueous humour- and growth factor-induced lens cell proliferation is dependent on MAPK/ERK1/2 and Akt/PI3-K signalling.
%B Experimental eye research
%D 2006
%C United Kingdom
%I Academic Press
%V 83
%N 3
%P 667-678
%@ 0014-4835
%X The aqueous humour of the eye is a rich source of growth factors, many of which have been shown to be lens cell mitogens; however, the identity of the endogenous mitogen(s) for lens cells is still unknown. As a first approach to identify the mechanisms by which these aqueous humour-derived growth factors induce lens cell proliferation, the present study set out to examine MAPK/ERK1/2 and PI3-K/Akt signalling associated with lens cell proliferation. Using a lens explant system, we examined the effects of different lens mitogens (aqueous humour, FGF, PDGF, IGF and EGF) using 5''-2''-bromo-deoxyuridine incorporation. In addition, we adopted immunolabelling techniques to compare the roles that the ERK1/2 and PI3-K signalling pathways play in regulating lens cell proliferation. We showed that the aqueous humour, and all the other growth factors examined, could activate ERK1/2 and PI3-K/Akt signalling. By targeting these pathways using specific pharmacological inhibitors, we were able to show that both ERK1/2 and PI3-K signalling are required for growth factor-induced lens cell proliferation, and that there was a strong correlation between the spatial distribution of proliferating cells in lens explants with ERK1/2 labelling. Furthermore, our blocking studies confirmed that PI3-K/Akt signalling can act upstream of ERK1/2, potentiating ERK1/2 phosphorylation in growth factor-induced lens cell proliferation. A better understanding of the signalling pathways required for aqueous humour-induced lens cell proliferation may ultimately allow us to identify the mitogen(s) that are important for regulating lens cell proliferation in situ.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Lovicu, Frank J
%T Cell signaling in lens development.
%B Seminars in cell & developmental biology
%D 2006
%C UK
%I Academic Press
%V 17
%N 0
%P 675
%@ 1084-9521
%X 
%Z FOR Codes:


%0 Journal Article
%~ PubMed
%A Symonds, Joel G
%A Lovicu, Frank J
%A Chamberlain, Coral G
%T Differing effects of dexamethasone and diclofenac on posterior capsule opacification-like changes in a rat lens explant model.
%B Experimental eye research
%D 2006
%C United Kingdom
%I Academic Press
%V 83
%N 
%P 771-82
%@ 0014-4835
%X Posterior capsular opacification (PCO) arises from lens cells that remain associated with the lens capsule after cataract surgery and subsequently become abnormal, proliferate and migrate into the visual pathway. In this study, a rat lens explant model was used to assess the effects of the prototype steroidal and non-steroidal anti-inflammatory drugs, dexamethasone (DEX) and diclofenac (DIC), on epithelial cells undergoing PCO-like changes. Such drugs are widely used at the time of cataract surgery. TGFbeta2 and FGF-2 were added sequentially and explants were cultured for up to 30 days, with or without addition of DEX or DIC at a clinically relevant concentration. Without DEX or DIC, explants became multilayered and cells tended to retract into PCO-like plaques. Inclusion of DEX, but not DIC, resulted in transient formation of needle-like cells, enhanced cell coverage, and the retention a monolayer of migratory cells surrounding PCO-like plaques. With or without drug addition, most cells became aberrant, as indicated by loss of Pax6 expression and the presence of PCO markers alpha-smooth muscle actin and type I collagen; however, DEX and DIC both strongly enhanced type I collagen accumulation. Furthermore, DEX enhanced cell coverage in explants treated with TGFbeta alone. Thus the behaviour of lens cells was significantly and differentially affected by the presence of DEX and DIC, highlighting the possibility that drugs used to control inflammation after cataract surgery, and the clinician''s choice of drugs, may influence PCO development.
%Z FOR Codes: 111301 111301


%0 Journal Article
%~ PubMed
%A Stump, Rjw
%A Lovicu, Fj
%A Ang, Sl
%A Pandey, Sk
%A McAvoy, Jw
%T Lithium stabilizes the polarized lens epithelial phenotype and inhibits proliferation, migration, and epithelial mesenchymal transition.
%B The Journal of pathology
%D 2006
%C United Kingdom
%I John Wiley & Sons Ltd.
%V 210
%N 2
%P 249-57
%@ 0022-3417
%X Posterior capsule opacification (PCO) is a common complication of cataract surgery caused by epithelial mesenchymal transition (EMT) and aberrant lens cell growth. One path to prevention depends on maintaining the quiescent lens epithelial phenotype. Here we report that lithium chloride (LiCl) is a potent stabilizer of the lens epithelial phenotype. In lens epithelial explants (controls), at low cell density, cells readily depolarized, spread out, and proliferated. By contrast, in the presence of LiCl, cells did not spread out or exhibit migratory behaviour. Using concentrations of 1-30 mM LiCl we also showed that cell proliferation is inhibited in a dose-dependent manner. Confocal microscopy and immunohistochemistry for ZO-1 and E-cadherin showed that LiCl treatment maintained tight junctions at the apical margins of cells. Taken together with measurements of cell heights, this showed that the cells in LiCl-treated explants maintained the apical baso-lateral polarity and cobblestone-like packing that is characteristic of lens epithelial cells in vivo. Significantly, the effects of LiCl also extended to blocking the potent EMT/cataract-promoting effects of transforming growth factor beta (TGFbeta) on lens epithelial cells. In TGFbeta-treated explants, cells progressively dissociated from one another, taking on various elongated spindle shapes and strongly expressing alpha-smooth muscle actin (alpha-SMA). These features are characteristic of PCO. In both rat and human capsulorhexis explants, LiCl treatment effectively blocked the accumulation of alpha-SMA and maintained the cells in a polarized, adherent, cobblestone-packed monolayer. These findings highlight the feasibility of applying molecular strategies to stabilize lens epithelial cells and prevent aberrant differentiation and growth that leads to cataract.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Symonds, Joel G
%A Lovicu, Frank J
%A Chamberlain, Coral G
%T Posterior capsule opacification-like changes in rat lens explants cultured with TGFbeta and FGF: effects of cell coverage and regional differences.
%B Experimental eye research
%D 2006
%C United Kingdom
%I Academic Press
%V 82
%N 4
%P 693-9
%@ 0014-4835
%X Following cataract surgery, many patients suffer secondary loss of vision because of posterior capsule opacification (PCO), which arises when residual lens epithelial cells become aberrant and migrate into the light path. Transforming growth factor-beta (TGFbeta)-induced transdifferentiation of lens cells appears to play a key role in this process. Fibroblast growth factor (FGF) may also play a role by promoting the survival of TGFbeta-affected cells and influencing their subsequent behaviour. In the present study, the effects of two different TGFbeta and FGF treatment regimes were compared in rat lens epithelial explants with either low or high initial cell coverage. Explants treated with 50 pg ml(-1) TGFbeta2 and 20 ng ml(-1) FGF-2 sequentially (day 0, day 1) or simultaneously (day 0), then cultured for up to 30 days with FGF, were assessed by light microscopy and immunolocalisation of markers for transdifferentiation (alpha-smooth muscle actin (alphaSMA) and type I collagen) or lens epithelial phenotype (Pax6) and fibre differentiation (beta-crystallin). By day 4, most cells had lost Pax6 reactivity, alphaSMA reactivity was evident, and there were differences between growth factor treatment groups, low and high initial cell coverage explants, and peripheral and central regions of explants. On day 30 of culture, all explants were well populated with cells, irrespective of treatment and initial cell coverage, and exhibited diverse PCO-like morphological changes, with expression of transdifferentiation markers and beta-crystallin in virtually all cells. Such overall resilience to variations in conditions may contribute to the insidious nature of PCO, while factors related to observed early differences between groups may contribute to PCO pleiomorphism.
%Z FOR Codes: 111301


%0 Journal Article
%~ PubMed
%A Adams, David J
%A Head, Geoffrey A
%A Markus, M Andrea
%A Lovicu, Frank J
%A van der Weyden, Louise
%A Köntgen, Frank
%A Arends, Mark J
%A Thiru, Sathia
%A Mayorov, Dmitry N
%A Morris, Brian J
%T Renin enhancer is critical for control of renin gene expression and cardiovascular function.
%B The Journal of biological chemistry
%D 2006
%C UK
%I American Society for Biochemistry and Molecular Bi
%V 281
%N 
%P 31753-61
%@ 0021-9258
%X The important cardiovascular regulator renin contains a strong in vitro enhancer 2.7 kb upstream of its gene. Here we tested the in vivo role of the mouse Ren-1c enhancer. In renin-expressing As4.1 cells stably transfected with Ren-1c promoter with or without enhancer, expression of linked beta-geo reporter, stable expression, and colony formation were dependent on the presence of the enhancer. We then generated mice carrying a targeted deletion of the enhancer (REKO mice) and found marked depletion of renin in renal juxtaglomerular and submandibular ductal cells, as well as hyperplasia of macula densa cells. Plasma creatinine was increased, but electrolytes were normal. Male REKO mice implanted with telemetry devices had 9 +/- 1 mm Hg lower mean arterial pressure (p < 0.001), which was partly normalized by a high NaCl diet. Locomotor activity was lower, and baroreflex sensitivity was normal. Markedly reduced mean arterial pressure variability in the midfrequency band indicated a contribution of reduced sympathetic vasomotor tone to the hypotension. In conclusion, the renin enhancer is critical for renin gene expression and physiological sequelae, including response to alteration in salt intake. The REKO mouse may be useful as a low renin expression model.
%Z FOR Codes: 110105 111603


%0 Journal Article
%~ PubMed
%A Boros, Jessica
%A Newitt, Peter
%A Wang, Qian
%A McAvoy, John W
%A Lovicu, Frank J
%T Sef and Sprouty expression in the developing ocular lens: Implications for regulating lens cell proliferation and differentiation.
%B Seminars in cell & developmental biology
%D 2006
%C United Kingdom
%I Academic Press
%V 17
%N 
%P 741-52
%@ 1084-9521
%X In many developmental systems, growth factor signalling must be temporally and spatially regulated, and this is commonly achieved by growth factor antagonists. Here, we describe the expression patterns of newly identified growth factor inhibitors, Sprouty and Sef, in the developing ocular lens. Sprouty and Sef are both expressed in the lens throughout embryogenesis, and become restricted to the lens epithelium, indicating that lens cell proliferation and fibre differentiation may be tightly regulated by such antagonists. Future studies will be aimed at understanding how these negative regulatory molecules modulate growth factor-induced signalling pathways and cellular processes in the lens.
%Z FOR Codes: