scholarly journals Transcriptomic analysis and novel insights into lens fibre cell differentiation regulated by Gata3

Open Biology ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 190220
Author(s):  
Elena Martynova ◽  
Yilin Zhao ◽  
Qing Xie ◽  
Deyou Zheng ◽  
Ales Cvekl
Keyword(s):  
Cell Differentiation ◽  
Transcriptional Control ◽  
Kinase Inhibitors ◽  
Neuroendocrine Cells ◽  
Intermediate Filament Protein ◽  
Loss Of Function ◽  
Fibre Cell ◽  
Lens Fibre ◽  
Lens Fibre Cell

Gata3 is a DNA-binding transcription factor involved in cellular differentiation in a variety of tissues including inner ear, hair follicle, kidney, mammary gland and T-cells. In a previous study in 2009, Maeda et al . ( Dev. Dyn. 238 , 2280–2291; doi:10.1002/dvdy.22035 ) found that Gata3 mutants could be rescued from midgestational lethality by the expression of a Gata3 transgene in sympathoadrenal neuroendocrine cells. The rescued embryos clearly showed multiple defects in lens fibre cell differentiation. To determine whether these defects were truly due to the loss of Gata3 expression in the lens, we generated a lens-specific Gata3 loss-of-function model. Analogous to the previous findings, our Gata3 null embryos showed abnormal regulation of cell cycle exit during lens fibre cell differentiation, marked by reduction in the expression of the cyclin-dependent kinase inhibitors Cdkn1b/p27 and Cdkn1c/p57, and the retention of nuclei accompanied by downregulation of Dnase IIβ. Comparisons of transcriptomes between control and mutated lenses by RNA-Seq revealed dysregulation of lens-specific crystallin genes and intermediate filament protein Bfsp2. Both Cdkn1b/p27 and Cdkn1c/p57 loci are occupied in vivo by Gata3, as well as Prox1 and c-Jun, in lens chromatin. Collectively, our studies suggest that Gata3 regulates lens differentiation through the direct regulation of the Cdkn1b/p27and Cdkn1c/p57 expression, and the direct/or indirect transcriptional control of Bfsp2 and Dnase IIβ.

scholarly journals Vimentin and CP49/filensin form distinct networks in the lens which are independently modulated during lens fibre cell differentiation

1995 ◽  
Vol 108 (4) ◽  
pp. 1397-1406 ◽  
Author(s):  
A. Sandilands ◽  
A.R. Prescott ◽  
J.M. Carter ◽  
A.M. Hutcheson ◽  
R.A. Quinlan ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Epithelial Cells ◽  
Confocal Microscopy ◽  
Intermediate Filament ◽  
Nuclear Lamina ◽  
Intermediate Filament Protein ◽  
Intermediate Filament Proteins ◽  
Fibre Cell ◽  
Lens Fibre ◽  
Lens Fibre Cell

The cells of the eye lens contain the type III intermediate filament protein vimentin, as well as two other intermediate filament proteins, CP49 and filensin. These two proteins appear to be unique to the differentiated lens fibre cell. Immunoblotting and confocal microscopy were used to describe changes which occur in these three intermediate filament proteins and the networks they form during fibre cell differentiation and maturation. The vimentin network was present in both epithelial cells and some fibre cells. Fibre cells were vimentin positive up to a specific point 2–3 mm in from the lens capsule where the vimentin signal was drastically reduced. The CP49/filensin network was not present in the undifferentiated epithelial cells but emerged in the differentiating fibre cells. This latter network exhibited a principally plasma membrane localization in younger fibre cells but became more cytoplasmic in older fibre cells. This change also occurred at a distinct point in fibre cell differentiation, much earlier than the observed loss of the vimentin network. The subcellular changes in the distributions of these cytoskeletal networks were correlated to the loss of the fibre cell nucleus, another feature of fibre cell differentiation. No correlation was found to changes in the vimentin network but nuclear loss did coincide with changes in the CP49/filensin network. Concomitant with nuclear pyknosis, there were also changes in the nuclear lamina as well as infringement of the nuclear compartment by CP49, as shown by confocal microscopy. This study demonstrates vimentin and the CP49/filensin network to be independent in the lens but both networks undergo dramatic changes in subcellular distribution during the differentiation/maturation of the fibre cell. Only changes in the CP49/filensin network can be correlated to nuclear loss. Thus in the lens, unlike mammalian erythropoiesis which is also characterized by nuclear loss, the vimentin network does not appear linked to nuclear retention.

scholarly journals Lens fibre cell differentiation and organelle loss: many paths lead to clarity

2011 ◽  
Vol 366 (1568) ◽  
pp. 1219-1233 ◽  
Author(s):  
Michael A. Wride
Keyword(s):  
Cell Differentiation ◽  
Proteolytic Enzymes ◽  
Specific Gene ◽  
Fibre Cell ◽  
Free Zone ◽  
Lens Fibre ◽  
Evolutionary Context ◽  
Lens Fibre Cell ◽  
Ubiquitin Proteasome ◽  
Interacting Networks

The programmed removal of organelles from differentiating lens fibre cells contributes towards lens transparency through formation of an organelle-free zone (OFZ). Disruptions in OFZ formation are accompanied by the persistence of organelles in lens fibre cells and can contribute towards cataract. A great deal of work has gone into elucidating the nature of the mechanisms and signalling pathways involved. It is apparent that multiple, parallel and redundant pathways are involved in this process and that these pathways form interacting networks. Furthermore, it is possible that the pathways can functionally compensate for each other, for example in mouse knockout studies. This makes sense given the importance of lens clarity in an evolutionary context. Apoptosis signalling and proteolytic pathways have been implicated in both lens fibre cell differentiation and organelle loss, including the Bcl-2 and inhibitor of apoptosis families, tumour necrosis factors, p53 and its regulators (such as Mdm2) and proteolytic enzymes, including caspases, cathepsins, calpains and the ubiquitin–proteasome pathway. Ongoing approaches being used to dissect the molecular pathways involved, such as transgenics, lens-specific gene deletion and zebrafish mutants, are discussed here. Finally, some of the remaining unresolved issues and potential areas for future studies are highlighted.

SCL-mediated regulation of the cell-cycle regulator p21 is critical for murine megakaryopoiesis

Blood ◽  
2011 ◽  
Vol 118 (3) ◽  
pp. 723-735 ◽  
Author(s):  
Hedia Chagraoui ◽  
Mira Kassouf ◽  
Sreemoti Banerjee ◽  
Nicolas Goardon ◽  
Kevin Clark ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcriptional Control ◽  
Cell Cycle Progression ◽  
Cellular Proliferation ◽  
Loss Of Function ◽  
Cycle Progression ◽  
Cell Cycle Regulator ◽  
Nuclear Changes ◽  
Cytoplasmic Maturation

Abstract Megakaryopoiesis is a complex process that involves major cellular and nuclear changes and relies on controlled coordination of cellular proliferation and differentiation. These mechanisms are orchestrated in part by transcriptional regulators. The key hematopoietic transcription factor stem cell leukemia (SCL)/TAL1 is required in early hematopoietic progenitors for specification of the megakaryocytic lineage. These early functions have, so far, prevented full investigation of its role in megakaryocyte development in loss-of-function studies. Here, we report that SCL critically controls terminal megakaryocyte maturation. In vivo deletion of Scl specifically in the megakaryocytic lineage affects all key attributes of megakaryocyte progenitors (MkPs), namely, proliferation, ploidization, cytoplasmic maturation, and platelet release. Genome-wide expression analysis reveals increased expression of the cell-cycle regulator p21 in Scl-deleted MkPs. Importantly, p21 knockdown-mediated rescue of Scl-mutant MkPs shows full restoration of cell-cycle progression and partial rescue of the nuclear and cytoplasmic maturation defects. Therefore, SCL-mediated transcriptional control of p21 is essential for terminal maturation of MkPs. Our study provides a mechanistic link between a major hematopoietic transcriptional regulator, cell-cycle progression, and megakaryocytic differentiation.

scholarly journals Macroautophagy is dispensable for growth of KRAS mutant tumors and chloroquine efficacy

2015 ◽  
Vol 113 (1) ◽  
pp. 182-187 ◽  
Author(s):  
Christina H. Eng ◽  
Zuncai Wang ◽  
Diane Tkach ◽  
Lourdes Toral-Barza ◽  
Savuth Ugwonali ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Kinase Inhibitors ◽  
Cell Types ◽  
Loss Of Function ◽  
Growth And Survival ◽  
Oncogenic Mutations ◽  
Cellular Context ◽  
Genetic Stratification

Macroautophagy is a key stress-response pathway that can suppress or promote tumorigenesis depending on the cellular context. Notably, Kirsten rat sarcoma (KRAS)-driven tumors have been reported to rely on macroautophagy for growth and survival, suggesting a potential therapeutic approach of using autophagy inhibitors based on genetic stratification. In this study, we evaluated whether KRAS mutation status can predict the efficacy to macroautophagy inhibition. By profiling 47 cell lines with pharmacological and genetic loss-of-function tools, we were unable to confirm that KRAS-driven tumor lines require macroautophagy for growth. Deletion of autophagy-related 7 (ATG7) by genome editing completely blocked macroautophagy in several tumor lines with oncogenic mutations in KRAS but did not inhibit cell proliferation in vitro or tumorigenesis in vivo. Furthermore, ATG7 knockout did not sensitize cells to irradiation or to several anticancer agents tested. Interestingly, ATG7-deficient and -proficient cells were equally sensitive to the antiproliferative effect of chloroquine, a lysosomotropic agent often used as a pharmacological tool to evaluate the response to macroautophagy inhibition. Moreover, both cell types manifested synergistic growth inhibition when treated with chloroquine plus the tyrosine kinase inhibitors erlotinib or sunitinib, suggesting that the antiproliferative effects of chloroquine are independent of its suppressive actions on autophagy.

Bfsp2 mutation found in mouse 129 strains causes the loss of CP49 and induces vimentin-dependent changes in the lens fibre cell cytoskeleton

2004 ◽  
Vol 78 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Aileen Sandilands ◽  
Xin Wang ◽  
Aileen M Hutcheson ◽  
John James ◽  
Alan R Prescott ◽  
...  
Keyword(s):  
Fibre Cell ◽  
Cell Cytoskeleton ◽  
Lens Fibre ◽  
Lens Fibre Cell
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