June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
CRB2 is involved in the apicobasal polarization of RPE cells by participating in tight junction maintenance and cell cycle arrest
Author Affiliations & Notes
  • Concepcion Lillo
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Alicia Segurado
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Vicente Valle
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Jorge Fernández-Dolon
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Almudena Velasco
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Henar Albertos
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Antonio E Paniagua
    Cell Biology and Pathology, Institute of Neurosciences of Castilla and León, IBSAL, University of Salamanca, Salamanca, Spain
  • Footnotes
    Commercial Relationships   Concepcion Lillo, None; Alicia Segurado, None; Vicente Valle, None; Jorge Fernández-Dolon, None; Almudena Velasco, None; Henar Albertos, None; Antonio Paniagua, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 1042. doi:
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      Concepcion Lillo, Alicia Segurado, Vicente Valle, Jorge Fernández-Dolon, Almudena Velasco, Henar Albertos, Antonio E Paniagua; CRB2 is involved in the apicobasal polarization of RPE cells by participating in tight junction maintenance and cell cycle arrest. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1042.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Apicobasal polarity is essential for epithelial cell function and it is determined by the expression of three polarity protein complexes named Scribble, Par and Crumbs complexes. Scribble complex has been shown to promote basolateral membrane identity while both the Par and the Crumbs complex, promote apical membrane identity. The Crumbs complex is typically composed by PALS1, PATJ and the Crumbs homologs (CRB) proteins. We have recently described the expression of one of these Crumbs proteins named CRB2 in the RPE cells. To better understand this highly regulated process, we have studied the role of the polarity protein, CRB2, in human retinal pigment epithelial (RPE) cells during differentiation in vitro.

Methods : To achieve this goal, we have studied the temporal sequence of the establishment of the polarity proteins during human fetal RPE cells polarization. We have then knockdown CRB2 in cultured RPE cells and analyzed their proliferation rate, expression and localization of proteins related with the establishment of junctional complexes and those involved in the acquisition of apicobasal polarization compared to the control RPE cultures. We have finally measured the transepithelial electrical resistance (TER), a direct measure of the strength of the cell-cell junctions, during ordinary differentiation and after a severe disruption of junctional complexes with an acute depletion of Ca2+ (calcium switch assay).

Results : We have found that CRB2 is the latest of the entire pull of polarity proteins to be positioned at the cell membrane. Subsequently, the absence of the CRB2 protein from these cells results in a delay in the formation of cell-cell junctions and in an increase in cell proliferation in human RPE cells.

Conclusions : Here, we demonstrate that, in differentiating cultures of RPE cells, CRB2 functions in a late stage in the formation of the junctional complex and apicobasal polarity. Additionally, CRB2 knockdown causes a significant increase in cellular proliferation at the time point when this protein reaches the plasma membrane.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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