RPGRIP1L is required for stabilizing epidermal keratinocyte adhesion through regulating desmoglein endocytosis

• Authors: Yeon Ja Choi, SUNY Stony Brook; Christine Laclef, Sorbonne Universite; Ning Yang, SUNY Stony Brook; Abraham Andreu-Cervera, Sorbonne Universite; Joshua Lewis, Emory University; Xuming Mao, University of Pennsylvania; Li Li, Peking Union Medical College Hospital; Elizabeth R. Snedecor, SUNY Stony Brook; Ken-Ichi Takemaru, SUNY Stony Brook; Chuan Qin, Chinese Academy of Medical Sciences; Sylvie Schneider-Maunoury, Sorbonne Universite; Kenneth R. Shroyer, SUNY Stony Brook; Yusuf A. Hannun, SUNY Stony Brook; Peter J. Koch, University of Colorado; Richard A. Clark, SUNY Stony Brook; Aimee S. Payne, University of Pennsylvania; Andrew Kowalczyk, Emory University; Jiang Chen, SUNY Stony Brook
• Journal Title: PLoS Genetics
• Volume: Volume 15, Number 1
• Publisher: Public Library of Science | 2019-01-01, Pages e1007914-e1007914
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1371/journal.pgen.1007914
• Subjects: Health Sciences, Pathology; Biology, Cell; Health Sciences, Pharmacology
• Keywords: Science & Technology; Life Sciences & Biomedicine; Genetics & Heredity; BASAL BODY PROTEIN; DESMOSOMAL ADHESION; GENE RPGRIP1L; PRIMARY CILIA; PKC-ALPHA; HAIR; SKIN; NEPHROCYSTIN-4; COHESION; DIFFERENTIATION

Abstract

Cilia-related proteins are believed to be involved in a broad range of cellular processes. Retinitis pigmentosa GTPase regulator interacting protein 1-like (RPGRIP1L) is a ciliary protein required for ciliogenesis in many cell types, including epidermal keratinocytes. Here we report that RPGRIP1L is also involved in the maintenance of desmosomal junctions between keratinocytes. Genetically disrupting the Rpgrip1l gene in mice caused intraepidermal blistering, primarily between basal and suprabasal keratinocytes. This blistering phenotype was associated with aberrant expression patterns of desmosomal proteins, impaired desmosome ultrastructure, and compromised cell-cell adhesion in vivo and in vitro. We found that disrupting the RPGRIP1L gene in HaCaT cells, which do not form primary cilia, resulted in mislocalization of desmosomal proteins to the cytoplasm, suggesting a cilia-independent function of RPGRIP1L. Mechanistically, we found that RPGRIP1L regulates the endocytosis of desmogleins such that RPGRIP1L-knockdown not only induced spontaneous desmoglein endocytosis, as determined by AK23 labeling and biotinylation assays, but also exacerbated EGTA- or pemphigus vulgaris IgG-induced desmoglein endocytosis. Accordingly, inhibiting endocytosis with dynasore or sucrose rescued these desmosomal phenotypes. Biotinylation assays on cell surface proteins not only reinforced the role of RPGRIP1L in desmoglein endocytosis, but also suggested that RPGRIP1L may be more broadly involved in endocytosis. Thus, data obtained from this study advanced our understanding of the biological functions of RPGRIP1L by identifying its role in the cellular endocytic pathway.