title: The calcium-sensing receptor-dependent regulation of cell-cell adhesion and keratinocyte differentiation requires Rho and filamin A.
abstract: Extracellular Ca(2+) (Ca(2+)(o)) functioning through the calcium-sensing receptor (CaR) induces E-cadherin-mediated cell-cell adhesion and cellular signals mediating cell differentiation in epidermal keratinocytes. Previous studies indicate that CaR regulates cell-cell adhesion through Fyn/Src tyrosine kinases. In this study, we investigate whether Rho GTPase is a part of the CaR-mediated signaling cascade regulating cell adhesion and differentiation. Suppressing endogenous Rho A expression by small interfering RNA (siRNA)-mediated gene silencing blocked the Ca(2+)(o)-induced association of Fyn with E-cadherin and suppressed the Ca(2+)(o)-induced tyrosine phosphorylation of β-, γ-, and p120-catenin and formation of intercellular adherens junctions. Rho A silencing also decreased the Ca(2+)(o)-stimulated expression of terminal differentiation markers. Elevating the Ca(2+)(o) level induced interactions among CaR, Rho A, E-cadherin, and the scaffolding protein filamin A at the cell membrane. Inactivation of CaR expression by adenoviral expression of a CaR antisense complementary DNA inhibited Ca(2+)(o)-induced activation of endogenous Rho. Ca(2+)(o) activation of Rho required a direct interaction between CaR and filamin A. Interference of CaR-filamin interaction inhibited Ca(2+)(o)-induced Rho activation and the formation of cell-cell junctions. These results indicate that Rho is a downstream mediator of CaR in the regulation of Ca(2+)(o)-induced E-cadherin-mediated cell-cell adhesion and keratinocyte differentiation.
authors.affiliation: Endocrine Unit, Veteran Affairs Medical Center and University of California, San Francisco, California 94121, USA. chia-ling.tu@ucsf.edu
authors.forename: Chia-Ling
authors.initials: CL
authors.lastname: Tu
authors.forename: Wenhan
authors.initials: W
authors.lastname: Chang
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Bikle
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D051177:Catenins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000378:metabolism / Q000502:physiology*; D004817:Epidermis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D064448:Filamins; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D044169:Receptors, Calcium-Sensing / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D015820:Cadherins; D051177:Catenins; D003285:Contractile Proteins; D064448:Filamins; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; D044169:Receptors, Calcium-Sensing; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases; D020741:rho GTP-Binding Proteins