title: The zinc sensing receptor, ZnR/GPR39, controls proliferation and differentiation of colonocytes and thereby tight junction formation in the colon.
abstract: The intestinal epithelium is a renewable tissue that requires precise balance between proliferation and differentiation, an essential process for the formation of a tightly sealed barrier. Zinc deficiency impairs the integrity of the intestinal epithelial barrier and is associated with ulcerative and diarrheal pathologies, but the mechanisms underlying the role of Zn(2+) are not well understood. Here, we determined a role of the colonocytic Zn(2+) sensing receptor, ZnR/GPR39, in mediating Zn(2+)-dependent signaling and regulating the proliferation and differentiation of colonocytes. Silencing of ZnR/GPR39 expression attenuated Zn(2+)-dependent activation of ERK1/2 and AKT as well as downstream activation of mTOR/p70S6K, pathways that are linked with proliferation. Consistently, ZnR/GPR39 silencing inhibited HT29 and Caco-2 colonocyte proliferation, while not inducing caspase-3 cleavage. Remarkably, in differentiating HT29 colonocytes, silencing of ZnR/GPR39 expression inhibited alkaline phosphatase activity, a marker of differentiation. Furthermore, Caco-2 colonocytes showed elevated expression of ZnR/GPR39 during differentiation, whereas silencing of ZnR/GPR39 decreased monolayer transepithelial electrical resistance, suggesting compromised barrier formation. Indeed, silencing of ZnR/GPR39 or chelation of Zn(2+) by the cell impermeable chelator CaEDTA was followed by impaired expression of the junctional proteins, that is, occludin, zonula-1 (ZO-1) and E-cadherin. Importantly, colon tissues of GPR39 knockout mice also showed a decrease in expression levels of ZO-1 and occludin compared with wildtype mice. Altogether, our results indicate that ZnR/GPR39 has a dual role in promoting proliferation of colonocytes and in controlling their differentiation. The latter is followed by ZnR/GPR39-dependent expression of tight junctional proteins, thereby leading to formation of a sealed intestinal epithelial barrier. Thus, ZnR/GPR39 may be a therapeutic target for promoting epithelial function and tight junction barrier integrity during ulcerative colon diseases.
authors: Department of Physiology and Cell Biology, Faculty of Health Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: L
authors: L
authors: Cohen
authors: Department of Physiology and Cell Biology, Faculty of Health Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: I
authors: I
authors: Sekler
authors: Department of Physiology and Cell Biology, Faculty of Health Science, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors: M
authors: M
authors: Hershfinkel
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation / Q000502:physiology*; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D062793:Occludin / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis* / Q000235:genetics; D015032:Zinc / Q000378:metabolism; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C495797:GPR39 protein, human; C512928:GPR39 protein, mouse; C568985:OCLN protein, human; D062793:Occludin; C568986:Ocln protein, mouse; D043562:Receptors, G-Protein-Coupled; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D051057:Proto-Oncogene Proteins c-akt; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D015032:Zinc