Rho-family small GTPases are involved in forskolin-induced cell-cell contact formation of renal glomerular podocytes in vitro.
Intercellular adhesions between renal glomerular epithelial cells (also called podocytes) are necessary for the proper function of the glomerular filtration barrier. Although our knowledge of the molecular composition of podocyte cell-cell contact sites has greatly progressed, the underlying molecular mechanism regulating the formation of these cell-cell contacts remains largely unknown. We have used forskolin, an activator of adenylyl cyclase that elevates the level of intracellular cAMP, to investigate the effect of cAMP and three Rho-family small GTPases (RhoA, Cdc42, and Rac1) on the regulation of cell-cell contact formation in a murine podocyte cell line. Transmission electron microscopy and the immunostaining of cell adhesion molecules and actin-associated proteins have revealed a structural change at the site of cell-cell contact following forskolin treatment. The activity of the Rho-family small GTPases before and after forskolin treatment has been evaluated with a glutathione-S-transferase pull-down assay. Forskolin reinforces the integrity of cell-cell contacts, resulting in the closure of an intercellular adhesion zipper, accompanied by a redistribution of cell adhesion molecules and actin-associated proteins in a continuous linear pattern at cell-cell contacts. The Rho-family small GTPases Rac1 and Cdc42 are activated during closure of the adhesion zipper, whereas RhoA is suppressed. Thus, cAMP promotes the assembly of cell-cell contacts between podocytes via a mechanism that probably involves Rho-family small GTPases.
Gao
Shuang-Yan
SY
Department of Anatomy and Embryology, School of Medicine, Ehime University, To-on City, Ehime, Japan.
Li
Chun-Yu
CY
Shimokawa
Tetsuya
T
Terashita
Takehiro
T
Matsuda
Seiji
S
Yaoita
Eishin
E
Kobayashi
Naoto
N
D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000187:drug effects; D000577:Amides / Q000494:pharmacology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002450:Cell Communication / Q000187:drug effects*; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology*; D005110:Extracellular Space / Q000187:drug effects; D007678:Kidney Glomerulus / Q000166:cytology* / Q000187:drug effects* / Q000648:ultrastructure; D051379:Mice; D050199:Podocytes / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D011725:Pyridines / Q000494:pharmacology; D053778:Thiazolidines / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000199:Actins; D000577:Amides; D019086:Bridged Bicyclo Compounds, Heterocyclic; D015815:Cell Adhesion Molecules; D011725:Pyridines; D053778:Thiazolidines; C108830:Y 27632; D005576:Colforsin; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C037067:latrunculin A