In vivo interaction of the adapter protein CD2-associated protein with the type 2 polycystic kidney disease protein, polycystin-2.
We identified a developmentally regulated gene from mouse kidney whose expression is up-regulated in metanephrogenic mesenchyme cells when they are induced to differentiate to epithelial cells during kidney organogenesis. The deduced 70.5-kDa protein, originally named METS-1 (mesenchyme-to-epithelium transition protein with SH3 domains), has since been cloned as a CD2-associated protein (CD2AP). CD2AP is strongly expressed in glomerular podocytes, and the absence of CD2AP in mice results in congenital nephrotic syndrome. We have found that METS-1/CD2AP (hereafter referred to as CD2AP) is expressed at lower levels in renal tubular epithelial cells in the adult kidney, particularly in distal nephron segments. Independent yeast two-hybrid screens using the COOH-terminal region of either CD2AP or polycystin-2 as bait identified the COOH termini of polycystin-2 and CD2AP, respectively, as strong interacting partners. This interaction was confirmed in cultured cells by co-immunoprecipitation of endogenous polycystin-2 with endogenous CD2AP and vice versa. CD2AP shows a diffuse reticular cytoplasmic and perinuclear pattern of distribution, similar to polycystin-2, in cultured cells, and the two proteins co-localize by indirect double immunofluorescence microscopy. CD2AP is an adapter molecule that associates with a variety of membrane proteins to organize the cytoskeleton around a polarized site. Such a function fits well with that hypothesized for the polycystin proteins in renal tubular epithelial cells, and the present findings suggest that CD2AP has a role in polycystin-2 function.
Lehtonen
S
S
Department of Pathology, Haartman Institute, University of Helsinki, P. O. Box 21, FIN-00014 Helsinki, Finland.
Ora
A
A
Olkkonen
V M
VM
Geng
L
L
Zerial
M
M
Somlo
S
S
Lehtonen
E
E
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D018507:Gene Expression Regulation, Developmental; D007668:Kidney / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009399:Nephrons / Q000378:metabolism; D016366:Open Reading Frames; D007690:Polycystic Kidney Diseases / Q000235:genetics; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D050396:TRPP Cation Channels; D014162:Transfection; D019459:Urothelium / Q000378:metabolism; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D011506:Proteins; D011994:Recombinant Proteins; D050396:TRPP Cation Channels; C114545:CD2-associated protein