Cell-cell contact regulates gene expression in CDK4-transformed mouse podocytes.
We transformed mouse podocytes by ectopic expression of cyclin-dependent kinase 4 (CDK4). Compared with podocytes transformed with a thermo-sensitive SV40 large T antigen mutant tsA58U19 (tsT podocytes), podocytes transformed with CDK4 (CDK4 podocytes) exhibited significantly higher expression of nephrin mRNA. Synaptopodin mRNA expression was significantly lower in CDK4 podocytes and in tsT podocytes under growth-permissive conditions (33°C) compared with tsT podocytes under growth-restricted conditions (37°C), which suggests a role for cell cycle arrest in synaptopodin mRNA expression. Confluent CDK4 podocytes showed significantly higher mRNA expression levels for nephrin, synaptopodin, Wilms tumor 1, podocalyxin, and P-cadherin compared with subconfluent cultures. We carried out experiments to clarify roles of various factors in the confluent podocyte cultures; our findings indicate that cell-cell contact promotes expression of five podocyte marker genes studied, that cellular quiescence increases synaptopodin and podocalyxin mRNA expression, and that soluble factors play a role in nephrin mRNA expression. Our findings suggest that CDK4 podocytes are useful tools to study podocyte biology. Furthermore, the role of cell-cell contact in podocyte gene expression may have relevance for podocyte function in vivo.
Sakairi
Toru
T
Kidney Disease Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA.
Abe
Yoshifusa
Y
Jat
Parmijit S
PS
Kopp
Jeffrey B
JB
D000199:Actins / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology*; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D051358:Cyclin-Dependent Kinase 4 / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D008840:Microfilament Proteins / Q000378:metabolism; D023421:Models, Animal; D009687:Nuclear Proteins / Q000378:metabolism; D050199:Podocytes / Q000166:cytology / Q000378:metabolism*; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism
D000199:Actins; D015820:Cadherins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; C503968:Synpo protein, mouse; C486008:Wtap protein, mouse; C113267:nephrin; C001643:podocalyxin; D051358:Cyclin-Dependent Kinase 4