HCaRG is a novel regulator of renal epithelial cell growth and differentiation causing G2M arrest.
We recently identified a novel calcium-regulated gene, HCaRG, that is highly expressed in the kidney and maps to a chromosomal locus determining kidney weight in rats. The mRNA levels of HCaRG negatively correlate with the proliferative status of the kidney cells. To investigate its role in renal epithelial cellular growth directly, we studied the human embryonic kidney cell line (HEK-293) stably transfected with either plasmid alone or plasmid containing rat HCaRG. [(3)H]thymidine incorporation was significantly lower in HCaRG clones. Although HCaRG clones exhibited some enhanced susceptibility to cell death, this was not the primary mechanism of reduced proliferation. Cell cycle analysis revealed a G(2)M phase accumulation in HCaRG clones that was associated with upregulation of p21(Cip1/WAF1) and downregulation of p27(Kip1). HCaRG clones had a greater protein content, larger cell size, and released 4.5- to 8-fold more of an atrial natriuretic peptide-like immunoreactivity compared with controls. In addition, HCaRG clones demonstrated the presence of differentiated junctions and a lower incidence of mitotic figures. Genistein treatment of wild-type HEK-293 cells mimicked several phenotypic characteristics associated with HCaRG overexpresssion, including increased cell size and increased release of atrial natriuretic peptide. Taken together, our results suggest that HCaRG is a regulator of renal epithelial cell growth and differentiation causing G(2)M cell cycle arrest.
Devlin
Alison M
AM
Laboratory of Cellular Biology of Hypertension, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, University of Montreal, Montreal, Quebec, Canada.
Solban
Nicolas
N
Tremblay
Sandra
S
Gutkowska
Jolanta
J
Schürch
Walter
W
Orlov
Sergei N
SN
Lewanczuk
Richard
R
Hamet
Pavel
P
Tremblay
Johanne
J
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D002999:Clone Cells; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016195:G2 Phase / Q000187:drug effects / Q000502:physiology; D020869:Gene Expression Profiling; D006801:Humans; D007668:Kidney / Q000166:cytology*; D008938:Mitosis / Q000187:drug effects / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C493956:CDKN1A protein, human; C485926:COMMD5 protein, human; C493958:Cdkn1a protein, rat; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; C415469:Commd5 protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D009320:Atrial Natriuretic Factor