SREBP isoform and SREBP target gene expression during rat primary hepatocyte culture.
Expression of mRNA encoding sterol regulatory element binding protein (SREBP) isoforms (SREBP-1a, -1c, -2) and seven SREBP target genes decreased dramatically as a result of isolation and subsequent culture of primary rat hepatocytes. In standard maintenance medium (MM) expression remained low but when cultured in HepatoZYME (HZM), there was a selective increase in mRNA encoding SREBP-2 and a subset of SREBP target genes, a group characterised by promoters containing adjacent sterol regulatory element and nuclear factor Y (NF-Y) binding sequences. Quantification of all three NF-Y transcripts showed that expression of nuclear factor Y alpha subunit and nuclear factor Y beta subunit mRNA increased during culture in HZM (in contrast to the situation with MM) whilst specificity protein 1, liver-x-receptor and hepatocyte nuclear factor-4 alpha mRNA exhibited equivalent decreased expression in both HZM and MM. Our data indicate that HZM exerts a selective preservation of hepatocyte phenotype through actions on NF-Y expression directly or via an effect secondary to actions on SREBP-2 expression. These data add to the molecular dissection of the causes of hepatocyte dedifferentiation during culture and address means to develop approaches to prevent/limit phenotype change.
Wu
Jiakai
J
Faculty of Life Sciences, The University of Manchester, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK. jackywu11@hotmail.com
Dickson
Alan J
AJ
D000818:Animals; D023081:CCAAT-Binding Factor / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D015870:Gene Expression; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism*; D000071518:Liver X Receptors; D008297:Male; D057093:Orphan Nuclear Receptors / Q000378:metabolism; D010641:Phenotype; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051779:Sterol Regulatory Element Binding Proteins / Q000235:genetics / Q000378:metabolism*
D023081:CCAAT-Binding Factor; D051557:Hepatocyte Nuclear Factor 4; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D020033:Protein Isoforms; D016329:Sp1 Transcription Factor; D051779:Sterol Regulatory Element Binding Proteins; C402244:nuclear factor Y