Conditional enhancement of liver-specific gene transcription.
We sought to develop a cell line in which liver-specific transcription could be induced at will, to facilitate the study of factors that cause hepatocyte-specific transcription of the serum albumin gene in mice. We therefore created the H2.35 cell line from mouse hepatocytes infected with a temperature-sensitive strain of simian virus 40. During routine propagation at the permissive temperature, H2.35 cells exhibit extremely low levels of albumin transcription and mRNA. Albumin mRNA increases at least 100-fold when H2.35 cells are cultured at the restrictive temperature and in serum-free medium on a collagen substratum; the two latter conditions maintain the differentiated state of primary hepatocyte cultures. Although a major cause of the mRNA increase is posttranscriptional, the transcription rates of albumin and other liver-specific genes increase significantly. Transient-transfection experiments demonstrated that an induction of transcription is caused by activation of an albumin upstream sequence that was previously shown to enhance liver-specific transcription in transgenic mice. Thus, hepatocyte differentiation appears to be maintained in part by extracellular signals that stimulate the activity of a tissue-specific enhancer element.
Zaret
K S
KS
Section of Biochemistry, Brown University, Providence, RI 02912.
DiPersio
C M
CM
Jackson
D A
DA
Montigny
W J
WJ
Weinstat
D L
DL
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002999:Clone Cells; D004742:Enhancer Elements, Genetic; D005260:Female; D005786:Gene Expression Regulation; D005796:Genes; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D012709:Serum Albumin / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection
D012333:RNA, Messenger; D011994:Recombinant Proteins; D012709:Serum Albumin