Regulatory elements that mediate expression of the gene for the angiotensin II type 1a receptor for the rat.
To analyze the mechanism of the cell type-specific expression of rat angiotensin II type 1a receptor (AT1a-R) gene, we isolated the 5'-portion of the gene and identified multiple positive and negative regulatory sequences that regulate its transcription. Primer extension and S1 mapping identified a transcriptional initiation site at 33 (position +1) base pairs (bp) downstream of TATA sequence. The transcriptional activities of various 5'-deletion mutants of the AT1a-R gene upstream region, fused to the chloramphenicol acetyltransferase (CAT) gene, were examined using rat vascular smooth muscle cells (A10) and glial cells expressing AT1a-R mRNA predominantly or PC12 cells expressing AT2-R and very small amounts of AT1a-R mRNA. A 980-bp 5'-flanking sequence contained at least three positive elements, P1 (-560 to -489), P2 (-331 to -201), and P3 (-201 to -61). P1 and P3 were active in the tested three cells, and P2 was functional only in glial and PC12 cells. In addition to these positive elements, there was negative element, N1 (-489 to -331), which was active only in PC12 cells. These elements, when cotransfected with the AT1a-CAT fusion gene, had competitive effects against its promoter activity. The present study suggests the presence of multiple trans-acting factors that act on these positive and negative cis-acting elements and regulate the cell type-specific expression of the rat AT1a-R gene.
Murasawa
S
S
Second Department of Internal Medicine, Kansai Medical University, Osaka, Japan.
Matsubara
H
H
Urakami
M
M
Inada
M
M
D000818:Animals; D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D018076:DNA, Complementary; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D016716:PC12 Cells; D051381:Rats; D011945:Receptors, Angiotensin / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection
D018076:DNA, Complementary; D011945:Receptors, Angiotensin; D015500:Chloramphenicol O-Acetyltransferase