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Possible role of c-Jun in transcription of the mouse renin gene
1Department of Internal Medicine II, Yokohama City University School of Medicine, Japan. tamukou@yellow.med.yokohama-cu.ac.jp
Background:
Renin is a rate-limiting enzyme for activity of the circulating renin-angiotensin system (RAS) and expression of the renin gene is regulated by a variety of stimuli. In this study, we examined a possible role of c-Jun in the transcription of renin gene.
Methods:
The renin promoter, chloramphenicol acetyltransferase (CAT), fusion genes with or without c-Jun expression vector (pSV-c-Jun) were transfected into human embryonic kidney (HEK) cells, and the effects of c-Jun were examined by deletion and mutation analyses of CAT assay and by in vitro transcription-primer extension assay. We also examined the effects of c-Jun on DNA-binding activity to the renin promoter by electrophoretic mobility shift assay (EMSA). Furthermore, we examined the effects of c-Jun on transcription of the renin gene in enriched juxtaglomerular (JG) cells by cotransfection with pSV-c-Jun and by treatment with antisense c-jun oligodeoxynucleotides.
Results:
Promoter activity of the renin gene was increased by c-Jun overexpression in HEK cells, and the proximal promoter region from -47 to +16 was sufficient for transcriptional activation by c-Jun. Although mutation of activator protein-1 (AP-1) element-like sequences in the proximal promoter did not affect c-Jun-mediated stimulation, mutation of the core promoter including the TATA box inhibited c-Jun-mediated transcription. The results of EMSA showed that c-Jun overexpression produced a binding of nuclear factor, which was HEK cell-specific and distinct from TATA box-binding protein and AP-1 family transcription factor, to the renin core promoter region (RC element) from -36 to -20. The overexpression of c-Jun activated the renin promoter in renin-expressing JG cells, and antisense c-jun decreased the activity of renin promoter and expression of renin mRNA in JG cells.
Conclusions:
These results indicate that the RC element plays a role in c-Jun-mediated transcriptional regulation of the renin gene in HEK cells, and suggest that c-Jun participates in the regulation of renin gene expression in JG cells of the kidney.
Insights
The transcription factor c-Jun enhances renin gene expression by binding to a specific region in the renin promoter. This finding suggests c-Jun plays a role in regulating renin levels in kidney cells.
Area of Science:
- Molecular Biology
- Genetics
- Physiology
Background:
- Renin is a key enzyme in the renin-angiotensin system (RAS).
- Renin gene expression is influenced by various stimuli.
- The role of c-Jun in renin gene transcription was investigated.
Purpose of the Study:
- To determine if c-Jun influences renin gene transcription.
- To identify the specific region of the renin gene promoter involved in c-Jun's action.
- To explore c-Jun's role in renin-expressing kidney cells.
Main Methods:
- Transfection of human embryonic kidney (HEK) cells with renin promoter-reporter constructs and c-Jun expression vectors.
- Deletion and mutation analyses of the renin promoter.
- Electrophoretic mobility shift assay (EMSA) to assess DNA-binding activity.
- In vitro transcription-primer extension assays.
- Cotransfection and antisense oligodeoxynucleotide treatment in juxtaglomerular (JG) cells.
Main Results:
- c-Jun overexpression increased renin gene promoter activity in HEK cells.
- A core promoter region (RC element, -36 to -20) was identified as crucial for c-Jun-mediated activation.
- c-Jun binding to the RC element was cell-specific and distinct from known transcription factors.
- c-Jun activated the renin promoter in JG cells, and its inhibition reduced renin gene expression.
Conclusions:
- The RC element is critical for c-Jun-mediated transcriptional regulation of the renin gene.
- c-Jun is implicated in the regulation of renin gene expression within kidney JG cells.