Mutation of mouse Cyp11a1 promoter caused tissue-specific reduction of gene expression and blunted stress response without affecting reproduction.
Steroids are synthesized mainly from the adrenal glands catalyzed by steroidogenic enzymes; the expression of these enzymes is controlled by transcription factor steroidogenic factor-1 (SF-1; NR5A1). To understand the physiological effect of genetic changes on steroid secretion, we used Cre-LoxP and gene targeting technology to mutate the binding sequence for SF-1 (SF-1 response element) on the promoter of the mouse Cyp11a1 gene, which encodes a critical enzyme for steroid biosynthesis. The resulting Cyp11a1 L/L mice expressed about 7-fold less cytochrome P450 side-chain cleavage enzyme (CYP11A1) in the adrenal and testis but expressed normal amounts of CYP11A1 in the placenta and ovary. This tissue-specific reduction of gene expression did not affect basal steroid secretion but attenuated the circadian rhythm of glucocorticoid secretion. These mice also failed to induce glucocorticoid secretion in response to stress, leading to retention of CD4+CD8+ double-positive thymocytes. Unlike complete Cyp11a1 disruption, which causes neonatal death, promoter mutation did not decrease life span and caused no defect in reproduction. Thus, CYP11A1 appears in normal mice to be expressed above the minimal required level, providing a large capacity for use in response to stress. Mutation of the SF-1 response element of Cyp11a1 results in reduced stress response due to decreased adrenal CYP11A1 expression and insufficient stress-induced glucocorticoids secretion.
Shih
Meng-Chun
MC
Institute of Molecular Biology, 48, Academia Sinica, Nankang, Taipei 115, Taiwan.
Hsu
Nai-Chi
NC
Huang
Chen-Che
CC
Wu
Tzong-Shoon
TS
Lai
Pao-Yen
PY
Chung
Bon-Chu
BC
D000311:Adrenal Glands / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D000312:Adrenal Hyperplasia, Congenital / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000235:genetics* / Q000378:metabolism; D002940:Circadian Rhythm; D003345:Corticosterone / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005298:Fertility / Q000235:genetics; D005434:Flow Cytometry; D015870:Gene Expression; D008136:Longevity / Q000235:genetics; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008854:Microscopy, Electron; D009154:Mutation; D010053:Ovary / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012098:Reproduction / Q000235:genetics; D054339:Steroidogenic Factor 1 / Q000378:metabolism; D013737:Testis / Q000378:metabolism*
D054339:Steroidogenic Factor 1; D002786:Cholesterol Side-Chain Cleavage Enzyme; D003345:Corticosterone