| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Acetoacetyl-CoA synthetase (AACS, EC 6.2.1.16) is a novel ketone body-utilizing enzyme, the physiological role of which is regarded to be different from that of CoA transferase. In order to identify the regulatory region of AACS gene, several deletion constructs were fused to luciferase gene and expressed in 3T3-L1 cells. By the deletion of the bases -335 to -3,promoter activity was essentially abolished. Furthermore, point mutation study revealed that GC-box motif (-87 to -74) and C/EBP family recognition sequence (-196 to -183) were important cis-regulatory elements. Since our previous studies revealed that AACS was highly expressed in various lipogenic tissues, especially white adipose tissue(WAT) in male rats, AACS seems to be related to metabolic differences between male and female. Indeed, we found that estrogen enhanced AACS mRNA expression in ST-13 cells. In order to further investigate sex-differences of AACS in WAT, we compared mRNA expression levels of AACS and various factors in WAT of male rats with those in WAT of female rats. In whole tissues, expression level of AACS mRNA was higher in male subcutaneous WAT than in female one, but in mesenteric WAT, such difference was not observed. CoA transferase, ATP-dependent citrate lyase(ACL) and Acetyl-CoA carboxylase-1(ACC-1) mRNA exhibited no significant sex-difference in either tissue. Next, we examined AACS mRNA expression levels in preadipocytes, small-size (about 100μm) adipocytes, and large-size (over 200μm) mature adipocytes. In both male and female WAT, AACS mRNA was mainly and similarly expressed in small-size adipocytes. However, in large-size adipocytes, AACS mRNA was expressed much higher level in male subcutaneous WAT than in female one. These findings raise the possibility that AACS plays important roles in overgrowth of male subcutaneous adipocytes.
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