Adipocytes as endocrine cells and their roles in mice (PPARgamma knockout mice)

为了阐明完整动物脂肪细胞的生理功能，我们尝试构建PPAR_< γ >敲除小鼠。然而，在我们的实验中，我们被告知PPAR_< γ >敲除小鼠是胚胎致死的。因此，我们尝试了另一种方法。为了寻找PPAR_< γ >的显性阴性突变体，我们制作了多个突变体，利用腺病毒载体在3T3-L1前脂肪细胞中表达，发现缺失了c端16个氨基酸的突变体能够抑制噻唑烷二酮诱导的脂肪细胞分化。因此，该突变体可能有助于通过转基因方法制备低脂小鼠。由于PPAR_< γ >在脂肪细胞分化和全身胰岛素作用中起重要作用，PPAR_< γ >的功能缺陷可能导致脂肪生成受损和胰岛素抵抗，这是脂肪萎缩性糖尿病的典型症状。因此，我们通过PCR-SSCP检测了PPAR_< γ >基因编码序列的突变，发现PPAR_< γ >基因编码序列在脂肪萎缩性糖尿病个体中是正常的。此外，我们还检测了2型糖尿病患者PPAR_< γ >基因编码序列的突变，发现了Prol2Ala突变。然而，这种突变的等位基因频率在正常和2型糖尿病患者之间没有改变。

To elucidate the physiological function of adipocytes in intact animals, we tried to make PPAR_<gamma> knockout mice. However, during our experiments, we were informed that PPAR_<gamma> knockout mice were embryonic lethal. therefore, we tried another approach. That is, adipose tissue-specific expression of dominant-negative mutants of PPAR_<gamma>, To find dominant-negative mutants of PPAR_<gamma>, we made several mutants and expressed in 3T3-L1 preadipocytes using adenovirus vector and found that the mutant, in which 16 amino acids in C-terminal were deleted, inhibited the adipocyte differentiation induced by thiazolidinedione. Therefore, this mutant may be useful to make fat-less mice by the transgenic method.Since PPAR_<gamma> has an important role in adipocyte differentiation and systemic insulin action, functional defects in PPAR_<gamma> might be expected to result in the impaired adipogenesis and insulin resistance, conditiones typical of lipoatrophic diabetes. Therefore, we examined the mutation in the coding sequences of PPAR_<gamma> gene by PCR-SSCP and found that the coding sequences of the PPAR_<gamma> gene are normal in individuals with lipoatrophic diabetes.Furthermore, we also examined the mutation in the coding sequences of the PPAR_<gamma> gene in individuals with type 2 diabetes and found the Prol2Ala mutations. However, the allele frequency of this mutation between normal and type2 diabetic patiants were not changed.