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

为了阐明完整动物中脂肪细胞的生理功能，我们试图制造PPAR；；伽马；基因敲除小鼠。然而，在我们的实验中，我们被告知PPAR；；伽马；基因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_1的显性-负性突变体，我们用腺病毒载体构建了几个突变体并在3T3-L1前脂肪细胞中表达，发现缺失C端16个氨基酸的突变体抑制了噻唑烷二酮诱导的脂肪细胞分化。由于PPAR_1在脂肪细胞分化和全身性胰岛素作用中具有重要作用，PPAR_1基因的功能缺陷可能会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，我们用聚合酶链式反应-单链构象多态性方法检测了PPAR基因编码序列的突变，发现脂肪萎缩性糖尿病患者的PPAR基因编码序列是正常的。此外，我们还检测了2型糖尿病患者PPAR基因编码序列的突变，发现了Prol2Ala突变。然而，该突变在正常人和2型糖尿病患者之间的等位基因频率没有改变。

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.