Peroxisome proliferator-activated receptor gamma (PPARG), as a member of the nuclear receptor superfamily, plays an important role in adipocyte differentiation and regulation of lipid and glucose metabolism. In this study, the transcripts of PPARG gene were isolated and identified in buffalo mammary gland. The results showed that two types of transcripts (PPARG1 and PPARG2) of PPARG gene produced by alternative 5′ end use were expressed in buffalo mammary gland, and each of them had four different alternative splicing variants. The PPARG1 includes PPARG1a, PPARG1b, PPARG1c and PPARG1d, while the PPARG2 contains PPARG2a, PPARG2b, PPARG2c and PPARG2d. Among them, only PPARG1a, PPARG2a and PPARG2d can encode complete functional proteins with three complete functional domains, and the rest encode truncated proteins with incomplete functional domains. All the eight variants of PPARG protein do not contain transmembrane regions and signal peptides, but their conserved domain, secondary and tertiary structure and subcellular localization were different. Subcellular localization confirmed that the main transcripts PPARG1a and PPARG2a played a functional role in the nucleus, which was consistent with the results by in silico prediction. RT-qPCR analysis of buffalo mammary tissue showed that the mRNA expression levels of PPARG1 and PPARG2 in lactation were higher than those in non-lactation, and the expression levels of transcripts PPARG2d and PPARG1b + PPARG2b in lactating stage were also higher than those in non-lactating stage, but the mRNA abundance of transcripts PPARG1c, PPARG1d and PPARG2c in non-lactating period was higher than that in lactating period. The results of this study suggest that PPARG1 and PPARG2 may play important role in buffalo milk fat synthesis, and the eight alternative splicing variants found here are likely to be related to the post-transcriptional regulation of lactation.

过氧化物酶体增殖物激活受体γ（PPARG），作为核受体超家族的成员，在脂肪细胞分化和脂质和葡萄糖代谢的调节中起重要作用。在这项研究中，PPARG基因的转录本是在水牛乳腺中分离和鉴定的。结果表明，由5'末端使用产生的PPARG基因的两种转录本（PPARG1和PPARG2）在水牛乳腺中表达，每种都有四种不同的剪接变体。所述PPARG1包括PPARG1a，PPARG1b，PPARG1c和PPARG1d，而PPARG2包含PPARG2a，PPARG2b，PPARG2c和PPARG2d。其中，只有PPARG1a，PPARG2a和PPARG2d可以编码具有三个完整功能域的完整功能蛋白，其余的则编码具有不完整功能域的截短蛋白。PPARG蛋白的所有八个变体均不包含跨膜区和信号肽，但它们的保守域，二级和三级结构以及亚细胞定位均不同。亚细胞定位证实了主要转录本PPARG1a和PPARG2a在核中发挥了功能性作用，这与计算机模拟的结果相符。水牛乳腺组织的RT-qPCR分析显示，哺乳期PPARG1和PPARG2的mRNA表达水平高于非哺乳期，而泌乳期PPARG2d和PPARG1b  +  PPARG2b的转录水平也高于非哺乳期。 -哺乳期，但转录本PPARG1c，PPARG1d和PPARG2c的mRNA丰度高于哺乳期。这项研究的结果表明，PPARG1和PPARG2 可能在水牛乳脂的合成中起重要作用，这里发现的8个可变剪接变体可能与转录后的泌乳调控有关。