目的:Picalm(磷脂酰肌醇结合网格蛋白组装蛋白),一种普遍表达的网格蛋白-接头蛋白,是众所周知的阿尔茨海默病易感基因,但其在白色脂肪组织(WAT)功能中的作用尚未被研究。转录组分析显示Picalm在糖尿病易感和糖尿病抗性小鼠的WAT中的差异表达,因此,我们旨在研究Picalm表达与葡萄糖稳态之间的潜在联系,肥胖相关的代谢表型,及其在脂肪细胞中胰岛素调节的GLUT4运输中的特定作用。
方法:分析了糖尿病抗性(DR)和糖尿病易感(DP)雌性新西兰肥胖(NZO)小鼠的WAT和在限时喂养(TRF)和隔日禁食(ADF)后的雄性NZO中的Picalm表达和microRNA(miRNA)和DNA甲基化的表观遗传调控。在横断面队列中评估人WAT中的PICALM表达,并在减肥手术诱导的体重减轻之前和之后进行评估。在3T3-L1脂肪细胞中进行siRNA介导的Picalm敲低以阐明GLUT4易位以及胰岛素信号传导和脂肪形成的功能结果。
结果:与DPNZO雌性小鼠相比,DR中WAT中的Picalm表达显着降低,以及在胰岛素敏感性与抗性NZO雄性,在TRF和ADF后,NZO男性也有所减少。四个miRNA(let-7c,miR-30c,miR-335,miR-344)被鉴定为糖尿病易感性相关差异的潜在介质Picalm表达,而11个miRNA(包括miR-23a,miR-29b,和miR-101a)与TRF和ADF效应有关。人PICALM在脂肪组织中的表达在无肥胖个体中较低。与肥胖和减肥手术后体重减轻结果相关。siRNA介导的Picalm在成熟3T3-L1脂肪细胞中的敲低导致内源性葡萄糖转运蛋白GLUT4向质膜的胰岛素刺激的扩增易位和Akt和Tbc1d4的磷酸化增加。此外,在3T3-L1分化之前和期间耗尽Picalm显着抑制了脂肪生成,这表明Picalm可能在前期和成熟脂肪细胞的生物学中起着不同的作用。
结论:Picalm是WAT中GLUT4易位的新型调节剂,其表达受糖尿病遗传易感性和饮食干预的调节。这些发现表明Picalm在改善葡萄糖稳态方面的潜在作用,并强调了其作为代谢紊乱治疗靶标的相关性。
OBJECTIVE: Picalm (phosphatidylinositol-binding clathrin assembly protein), a ubiquitously expressed clathrin-adapter protein, is a well-known susceptibility gene for Alzheimer\'s disease, but its role in white adipose tissue (WAT) function has not yet been studied. Transcriptome analysis revealed differential expression of Picalm in WAT of diabetes-prone and diabetes-resistant mice, hence we aimed to investigate the potential link between Picalm expression and glucose homeostasis, obesity-related metabolic phenotypes, and its specific role in insulin-regulated GLUT4 trafficking in adipocytes.
METHODS: Picalm expression and epigenetic regulation by microRNAs (miRNAs) and DNA methylation were analyzed in WAT of diabetes-resistant (DR) and diabetes-prone (DP) female New Zealand Obese (NZO) mice and in male NZO after time-restricted feeding (TRF) and alternate-day fasting (ADF). PICALM expression in human WAT was evaluated in a cross-sectional cohort and assessed before and after weight loss induced by bariatric surgery. siRNA-mediated knockdown of Picalm in 3T3-L1-cells was performed to elucidate functional outcomes on GLUT4-translocation as well as insulin signaling and adipogenesis.
RESULTS: Picalm expression in WAT was significantly lower in DR compared to DP female mice, as well as in insulin-sensitive vs. resistant NZO males, and was also reduced in NZO males following TRF and ADF. Four miRNAs (let-7c, miR-30c, miR-335, miR-344) were identified as potential mediators of diabetes susceptibility-related differences in Picalm expression, while 11 miRNAs (including miR-23a, miR-29b, and miR-101a) were implicated in TRF and ADF effects. Human PICALM expression in adipose tissue was lower in individuals without obesity vs. with obesity and associated with weight-loss outcomes post-bariatric surgery. siRNA-mediated knockdown of Picalm in mature 3T3-L1-adipocytes resulted in amplified insulin-stimulated translocation of the endogenous glucose transporter GLUT4 to the plasma membrane and increased phosphorylation of Akt and Tbc1d4. Moreover, depleting Picalm before and during 3T3-L1 differentiation significantly suppressed adipogenesis, suggesting that Picalm may have distinct roles in the biology of pre- and mature adipocytes.
CONCLUSIONS: Picalm is a novel regulator of GLUT4-translocation in WAT, with its expression modulated by both genetic predisposition to diabetes and dietary interventions. These findings suggest a potential role for Picalm in improving glucose homeostasis and highlight its relevance as a therapeutic target for metabolic disorders.