Catalán Victoria, Gómez-Ambrosi Javier, Pastor Carlos, Rotellar Fernando, Silva Camilo, Rodríguez Amaia, Gil María J, Cienfuegos Javier A, Salvador Javier, Vendrell Joan, Frühbeck Gema
Metabolic Research Laboratory, Clínica Universitaria de Navarra, University of Navarra, Pamplona, Spain.
Obes Surg. 2008 Jun;18(6):695-701. doi: 10.1007/s11695-008-9453-7. Epub 2008 Apr 10.
Glycerol production and its efflux from adipocytes to the liver are key to modulate lipid and glucose homeostasis. Aquaporin 7 (AQP7) is an aquaglyceroporin that acts as the adipose glycerol channel, whereas aquaporin 9 (AQP9) is the specific channel operating in the liver. The aim of the present work was to evaluate the effect of obesity and type 2 diabetes mellitus (T2DM) on gene expression levels of AQP7 in visceral adipose tissue (VAT) and AQP9 in liver.
VAT and liver biopsies obtained from 20 women were used in the study. Patients were classified as lean or obese with the last group being further subclassified as normoglycemic (NG), patients with impaired glucose tolerance (IGT), or with T2DM. Anthropometric measurements as well as circulating metabolites, hormones, and adipokines were determined. Real-time polymerase chain reaction analyses were performed to quantify transcript levels of AQP7 in VAT and AQP9 in the liver.
Gene expression levels of AQP7 in VAT showed a tendency toward an increase (P = 0.065) in obese patients (both NG and T2DM) compared to lean subjects. AQP9 showed a significant downregulation in the hepatic biopsies obtained from obese T2DM patients compared to obese NG and IGT patients (P = 0.028).
The tendency toward an elevation of mRNA expression of VAT AQP7 in obesity together with the decreased hepatic AQP9 expression observed in obese T2DM subjects suggests a potential role in facilitating glycerol release from adipose tissue and reducing glycerol entry into hepatocytes in obesity and T2DM, respectively.
甘油的产生及其从脂肪细胞向肝脏的流出是调节脂质和葡萄糖稳态的关键。水通道蛋白7（AQP7）是一种水甘油通道蛋白，作为脂肪甘油通道发挥作用，而水通道蛋白9（AQP9）是肝脏中起作用的特定通道。本研究的目的是评估肥胖和2型糖尿病（T2DM）对内脏脂肪组织（VAT）中AQP7和肝脏中AQP9基因表达水平的影响。
本研究使用了从20名女性身上获取的VAT和肝脏活检样本。患者被分为瘦型或肥胖型，肥胖组进一步细分为血糖正常（NG）、糖耐量受损（IGT）或T2DM患者。测定了人体测量指标以及循环代谢物、激素和脂肪因子。进行实时聚合酶链反应分析以量化VAT中AQP7和肝脏中AQP9的转录水平。
与瘦型受试者相比，肥胖患者（包括NG和T2DM）VAT中AQP7的基因表达水平有升高趋势（P = 0.065）。与肥胖NG和IGT患者相比，肥胖T2DM患者肝脏活检样本中AQP9显著下调（P = 0.028）。
肥胖时VAT中AQP7 mRNA表达升高的趋势，以及肥胖T2DM患者肝脏中AQP9表达降低，分别提示在肥胖和T2DM中，AQP7在促进甘油从脂肪组织释放以及减少甘油进入肝细胞方面可能发挥作用。
