Liu Shengnan, Jiang Ya-Ping, Ballou Lisa M, Zong Wei-Xing, Lin Richard Z
*Department of Physiology & Biophysics and Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY;†Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY;‡Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ; and§Medical Service, Northport Veterans Affairs Medical Center, Northport, NY.
J Cardiovasc Pharmacol. 2017 Apr;69(4):198-211. doi: 10.1097/FJC.0000000000000461.
Receptors that activate the heterotrimeric G protein Gαq are thought to play a role in the development of heart failure. Dysregulation of autophagy occurs in some pathological cardiac conditions including heart failure, but whether Gαq is involved in this process is unknown. We used a cardiomyocyte-specific transgenic mouse model of inducible Gαq activation (termed GαqQ209L) to address this question. After 7 days of Gαq activation, GαqQ209L hearts contained more autophagic vacuoles than wild type hearts. Increased levels of proteins involved in autophagy, especially p62 and LC3-II, were also seen. LysoTracker staining and western blotting showed that the number and size of lysosomes and lysosomal protein levels were increased in GαqQ209L hearts, indicating enhanced lysosomal degradation activity. Importantly, an autophagic flux assay measuring LC3-II turnover in isolated adult cardiomyocytes indicated that autophagic activity is enhanced in GαqQ209L hearts. GαqQ209L hearts exhibited elevated levels of the autophagy initiation complex, which contains the Class III phosphoinositide 3-kinase Vps34. As a consequence, Vps34 activity and phosphatidylinositol 3-phosphate levels were higher in GαqQ209L hearts than wild type hearts, thus accounting for the higher abundance of autophagic vacuoles. These results indicate that an increase in autophagy is an early response to Gαq activation in the heart.
激活异源三聚体G蛋白Gαq的受体被认为在心力衰竭的发展中起作用。自噬失调发生在包括心力衰竭在内的一些病理性心脏疾病中，但Gαq是否参与这一过程尚不清楚。我们使用了一种可诱导Gαq激活的心肌细胞特异性转基因小鼠模型（称为GαqQ209L）来解决这个问题。在Gαq激活7天后，GαqQ209L心脏中的自噬空泡比野生型心脏更多。还观察到自噬相关蛋白水平升高，尤其是p62和LC3-II。溶酶体追踪染料染色和蛋白质印迹显示，GαqQ209L心脏中溶酶体的数量和大小以及溶酶体蛋白水平均增加，表明溶酶体降解活性增强。重要的是，一项在分离的成年心肌细胞中测量LC3-II周转的自噬通量分析表明，GαqQ209L心脏中的自噬活性增强。GαqQ209L心脏中自噬起始复合物的水平升高，该复合物包含III类磷酸肌醇3激酶Vps34。因此，GαqQ2L心脏中Vps34活性和磷脂酰肌醇3磷酸水平高于野生型心脏，这就解释了自噬空泡丰度较高的原因。这些结果表明，自噬增加是心脏对Gαq激活的早期反应。
