Boyer-Guittaut Michaël, Poillet Laura, Liang Qiuli, Bôle-Richard Elodie, Ouyang Xiaosen, Benavides Gloria A, Chakrama Fatima-Zahra, Fraichard Annick, Darley-Usmar Victor M, Despouy Gilles, Jouvenot Michèle, Delage-Mourroux Régis, Zhang Jianhua
Université de Franche-Comté; Laboratoire de Biochimie; EA3922 Estrogènes; Expression Génique et Pathologies du Système Nerveux Central; Sciences et Techniques; Besançon, France; Department of Pathology; University of Alabama at Birmingham; Birmingham, AL USA; Center for Free Radical Biology; University of Alabama at Birmingham; Birmingham, AL USA.
Université de Franche-Comté; Laboratoire de Biochimie; EA3922 Estrogènes; Expression Génique et Pathologies du Système Nerveux Central; Sciences et Techniques; Besançon, France.
Autophagy. 2014 Jun;10(6):986-1003. doi: 10.4161/auto.28390.
GABARAPL1/GEC1 is an early estrogen-induced gene which encodes a protein highly conserved from C. elegans to humans. Overexpressed GABARAPL1 interacts with GABAA or kappa opioid receptors, associates with autophagic vesicles, and inhibits breast cancer cell proliferation. However, the function of endogenous GABARAPL1 has not been extensively studied. We hypothesized that GABARAPL1 is required for maintaining normal autophagic flux, and plays an important role in regulating cellular bioenergetics and metabolism. To test this hypothesis, we knocked down GABARAPL1 expression in the breast cancer MDA-MB-436 cell line by shRNA. Decreased expression of GABARAPL1 activated procancer responses of the MDA-MB-436 cells including increased proliferation, colony formation, and invasion. In addition, cells with decreased expression of GABARAPL1 exhibited attenuated autophagic flux and a decreased number of lysosomes. Moreover, decreased GABARAPL1 expression led to cellular bioenergetic changes including increased basal oxygen consumption rate, increased intracellular ATP, increased total glutathione, and an accumulation of damaged mitochondria. Taken together, our results demonstrate that GABARAPL1 plays an important role in cell proliferation, invasion, and autophagic flux, as well as in mitochondrial homeostasis and cellular metabolic programs.
GABARAPL1/GEC1是一种早期雌激素诱导基因，其编码的蛋白质从秀丽隐杆线虫到人类都高度保守。过表达的GABARAPL1与GABAA或κ阿片受体相互作用，与自噬小泡相关联，并抑制乳腺癌细胞增殖。然而，内源性GABARAPL1的功能尚未得到广泛研究。我们推测GABARAPL1是维持正常自噬通量所必需的，并且在调节细胞生物能量学和代谢中起重要作用。为了验证这一假设，我们通过短发夹RNA（shRNA）敲低了乳腺癌MDA-MB-436细胞系中GABARAPL1的表达。GABARAPL1表达的降低激活了MDA-MB-436细胞的促癌反应，包括增殖增加、集落形成和侵袭增加。此外，GABARAPL1表达降低的细胞表现出自噬通量减弱和溶酶体数量减少。此外，GABARAPL1表达降低导致细胞生物能量学变化，包括基础耗氧率增加、细胞内ATP增加、总谷胱甘肽增加以及受损线粒体的积累。综上所述，我们的结果表明GABARAPL1在细胞增殖、侵袭和自噬通量以及线粒体稳态和细胞代谢程序中起重要作用。
