title: Identification of a small molecule targeting annexin A7.
abstract: Autophagy involves multiple membrane trafficking and fusion events. Annexin A7 (ANXA7) is postulated to play a role in membrane fusion during exocytosis, while the contribution of ANXA7 to autophagy is poorly understood. Our recent studies demonstrated that ABO could promote autophagy via elevation of ANXA7 and triggering ANXA7 subcellular redistribution. However, little is known about the molecular mechanisms how ANXA7 regulates autophagy. As molecular disruption of ANXA7 in mice results in several unwished phenotypes, small molecule modulators may be efficacious in defining the mechanisms of ANXA7 action. However, so far no compounds that selectively target ANXA7 have been identified. So, we hypothesize that ABO might be a potent modulator of ANXA7. We also have detected the colocalization of ANXA7 and microtubule-associated protein 1 light chain 3 (LC3), and ANXA7 was essential for LC3 accumulation in VEC autophagy. As a GTPase, whether ANXA7 affects the phosphorylation of LC3 or other proteins needs further investigation. In this study, we performed site-directed mutagenesis and found that ABO directly bound to Thr(286) of ANXA7 and inhibited its phosphorylation. By yeast two-hybrid screening, we found that ANXA7 could interact with grancalcin (GCA). ABO promoted the interaction and inhibited GCA phosphorylation, leading to the decrease of intracellular Ca(2+) concentration. At the same time, ABO inhibited the phosphorylation of LC3. Hence, by identifying ABO as an unprecedented modulator of ANXA7 as well as GCA and LC3 as interacting proteins of ANXA7, we demonstrated the possible mechanisms how ANXA7 regulates autophagy for the first time.
authors: Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Science, Shandong University, Jinan 250100, China.
authors: Haiying
authors: H
authors: Li
authors: Ning
authors: N
authors: Liu
authors: Shengqing
authors: S
authors: Wang
authors: Li
authors: L
authors: Wang
authors: Jing
authors: J
authors: Zhao
authors: Le
authors: L
authors: Su
authors: Yun
authors: Y
authors: Zhang
authors: Shangli
authors: S
authors: Zhang
authors: Zhigang
authors: Z
authors: Xu
authors: Baoxiang
authors: B
authors: Zhao
authors: Junying
authors: J
authors: Miao
mesh_terms: D000818:Animals; D017310:Annexin A7 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000187:drug effects*; D048588:Benzoxazines / Q000737:chemistry / Q000494:pharmacology*; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects
chemical_list: C541593:6-amino-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine; D017310:Annexin A7; D048588:Benzoxazines; D002135:Calcium-Binding Proteins; C503121:GCA protein, human; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D002118:Calcium