Person: Zhu, Hong
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Publication Degradation of HK2 by chaperone-mediated autophagy promotes metabolic catastrophe and cell death
(The Rockefeller University Press, 2015) Xia, Hong-guang; Najafov, Ayaz; Geng, Jiefei; Galan-Acosta, Lorena; Han, Xuemei; Guo, Yuan; Shan, Bing; Zhang, Yaoyang; Norberg, Erik; Zhang, Tao; Pan, Lifeng; Liu, Junli; Coloff, Jonathan L.; Ofengeim, Dimitry; Zhu, Hong; Wu, Kejia; Cai, Yu; Yates, John R.; Zhu, Zhengjiang; Yuan, Junying; Vakifahmetoglu-Norberg, HelinHexokinase II (HK2), a key enzyme involved in glucose metabolism, is regulated by growth factor signaling and is required for initiation and maintenance of tumors. Here we show that metabolic stress triggered by perturbation of receptor tyrosine kinase FLT3 in non–acute myeloid leukemia cells sensitizes cancer cells to autophagy inhibition and leads to excessive activation of chaperone-mediated autophagy (CMA). Our data demonstrate that FLT3 is an important sensor of cellular nutritional state and elucidate the role and molecular mechanism of CMA in metabolic regulation and mediating cancer cell death. Importantly, our proteome analysis revealed that HK2 is a CMA substrate and that its degradation by CMA is regulated by glucose availability. We reveal a new mechanism by which excessive activation of CMA may be exploited pharmacologically to eliminate cancer cells by inhibiting both FLT3 and autophagy. Our study delineates a novel pharmacological strategy to promote the degradation of HK2 in cancer cells.
Publication G-protein-coupled receptors regulate autophagy by ZBTB16-mediated ubiquitination and proteasomal degradation of Atg14L
(eLife Sciences Publications, Ltd, 2015) Zhang, Tao; Dong, Kangyun; Liang, Wei; Xu, Daichao; Xia, Hongguang; Geng, Jiefei; Najafov, Ayaz; Liu, Min; Li, Yanxia; Han, Xiaoran; Xiao, Juan; Jin, Zhenzhen; Peng, Ting; Gao, Yang; Cai, Yu; Qi, Chunting; Zhang, Qing; Sun, Anyang; Lipinski, Marta; Zhu, Hong; Xiong, Yue; Pandolfi, Pier Paolo; Li, He; Yu, Qiang; Yuan, JunyingAutophagy is an important intracellular catabolic mechanism involved in the removal of misfolded proteins. Atg14L, the mammalian ortholog of Atg14 in yeast and a critical regulator of autophagy, mediates the production PtdIns3P to initiate the formation of autophagosomes. However, it is not clear how Atg14L is regulated. In this study, we demonstrate that ubiquitination and degradation of Atg14L is controlled by ZBTB16-Cullin3-Roc1 E3 ubiquitin ligase complex. Furthermore, we show that a wide range of G-protein-coupled receptor (GPCR) ligands and agonists regulate the levels of Atg14L through ZBTB16. In addition, we show that the activation of autophagy by pharmacological inhibition of GPCR reduces the accumulation of misfolded proteins and protects against behavior dysfunction in a mouse model of Huntington's disease. Our study demonstrates a common molecular mechanism by which the activation of GPCRs leads to the suppression of autophagy and a pharmacological strategy to activate autophagy in the CNS for the treatment of neurodegenerative diseases. DOI: http://dx.doi.org/10.7554/eLife.06734.001