Browsing by Author "Li, Hong-Yu"

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    Identification of myo-inositol-binding proteins by using the biotin pull-down strategy in cultured cells.
    (STAR protocols, 2022-06) Hsu, Che-Chia; Xu, Zhi-Gang; Lei, Jie; Chen, Zhong-Zhu; Li, Hong-Yu; Lin, Hui-Kuan
    Metabolites are not only substrates in metabolic reactions, but they also serve as signaling molecules to regulate diverse biological functions. Identification of the binding proteins for the metabolites helps in the understanding of their functions beyond the classic metabolic pathways in which they are involved. We provide the protocol for synthesizing the biotin-labeled myo-inositol, which is used to identify its binding proteins by using biotin pull-down assay, given there is no available tool for the rapid screening of inositol-binding proteins in cells and in vitro systems. Biotin-labeled inositol probe therefore provides a tool to identify inositol's sensors. For complete details on the use and execution of this protocol, please refer to Hsu et al. (2021).
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    Inositol serves as a natural inhibitor of mitochondrial fission by directly targeting AMPK.
    (Molecular cell, 2021-09) Hsu, Che-Chia; Zhang, Xian; Wang, Guihua; Zhang, Weina; Cai, Zhen; Pan, Bo-Syong; Gu, Haiwei; Xu, Chuan; Jin, Guoxiang; Xu, Xiangshang; Manne, Rajesh Kumar; Jin, Yan; Yan, Wei; Shao, Jingwei; Chen, Tingjin; Lin, Emily; Ketkar, Amit; Eoff, Robert; Xu, Zhi-Gang; Chen, Zhong-Zhu; Li, Hong-Yu; Lin, Hui-Kuan
    Mitochondrial dynamics regulated by mitochondrial fusion and fission maintain mitochondrial functions, whose alterations underline various human diseases. Here, we show that inositol is a critical metabolite directly restricting AMPK-dependent mitochondrial fission independently of its classical mode as a precursor for phosphoinositide generation. Inositol decline by IMPA1/2 deficiency elicits AMPK activation and mitochondrial fission without affecting ATP level, whereas inositol accumulation prevents AMPK-dependent mitochondrial fission. Metabolic stress or mitochondrial damage causes inositol decline in cells and mice to elicit AMPK-dependent mitochondrial fission. Inositol directly binds to AMPKγ and competes with AMP for AMPKγ binding, leading to restriction of AMPK activation and mitochondrial fission. Our study suggests that the AMP/inositol ratio is a critical determinant for AMPK activation and establishes a model in which AMPK activation requires inositol decline to release AMPKγ for AMP binding. Hence, AMPK is an inositol sensor, whose inactivation by inositol serves as a mechanism to restrict mitochondrial fission.
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    Lactate Is a Natural Suppressor of RLR Signaling by Targeting MAVS
    (Cell, 2019-06) Zhang, Weina; Wang, Guihua; Xu, Zhi-Gang; Tu, Haiqing; Hu, Fuqing; Dai, Jiang; Chang, Yan; Chen, Yaqi; Lu, Yanjun; Zeng, Haolong; Cai, Zhen; Han, Fei; Xu, Chuan; Jin, Guoxiang; Sun, Li; Pan, Bo-Syong; Lai, Shiue-Wei; Hsu, Che-Chia; Xu, Jia; Chen, Zhong-Zhu; Li, Hong-Yu; Seth, Pankaj; Hu, Junbo; Zhang, Xuemin; Li, Huiyan; Lin, Hui-Kuan
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    The Skp2 Pathway: A Critical Target for Cancer Therapy.
    (Seminars in cancer biology, 2020-12) Cai, Zhen; Moten, Asad; Peng, Danni; Hsu, Che-Chia; Pan, Bo-Syong; Manne, Rajeshkumar; Li, Hong-Yu; Lin, Hui-Kuan
    Strictly regulated protein degradation by ubiquitin-proteasome system (UPS) is essential for various cellular processes whose dysregulation is linked to serious diseases including cancer. Skp2, a well characterized component of Skp2-SCF E3 ligase complex, is able to conjugate both K48-linked ubiquitin chains and K63-linked ubiquitin chains on its diverse substrates, inducing proteasome mediated proteolysis or modulating the function of tagged substrates respectively. Overexpression of Skp2 is observed in various human cancers associated with poor survival and adverse therapeutic outcomes, which in turn suggests that Skp2 engages in tumorigenic activity. To that end, the oncogenic properties of Skp2 are demonstrated by various genetic mouse models, highlighting the potential of Skp2 as a target for tackling cancer. In this article, we will describe the downstream substrates of Skp2 as well as upstream regulators for Skp2-SCF complex activity. We will further summarize the comprehensive oncogenic functions of Skp2 while describing diverse strategies and therapeutic platforms currently available for developing Skp2 inhibitors.