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Biology subjects

Zi, Z.

Publications and source records attributed to Zi, Z..

2 recordsLinked to original sources
bioRxiv2021

Pro70 Hydroxylation of Actin Impairs Cell Motility Through Binding with VHL and Blocking His73 Methylation

Actin filaments generate intrinsic forces that are essential for cell motility. This process is tightly regulated by various posttranslational modifications (PTMs), including acetylation, arginylation, and oxidation. However, the role of actin hydroxylation in regulating its dynamics remains poorly understood. Here, we demonstrate that the inhibition of Prolyl Hydroxylase Domain-containing proteins (PHDs) activity significantly promotes actin polymerization and enhances cell motility. Using hydroxylation proteomics, we identified actin as a substrate for PHDs, with hydroxylation occurring at multiple proline residues, especially at proline 70 (Pro70). This modification recruits the von Hippel-Lindau (VHL) tumor suppressor protein, which then leads to the disruption of the interaction between actin and the histidine methyltransferase SET Domain Containing 3 (SETD3). Consequently, SETD3-mediated methylation of histidine 73 (His73) on actin is suppressed, impairing actin polymerization and compromising cell motility. Notably, genetic loss of VHL or pharmacological inhibition of PHDs restores His73 methylation, enhances actin filament formation, and promotes cell motility. Together, our findings uncover a novel regulatory crosstalk between hydroxylation and methylation on actin, establishing a critical mechanism by which PTMs fine-tune actin dynamics to govern cell motility. HighlightsO_LIMK-8617 augments cell motility and actin polymerization in VHL dependent manner; C_LIO_LIHydroxylation proteomics reveals that actin is hydroxylated by PHDs; C_LIO_LIHydroxylation at Pro70 recruits VHL, disrupting actins interaction with SETD3 and reducing His73 methylation; C_LIO_LIGenetic loss of VHL in clear cell renal cell carcinoma (ccRCC) potentially promotes cell motility by increasing His73 methylation on actin. C_LI

biochemistry↗
bioRxiv2021

Quantitative Phosphoproteomic Analyses Identify STK11IP as a Lysosome-Specific Substrate of mTORC1 that Regulates Lysosomal Acidification

The evolutionarily conserved serine/threonine kinase mTORC1 is a central regulator of cell growth and proliferation. mTORC1 is activated on the lysosome surface. However, once mTORC1 is activated, it is unclear whether mTORC1 phosphorylates local lysosomal proteins to regulate specific aspects of lysosomal biology. Through cross-reference analyses of lysosome proteomic with mTORC1-regulated phosphoproteomic, we identified STK11IP as a novel lysosome-specific substrate of mTORC1. mTORC1 directly phosphorylates STK11IP at S404. Knockout of STK11IP led to a robust increase of autophagosome-lysosome fusion and autophagy flux. Dephosphorylation of STK11IP at S404 represses the role of STK11IP as an autophagy inhibitor. Mechanistically, STK11IP binds to V-ATPase, and regulates the activity of V-ATPase. Knockout of STK11IP protects mice from fasting and Methionine and Choline-Deficient Diet (MCD) diet induced fatty liver. Thus, our study demonstrates that STK11IP phosphorylation represents a novel mechanism for mTORC1 to regulate lysosomal acidification, and points to STK11IP as a promising therapeutic target for the amelioration of diseases with aberrant autophagy signaling.

cell biology↗