Biology subjects

Zuo, P.

Publications and source records attributed to Zuo, P..

5 recordsLinked to original sources

bioRxiv2025

KDM5A enhances MHC-I antigen presentation and potentiates antitumor immunity unleashed by immune checkpoint blockade

While some studies have implicated the histone 3 lysine 4 demethylase KDM5A in tumorigenesis and promotion of metastasis, KDM5A has also been shown to boost immunotherapy responses in melanoma. The distinct functional role of KDM5A in the context of immunotherapy and the underlying mechanisms remain largely unknown. Here, we report that higher KDM5A expression strongly correlates with higher MHC-I expression, CD8+ T cell infiltration, and prolonged survival in colorectal cancer and gastric cancer patients receiving anti- PD-1 therapy. KDM5A promotes MHC-I-mediated antigen presentation and CD8+ T cell-mediated tumor killing across multiple murine cancer models. Mechanistically, KDM5A upregulates MHC-I expression through the SOCS1/IFN-{gamma}/STAT1 signaling and improves tumor cell-intrinsic antigen presentation capacity by inhibiting lysosomal proteases in a demethylase-dependent manner. Moreover, KDM5A directly represses lysosomal cathepsins in dendritic cells and promotes the cross-priming activity. Through a high-throughput chemical compound library-based screen, we identified Clomiphene, an FDA-approved small molecule, which significantly elevates KDM5A expression, and enhances antitumor immunity during anti-PD-1 immunotherapy in mouse models of melanoma and colon cancer. Our findings that KDM5A functions in MHC-I-mediated immune activation during anti-PD-1 therapy present an opportunity for developing KDM5A-enhancing therapies to increase tumor immunogenicity, sensitize solid tumors to immunotherapy and exclude immune evasion.

immunology↗

bioRxiv2025

Dynamic early recruitment of GAK-Hsc70 regulates coated pit maturation

Clathrin-mediated endocytosis (CME) is the process by which clathrin assembles on the plasma membrane to form clathrin-coated pits (CCPs), which then invaginate, accumulate cargo and are released by fission from the membrane to form clathrin-coated vesicles (CCVs). A transition of nascent CCPs from flat-to-curved has been observed by various methods. However, what drives this transition remains unknown and controversial. GAK and its chaperone protein, Hsc70, are well-known to mediate clathrin release from CCVs and several studies have observed a late burst of GAK recruitment as CCVs form. Other studies have proposed that early recruitment of GAK-Hsc70 could function to provide the necessary energy source to remodel nascent flat clathrin lattices, replacing hexagons with pentagons and enabling a gain of curvature and invagination of the growing CCP; however, direct functional evidence is lacking. Here we show that GAK knockdown inhibits CCP formation and invagination. Furthermore, mutations in the J domain of GAK that abolish Hsc70 recruitment to and activation at CCPs, lead to the accumulation of GAK at CCPs, hinder CCP stabilization and invagination and result in a striking increase in the proportion of short-lived, abortive CCPs. These findings support the hypothesis that GAK-Hsc70 promotes the turnover and remodeling of nascent clathrin assemblies required for curvature development during CME. Significance StatementGAK and its chaperone protein, Hsc70, are known to be recruited to clathrin-coated vesicles (CCVs) to mediate clathrin uncoating. Previous studies have proposed that early recruitment of GAK-Hsc70 to CCPs could function to remodel nascent flat clathrin lattices, replacing hexagons with pentagons and enabling a gain of curvature of the assembling polymeric coat. However, there are conflicting views, and direct functional evidence is lacking. Here we show that GAK knockdown inhibits CCP formation and invagination. A detailed domain-specific mutational analysis of GAK pinpointed the importance of J domain-Hsc70 interactions in regulating crucial early steps of CME including CCP stabilization and invagination. These findings support a hypothesis that GAK-Hsc70 promotes turnover of clathrin at nascent CCPs required for curvature development.

cell biology↗

bioRxiv2024

Synergistic activation of the human phosphate exporter XPR1 by KIDINS220 and inositol pyrophosphate

Inorganic phosphate (Pi) is fundamental to life, and its intracellular concentration must be tightly regulated to prevent toxicity. XPR1, the only known phosphate exporter, plays a crucial role in maintaining this delicate balance. However, the mechanisms underlying the function and regulation of XPR1 remain elusive until now. Here we present cryo-electron microscopy structures of the human XPR1-KIDINS220 complex in both substrate-free closed states and substrate-bound outward-open states, as well as the structure of an XPR1 mutant alone in a substrate-bound inward-facing state. In the presence of inositol hexaphosphate (InsP6) and phosphate, the XPR1-KIDINS220 complex adopts an outward-open conformation. InsP6 binds both the SPX domain and the peripheral juxtamembrane regions of XPR1, indicative of an active phosphate-export state. Conversely, in the absence of either phosphate or InsP6, the complex assumes a closed state, where the extracellular half of transmembrane 9 occupies the outward cavity, and a C-terminal plug-in loop blocks the intracellular cavity. Notably, XPR1 without KIDINS220 adopts a closed state despite the presence of phosphate and InsP6. The functional mutagenesis experiments further demonstrate that InsP6, whose concentrations fluctuate in response to Pi availability, functions synergistically with KIDINS220 to regulate the phosphate export activity of XPR1. These findings not only elucidate the intricate mechanisms of cellular phosphate regulation but also hold promise for the development of targeted therapies for ovarian cancer, where XPR1 plays a significant role.

biophysics↗

bioRxiv2024

Structural insights into cholesterol sensing by the LYCHOS-mTORC1 pathway

The mechanistic target of rapamycin complex 1 (mTORC1) pathway regulates cellular metabolism and growth by coordinating nutrient resources, including cholesterol, and its aberrant activation is linked to various age-related diseases. LYCHOS is a cholesterol sensor on the lysosome and bound to the GATOR1 complex, a GTPase-activating protein for the Rag GTPase, at high cholesterol concentrations, thereby activating the protein kinase mTORC1. However, how LYCHOS senses cholesterol and transduces signal to GATOR1 remain largely unknown. Here we report six cryo-electron microscopy structures of human LYCHOS, depicting five distinct states. These are categorized into a contracted state when complexed with a sufficient amount of the cholesterol analogue cholesteryl hemisuccinate (CHS), and an expanded state when CHS is deficient. The structure forms a homodimer, within each monomer the transmembrane region is divided into a permease-like domain (PLD) and a GPCR-like domain (GLD) with two clearly defined adjacent cholesterol binding sites between them. The PLD shares a conserved Na+/H+ antiporter (NhaA) fold, which much resembles plant auxin transporter PINs. Cholesterol locates between PLD and GLD and cholesterol binding induces a translation of GLD towards PLD and exposes the cytosolic extension of transmembrane 15, which mediates the interaction between LYCHOS and GATOR1. Strikingly, structure-guided mutations of Gly702 in GLD of LYCHOS increase its affinity for cholesterol, leading to sustained mTORC1 activation in cells. This indicates that LYCHOSs moderate affinity for cholesterol is crucial as a cholesterol sensor. Our results not only showed a solute carrier mechanistically coordinates a GPCR domain, elucidating the structural mechanism of cholesterol sensing by the mTORC1 pathway on the lysosome; but also provides a structural basis for developing inhibitors that selectively target to mTORC1 pathway to treat age-related diseases by blocking LYCHOS in its expanded state.

biochemistry↗

bioRxiv2023

A conserved N-terminal motif of CUL3 mediates assembly and licenses E3 ligase activation of CRL3KLHL22

The CUL3-RING E3 ubiquitin ligases (CRL3s) play an essential role in response to extracellular nutrition and stress stimuli. The ubiquitin ligase function of CRL3s is activated through E3-E3 dimerization. However, how and why such a dimeric assembly is required for its ligase activity remains elusive. Here, we report the cryo-EM structure of the dimeric CRL3KLHL22 complex and reveal a conserved N-terminal motif in CUL3 that mediates the dimerization assembly and licenses the activation of CRL3KLHL22. Deletion of the CUL3 N-terminal motif leads to non-stochiometric assembly and impairs E3 activity of both CRL3KLHL22 and several other CRL3s. In addition, we found that the dynamics of dimeric E3-E3 superassembly generates a variable ubiquitination zone, potentially facilitating substrate recognition and ubiquitination. These findings demonstrate a CUL3 N-terminal motif-dependent E3-E3 superassembly mechanism and provide insights into the assembly and activation of CRL3s.

molecular biology↗