Biology subjects

zhou, t.

Publications and source records attributed to zhou, t..

3 recordsLinked to original sources

bioRxiv2025

Oncometabolite fumarate impairs ATR-CHK1 signaling by succinating RPA1 in Fumarate Hydratase-deficient renal cell carcinoma cells

Abnormal accumulation of oncometabolite fumarate drives susceptibility in fumarate hydratase-deficient renal cell carcinoma (FH-dRCC), but the precise mechanisms remain not fully understood. In this study, we demonstrate that high fumarate levels impair activation of ATR-CHK1 signaling in response to replication stress and DNA damage. Mechanistically, fumarate modifies RPA1, an essential factor for ATR-CHK1 activation through succination, a post-translational modification. Succination of RPA1 occurs mainly at cysteine residues 481 and 486, which reduces its binding affinity for single-stranded DNA (ssDNA). RPA1 succination leads to deficient recruitment of TOPBP1 to ssDNA, resulting in attenuated CHK1 activation and defective cell cycle arrest in response to DNA damage. Succinated RPA1 compromises homologous recombination-mediated DNA repair. Our findings establish that fumarate-induced succination of RPA1 impairs DNA repair and cell cycle control, promoting genomic instability in FH-dRCC. This work reveals a novel mechanism by which oncometabolites contribute to genomic instability.

cancer biology↗

bioRxiv2025

BLTP2 orchestrates lysobisphosphatidic acid synthesis and exosome biogenesis via SCAMP3-dependent ER contacts in tumorigenesis

Multivesicular bodies (MVBs) contain intraluminal vesicles (ILVs) designated for degradation in lysosomes or release as exosomes for cell-to-cell communication. The mechanisms governing ILV/exosome formation are not fully understood. Here, we show that the integral endoplasmic reticulum (ER) membrane protein bridge-like lipid transfer protein 2 (BLTP2; KIAA0100) is indispensable in ILV/exosome formation and that secretory carrier membrane protein 3 (SCAMP3) recruits BLTP2 to ER-MVB membrane contact sites (MCSs) in a Rab5-dependent manner. Our results indicate that this recruitment is hindered by NEDD4-mediated ubiquitination of SCAMP3. Depletion of BLTP2 was found to impede ILV/exosome formation and selectively diminish the levels of cone-shaped phospholipids, including bis(monoacylglycero)phosphate (BMP) and the BMP precursor phosphatidylglycerol (PG) within endosomes. BLTP2 knockout also hampered cell proliferation and tumorigenicity, which could be restored to a significant extent by supplementation with exosomes from wild-type cells. Since BLTP2 is associated with acute monocytic leukemia and is highly expressed in breast cancer, our findings suggest that BLTP2 transfers the BMP/LBPA precursor PG to MVBs for BMP/LBPA synthesis and promotes ILV/exosome formation at SCAMP3-dependent ER-MVB MCSs, a process crucial for cell proliferation and tumorigenesis.

cell biology↗

bioRxiv2024

Sec14L6 is a PS and PI4P transporter that promotes lipid droplet formation

Lipid droplets (LDs) are evolutionarily conserved organelles that are crucial for cellular metabolism. LD biogenesis and growth occurs in the ER and requires the supply of phospholipid from the ER, but the molecular basis is largely unclear. Here, we have identified Sec14L6, a unique protein of the Sec14 family, as a PS/PI4P transporter required for LD biogenesis. Sec14L6 knockout (KO) greatly reduces the number of LDs that can be rescued by wild-type rather than lipid transfer-defective Sec14L6 mutants. We found that Sec14L6 directly interacts with ACSL3, and that this interaction facilitates targeting of Sec14L6 to LDs and activates the PS transfer activity of Sec14L6 in vitro. We also identified PGRMC1, an ER membrane protein, as an adaptor that recruits Sec14L6 to the ER. Furthermore, depletion of Sec14L6 impairs differentiation of adipose-derived mesenchymal stem cells. Together, our study suggests that Sec14L6 transports PS and/or PI4P between the ER and LDs to promote LD formation.

cell biology↗