Biology subjects

Wu, J. Z.

Publications and source records attributed to Wu, J. Z..

5 recordsLinked to original sources

bioRxiv2025

Mechanoresilience of lysosomes conferred by TMEM63A

Lysosomes are subject to perturbations that can cause damage to their limiting membrane. Osmotic shifts, pore-forming toxins, and the growth of luminal polymers or pathogens all stand to increase lysosomal membrane tension and/or disrupt the bilayer. In some contexts, this leads to lysosomal rupture and cell death. Here we describe a mechanism that enables lysosomes to sense and respond to acute increases in tension of their limiting membrane. We report that the lysosome-resident non-selective cation channel, TMEM63A, can drive the directional flux of monovalent cations, major osmoticants, out of the lumen when gated by mechanical tension on the organelle. This results in the ability for lysosomes to relieve hydrostatic pressure and, proportionally, membrane tension, affording lysosomes the time to acquire additional lipids. Lysosomes without this mechanism -either because TMEM63A is deleted or in the case when cells express disease-causing variants of TMEM63A- are an order of magnitude more sensitive to lysis upon increases to their membrane tension when compared to their wildtype counterparts. These findings suggest that lysosomes are capable of regulating hydrostatic pressure and volume in response to high tension.

cell biology↗

bioRxiv2025

Metabolomics biomarkers of frailty: a longitudinal study of aging female and male mice

Frailty is an age-related geriatric syndrome, for which the mechanisms remain largely unknown. We performed a longitudinal study of aging female (n = 40) and male (n = 47) C57BL/6NIA mice, measured frailty index and derived metabolomics data from plasma samples. We identify differentially abundant metabolites related to aging, determine frailty related metabolites via a machine learning approach, and generate a union set of frailty features, both in the whole cohort and in sex-stratified subgroups. Using the features, we perform an association study and build a metabolomics-based frailty clock. We find that frailty related metabolites are enriched for amino acid metabolism and metabolism of cofactors and vitamins, include ergothioneine, tryptophan, and alpha-ketoglutarate, and present sex dimorphism. We identify B vitamin metabolism related flavin adenine dinucleotide and pyridoxate as female-specific frailty biomarkers, and lipid metabolism related sphingomyelins, glycerophosphoethanolamine and glycerophosphocholine as male-specific frailty biomarkers. These associations are confirmed in a validation cohort, with ergothioneine and perfluorooctanesulfonate identified as robust frailty biomarkers. In summary, our results identify sex-specific metabolite biomarkers of frailty in aging, and shed light on potential mechanisms involved in frailty.

biochemistry↗

bioRxiv2021

Structure of mammalian V-ATPase with the TLDc domain protein mEAK7 bound

V-ATPases are rotary proton pumps that serve as signaling hubs with numerous proposed binding partners in cells. We used cryoEM combined with exhaustive focused classification to detect endogenous proteins that associate with V-ATPase from porcine kidney. A super-stoichiometric copy of subunit C was found in ~3% of complexes, while an additional ~1.6% of complexes bound mEAK-7, a protein with proposed roles in dauer formation in nematodes and mTOR signaling in mammals. High-resolution cryoEM of porcine kidney V-ATPase with recombinant mEAK-7 shows that mEAK-7s TLDc domain interacts with V-ATPases stator while its C-terminal helix binds V-ATPases rotor. This crosslink would be expected to inhibit rotary catalysis. However, unlike inhibition of yeast V-ATPase by the TLDc protein Oxr1p, exogenous mEAK-7 does not inhibit V-ATPase and mEAK-7 overexpression in cells does not alter lysosomal or phagosomal pH. Instead, cryoEM suggests that interaction of mEAK-7 with V-ATPase is disrupted by ATP-induced rotation of the rotor. Comparison of Oxr1p and mEAK-7 binding explains this difference. Together, these results show that differences in V-ATPase binding by TLDc domain-containing proteins can lead to effects ranging from strong inhibition to formation of labile interactions that are sensitive to the enzymes activity.

biochemistry↗

bioRxiv2021

Detection and quantification of the vacuolar H ATPase using the Legionella effector protein SidK

Acidification of secretory and endocytic organelles is required for proper receptor recycling, membrane traffic, protein degradation, and solute transport. Proton-pumping vacuolar ATPases (V-ATPases) are responsible for this luminal acidification, which increases progressively as secretory and endocytic vesicles mature. An increasing density of V-ATPase complexes is thought to account for the gradual decrease in pH, but available reagents have not been sufficiently sensitive nor specific to test this hypothesis. We introduce a new probe to localize and quantify V-ATPases in eukaryotic cells. The probe is derived from SidK, a Legionella pneumophila effector protein that binds to the V-ATPase A subunit. We generated plasmids encoding fluorescent chimeras of SidK1-278, and labeled recombinant SidK1-278 with AlexaFluor-568 to visualize and quantify V-ATPases with high specificity in live and fixed cells, respectively. We show that V-ATPases are acquired progressively during phagosome maturation, that they distribute in discrete membrane subdomains, and that their density in lysosomes depends on the subcellular localization of the lysosome.

cell biology↗

bioRxiv2019

RanBP2/Nup358 enhances RNAi activity by sumoylating and stabilizing Argonaute 1

RanBP2/Nup358 is one of the main components of the cytoplasmic filaments of the nuclear pore complex. It has been speculated that RanBP2, which has an E3 SUMO-ligase domain, may alter the composition of messenger ribonucleoprotein (mRNP) complexes as they emerge from the nuclear pore and thus regulate the ultimate fate of the mRNA in the cytoplasm. Four separate missense mutations in RanBP2 cause Acute Necrotizing Encephalopathy 1 (ANE1), which manifests as a sharp rise in cytokine production after common viral infections such as influenza and parainfluenza. However, how RanBP2 and its ANE1-associated mutations affect cytokine production is not well understood. Here we report that RanBP2 represses the translation of the interleukin-6 (IL6) mRNA, which encodes a cytokine that is aberrantly up-regulated in ANE1. Our data indicates that soon after its production, the IL6 mRNP recruits the RNA-induced silencing complex (RISC) bound to Let7 miRNA. After this mRNP is exported, RanBP2 sumoylates the RISC-component AGO1, thereby stabilizing it and enforcing mRNA silencing. Collectively, these results support a model whereby RanBP2 promotes an mRNP remodelling event that is critical for the miRNA-mediated suppression of clinically relevant mRNAs, such as IL6.

molecular biology↗