Biology subjects

Kew, C.

Publications and source records attributed to Kew, C..

3 recordsLinked to original sources

bioRxiv2025

Vitamin B12 alleviates Verheij syndrome-like defects via phospholipid remodeling in a C. elegans PUF60 spliceosomopathy model

Verheij syndrome (VRJS) is a rare genetic disorder caused by mutations in the poly(U)-binding splicing factor 60 (PUF60), a core component of the spliceosomal complex. VRJS triggers multiple congenital anomalies, but the underlying pathomechanisms remain poorly understood. Mutation of the Caenorhabditis elegans PUF60 ortholog, rnp-6, recapitulates several hallmarks of VRJS, including growth delay and smaller body size. Here, we demonstrate that developmental defects in rnp-6 mutants are rescued by dietary K12-type Escherichia coli strains. Through complementary genetic screens and multi-omics analyses, we identify vitamin B12 (VB12) as a potent suppressor of these defects, acting via the methionine/S-adenosylmethionine/phosphatidylcholine metabolic axis. Mechanistically, rnp-6 mutation causes aberrant splicing with methionine and phospholipid metabolism-related genes, which cumulatively impair cellular methylation potential, dysregulate phosphatidylcholine metabolism, and induce integrated stress response. We identify intron retention of the nhr-114/HNF4 transcription factor as a primary driver of growth defects, and restoring its splicing robustly suppresses these phenotypes. VB12 supplementation bypasses the aberrant splicing, restores metabolic balance, and activates mTORC1 to rescue developmental phenotypes. Finally, we show that PUF60 deficiency induces aberrant splicing of methionine and phospholipid metabolism-related genes in a human cell line, and is associated with altered plasma methionine and phospholipid levels in VRJS patients. Our findings establish C. elegans as a tractable model for VRJS and uncover SAM/SAH/phospholipid dysregulation as a key mechanism underlying the spliceosomopathy, suggesting VB12 as a potential strategy to mitigate VRJS-related anomalies.

genetics↗

bioRxiv2024

Intracellular lipopolysaccharide regulates ER remodeling upon bacterial infection

Selective autophagy of the endoplasmic reticulum (ER), termed ERphagy or reticulophagy, plays a key role in organelle remodeling and cellular homeostasis. However, whether and how ERphagy is regulated during Gram-negative bacteria infection to influence host responses remains unclear. Here, we show that Salmonella enterica serovar Typhimurium releases lipopolysaccharide (LPS) that colocalizes with RETREG1/FAM134B, a reticulon-like ER-resident receptor for ERphagy. Cytosolic delivery of LPS, either during infection or via transfection, markedly increases RETREG1- and LC3B-decorated ER fragments. Mechanistically, affinity-isolation assays demonstrate that LPS directly binds RETREG1 through interactions between lipid A and positively charged residues within its amphipathic helices and C-terminal region. This interaction promotes RETREG1 oligomerization and drives ER membrane fragmentation, a process further amplified by the O-antigen moiety of LPS. The resulting ER fragments accumulate around LC3-positive Salmonella-containing vacuoles, facilitating bacterial clearance. Importantly, both intracellular and extracellular Salmonella exploit outer membrane vesicles (OMVs) to deliver LPS into the host cytosol, triggering RETREG1 activation and ER remodeling. Collectively, our findings reveal a previously unrecognized host response by which LPS of Gram-negative bacteria are sensed by the host ERphagy machinery to promote xenophagy and enhance antibacterial defense.

cell biology↗

bioRxiv2022

Decreased spliceosome fidelity inhibits mTOR signalling and promotes longevity via an intron retention event

Changes in splicing fidelity are associated with loss of homeostasis and ageing1-3, yet only a handful of splicing factors have been shown to be causally required to promote longevity 1-3, and the underlying mechanisms and downstream targets in these paradigms remain elusive. Surprisingly, we found a hypomorphic mutation within RNP-6/PUF60, a spliceosome component promoting weak 3 splice site recognition, which causes aberrant splicing, elevated stress responses, and enhances longevity in Caenorhabditis elegans. Through genetic suppressor screens, we identify a gain-of-function mutation within rbm-39, an RNP-6 interacting splicing factor, which increases nuclear speckle formation, alleviates splicing defects and curtails longevity caused by rnp-6 mutation. By leveraging the splicing changes induced by RNP-6/RBM-39 activities, we uncover a single intron retention event in egl-8/phospholipase C B4 as a key splicing target prolonging life. Genetic and biochemical evidence show that neuronal RNP-6/EGL-8 downregulate mTORC1 signaling to control organismal life span. In mammalian cells, PUF60 downregulation also potently and specifically inhibits mTORC1 signaling. Altogether, our results reveal that splicing fidelity modulates mTOR signaling and suggest a potential therapeutic strategy to delay ageing.

genetics↗