Biology subjects

Woodman, P.

Publications and source records attributed to Woodman, P..

3 recordsLinked to original sources

bioRxiv2026

STRIPAK associates with Rabex5-Rabaptin5 to promote Rab5-dependent early endosome formation and EGFR transport

His Domain Protein Tyrosine Phosphatase (HD-PTP) is required for multivesicular body (MVB) formation and endosome maturation, with Rab5-GTP levels raised upon HD-PTP depletion (Parkinson et al., 2021. doi: 10/1242/jcs.259192). Mass Spectrometry-based interactomics revealed that HD-PTP depletion increased association of Rabaptin5, a component of the early endosome Rabex5-Rabaptin5 Rab5-GEF, with multiple components of STRIPAK (striatin-interacting phosphatase and kinase). Native IPs and co-expression studies confirmed association between STRIPAK and Rabex5-Rabaptin5, including Strip1-Rabex5 and SLMAP-Rabaptin5 interactions. Consistent with functional Rabaptin5-STRIPAK links, co-depletion of Strip1 or Rabaptin5 with HD-PTP restored normal early endosome positioning and Rab5 distribution. Strip1 depletion impaired formation of central, Rab5-positive early endosomes, reduced cellular Rab5-GTP levels, and prevented the accumulation of internalised EGF-EGFR into centrally located endosomes. SLMAP depletion accentuated the central clustering of early endosomes and other endosomal compartments while also retarding the generation of new, EGFR-containing endosomes and EGFR lysosomal transport. We conclude that STRIPAK is a novel co-assembly factor of Rabex5-Rabaptin5, exerting subunit-specific effects on early endosomes.

cell biology↗

bioRxiv2021

TOR complex 2 promotes proteasome dependent Pub1 (NEDD4 family E3 ligase) turnover in fission yeast.

Cells respond to changing nutrient environments by adjusting the abundance of surface nutrient transporters and receptors. This can be achieved by modulating ubiquitin-dependent endocytosis, which in part is regulated by the NEDD4 family of E3 ligases. Here we report novel regulation of Pub1, a fission yeast Schizosaccharomyces pombe member of the NEDD4-family of E3 ligases. We show that nitrogen stress inhibits Pub1 function, thereby increasing the abundance of the amino acid transporter Aat1 at the plasma membrane and enhancing sensitivity to the toxic arginine analogue canavanine. We show that TOR complex 2 (TORC2) signalling negatively regulates Pub1, thus TORC2 mutants under nutrient stress have decreased Aat1 at the plasma membrane and are resistant to canavanine. Inhibition of TORC2 signalling increases Pub1 phosphorylation, and this is dependent on Gsk3 activity. Addition of the Tor inhibitor Torin1 increases phosphorylation of Pub1 at serine 199 (S199) by 2.5-fold, and Pub1 protein levels in S199A phospho-ablated mutants are reduced. S199 is conserved in NEDD4 and is located immediately upstream of a WW domain required for protein interaction. Together, we describe how the major TORC2 nutrient-sensing signalling network regulates environmental control of Pub1 to modulate the abundance of nutrient transporters.

cell biology↗

bioRxiv2018

ESCRT-III accumulates in micronuclei with ruptured nuclear envelopes

1.Micronuclei represent the cellular attempt to compartmentalize DNA to maintain genomic integrity threatened by mitotic errors and genotoxic events. Micronuclei show aberrant nuclear envelopes that collapse, generating damaged DNA and promoting complex genome alterations. However, ruptured micronuclei also provide a pool of cytosolic DNA that stimulates anti-tumour immunity, revealing the complexity of micronuclei impact on tumour progression.\n\nThe ESCRT-III complex ensures nuclear envelope (NE) resealing during late mitosis and NE repair in interphase. Therefore, ESCRT-III activity maybe crucial for maintaining the integrity of other genomic structures enclosed by a nuclear envelope. ESCRT-III activity at the nuclear envelope is coordinated by the subunit CHMP7.\n\nWe show that CHMP7 and ESCRT-III protects against the genomic instability associated with micronuclei formation. Loss of ESCRT-III activity increases the population of micronuclei with ruptured nuclear envelopes, in interphase cells. Surprisingly, ESCRT-III is retained at acentric micronuclei suggesting that ESCRT-III cannot repair these structures. Depletion of CHMP7 expression removes ESCRT-III accumulations at ruptured micronuclei, and removes the population of micronuclei with damaged DNA also containing a sensor for cytosolic DNA.\n\nThus, ESCRT-III activity appears to protect from the consequence of genomic instability in a dichotomous fashion. Membrane repair activity prevents the occurrence of MN with weak envelopes; conversely, aberrant membrane remodelling at micronuclei generates a steady state pool of cytosolic DNA that may contribute to sustaining pro-inflammatory pathways in cancer cells.

cancer biology↗