Biology subjects

Bembenek, J. N.

Publications and source records attributed to Bembenek, J. N..

3 recordsLinked to original sources

bioRxiv2018

Programmed Variations of Cytokinesis Contribute to Morphogenesis in the C. elegans embryo

While cytokinesis has been intensely studied, how it is executed during development is not well understood, despite a long-standing appreciation that various aspects of cytokinesis vary across cell and tissue types. To address this, we investigated cytokinesis during the invariant C. elegans embryo lineage and found several reproducibly altered parameters at different stages. During early divisions, furrow ingression asymmetry and midbody inheritance is consistent, suggesting specific regulation of these events. During morphogenesis, we find several unexpected alterations including migration of midbodies to the apical surface during epithelial polarization in different tissues. Aurora B kinase, which is essential for several aspects of cytokinesis, remains localized to the apical membrane after internalization of other midbody components. Inactivation of Aurora B causes cytokinesis failure, which disrupts polarization and tissue formation. Therefore, cytokinesis shows surprising diversity during development and is required during epithelial polarization to establish cellular architecture during morphogenesis.

cell biology↗

bioRxiv2017

Conservation of separase N-terminal domain

We report a reanalysis of the sequence conservation of the cell cycle regulatory protease, separase. The sequence and structural conservation of the protease domain has long been recognized. Here we reexamine the protein sequence conservation at the N-terminus using PSI-BLAST analysis and report our discovery of a cysteine rich motif (CxCXXC) conserved in nematodes and vertebrates. This motif is found in a solvent exposed linker region connecting two TPR-like helical motifs. Mutation of this motif in Caenorhabditis elegans separase leads to a temperature sensitive hypomorphic protein, and several N-terminal residues identified as intragenic suppressors are not conserved. Conservation of this motif in multiple organisms raises the possibility that the motif plays similar roles across species.

bioinformatics↗

bioRxiv2017

Genetic Identification of Novel Separase regulators in Caenorhabditis elegans

Separase is a highly conserved protease required for chromosome segregation. Although observations that separase also regulates membrane trafficking events have been made, it is still not clear how separase achieves this function. Here we present an extensive ENU mutagenesis suppressor screen aimed at identifying suppressors of sep-1(e2406), a temperature sensitive maternal effect embryonic lethal separase mutant. We screened nearly a million haploid genomes, and isolated sixty-eight suppressed lines. We identified fourteen independent intragenic sep-1(e2406) suppressed lines. These intragenic alleles map to seven SEP-1 residues within the N-terminus, compensating for the original mutation within the poorly conserved N-terminal domain. Interestingly, 47 of the suppressed lines have novel mutations throughout the entire coding region of the pph-5 phosphatase, indicating that this is an important regulator of separase. We also found that a mutation near the MEEVD motif of HSP-90, which binds and activates PPH-5, also rescues sep-1(e2406) mutants. Finally, we identified six potentially novel suppressor lines that fall into five complementation groups. These new alleles provide the opportunity to more exhaustively investigate the regulation and function of separase.

genetics↗