Biology subjects

Dalal, S. N.

Publications and source records attributed to Dalal, S. N..

4 recordsLinked to original sources

bioRxiv2024

14-3-3 epsilon inhibits premature centriole disengagement by inhibiting the activity of Plk1 and Separase.

The 14-3-3 protein family regulates several pathways in mammalian cells, including centrosome duplication. However, the precise mechanisms by which 14-3-3 paralogs regulate the centrosome cycle remain unclear. To identify the mechanisms by which 14-3-3{varepsilon} regulates centrosome duplication, we altered two conserved acidic residues in the 14-3-3{varepsilon} phospho-peptide-binding pocket that regulate complex formation and dissociation with the associated ligands, D127 and E134, to Alanine. Altering these residues to Alanine led to opposing effects on centrosome duplication; the D127A mutant inhibited centrosome duplication, while cells expressing the E134A mutant showed the presence of supernumerary centrosomes. We demonstrate that 14-3-3{varepsilon} does not inhibit centriole duplication, as reported for 14-3-3{gamma}, but inhibits centriole disengagement. Using a combination of pharmacological and genetic approaches, we demonstrate that 14-3-3{varepsilon} inhibits the activity of Plk1 and Separase, leading to disengagement defects that ultimately lead to decreased proliferation and cell death. Our work demonstrates that different 14-3-3 paralogs regulate different steps in the centrosome cycle, and disrupting complex formation between 14-3-3{varepsilon} and Plk1 or Separase could be a novel therapeutic strategy in tumor cells.

cell biology↗

bioRxiv2024

LCN2 promotes focal adhesion formation and invasion by stimulating Src activation.

Previous work has demonstrated that Lipocalin2 (LCN2) expression promotes invasion and migration in multiple tumor types. The mechanisms by which LCN2 promotes invasion and migration remain unclear. Previous work from our laboratory demonstrated that LCN2 promotes actin filament formation by inhibiting actin glutathionylation. In this report, we demonstrate that in addition to inhibiting actin glutathionylation, LCN2 stimulates invasion by promoting the formation of focal adhesions, which is independent of the ability of LCN2 to bind iron. LCN2 promotes focal adhesion formation by promoting the activation of c-Src by stimulating the expression of the transcription factor ETS1. ETS1 activates the expression of the protein phosphatase, PTP1B, resulting in the auto-activation of c-Src and increased paxillin phosphorylation leading to focal adhesion formation. These results demonstrate that LCN2 has iron-dependent and independent functions in promoting invasion and highlight the multiple mechanisms by which LCN2 promotes invasion and suggest that c-Src inhibitors could be used to treat invasive colorectal cancer. SUMMARYExpression of LCN2 is elevated in invasive colorectal cancer. We demonstrate that LCN2 promotes invasion by stimulating the formation of focal adhesions by promoting Src activation.

cell biology↗

bioRxiv2023

GPX4-VIM equates a proliferating DTP state in TNBC subtypes with converged vulnerabilities to autophagy and glutathione inhibition.

Frequent metastatic relapses in Triple-Negative Breast Cancer (TNBC) patients with residual disease is a clinical challenge, largely due to tumor heterogeneity and absence of strategies that target proliferating chemo-tolerant cells. Here, we longitudinally modeled cellular state transitions from dormant drug-tolerant persister (DTP) into proliferating drug-tolerant persister (PDTP) in cells representing all TNBC subtypes. Combining subcellular imaging with phenotypic and biochemical assays, we identified distinct and converged spectrums of alterations in TNBC-PDTPs. We show that PDTPs retain acquired resistance with increased invasion potential. Moreover, Basal-Like DTPs enter into a non-reversible mesenchymal state while luminal androgen receptor-positive gain partial-Epithelial-to-Mesenchymal Transition (EMT) with vimentin upregulation. PDTP state dwells on high autophagy with reduced glutathione and GPX4 levels, rendering it vulnerable to autophagy suppression and ferroptosis. Interestingly, we find that GPX4 negatively regulates EMT and autophagy in TNBC, and an inverse correlation of GPX4-VIM expression along with autophagy genes predicts survival in TNBC patients undergoing chemotherapy.

cancer biology↗

bioRxiv2019

14-3-3γ prevents centrosome duplication by inhibiting NPM1 function.

14-3-3 proteins bind to ligands via phospho-Serine containing consensus motifs. However, the molecular mechanisms underlying complex formation and dissociation between 14-3-3 proteins and their ligands remain unclear. We identified two conserved acidic residues in the 14-3-3 peptide-binding pocket (D129 and E136) that potentially regulate complex formation and dissociation. Altering these residues to Alanine led to opposing effects on centrosome duplication. D129A inhibited centrosome duplication while E136A stimulated centrosome amplification. These results were due to the differing abilities of these mutant proteins to form a complex with NPM1. Inhibiting complex formation between NPM1 and 14-3-3{gamma} led to an increase in centrosome duplication and overrode the ability of D129A to inhibit centrosome duplication. We identify a novel role of 14-3-3 in regulating centrosome licensing and a novel mechanism underlying the formation and dissociation of 14-3-3 ligand complexes dictated by conserved residues in the 14-3-3 family.

cell biology↗