Biology subjects

Verde, F.

Publications and source records attributed to Verde, F..

4 recordsLinked to original sources

bioRxiv2025

NDR1/2 kinases regulate cell polarization and cell motility through Cdc42 GTPase and Pard3 signaling in mammalian cells

Controlling cell polarity and the directionality of cell motility is critical for effective cell migration during wound healing. NDR (nuclear dbf2-related) kinase pathways have roles in cell morphogenesis that are conserved from yeast to humans. Here, we reveal that knockdown of NDR1/2 kinases significantly alters cell size, shape, and the actin cytoskeleton, while reducing migration persistence and impairing cell polarization in wound healing assays. Mechanistically, we find that NDR1/2 kinases regulate the spatial and temporal dynamics of Cdc42 GTPase. Reduced NDR kinase levels increase Cdc42 GTPase activity and disrupt Pard3 subcellular location. NDR kinases phosphorylate Pard3 at Serine144, and overexpressing Pard3 can partially restore wound healing in NDR-depleted cells, an effect lost when Serine144 is mutated. Finally, we determine that NDR1 knockdown significantly impairs wound closure in human skin ex vivo wound healing assays, highlighting NDR kinase physiological importance. Collectively, this study demonstrates that NDR kinases modulate cell motility and polarization through the control of Pard3 and Cdc42 signaling in human fibroblasts.

cell biology↗

bioRxiv2025

Control of stress-activated Cdc42 dynamics by the MAP kinase Sty1-NDR kinase Orb6 regulatory axis

Cdc42 is a Rho-family GTPase that controls cell polarization from yeast to human cells. In fission yeast, under normal growth conditions, Cdc42-GTP oscillates between cell tips to promote polarized growth. However, when exposed to environmental stressors, Cdc42 adopts an "exploratory" pattern of Cdc42 activation along the cell membrane. This pattern also occurs when the NDR kinase Orb6 is downregulated. Here, we describe the molecular mechanism behind the emergence of exploratory Cdc42 dynamics and identify a new substrate of Orb6 kinase, the Cdc42 GAP Rga3. Additionally, we show that MAP kinase Sty1, known for linking stress signals to the Cdc42 polarity module, negatively regulates Orb6 kinase. During nutritional stress, activation of Sty1 and inactivation of Orb6 are associated with chronological lifespan extension. Our findings reveal a novel mechanism controlling cell morphology during stress, with important implications for cell survival.

cell biology↗

bioRxiv2021

The Orb6-Sts5 Axis Regulates Stress Granule Formation and Heat Stress Response in Fission Yeast

Cellular response to environmental fluctuations, such as increased temperature, is crucial in promoting cell survival and plays an increasingly recognized role in cancer biology. Important cellular functions altered by heat stress are cell polarization and protein translation. Previous studies have shown that heat stress alters the dynamics of Cdc42, a key regulator of cell polarization in eukaryotes, and promotes RNP granule formation, reprogramming protein translation. The biological mechanisms underlying these vast changes are only partially known. Here, we report that conserved NDR kinase Orb6, a homologue of mammalian STK38, responds to heat stress and regulates heat stress resilience by modulating Cdc42 dynamics and promoting stress granule assembly. Also, we discovered a finely tuned mechanism whereby stress-activated MAP kinase Sty1 negatively regulates Orb6 kinase and Orb6 C-terminal phosphorylation during heat stress. Orb6 inhibition by Sty1 increases the sensitivity of the cell to heat stress in a temperature-specific manner, fostering increased stress resilience and metabolic adaptation. These observations highlight the role of NDR kinase in the process of heat adaptation and thermotolerance during environmental cell exposure to elevated temperatures. Summary statementNuclear Dbf2-related kinase Orb6 inhibition by stress-activated protein kinase Sty1 promotes heat stress resilience in a temperature specific manner.

cell biology↗

bioRxiv2020

Cdc42 GTPase Activating Proteins (GAPs) Maintain Generational Inheritance of Cell Polarity and Cell Shape in Fission Yeast

The highly conserved small GTPase Cdc42 regulates polarized cell growth and morphogenesis from yeast to humans. We previously reported that Cdc42 activation exhibits oscillatory dynamics in Schizosaccharomyces pombe cells. Mathematical modeling suggests that this dynamic behavior enables a variety of symmetric and asymmetric Cdc42 distributions to coexist in cell populations. For individual wild type cells, however, growth follows a stereotypical pattern where Cdc42 distribution is initially asymmetrical in young daughter cells and becomes more symmetrical as cell volume increases, enabling bipolar growth activation. To explore whether different states of Cdc42 activation are possible in a biological context, we examined S. pombe rga4{Delta} mutant cells, lacking the Cdc42 GTPase activating protein (GAP) Rga4. We found that monopolar rga4{Delta} mother cells divide asymmetrically leading to the emergence of both symmetric and asymmetric Cdc42 distributions in rga4{Delta} daughter cells. Using genetic screening approaches to identify mutants that alter the rga4{Delta} phenotype, we tested the predictions of different computational models that reproduce the unequal fate of daughter cells. We found experimentally that the unequal distribution of active Cdc42 GTPase in daughter cells is consistent with an unequal inheritance of another Cdc42 GAP, Rga6, in the two daughter cells. Our findings highlight the crucial role of Cdc42 GAP protein localization in determining the morphological fate of cell progeny and ensuring consistent Cdc42 activation and growth patterns across generations.

cell biology↗