Biology subjects

Ou, G.

Publications and source records attributed to Ou, G..

24 records · Page 2Linked to original sources

bioRxiv2023

A Plant Flavonol Rescues a Pathogenic Mutation Associated with Kinesin in Neurons

KIF1A, a microtubule-based motor protein responsible for axonal transport, is linked to a group of neurological disorders known as KIF1A-associated neurological disorder (KAND). Current therapeutic options for KAND are limited. Here, we introduced the clinically relevant KIF1A(R11Q) variant into the C. elegans homolog UNC-104, resulting in uncoordinated animal behaviors. Through genetic suppressor screens, we identified intragenic mutations in UNC-104s motor domain that rescued synaptic vesicle localization and coordinated movement. We showed that two suppressor mutations partially recovered motor activity in vitro by counteracting the structural defect caused by R11Q at KIF1As nucleotide-binding pocket. We found that supplementation with fisetin, a plant flavonol, improved KIF1A(R11Q) worms movement and morphology. Notably, our biochemical and single-molecule assays revealed that fisetin directly restored the ATPase activity and processive movement of human KIF1A(R11Q) without affecting wild-type KIF1A. These findings suggest fisetin as a potential intervention for enhancing KIF1A(R11Q) activity and alleviating associated defects in KAND.

cell biology↗

bioRxiv2023

Vacuolar H+-ATPase Determines Daughter Cell Fates through Asymmetric Segregation of the Nucleosome Remodeling and Deacetylase Complex

Asymmetric cell divisions (ACDs) generate two daughter cells with identical genetic information but distinct cell fates through epigenetic mechanisms. However, the process of partitioning different epigenetic information into daughter cells remains unclear. Here, we demonstrate that the nucleosome remodeling and deacetylase (NuRD) complex is asymmetrically segregated into the surviving daughter cell rather than the apoptotic one during ACDs in Caenorhabditis elegans. The absence of NuRD triggers apoptosis via the EGL-1-CED-9-CED-4-CED-3 pathway, while an ectopic gain of NuRD enables apoptotic daughter cells to survive. We identify the vacuolar H+-adenosine triphosphatase (V-ATPase) complex as a crucial regulator of NuRDs asymmetric segregation. V-ATPase interacts with NuRD and is asymmetrically segregated into the surviving daughter cell. Inhibition of V-ATPase disrupts cytosolic pH asymmetry and NuRD asymmetry. We suggest that asymmetric segregation of V-ATPase may cause distinct acidification levels in the two daughter cells, enabling asymmetric epigenetic inheritance that specifies their respective life-versus-death fates.

cell biology↗

bioRxiv2021

RPRM negatively regulates ATM levels involving its phosphorylation mediated by CDK4/CDK6

Sensitizing cancer cells to radio- and chemotherapy remains a hot topic in cancer treatment. Here it is identified that Protein Reprimo (RPRM) negatively regulates the levels of ataxia-telangiectasia mutated (ATM) protein kinase, a master regulator of DNA damage response (DDR) in the presence of DNA double-strand breaks (DSBs), resulting in impaired DNA repair efficiency and enhanced cellular sensitivity to genotoxic agents. Mechanistically, although RPRM is primarily located in cytoplasm, it rapidly translocates to nucleus shortly after induced by X-irradiation, interacts with ATM and promotes the nuclear export and proteasomal degradation of ATM. The nuclear translocation of RPRM is associated with its phosphorylation at serine 98, which is mediated by cyclin-dependent kinases 4/6 (CDK4/6). Inhibition of CDK4/6 stabilizes RPRM and promotes its nuclear import, in turn enhances the nuclear export of ATM and the reduction of ATM levels. As a result, RPRM overexpression and its phosphorylation inhibition sensitize cells to genotoxic agents. Moreover, RPRM deficiency significantly increases resistance to radiation-induced damage both in vitro and in vivo. These findings establish a crucial regulatory mechanism in which ATM is negatively modulated by RPRM, suggesting that RPRM may serve as a novel target for both cancer therapy and radiation protection.

cancer biology↗

bioRxiv2021

ECM dimensionality tunes actin tension to modulate the endoplasmic reticulum and spheroid phenotype

Primary tissue organoids and cell spheroids recapitulate tissue physiology with remarkable fidelity. We investigated how engagement with a three dimensional laminin-rich extracellular matrix supports the polarized, stress resilient spheroid phenotype of mammary epithelial cells. Cells within a three dimensional laminin-rich extracellular matrix decreased and redistributed the actin crosslinker filamin to reduce their cortical actin tension. Cells with low cortical actin tension had increased plasma membrane protrusions that promoted negative plasma membrane curvature and fostered protein associations with the plasma membrane, consistent with efficient protein secretion. By contrast, cells engaging a laminin-rich extracellular matrix in two dimensions had high filamin-dependent cortical actin tension, exhibited compromised endoplasmic reticulum function including increased expression of PKR-like Endoplasmic Reticulum Kinase signaling effectors, and had compromised protein secretion. Cells with low filamin-mediated cortical actin tension and reduced endoplasmic reticulum stress response signaling secreted, and assembled, a polarized endogenous basement membrane and survived better, and their spheroids were more resistant to exogenous stress. The findings implicate filamin-dependent cortical actin tension in endoplasmic reticulum function and highlight a role for mechanics in organoid homeostasis.

cell biology↗

bioRxiv2020

Spectrin-based Membrane Mechanics Is Asymmetric and Remodels during Neural Development

Perturbation of spectrin-based membrane mechanics causes hereditary elliptocytosis and spinocerebellar ataxia, but the underlying cellular basis of pathogenesis remains unclear. Here, we introduced the conserved disease-associated spectrin mutations into the C. elegans genome and studied the contribution of spectrin to neuronal migration and dendrite formation in developing larvae. The loss of spectrin generates an ectopic actin polymerization outside of the existing front and secondary membrane protrusions, leading to defective neuronal positioning and dendrite morphology in adult animals. Spectrin accumulates in the lateral and the rear of migrating neuroblasts and redistributes from the soma into the newly formed dendrites, indicating that the spectrin-based membrane skeleton is asymmetric and remodels to regulate actin assembly and cell shape during development. We affinity-purified spectrin from C. elegans and showed that its binding partner ankyrin functions with spectrin. Asymmetry and remodeling of membrane skeleton may enable spatiotemporal modulation of membrane mechanics for distinct developmental events. Significance StatementThe biomechanical regulation of neural development is largely unknown. The spectrin-based membrane skeleton is essential for the structural integrity of the plasma membrane. This study addresses the function and behavior of spectrin in neuroblast migration and dendrite formation. The loss of spectrin generates an ectopic actin polymerization outside of the existing front, leading to defective neuronal positioning and dendrite morphology. Spectrin is absent from the leading edge but accumulates in the posterior of migrating neuroblasts and redistributes from the soma into the nascent dendrites, indicating that the membrane skeleton is asymmetric and remodels. Asymmetry and remodeling of the membrane skeleton may enable spatiotemporal modulation of membrane mechanics for distinct developmental events.

developmental biology↗

bioRxiv2017

MAK and CCRK kinases regulate kinesin-2 motility in C. elegans neuronal cilia

Kinesin-2 motors power the anterograde intraflagellar transport (IFT), a highly ordered process that assembles and maintains cilia. It remains elusive how kinesin-2 motors are regulated in vivo. Here we perform forward genetic screen to isolate suppressors that rescue the ciliary defects in the constitutive active mutation of OSM-3-kinesin (G444E) in C. elegans sensory neurons. We identify the C. elegans DYF-5 and DYF-18, which encode the homologs of mammalian male germ cell-associated kinase (MAK) and cell cycle-related kinase (CCRK). Using time-lapse fluorescence microscopy, we show that DYF-5 and DYF-18 are IFT cargo molecules and are enriched at the distal segments of sensory cilia. Mutations of dyf-5 and dyf-18 generate the elongated cilia and ectopic localization of kinesin-II at the ciliary distal segments. Genetic analyses reveal that dyf-5 and dyf-18 are also important for stabilizing the interaction between IFT particle and OSM-3-kinesin. Our data suggest that DYF-5 and DYF-18 act in the same pathway to promote handover between kinesin-II and OSM-3 in sensory cilia.

cell biology↗