Biology subjects

Matter, K.

Publications and source records attributed to Matter, K..

7 recordsLinked to original sources

bioRxiv2025

ZONAB regulates DNA methylation and mitochondrial function to control endothelial cell senescence

Regulation of the endothelial stress response is important for blood vessel homeostasis and angiogenesis, processes disrupted in common vascular diseases and ageing. Here, we discovered that the Y-box factor ZONAB (ZO-1-associated nucleic acid binding protein; YBX3), a gene associated with risk loci for severe vascular disorders, regulates endothelial homeostasis and angiogenesis. By combining cell-based assays with primary endothelial cells and genome-wide expression and methylation measurements, we found that ZONAB depletion results in mitochondrial deregulation, increased reactive oxygen species and a defective oxidative stress response, as well as increased promoter methylation of cell cycle genes. Consequently, ZONAB depletion triggered cellular senescence via a phosphatidylinositol 3-kinase (PI3K)/Akt-dependent pathway, which was attenuated by an antioxidant or by drugs targeting mitochondrial function or fragmentation. Thus, our results reveal how ZONAB controls changes in gene expression and DNA methylation to regulate endothelial proliferation, inflammation, and angiogenesis, indicating a central role of ZONAB in vascular health.

cell biology↗

bioRxiv2025

Arhgef18 is a component of the outer limiting membrane required for retinal homeostasis

Biallelic ARHGEF18 mutations cause human adult-onset retinal degeneration. We now find that Arhgef18 associates with the retinal outer limiting membrane (OLM), an adherens junction between Muller glia and photoreceptors. Arhgef18 knockout in Muller glial cells led to OLM disruption and vision loss by P60. While mice developed morphologically normal retinas, retinal rosettes started to form by P8, and retinas then progressively degenerated with OLM disintegration, retinal thinning, and vascular leakage. ARHGEF18/p114RhoGEF depletion in Muller cells in culture confirmed disruption of junctional recruitment of OLM proteins. Depletion also induced activation of NF-{kappa}B and {beta}-catenin signalling, activation of the multifunctional kinase Tank-binding kinase 1 (TBK1) and reduced mitochondrial activity. TBK1 inhibition or directly supporting mitochondrial activity with nicotinamide attenuated NF-{kappa}B and {beta}-catenin signalling and rescued mitochondrial activity. Thus, Arhgef18 is essential for OLM maintenance, and its disruption leads to activation of mechanisms that are targetable for possible therapeutic approaches.

cell biology↗

bioRxiv2025

Interdependent regulation of trabecular meshwork cell physiology and intraocular pressure by KALRN and TMCO1

Glaucoma is a leading cause of irreversible blindness. Primary open-angle glaucoma (POAG) is its most common form. Higher intraocular pressure (IOP), resulting from impaired aqueous humour outflow, is the cardinal mediating factor, and all proven treatments aim to lower IOP. POAG is a complex genetic disease with numerous loci linked to POAG and higher IOP. The mechanisms by which risk alleles cause disease remain unclear. Here, using primary trabecular meshwork (TM) cells, a cell type controlling outflow, and mice, we found that the POAG-associated gene KALRN encodes an endoplasmic reticulum (ER)-associated Rac regulator essential for TM homeostasis and normal IOP. KALRN loss caused widespread disruption from ER to calcium homeostasis and energy metabolism, leading to induction of cell senescence. KALRN-depletion also led to suppression of the ER translocase and calcium regulator TMCO1, encoded by a gene at one of the most significantly associated genomic loci for POAG. TMCO1-depletion in vitro and in vivo phenocopied KALRN-induced phenotypes, and reduced KALRN expression. These findings establish KALRN and TMCO1 as interdependent regulators of TM homeostasis and IOP, that link regulation of ER and intracellular calcium homeostasis to cell and tissue physiology, and illustrate how different genes linked to glaucoma can form regulatory pathways.

cell biology↗

bioRxiv2024

Inhibition of GEF-H1-RhoA signaling in inflammation with a stapled peptide mimicry of the RhoA67-78 helix

Guanine exchange factors (GEFs) are considered hard to drug with conventional small molecules, they lack conventional deep binding pockets and binding ligands are seldom reported. Here we report the design of a stapled peptide stP5 targeting the interaction between cytoskeletal regulator RhoA GTPase and its activator guanine exchange factor H1 (GEF-H1). StP5 is a modified RhoA mimic based on a previously identified bioactive -helical epitope to GEF-H1. StP5 effectively inhibits GEF-H1-induced morphological and transcriptional changes in cellular models for inflammation and does not affect the related GEF p114RhoGEF (ARHGEF18). StP5 peptide is approximately 100 fold more active in cellular assays than the unstapled P5 peptide. We provide a bioinformatic analysis of the stP5 bindings site in different GEFs, providing a basis for this selectivity. The GEF-H1 inhibitor stP5 represents a step towards fully drugging GEF-H1. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=102 SRC="FIGDIR/small/624118v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@d783b3org.highwire.dtl.DTLVardef@10798b2org.highwire.dtl.DTLVardef@1ba0817org.highwire.dtl.DTLVardef@693367_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2023

ZO-1 regulates Hippo-independent YAP activity and cell proliferation via a GEF-H1- and TBK1-regulated mechanosensitive signalling network

Tight junctions are a barrier-forming cell-cell adhesion complex and have been proposed to regulate cell proliferation. However, the underlying mechanisms are not well understood. Here, we used cells deficient in the junction scaffold ZO-1 alone or together with its paralog ZO-2, which disrupts the junctional barrier. We found that ZO-1 knockout increased cell proliferation, loss of cell density-dependent proliferation control, and promoted cell death. These phenotypes were enhanced by double ZO-1/ZO-2 knockout. Increased proliferation was dependent on YAP and ZONAB, two transcriptional regulators. ZO-1 knockout stimulated YAP nuclear translocation and activity without changes in Hippo-dependent phosphorylation. Knockout promoted TANK-binding Kinase 1 (TBK1) activation and increased expression of the RhoA activator GEF-H1. Knockdown of ZO-3, another paralog interacting with ZO1, was sufficient to induce GEF-H1 expression and YAP activity. GEF-H1, TBK1, and mechanotransduction at focal adhesions were required for YAP/TEAD activation in ZO-1-deficient cells. Thus, ZO-1 controls cell proliferation and Hippo-independent YAP activity by activating a GEF-H1- and TBK1-regulated mechanosensitive signalling network.

cell biology↗

bioRxiv2022

Reciprocal regulation between cell mechanics and ZO-1 guides tight junction assembly and epithelial morphogenesis

Formation and maintenance of tissue barriers require the coordination of cell mechanics and cell-cell junction assembly. Here, we combined methods to modulate ECM stiffness and to measure mechanical forces on adhesion complexes to investigate how tight junctions regulate cell mechanics and epithelial morphogenesis. We found that depletion of the tight junction adaptor ZO-1 regulates cytoskeletal tension at cell-matrix and cell-cell interfaces in an ECM stiffness-regulated manner, possibly via differential organisation of the actin cytoskeleton. ZO-1 depletion inhibited junction assembly and disrupted morphogenesis in an ECM stiffness-dependent manner. Both processes were rescued by inhibition of cell contractility. Although ZO-1-deficient cells could assemble functional barriers at low tension, their tight junctions remained corrupted with strongly reduced and discontinuous recruitment of junctional components. Our results thus reveal that reciprocal regulation between ZO-1 and cell mechanics controls tight junction assembly and epithelial morphogenesis, and that tension-independent roles of ZO-1 control proper junction organisation.

cell biology↗

bioRxiv2021

Spatiotemporal Control of Actomyosin Contractility by MRCKβ Signaling Drives Phagocytosis

Phagocytosis requires myosin-generated contractile force to regulate actin dynamics. However, little is known about the molecular mechanisms that guide this complex morphodynamic process. Here we show that particle binding to Mer Tyrosine Kinase (MerTK), a widely expressed phagocytic receptor, stimulates phosphorylation of the Cdc42 GEF Dbl3 in the retinal pigment epithelium (RPE), triggering activation of MRCK{beta} and its co-effector N-WASP that cooperate to deform the membrane into cups. Continued MRCK{beta} activity then drives recruitment of a mechanosensing bridge enabling transmission of the cytoskeletal force required for cup closure and particle internalization. MRCK{beta} is also required for Fc receptor-mediated phagocytosis by macrophages. In vivo, MRCK{beta} is essential for RPE phagocytosis of photoreceptor debris and, hence, retinal integrity. MerTK-independent activation of MRCK{beta} signaling by a phosphomimetic Dbl3 mutant rescues phagocytosis in retinitis pigmentosa RPE cells lacking functional MerTK. Thus, conserved MRCK{beta} signaling controls spatiotemporal regulation of actomyosin contractility to guide actomyosin dynamics-driven phagocytosis and represents the principle phagocytic effector pathway downstream of MerTK.

cell biology↗