Chloride intracellular channel (CLIC) protein function in S1P-induced Rac1 activation requires membrane localization of the C-terminus, but not thiol-transferase nor ion channel activities.

We have established a novel and evolutionarily-conserved function for chloride intracellular channel proteins (CLICs) in regulating Rho/Rac GTPases downstream of G protein-coupled receptors (GPCRs). Endothelial CLIC1 and CLIC4 are rapidly and transiently re-localized from the cytoplasm to the plasma membrane in response to the GPCR ligand sphingosine-1-phosphate (S1P), and both CLICs are required to activate Rac1 in response to S1P, but how they perform this function remains unknown. Biochemical studies suggest that CLICs act as non-specific ion channels and/or as glutathione-S-transferases, dependent on N-terminal features, Here we investigate CLIC functional domains and membrane localization requirements for their function in S1P-mediated Rac1 signaling.

Chloride intracellular channel (CLIC) protein function in S1P-induced Rac1 activation requires membrane localization of the C-terminus, but not thiol-transferase nor ion channel activities.

We have established a novel and evolutionarily-conserved function for chloride intracellular channel proteins (CLICs) in regulating Rho/Rac GTPases downstream of G protein-coupled receptors (GPCRs). Endothelial CLIC1 and CLIC4 are rapidly and transiently re-localized from the cytoplasm to the plasma membrane in response to the GPCR ligand sphingosine-1-phosphate (S1P), and both CLICs are required to activate Rac1 in response to S1P, but how they perform this function remains unknown. Biochemical studies suggest that CLICs act as non-specific ion channels and/or as glutathione-S-transferases, dependent on N-terminal features, Here we investigate CLIC functional domains and membrane localization requirements for their function in S1P-mediated Rac1 signaling.

CLIC4 Regulates Endothelial Barrier Control by Mediating PAR1 Signaling via RhoA.

Background: Endothelial CLICs (chloride intracellular channel proteins) CLIC1 and CLIC4 are required for the GPCRs (G-protein-coupled receptors) S1PR1 (sphingosine-1-phosphate receptor 1) and S1PR3 to activate the small GTPases Rac1 (Ras-related C3 botulinum toxin substrate 1) and RhoA (Ras homolog family member A). To determine whether CLIC1 and CLIC4 function in additional endothelial GPCR pathways, we evaluated CLIC function in thrombin signaling via the thrombin-regulated PAR1 (protease-activated receptor 1) and downstream effector RhoA.

Methods: We assessed the ability of CLIC1 and CLIC4 to relocalize to cell membranes in response to thrombin in human umbilical vein endothelial cells (HUVEC).

A metazoan-specific C-terminal motif in EXC-4 and Gα-Rho/Rac signaling regulate cell outgrowth during tubulogenesis in C. elegans.

Chloride intracellular channels (CLICs) are conserved proteins for which the cellular and molecular functions remain mysterious. An important insight into CLIC function came from the discovery that Caenorhabditis elegans EXC-4/CLIC regulates morphogenesis of the excretory canal (ExCa) cell, a single-cell tube. Subsequent work showed that mammalian CLICs regulate vascular development and angiogenesis, and human CLIC1 can rescue exc-4 mutants, suggesting conserved function in biological tube formation (tubulogenesis) and maintenance.

Epithelial morphogenesis, tubulogenesis and forces in organogenesis.

As multi-cellular organisms evolved from small clusters of cells to complex metazoans, biological tubes became essential for life. Tubes are typically thought of as mainly playing a role in transport, with the hollow space (lumen) acting as a conduit to distribute nutrients and waste, or for gas exchange. However, biological tubes also provide a platform for physiological, mechanical, and structural functions.

A Screen of the Conserved Kinome for Negative Regulators of LIN-12 Negative Regulatory Region ("NRR")-Missense Activity in .

Genetic analysis of LIN-12/Notch signaling in has provided many insights into human biology. Activating missense mutations in the Negative Regulatory Region (NRR) of the ectodomain of LIN-12/Notch were first described in , and similar mutations in human Notch were later found to cause T-cell acute lymphoblastic leukemia (T-ALL). The ubiquitin ligase is the prototype of a conserved negative regulator of that was first defined by loss-of-function mutations that enhance NRR-missense activity in , and then demonstrated to regulate activity in mammalian cells and to be a tumor suppressor in T-ALL.

OrthoList 2: A New Comparative Genomic Analysis of Human and Genes.

OrthoList, a compendium of genes with human orthologs compiled in 2011 by a meta-analysis of four orthology-prediction methods, has been a popular tool for identifying conserved genes for research into biological and disease mechanisms. However, the efficacy of orthology prediction depends on the accuracy of gene-model predictions, an ongoing process, and orthology-prediction algorithms have also been updated over time. Here we present OrthoList 2 (OL2), a new comparative genomic analysis between and humans, and the first assessment of how changes over time affect the landscape of predicted orthologs between two species.

A network of conserved formins, regulated by the guanine exchange factor EXC-5 and the GTPase CDC-42, modulates tubulogenesis in vivo.

The C. elegans excretory cell (EC) is a powerful model for tubulogenesis, a conserved process that requires precise cytoskeletal regulation. EXC-6, an ortholog of the disease-associated formin INF2, coordinates cell outgrowth and lumen formation during EC tubulogenesis by regulating F-actin at the tip of the growing canal and the dynamics of basolateral microtubules.

The disease-associated formin INF2/EXC-6 organizes lumen and cell outgrowth during tubulogenesis by regulating F-actin and microtubule cytoskeletons.

We investigate how outgrowth at the basolateral cell membrane is coordinated with apical lumen formation in the development of a biological tube by characterizing exc-6, a gene required for C. elegans excretory cell (EC) tubulogenesis. We show that EXC-6 is orthologous to the human formin INF2, which polymerizes filamentous actin (F-actin) and binds microtubules (MTs) in vitro.

OrthoList: a compendium of C. elegans genes with human orthologs.

Background: C. elegans is an important model for genetic studies relevant to human biology and disease. We sought to assess the orthology between C.

Modulation of intracellular trafficking regulates cell intercalation in the Drosophila trachea.

Through intercalation, a fundamental mechanism underlying elongation during morphogenesis, epithelial cells exchange places in a spatially oriented manner. Epithelial cells are tightly coupled through distinct intercellular junctions, including adherens junctions. Whether trafficking-mediated regulation of adhesion through adherens junctions modulates intercalation in vivo remains controversial.

LIN-12/Notch trafficking and regulation of DSL ligand activity during vulval induction in Caenorhabditis elegans.

A novel mode of crosstalk between the EGFR-Ras-MAPK and LIN-12/Notch pathways occurs during the patterning of a row of vulval precursor cells (VPCs) in Caenorhabditis elegans: activation of the EGFR-Ras-MAPK pathway in the central VPC promotes endocytosis and degradation of LIN-12 protein. LIN-12 downregulation in the central VPC is a prerequisite for the activity of the lateral signal, which activates LIN-12 in neighboring VPCs. Here we characterize cis-acting targeting sequences in the LIN-12 intracellular domain and find that in addition to a di-leucine motif, serine/threonine residues are important for internalization and lysine residues are important for post-internalization trafficking and degradation.

Endocytosis-mediated downregulation of LIN-12/Notch upon Ras activation in Caenorhabditis elegans.

The coordination of signals from different pathways is important for cell fate specification during animal development. Here, we define a novel mode of crosstalk between the epidermal growth factor receptor/Ras/mitogen-activated protein kinase cascade and the LIN-12/Notch pathway during Caenorhabditis elegans vulval development. Six vulval precursor cells (VPCs) are initially equivalent but adopt different fates as a result of an inductive signal mediated by the Ras pathway and a lateral signal mediated by the LIN-12/Notch pathway.