Transcription regulatory networks in Caenorhabditis elegans

che-12 encodes a conserved protein that contains at least seven predicted HEAT repeats; CHE-12 activity is required continuously in sensory neurons for formation of distal ciliary segments and thus, for normal sensory cilium morphology and function and chemotaxis to a subset of attractants, including sodium chloride; a che-12::gfp promoter fusion is expressed in the two phasmid neurons and the subset of amphid neurons that contain relatively simple cilia; a CHE-12::GFP protein localizes to cilia in a manner suggesting that it requires intraflagellar transport for proper localization, but is unlikely to be a core IFT particle component; che-12 expression in ciliated neurons is dependent upon the presence of the DAF-19 RFX transcription factor.

cht-1 encodes a chitinase orthologous to human chitinase-1 (OMIM:600031, mutations are associated with chitotriosidase deficiency); CHT-1 is predicted to function as an extracellular O-glycosyl hydrolase that hydrolyzes the glycosidic bond between two or more carbohydrates; in C. elegans, CHT-1 may play a role in embryogenesis, and may also be required for cuticle degradation during molting and degradation of chitin-containing pathogens as part of a host defense mechanism.

ckb-2 encodes an isoform of choline kinase whose activity has been verified in vitro; CKB-1 through CKB-4 comprise a related group ('B') of choline kinases; purified CKB-2 has a strong preference for choline over ethanolamine, a specific activity of 2.4 micromol/min/mg protein and a pH optimum near 10.

clc-1 encodes a claudin homolog, closely similar to CLC-2, that is required for normal cohesion of apical junctions in epithelia; claudins are integral membrane proteins with four transmembrane sequences that are found in mammalian tight junctions (TJs), induce TJs when transgenically expressed in cells normally lacking them, and can mediate the specific conductance of of specific ions (e.g., magnesium or calcium) through TJs while blocking the flow of water; CLC-1 maintains the impermeability ('barrier function') of epithelia, since clc-1(RNAi) animals have abnormal permeability of the pharynx to dyes; clc-1 is expressed in spermatheca, pharynx, intestine, hypodermis, the excretory-secretory system, and the cell-cell junctions of the vulva; in pharyngeal cells, CLC-1 colocalizes with AJM-1 in long thin lines, parallel to the pharyngeal axis and lining the lumenal surface, that appear to correspond with apical intercellular junctions.

clh-1 encodes two CLC-type chloride channels via alternative splicing, homologous to human CLC1 (OMIM:118425) and CLC2 (OMIM:600570); CLH-1a and CLH-1b are required for maintenance of normal body shape; null mutations of clh-1 cause abnormal alae and a wider body than normal, with the body phenotype being reversible by culture medium of high osmolarity.

cpi-2 encodes a protein that contains a cystatin-like domain.

clk-1 encodes the C. elegans ortholog of COQ7/CAT5, a highly conserved demethoxyubiquinone (DMQ) hydroxylase that is necessary for the biosynthesis of ubiquinone (coenzyme Q, Q9) from 5-demethoxyubiquinone (DMQ9); in C. elegans, CLK-1 activity is required for normal physiological rates of growth, development, behavior, and aging, as well as for normal brood sizes.

clp-6 encodes a calpain homolog that has significant identity to mammalian calpains over its whole length and that contains motifs typical of calpains, including a thiol (cysteine) protease active site and a Ca[2+]-binding domain; CLP-6 is not required for degenerative (necrotic-like) cell death in neurons induced by mutations such as mec-4(d), deg-3(d), or gsa-1(gf), since clp-6(RNAi) has no effect on such degeneration.

A receptor tyrosine phosphatase that negatively regulates the FGF receptorsignaling pathway; it localizes to the plasma membrane.

col-8 encodes a collagen, individually dispensable for viability and gross morphology, which is specifically expressed in dauers and adults but not in eggs or L4 larvae, like col-7, col-18, and col-19; the amino- and carboxyl-terminal cysteine-rich regions of COL-8 are most closely related to those of COL-19, COL-35, and COL-39.