Transcription regulatory networks in Caenorhabditis elegans

a homolog of cadherin.

The cdk-7 gene encodes a cyclin-dependent kinase orthologous to human CDK7 (OMIM:601955) that is a component of the general transcription factor IIH (TFIIH) complex; CDK-7 is required during embryogenesis for mRNA transcription and phosphorylation of RNA polymerase II on serine 2 and serine 5, as well as for cell cycle progression, maintenance of ploidy, and completion of meiosis following fertilization.

cdk-9 encodes an ortholog of the metazoan transcription elongation factor kinase CDK-9; it is required for general expression of early embryonic genes, and thought (in conjunction with partners such as cyclin T) to form a transcription factor (P-TEFb) that which prevents transcription from stalling in vitro.

cec-1 encodes a nuclear protein with a chromodomain that is ubiquitously expressed in somatic cells, but is dispensable for embryonic survival or gross adult morphology.

ced-10 encodes a GTPase orthologous to human RAC1 (OMIM:602048) that is required for phagocytosis during programmed cell death and for migration of the distal tip cells of the somatic gonad; CED-10 functions in the engulfing cell during apoptosis, and is activated by a complex of CED-2(CrkII) and CED-5(DOCK180) to promote formation of the polarized cell extensions associated with cell corpse engulfment.

ceh-2 encodes a homeodomain protein homologous to Drosophila empty spiracles (EMS) and the vertebrate EMX1 and EMX2 proteins (OMIM:600034, 600035); although the exact biological role of CEH-2 in C. elegans development and/or behavior is not yet known, expression in pharyngeal neurons and muscle, as well as vulval cells (vulB1, vulB2, and vulC) at late stages of development suggests that CEH-2 may play a role in terminal differentiation events in diverse cell types.

ceh-10 encodes a member of the Paired-like class of homeodomain proteins; the CEH-10 homeodomain is closely related to the homeodomains of two vertebrate retina proteins (Chx10 from mice and Vsx-1 from goldfish); ceh-10 is required for CAN cell fate specification and migration, complete loss of ceh-10 function results in failure of CAN cell migration and loss of expression of CEH-23 and CEH-10 itself in the CAN and AIY interneurons; CEH-10, along with TTX-3 and CEH-23, constitutes a regulatory cascade of transcription factors that controls all sub-type specific features of the AIY interneurons.

ceh-14 encodes a LIM homeodomain protein orthologous to Drosophila Lim3 and the vertebrate Lhx3 and Lhx4 proteins; ceh-14 is required for specification of the AFD thermosensory neurons and for normal thermotactic behavior; a ceh-14::GFP reporter fusion is expressed in head and tail neurons, including the AFD thermosensory neurons, during late embryonic, larval, and adult stages. Animals triply mutant for the LIM homeobox genes ceh-14, lin-11, and ttx-3 which are required for function of the AFD, AIZ, and AIY neurons, respectively, exhibit a basic cryophilic thermotaxis response suggesting that, in C. elegans, there is more than one pathway for integration of thermosensory input.

ceh-20 encodes the C. elegans ortholog of the homeodomain co-factor Extradenticle (Exd/Pbx); together with ceh-40 and unc-62, ceh-20 activity is required for embryonic viability; ceh-20 is also required as a cofactor for LIN-39- and MAB-5- dependent postembryonic mesoderm patterning; in addition, ceh-20 is required for regulating post-embryonic migrations of the Q neuroblast descendants and for regulating vulval development; a CEH-20::GFP fusion protein is expressed in embryos and postembryonically in many cell types including the Q, P, and V cells and their descendants; CEH-20 localizes to the nucleus.

The ceh-22 gene encodes a NK-2 family homeodomain factor homologous to Drosophila TINMAN and vertebrate Nkx2-5 proteins.