High impact information on crn

• The sequence similarity and mutant phenotypes are consistent with a cell cycle requirement for the crn gene product [1].
• Loss of zygotic expression of crn causes defects in the proliferation of brain neuroblasts and results in the absence of identified neuronal lineages in the central and peripheral nervous systems [1].
• In this issue of Neuron, Edenfeld et al. identified a novel function for two regulators of mRNA splicing in Drosophila: peripheral glial cells require Crooked neck (Crn) and Held out wings (HOW) to mediate migration and ensheathment of peripheral axons [2].
• Moreover, reducing the levels of Cdc16 or Cdc27 by >90% in tissue culture cells led to a transient mitotic arrest that was both biochemically and morphologically distinct [3].
• CCN1 is homologous to the Saccharomyces cerevisiae CLF1 gene, which is required for pre-mRNA splicing, cell cycle progression, and DNA replication, and to the Drosophila melanogaster crn gene, which is involved in neurogenesis [4].

Biological context of crn

• Of the eight lethal complementation groups two are recessive embryonic lethals: hemizygous giant (gt) embryos possess segmental defects, and hemizygous crooked neck (crn) embryos exhibit a twisted phenotype [5].
• The D. virilis P1 clones were also used to determine the physical relations between ten genes that are located in the X chromosome of Drosophila melanogaster between the markers crn (2F1) and omb (4C5-6) [6].
• The Drosophila crooked neck (crn) gene encodes an unusual TPR-containing protein whose function is essential for embryonic development [7].
• The unusual crn protein consists of sixteen tandem repeats of the 34 amino acid tetratricopeptide (TPR) protein recognition domain [8].

Anatomical context of crn

• Analysis of these mutations in the female germ line indicates that gt does not show a maternal effect, whereas normal activity of crn is required for germ cell viability [5].
• Crooked neck is a component of the human spliceosome and implicated in the splicing process [9].

References