A novel rat orthologue and homologue for the Drosophila crooked neck gene in neural stem cells and their immediate descendants.
The crooked neck (crn) gene of Drosophila melanogaster encodes a scaffold protein carrying multiple tetratricopeptide repeat (TPR) motifs, and its mutation results in a reduction in the number of neuroblasts and lethality during larval stages. Here, we isolated two structurally related genes from a rat embryonic brain cDNA library. One gene is the rat orthologue of crn, which encodes 690 amino acids including 16 copies of TPR. The other gene, ATH55, encodes an 855 amino acid protein including 21 TPR motifs, which presumably represents a rat crn homologue and an orthologue of human XAB2. Both genes are highly expressed in embryonic brain but their expressions decrease during development. ATH55-like immunoreactivity is present in the ventricular zone and newly formed cortical plate, while CRN-like immunoreactivity is more abundant in a younger ventricular zone. In agreement, both proteins were found to be enriched in cultured neural stem cells and to decrease in response to cell differentiation signals. As indicated for the yeast CRN-like protein, ATH55 and CRN immunoreactivities were both recovered in the nuclear fraction and detected in the splicing complex carrying pre-mRNA. These findings suggest that both TPR-motif-containing proteins are involved in RNA processing of mammalian neural stem cells and their immediate descendants.
Amada
Naoki
N
Molecular Neurobiology, Brain Research Institute, Niigata University, Asahimachi-dori 1-757, Niigata 951-8585, Japan.
Tezuka
Tomoyuki
T
Mayeda
Akila
A
Araki
Kazuaki
K
Takei
Nobuyuki
N
Todokoro
Kazuo
K
Nawa
Hiroyuki
H
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003342:Corpus Striatum / Q000166:cytology; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006133:Growth Substances / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012326:RNA Splicing / Q000502:physiology; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020449:Repetitive Sequences, Amino Acid; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D013687:Telencephalon / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics
D029721:Drosophila Proteins; D006133:Growth Substances; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D014157:Transcription Factors; C417244:XAB2 protein, human; C069204:crn protein, Drosophila