Identification and characterization of human Inscuteable gene in silico.

Neuroblast undergoes asymmetrical cell division to produce the neuroblast itself and ganglion mother cell along the apical-basal axis. Inscuteable (Insc) and Partner of Inscuteable (Pins) are translocated to the apical cell cortex during asymmetrical cell division of Drosophila neuroblast. Insc is implicated in the apical-basal orientation of mitotic spindle and the basal localization of Prospero (Pros) and Numb. Here, we identified and characterized human Inscuteable (INSC) gene using bioinformatics. Human INSC gene, consisting of at least 13 exons, was located within human genome draft sequence AC090744.5 (around nucleotide position 150581-16936 in reverse orientation). Human INSC gene, closely linked to CALCB gene with an interval of about 30 kb, was assigned to human chromosome 11p15.2-p15.1. Amino-acid sequence of human INSC polypeptide (579 aa) was determined based on exon sequences of human INSC gene. C. elegans hypothetical protein F43E2.3 (NP_495539), homologous to human INSC, was designated C. elegans Insc. Central INSC homologous (ISH) domain and C-terminal PDZ-binding motif were evolutionary conserved among INSC proteins. The former part of ISH domain is implicated in Pros localization, while function of the latter part of ISH domain and C-terminal PDZ-binding motif remain to be elucidated. Human INSC mRNA was expressed in eye, kidney, fetal cochlea, parathyroid tumor, chondrosarcoma, epidermoid carcinoma, and skin tumor. Because LGN/Pins, PARD3/Par-3Bazooka, PARD6A/Par-6 and PRKCZ/aPKC genes implicated in asymmetrical cell division are evolutionarily and functionally conserved, human INSC protein might be implicated in asymmetrical cell division of human neural stem cells and other stem cells.