Gene knockout analysis of two gamma-tubulin isoforms in mice.
Gamma-tubulin regulates the nucleation of microtubules, but knowledge of its functions in vivo is still fragmentary. Here, we report the identification of two closely related gamma-tubulin isoforms, TUBG1 and TUBG2, in mice, and the generation of TUBG1- and TUBG2-deficient mice. TUBG1 was expressed ubiquitously, whereas TUBG2 was primarily detected in the brain. The development of TUBG1-deficient (Tubg1-/-) embryos stopped at the morula/blastocyst stages due to a characteristic mitotic arrest: the mitotic spindle was highly disorganized, and disorganized spindles showed one or two pole-like foci of bundled MTs that were surrounded by condensed chromosomes. TUBG2 was expressed in blastocysts, but could not rescue the TUBG1 deficiency. By contrast, TUBG2-deficient (Tubg2-/-) mice were born, grew, and intercrossed normally. In the brain of wild-type mice, TUBG2 was expressed in approximately the same amount as TUBG1, but no histological abnormalities were found in the Tubg2-/- brain. These findings indicated that TUBG1 and TUBG2 are not functionally equivalent in vivo, that TUBG1 corresponds to conventional gamma-tubulin, and that TUBG2 may have some unidentified function in the brain.
Yuba-Kubo
Akiko
A
Solution Oriented Research for Science and Technology, Japan Science and Technology Corporation, Sakyo-ku, Kyoto 606-8501, Japan.
Kubo
Akiharu
A
Hata
Masaki
M
Tsukita
Shoichiro
S
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D004622:Embryo, Mammalian / Q000378:metabolism*; D040461:Gene Components; D015151:Immunoblotting; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D008941:Spindle Apparatus / Q000378:metabolism; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism*
D017931:DNA Primers; D018076:DNA, Complementary; D020033:Protein Isoforms; D014404:Tubulin