Identification and characterization of a haploid germ cell-specific nuclear protein kinase (Haspin) in spermatid nuclei and its effects on somatic cells.
We have cloned the entire coding region of a mouse germ cell-specific cDNA encoding a unique protein kinase whose catalytic domain contains only three consensus subdomains (I-III) instead of the normal 12. The protein possesses intrinsic Ser/Thr kinase activity and is exclusively expressed in haploid germ cells, localizing only in their nuclei, and was thus named Haspin (for haploid germ cell-specific nuclear protein kinase). Western blot analysis showed that specific antibodies recognized a protein of Mr 83,000 in the testis. Ectopically expressed Haspin was detected exclusively in the nuclei of cultured somatic cells. Even in the absence of kinase activity, however, Haspin caused cell cycle arrest at G1, resulting in growth arrest of the transfected somatic cells. In a DNA binding experiment, approximately one-half of wild-type Haspin was able to bind to a DNA-cellulose column, whereas the other half was not. In contrast, all of the deletion mutant Haspin that lacked autophosphorylation bound to the DNA column. Thus, the DNA-binding activity of Haspin may, in some way, be associated with its kinase activity. These observations suggest that Haspin has some critical roles in cell cycle cessation and differentiation of haploid germ cells.
Tanaka
H
H
Department of Science for Laboratory Animal Experimentation, Osaka University, 3-1 Yamadaoka, Suita City, Osaka 565-0871, Japan.
Yoshimura
Y
Y
Nozaki
M
M
Yomogida
K
K
Tsuchida
J
J
Tosaka
Y
Y
Habu
T
T
Nakanishi
T
T
Okada
M
M
Nojima
H
H
Nishimune
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000201:enzymology*; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015723:Gene Library; D006238:Haploidy; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013087:Spermatids / Q000201:enzymology*; D014018:Tissue Distribution
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C530657:Haspin protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases