Identification and Characterization of a Haploid Germ Cell-specific Nuclear ProteinKinase (Haspin) in Spermatid Nuclei and Its Effects on Somatic Cells

Hiromitsu Tanaka; Yasuhide Yoshimura; Masami Nozaki; Kentaro Yomogida; Junji Tsuchida; Yasuhiro Tosaka; Toshiyuki Habu; Tomoko Nakanishi; Masato Okada; Hiroshi Nojima; Yoshitake Nishimune

doi:10.1074/jbc.274.24.17049

June 1, 1999Journal of Biological ChemistryOpen Access

Identification and Characterization of a Haploid Germ Cell-specific Nuclear ProteinKinase (Haspin) in Spermatid Nuclei and Its Effects on Somatic Cells

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Key Points

To clone and functionally characterize Haspin, a novel germ cell-specific protein kinase expressed in spermatid nuclei, and determine its regulatory effects on cell growth.
Cloned full-length cDNA from mouse testis libraries and engineered wild-type and catalytic deletion mutant constructs.
Evaluated intrinsic Ser/Thr kinase and autophosphorylation activity via in vitro kinase assays and Western blot analysis.
Expressed Haspin constructs in cultured somatic cells to analyze nuclear localization, cell cycle kinetics via flow cytometry, and DNA-binding properties on DNA-cellulose columns.
Identified Haspin as an 83 kDa nuclear Ser/Thr protein kinase possessing an atypical catalytic core containing only three consensus subdomains, expressed exclusively in haploid round spermatids.
Ectopic expression of Haspin arrested somatic cells at the G1 phase and ceased cell proliferation, even when catalytic kinase activity was absent.
DNA-cellulose binding assays showed that 100% of kinase-inactive mutant Haspin bound DNA compared to approximately 50% of wild-type Haspin, indicating autophosphorylation modulates DNA affinity.

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Implication

In vitro and cell culture study demonstrates nuclear kinase Haspin induces G1 cell cycle arrest, suggesting a key role in haploid germ cell differentiation.

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Tanaka et al. (1999) studied this question.

synapsesocial.com/papers/6a109c7d10ed65f1d0fd1630 https://doi.org/10.1074/jbc.274.24.17049

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Identification and Characterization of a Haploid Germ Cell-specific Nuclear ProteinKinase (Haspin) in Spermatid Nuclei and Its Effects on Somatic Cells

Key Points

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Implication

Discussion

Cite This Study

Identification and Characterization of a Haploid Germ Cell-specific Nuclear ProteinKinase (Haspin) in Spermatid Nuclei and Its Effects on Somatic Cells

Key Points

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Implication

Discussion

Cite This Study

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