Identification of SAMT family proteins as substrates of MARCH11 in mouse spermatids

• Yogo, Keiichiro

• Tojima, Hidehiro

• Ohno, Jun-ya

• Ogawa, Takuya

• Nakamura, Nobuhiro

• Hirose, Shigehisa

• Takeya, Tatsuo

• Kohsaka, Tetsuya

抄録

MARCH11, a RING-finger transmembrane ubiquitin ligase, is predominantly expressed in spermatids and localized to the trans-Golgi network (TGN) and multivesicular bodies (MVBs). Because ubiquitination acts as a sorting signal of cargo proteins, MARCH11 has been postulated to mediate selective protein sorting via the TGN-MVB pathway. However, the physiological substrate of MARCH11 has not been identified. In this study, we have identified and characterized SAMT1, a member of a novel 4-transmembrane protein family, which consists of 4 members. Samt1 mRNA and its expression product were found to be specific to the testis and were first detected in germ cells 25 days after birth in mice. Immunohistochemical analysis further revealed that SAMT1 was specifically expressed in haploid spermatids during the cap and acrosome phases. Confocal microscopic analysis showed that SAMT1 co-localized with MARCH11 as well as with fucose-containing glycoproteins, another TGN/MVB marker, and LAPM2, a late endosome/lysosome marker. Furthermore, we found that MARCH11 could increase the ubiquitination of SAMT1 and enhance its lysosomal delivery and degradation in an E3 ligase activity-dependent manner. In addition, the C-terminal region of SAMT1 was indispensable for its ubiquitination and proper localization. The other member proteins of the SAMT family also showed similar expression profile, intracellular localization, and biochemical properties, including ubiquitination by MARCH11. These results suggest that SAMT family proteins are physiological substrates of MARCH11 and are delivered to lysosomes through the TGN-MVB pathway by a ubiquitin-dependent sorting system in mouse spermatids.

収録刊行物

• Histochemistry and Cell Biology

  Histochemistry and Cell Biology 137 (1), 53-65, 2011-11-11

  Springer

詳細情報

• CRID: 1050001202802147968
• NII論文ID: 120003518501
• NII書誌ID: AA11033302
• ISSN: 09486143
• ISSN: 1432119X
• Web Site: http://hdl.handle.net/10297/6213
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles