ERM proteins as integrators at the cell cortex : Gene knockout study

• Project/Area Number: 15370083
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Cell biology
• Research Institution: KYOTO UNIVERSITY
• Principal Investigator: TSUKITA Sachiko KYOTO UNIVERSITY, FACULTY OF MEDICINE, PROFESSOR, 医学部, 教授 (00188517)
• Project Period (FY): 2003 – 2004
• Project Status: Completed (Fiscal Year 2004)
• Budget Amount: ¥14,600,000 (Direct Cost: ¥14,600,000); Fiscal Year 2004: ¥6,700,000 (Direct Cost: ¥6,700,000); Fiscal Year 2003: ¥7,900,000 (Direct Cost: ¥7,900,000)
• Keywords: actin / ezrin / radixin / moesin / ERM / cytoskeleton / cell adhesion / cell motility / 細胞膜 / 情報伝達 / 分泌 / 膜融合 / 細胞接着

Research Abstract

Radixin deficiency causes deafness associated with progressive degeneration of cochlear stereocilia
We found that, in cochlear and vestibular sensory hair cells of adult wild-type mice, radixin was specifically enriched in stereocilia, specially-developed giant microvilli, and that radixin-deficient (Rdx^<-/->) adult mice exhibited deafness but no obvious vestibular dysfunction. Before the age of hearing onset (〜2 weeks), in the cochlea and vestibule of Rdx^<-/-> mice, stereocilia developed normally in which ezrin was concentrated instead of radixin. As these Rdx^<-/-> mice grew, ezrin-based cochlear stereocilia progressively degenerated, causing deafness, whereas ezrin-based vestibular stereocilia were maintained normally in adult Rdx^<-/-> mice. We thus concluded that radixin is indispensable for the hearing ability in mice through the maintenance of cochlear stereocilia, once-developed.
Achlorhydria by ezrin knockdown : defects in the formation/expansion of apical canaliculi in gastri c parietal cells
Loss of gastric acid secretion is pathologically known as achlorhydria. Acid-secreting parietal cells are characterized by abundant expression of ezrin (Vil2), one of ERM (ezrin/radixin/moesin) proteins, which generally cross-link actin filaments with plasma membrane proteins. Here we show the direct in vivo involvement of ezrin in gastric acid secretion. Ezrin-knockout (Vil2^<-/->) mice did not survive more than one week after birth, making difficult to examine gastric acid secretion. We then generated ezrin-knockdown (Vil2^<kd/kd>) mice by introducing a neomycin resistance cassette between exons 2 and 3. Vil2^<kd/kd> mice born at the expected Mendelian ratio exhibited growth retardation and a high mortality. 〜7% of Vil2^<kd/kd> mice survived to adulthood. Ezrin protein levels in Vil2^<kd/kd> stomachs decreased to <5% of the wild-type levels without compensatory up-regulation of radixin or moesin. Adult Vil2^<kd/kd> mice suffered from severe achlorhydria. Immunofluorescence and electron microscopy revealed that this achlorhydria was caused by defects in the formation/expansion of canalicular apical membranes in gastric parietal cells.

Research Products

• [Journal Article] Achlorhydria by ezrin knockdown : defects in the formation/expansion of apical canaliculi in gastric parietal cells (2005)
  • Author(s): Tamura, A., et al.
  • Journal Title: J.Cell Biol. (印刷中)
• [Journal Article] Odf2/cenexin-deficient mother centrioles lack the distal/subdistal appendages and the ability to generate primary cilia (2005)
  • Author(s): Ishikawa, H., et al.
  • Journal Title: Nature Cell Biology (印刷中)
• [Journal Article] Radixin deficiency causes deafness associated with progressive degeneration of cochlear stereocilia. (2004)
  • Author(s): Kitajiri, S., et al.
  • Journal Title: J.Cell Biol. 166 Pages: 559-570
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Radixin deficiency causes deafness associated with progressive degeneration of cochlear stereocilia. (2004)
  • Author(s): Kitajiri, S., Fukumoto, K., Hata, M., Sasaki, R, Katsuno, T., Nakagawa, T., Ito, J., Tsukita, Sh., Tsukita, Sa.
  • Journal Title: J.Cell Biol. 166 Pages: 559-570
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Structural basis of adhesion-molecule recognition by ERM proteins revealed by the crystal structure of the radixin-ICAM-2 complex (2003)
  • Author(s): Hamada, K., et al.
  • Journal Title: EMBO J. 22 Pages: 502-514
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Insights into a single rod-like heliz in activated radixin required for membrane-cytoskeletal cross-linking (2003)
  • Author(s): Hoeflich, K.P., et al.
  • Journal Title: Biochemistry 42 Pages: 11634-11641
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Structural basis of adhesion-molecule recognition by ERM proteins revealed by the crystal structure of the radixin-ICAM-2 complex. (2003)
  • Author(s): Hamada, K., Shimizu, T., Yonemura, S., Tsukita, Sh., Tsukita, Sa., Hakoshima, T.
  • Journal Title: EMBO J. 22 Pages: 502-514
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Insights into a single rod-like heliz in activated radixin required for membrane-cytoskeletal cross-linking (2003)
  • Author(s): Hoeflich, K.P., Tsukita, Sa., Hicks, L., Kay, C.M., Tsukita, Sh., Ikura M.
  • Journal Title: Biochemistry 42 Pages: 11643-11641
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Achlorhydria by ezrin knockdown : defects in the formation/expansion of apical canaliculi in gastric parietal cells
  • Author(s): Tamura, A., et al.
  • Journal Title: J.Cell Biol. (in press)
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Odf2/cenexin-deficient mother centrioles lack the distal/subdistal appendages and the ability to generate primary cilia
  • Author(s): Ishikawa, H., et al.
  • Journal Title: Nat.Cell Biol. (in press)
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Odf2/cenexin-deficient mother centrioles lack the distal/subdistal appendages and the ability to generate primary cilia
  • Author(s): Ishikawa, H., Kubo, A., Tsukita, Sh., Tsukita, Sa.
  • Journal Title: Nat.Cell Biol. (in press)
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Achlorhydria by ezrin knockdown : defects in the formation/expansion of apical canaliculi in gastric parietal cells
  • Author(s): Tamura, A., Kikuchi, S., Hata, M., Katsuno, T., Matsui, T., Hayashi, H., Suzuki, Y., Noda, T., Tsukita, Sh., Tsukita, Sa.
  • Journal Title: J.Cell Biol. (in press)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Hoeflich, K.P., et al.: "Insights into a single rod-like helix in activated radixin required for membrane-cytoskeletal cross-linking"Biochemistry. 42. 11634-11641 (2003)
• [Publications] Hamada, K., et al.: "Structural basis of adhesion-molecule recognition by ERM proteins revealed by the crystal structure of the radixin-ICAM complex"EMBO Journal. 22. 502-514 (2003)