Auswirkungen einer Sertoli Zell-spezifischen Deletion des Connexin43-Gens auf die Regulation der Spermatogenese in transgenen Mäusen unter Verwendung des Cre/LoxP-Rekombinasesystems

• Applicant: Professor Dr. Ralph Brehm
• Subject Area: Veterinary Medical Science
• Term: from 2006 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 16154262

• Final Report Year: 2009

Final Report Abstract

The predominant testicular gap junctional protein Coimexin43 (Cx43) is located between neighbouring Sertoli cells (SC) and between SC and germ cells. It is involved in testicular development, germ cell differentiation, initiation and maintenance of spermatogenesis. As total disruption of the cx43 gene leads to perinatal death, our group generated a conditional cx43 knockout (KO) mouse using the Cre/loxP recombination system which lacks the cx43 gene solely in SC (SCCx43KO) to evaluate the SC specific functions of cx43 on spermatogenesis in-vivo. In our studies we demonstrated that the male progeny was viable and underwent successful excision of one or both alleles of the Cx43 gene only in SC. Adult SCCx43KO-/-mice showed normal testis descent and development of the urogenital tract, but testis size and weight was drastically lower when compared with heterozygous and wild-type (WT) littermates. Histological analysis and quantitation of mRNA expression of germ cell-specific marker genes revealed a significant reduction in the number of spermatogonia with only a few tubules left showing normal spermatogenesis. Thus, SC-specific deletion of cx43 mostly resulted in an arrest of spermatogenesis at the level of spermatogonia or SC-only syndrome and to intratubular SC clusters. In conclusion, results using our SCCx43KO mouse model indicate that (1) Cx43 expression in SC is an absolute requirement for normal testicular development and the initiation of spermatogenesis. (2) Cx43 in SC is urgently needed for the expansion of the germ cell population in adult mice as the SC-specific deletion of Cx43 leads to a significant germ cell deficiency. (3) Cx43 expression is essential for the cessation of proliferation and normal maturation of SC supporting the concept that Cx43 represents a key regulator of Sertoli cell development. Finally, our transgenic mouse model will contribute to clarify the functional roles of Cx43 in normal and impaired spermatogenesis, as well as its role in the etiology and pathogenesis of human spermatogenic disorders.

Publications

• Effects of a Sertoli cell specific knockout of the connexin43-gene on the regulation of spermatogenesis in transgenic mice using the Cre/loxP-recombination system. Andrologia 2005; 37, 235-236.
  Brehm R, Rütfinger C, Kibschull M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M
  
• Effects of a Sertoli cell specific knockout of the connexin43-gene on the regulation of spermatogenesis in transgenic mice using the Cre/IoxP-recombination system. Ital J Anat Embryol 2006; 111,7.
  Brehm R, Rüttinger C, Kibschull M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M.
  
• Effects of a Sertoli cell specific knockout of the connexin43-gene on the regulation of spermatogenesis in transgenic mice using the Cre/loxP-recombination system. Reprod Domest Anim 2006; 41,7.
  Brehm R, Rütfinger C, Kibschull M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M
  
• Untersuchung des Spermatogenesephänotyps in transgenen Mäusen mit Sertoli Zell-spezifischem Knockout des Connexin43-Gens. J Reprod Med Endocrinol 2006; 4, 244.
  Zeiler M, Kibschull M, Winterhager E, Willecke K, Guillou F, Steger K, Komad L, Bergmann M, Brehm R.
  
• Untersuchungen zum Spermatogenesephänotyp in transgenen Mäusen mit Sertoli Zell-spezifischem Knockout des Connexin43-Gens. DOI 10.3337/anatges.2006.0003; 184.
  Zeiler M, Kibschull M, Winterhager E, Willecke K, Guillou F, Steger K, Konrad L, Bergmann M, Brehm R.
  
• (2007) A Sertoli cell-specific knockout of connexin43 prevents initiafion of spermatogenesis. Am J Pathol 171: 19-31.
  Brehm R, Zeiler M, Rüttinger C, Kibschull M, Winterhager E, Willecke K, Guillou F, Lecureuil C, Steger K, Konrad L, Biermann K, Failing K, Bergmann M
  
• (2007) Role of connexin43 in Sertoli cells of testis. AnnN Y Acad Sei 1120: 131-143.
  Sridharan S, Brehm R, Bergmann M, Cooke PS
  
• Blood-testis barrier formafion in condifional Sertoli cell connexin43 knockout (SCCx43KO) mice is associated with an altered occludin gene expression. Magy Allatorv Lapja (Hungarian Veterinary Joumal, Supplement III) 2008; 130, 35.
  Zeiler M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M, Brehm R
  
• Differentiation of the blood-testis barrier in conditional Sertoli cell connexin43 knockout (SCCx43KO) mice. DOI 10.3337/anatges.2008.0005; 8.
  Zeiler M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M, Brehm R.
  
• Loss of connexin43 in Sertoli cells seems not to be associated with funcfional impairment of blood-tesfis barrier formation in mice. Reprod Domest Anim 2008; 43, 36.
  Zeiler M, Winterhager E, Willecke K, Guillou F, Steger K, Bergmann M, Brehm R.