title: TACE/ADAM17 is involved in germ cell apoptosis during rat spermatogenesis.
abstract: The pathways leading to male germ cell apoptosis in vivo are poorly understood, but are highly relevant for the comprehension of sperm production regulation by the testis. In this work, we show the evidence of a mechanism where germ cell apoptosis is induced through the inactivation and shedding of the extracellular domain of KIT (c-kit) by the protease TACE/a disintegrin and metalloprotease 17 (ADAM17) during the first wave of spermatogenesis in the rat. We show that germ cells undergoing apoptosis lacked the extracellular domain of the KIT receptor. TACE/ADAM17, a membrane-bound metalloprotease, was highly expressed in germ cells undergoing apoptosis as well. On the contrary, cell surface presence of ADAM10, a closely related metalloprotease isoform, was not associated with apoptotic germ cells. Pharmacological inhibition of TACE/ADAM17, but not ADAM10, significantly prevented germ cell apoptosis in the male pubertal rat. Induction of TACE/ADAM17 by the phorbol-ester phorbol 12-myristate 13-acetate (PMA) induced germ cell apoptosis, which was prevented when an inhibitor of TACE/ADAM17 was present in the assay. Ex-vivo rat testis culture showed that PMA induced the cleavage of the KIT extracellular domain. Isolation of apoptotic germ cells showed that even though protein levels of TACE/ADAM17 were higher in apoptotic germ cells than in nonapoptotic cells, the contrary was observed for ADAM10. These results suggest that TACE/ADAM17 is one of the elements triggering physiological germ cell apoptosis during the first wave of spermatogenesis.
authors.affiliation: Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Lizama
authors.forename: Diego
authors.initials: D
authors.lastname: Rojas-Benítez
authors.forename: Marcelo
authors.initials: M
authors.lastname: Antonelli
authors.forename: Andreas
authors.initials: A
authors.lastname: Ludwig
authors.forename: Ximena
authors.initials: X
authors.lastname: Bustamante-Marín
authors.forename: Jurriaan
authors.initials: J
authors.lastname: Brouwer-Visser
authors.forename: Ricardo D
authors.initials: RD
authors.lastname: Moreno
mesh_terms: D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016009:Chi-Square Distribution; D006877:Hydroxamic Acids / Q000494:pharmacology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D008297:Male; D019009:Proto-Oncogene Proteins c-kit / Q000502:physiology*; D012313:RNA / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D013737:Testis / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: C492546:GW280264X; D006877:Hydroxamic Acids; D012313:RNA; D019009:Proto-Oncogene Proteins c-kit; D051722:ADAM Proteins; D013755:Tetradecanoylphorbol Acetate