title: Seasonal changes in immunoreactivity of activin signaling component proteins in wild ground squirrel testes.
abstract: The seasonal spermatogenesis and localization of inhibin/activin subunits (alpha, betaA, betaB) in the testes of wild ground squirrel has been previously described; however, the expression pattern of activin receptors and cytoplasmic signaling SMADs has not been detected in any seasonal breeders. The objective of this study was to investigate the abundance and cellular localization of activin signaling components in testes of the wild ground squirrel during the breeding and nonbreeding seasons. The immunolocalizations of ActRIIB (activin type II receptor B) and activin-related SMADs (phospho-SMAD2/3, SMAD4 and SMAD7) were observed by immunohistochemistry. Total proteins were extracted from testicular tissues in the breeding and nonbreeding seasons and were used for Western blotting analysis for ActRIIB and SMADs. Immunoreactivities of activin signaling components were greater in the testes of the breeding season, and then decreased to a relatively low level in the nonbreeding season. ActRIIB and related SMADs were widely spread in the active testes, while spermatogonia were the predominant cellular sites of activin signal transduction during arrested spermatogenesis. The dynamic regulation of activin type II receptor and SMADs indicated that the activin signal pathway played an important paracrine role in seasonal spermatogenesis of the wild ground squirrel. Furthermore, the distinct localizations and immunoreactivity of ActRIIB and SMADs might suggest different functions of activin in seasonal spermatogenesis.
authors.affiliation: College of Biological Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Sheng
authors.forename: Haolin
authors.initials: H
authors.lastname: Zhang
authors.forename: Mengyuan
authors.initials: M
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Xiao
authors.initials: X
authors.lastname: Hu
authors.forename: Moshi
authors.initials: M
authors.lastname: Song
authors.forename: Jiao
authors.initials: J
authors.lastname: Zhou
authors.forename: Meiyu
authors.initials: M
authors.lastname: Xu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Weng
authors.forename: Gen
authors.initials: G
authors.lastname: Watanabe
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Taya
mesh_terms: D030301:Activin Receptors, Type II / Q000032:analysis; D028341:Activins / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D007150:Immunohistochemistry; D008297:Male; D012589:Sciuridae / Q000378:metabolism / Q000502:physiology*; D012621:Seasons; D015398:Signal Transduction; D051899:Smad2 Protein / Q000032:analysis; D051900:Smad3 Protein / Q000032:analysis; D051901:Smad4 Protein / Q000032:analysis; D051906:Smad7 Protein / Q000032:analysis; D013091:Spermatogenesis; D013093:Spermatogonia / Q000737:chemistry; D013737:Testis / Q000378:metabolism / Q000502:physiology*
chemical_list: D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D051906:Smad7 Protein; D028341:Activins; D030301:Activin Receptors, Type II