title: Integrin participates in the effect of thyroxine on plasma membrane in immature rat testis.
abstract: BACKGROUND
  The secretory activity of Sertoli cells (SC) is dependent on ion channel functions and protein synthesis and is critical to ongoing spermatogenesis. The aim of this study was to investigate the mechanism of action associated with a non-metabolizable amino acid [14C]-MeAIB (alpha-(methyl-amino)isobutyric acid) accumulation stimulated by T4 and the role of the integrin receptor in this event, and also to clarify whether the T4 effect on MeAIB accumulation and on Ca2+ influx culminates in cell secretion.
  
  
  METHODS
  We have studied the rapid and plasma membrane initiated effects of T4 by using 45Ca2+ uptake and [45C]-MeAIB accumulation assays, respectively. Thymidine incorporation into DNA was used to monitor nuclear activity and quinacrine to analyze the secretory activity on SC.
  
  
  RESULTS
  The stimulation of MeAIB accumulation byT4 appears to be mediated by the integrin receptor in the plasma membrane since tetrac and RGD peptide were able to nullify the effect of this hormone. In addition, T4 increases extracellular Ca2+ uptake and Ca2+ from intracellular stocks to enhance nuclear activity, but this genomic action seems not to influence SC secretion mediated by T4. Also, the cytoskeleton and CIC-3 chloride channel contribute to the membrane-associated responses of SC.
  
  
  CONCLUSIONS
  T4 integrin receptor activation ultimately determines the plasma membrane responses on amino acid transport in SC, but it is not involved in calcium influx, cell secretion or the nuclear effect of the hormone.
  
  
  CONCLUSIONS
  The integrin receptor activation by T4 may take a role in plasma membrane processes involved in the male reproductive system.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis-Santa Catarina, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Zanatta
authors.forename: Leila
authors.initials: L
authors.lastname: Zanatta
authors.forename: Renata
authors.initials: R
authors.lastname: Gonçalves
authors.forename: Ariane
authors.initials: A
authors.lastname: Zamoner
authors.forename: Fátima Regina Mena Barreto
authors.initials: FR
authors.lastname: Silva
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002250:Carbon Radioisotopes; D002462:Cell Membrane / Q000187:drug effects*; D018118:Chloride Channels / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D039302:Integrin alphaVbeta3 / Q000235:genetics* / Q000378:metabolism; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D012708:Sertoli Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D013091:Spermatogenesis / Q000187:drug effects / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism; D013974:Thyroxine / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D002250:Carbon Radioisotopes; D018118:Chloride Channels; C115376:ClC-3 channel; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D011956:Receptors, Cell Surface; C017911:2-(methylamino)isobutyric acid; C047981:arginyl-glycyl-aspartic acid; C011126:tetraiodothyroacetic acid; D013974:Thyroxine; D002118:Calcium; D013936:Thymidine