Expression and localization of Smad1, Smad2 and Smad4 proteins in rat testis during postnatal development.
OBJECTIVE
To study the expression and regulation of Smad1, Smad2 and Smad4 proteins (intracellular signaling molecules of transforming growth factor-b family) in rat testis during postnatal development.


METHODS
The whole testes were collected from SD rats aged 3, 7, 14, 28 and 90 (adult) days. The cellular localization and developmental changes were examined by immunohistochemistry ABC method with the glucose oxidase-DAB-nickel enhancement technique. Quantitative analysis of the immunostaining was made by the image analysis system. The Smads proteins coexistence in the adult rat testis was tested by the double immune staining for CD14-Smad4 and Smad2-Smad4. The protein expression of Smad during rat testicular development was examined by means of Western blots.


RESULTS
Smad1, Smad2 and Smad4 were present throughout testicular development. The immunostaining of Smad1 and Smad2 were present in spermatogenic cells. A positive immunoreactivity was located at the cytoplasm, but the nucleus was negative. Smad1 was immunolocalized at the d14, d28 and adult testes, while Smad2, at the d7, d14, d28 and adult testis. There was positive immunoreaction in the Sertoli cells and Leydig cells as well. The immunolocalization of Smad4 was exclusively at the cytoplasm of Leydig cells and the nuclei were negative throughout the testicular development. No expression was detected in the germ cells. The results of image and statistical analysis showed that generally the expression of Smad1, Smad2 and Smad4 in the testis tended to increase gradually with the growth of the rat.


CONCLUSIONS
The present data provide direct evidences for the molecular mechanism of TGF-bgr action in rat testes during postnatal development and spermatogenesis.
Hu
Jing
J
Department of Histology and Embryology, Fourth Military Medical University, Xi'an 710032, China.
Zhang
Yuan-Qiang
YQ
Liu
Xin-Ping
XP
Wang
Rui-An
RA
Jin
Yan
Y
Xu
Ruo-Jun
RJ
D000818:Animals; D015153:Blotting, Western; D004268:DNA-Binding Proteins / Q000032:analysis / Q000096:biosynthesis*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D051785:Smad Proteins; D051898:Smad1 Protein; D051899:Smad2 Protein; D051901:Smad4 Protein; D013737:Testis / Q000737:chemistry / Q000254:growth & development* / Q000502:physiology*; D015534:Trans-Activators / Q000032:analysis / Q000096:biosynthesis*
D004268:DNA-Binding Proteins; D051785:Smad Proteins; D051898:Smad1 Protein; C497400:Smad1 protein, rat; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051901:Smad4 Protein; C490811:Smad4 protein, rat; D015534:Trans-Activators