Altered phosphorylation and distribution status of vimentin in rat seminiferous epithelium following 17β-estradiol treatment

Abstract

Vimentin, type III intermediate filament, has stage-specific localization in the Sertoli cell. In the rat, during stages I-V and XI-XIV of the seminiferous epithelium, vimentin is localized in the perinuclear area with filaments projecting into the apical region toward the developing germ cells. These filaments decrease in length at stages VI-VII with perinuclear staining in stages VIII-IX, when spermiation occurs. Our earlier studies following 17β-estradiol treatment to adult male rats demonstrated an increase in germ cell apoptosis, spermiation failure and disruption of Sertoli cell microfilaments and microtubules. The present study was undertaken to determine the stage-specific distribution of vimentin and its involvement in spermiation failure and germ cell apoptosis. Immunofluorescence studies revealed that in contrast to the perinuclear localization with small extensions in control stages VII-IX, long extensions radiating apically to the spermatids in deep recess were observed in the treated group. Immunoprecipitation studies showed marked absence of phosphorylated vimentin in stages VII-VIII in the treated group. Further, localization of plectin, cytoskeletal linker protein, showed decrease in all the stages of spermatogenesis following estradiol treatment. Interestingly, for the first time the localization of plectin in the tubulobulbar complex was observed. In conclusion, the study suggests that estradiol treatment leads to an effect on vimentin phosphorylation, which could have inhibited the disassembly of vimentin leading to retention of apical projection in stages VII-VIII. These effects could be presumably due to a decrease in plectin, affecting the reorganization of vimentin and therefore the apical movement of spermatids, leading to spermiation failure.

Prenatal and lactation nicotine exposure affects Sertoli cell and gonadotropin levels in rats

“…Thus, the changes in the cytoskeleton of these cells could be the cause of the histopathological alterations observed in our analysis; however, the secretory function of Sertoli cells seemed to be preserved, since transferrin expression did not change. Structures formed by Sertoli cells, such as the tubulebulbar complex, work along with vimentin filaments in the cytoplasmic reduction of spermatids in steps 18 and 19 (Upadhyay et al 2011). So, the abundance of cytoplasmic area noticed in round spermatids of N90 rats might be a consequence of the nicotine effect on Sertoli cytoskeleton.…”

“…The reorganization/collapse of vimentin has also been correlated with loss of microtubules (Upadhyay et al 2011). Microtubules control the dynamics of cellular division (cytokinesis) and multinucleated formation is frequently observed in studies with toxic agents (Freitas et al 2002).…”

“…As previously described by Kopecky et al (2005) in rats treated with busulfan, the perinuclear condensation and the disorganization of the filaments in the basal region can be a result of a breakdown of these filaments around the nuclei of Sertoli cells. So, it is likely that nicotine altered the intracellular organization of vimentin, which depends on the action of kinase and protein phosphatase, regulator enzymes of the reorganization of the filaments through phosphorylation (Upadhyay et al 2011).…”

“…To obtain these stereological data at different stages of the cycle of the seminiferous epithelium we also used the referred image analysis system coupled with a light microscope using a !20 objective lens; when more details were needed to confirm a specific stage, higher magnifications were applied to complement the analysis. In addition, while stages VI-XI and XIV were individually analyzed stages I-V and XII-XIII were grouped, since the expression of vimentin is similar among these stages (Zhu et al 1997, Upadhyay et al 2011.…”

“…b-catenin participates in the Sertoligerm cell anchoring junction in the apical ectoplasmic specialization and also in the restructuring of the BTB at the basal ectoplasmic specialization between Sertoli cells (Kolasa et al 2011). In this dynamic process, the cytoskeleton of Sertoli cells also undergoes structural changes (Upadhyay et al 2011).…”