Expression pattern of acetylated α‐tubulin in porcine spermatogonia

Abstract

SUMMARY Mammalian spermatogonial stem cells reside on the basement membrane of the seminiferous tubules. The mechanisms responsible for maintenance of spermatogonia at the basement membrane are unclear. Since acetylated α-tubulin (Ac-α-Tu) is a component of long-lived, stable microtubules and deacetylation of α-tubulin enhances cell motility, we hypothesized that acetylation of α-tubulin might be associated with positioning of spermatogonia at the basement membrane. The expression pattern of Ac-α-Tu at different stages of testis development was characterized by immunohistochemistry for Ac-α-Tu and spermatogonia-specific proteins (PGP 9.5, DAZL). In immature pig testes, Ac-α-Tu was present exclusively in gonocytes at 1 week of age, and in a subset of spermatogonia at 10 weeks of age. At this age, spermatogonia are migrating toward the tubule periphery and Ac-α-Tu appeared polarized toward the basement membrane. In adult pig testes, Ac-α-Tu was detected in few single or paired spermatogonia at the basement membrane as well as in spermatids and spermatozoa. Only undifferentiated (DAZL–), proliferating (determined by BrdU incorporation) spermatogonia expressed high levels of Ac-α-Tu. Comparison with the expression pattern of β-tubulin and tyrosinated α-tubulin confirmed that only Ac-α-Tu is specific to germ cells. The unique pattern of Ac-α-Tu in undifferentiated germ cells during postnatal development suggests that posttranslational modifications of microtubules may play an important role in recruiting and anchoring spermatogonia at the basement membrane.

A tubulin alpha 8 mouse knockout model indicates a likely role in spermatogenesis but not in brain development

“…Localisation of acetylated tubulin to spermatozoal flagella has been described previously [30, 34], while the lack of Tuba8 shown here implies that it is not important for generating the microtubules comprising this motile structure. Indeed the lack of Tuba8 had little observable effect on the expression pattern of either tyrosinated or acetylated tubulin in the testis.…”

In Utero Exposure to Environmentally Relevant Concentrations of PCB 153 and PCB 118 Disrupts Fetal Testis Development in Sheep

“…Hurst et al (1998) concluded that a disturbance in the expression of many of the actin-capping proteins may underlie many of the abnormalities in sperm morphology observed in infertile semen. Furthermore, Luo et al (2010) found that F-actin capping protein alpha-3 subunit was absent in necrozoospermic human spermatozoa compared to normal spermatozoa. Capping protein β3 is a component of the cytoskeleton calyx of the mammalian sperm head (von Bülow et al, 1997).…”

“…As tubulin is the major constituent of microtubules, it may play an important role in movement and organization of spermatogonial stem cells in neonatal and hence prospective spermatogenesis. Luo et al (2010) suggested that posttranslational modifications of microtubules may play an important role in recruiting and anchoring spermatogonia at the basement membrane. Similarly, McGuinness and Orth (1992) indicated that microtubules are involved when postnatal gonocytes are relocating to the basement membrane by active migration.…”

Primary cilia in the developing pig testis

“…We reported previously that acetylated alpha tubulins are present in spermatogonia [(Luo et al 2010); see also Figure 1, germ cells indicated by arrows]. To distinguish these cytosolic microtubules from primary cilia we used two strategies.…”

“…We had shown previously that adenylate cyclase III is present in primary cilia (Ou et al 2009). To avoid overlap with acetylated alpha tubulin staining in germ cells (Luo et al 2010) we also labeled cilia with an antibody against ARL13B. ARL13B is a GTPase expressed in primary cilia.…”