Cellular Expression and Subcellular Localization of Wwox Protein During Testicular Development and Spermatogenesis in Rats

Abstract

A well-known putative tumor suppressor WW domain–containing oxidoreductase (Wwox) is highly expressed in hormonally regulated tissues and is considered important for the normal development and function of reproductive organs. In this study, we investigated the cellular and subcellular localization of Wwox in normal testes during postnatal days 0–70 using Western blotting and immunohistochemistry. Wwox is expressed in testes at all ages. Immunohistochemistry showed that fetal-type and adult-type Leydig cells, immature and mature Sertoli cells, and germ cells (from gonocytes to step 17 spermatids) expressed Wwox except peritubular myoid cells, step 18–19 spermatids, and mature sperm. Wwox localized diffusely in the cytoplasm with focal intense signals in all testicular cells. These signals gradually condensed in germ cells with their differentiation and colocalized with giantin for cis-Golgi marker and partially with golgin-97 for trans-Golgi marker. Biochemically, Wwox was detected in isolated Golgi-enriched fractions. But Wwox was undetectable in the nucleus. This subcellular localization pattern of Wwox was also confirmed in single-cell suspension. These findings indicate that Wwox is functional in most cell types of testis and might locate into Golgi apparatus via interaction with Golgi proteins. These unique localizations might be related to the function of Wwox in testicular development and spermatogenesis:

cAMP-specific phosphodiesterase 8A and 8B isoforms are differentially expressed in human testis and Leydig cell tumor

“…In order to determine the nature of the structure labeled with PDE8A antibody we decide to perform immunofluorescence costaining with known marker of intracellular organelles. Giving the similarity of PDE8A structure with Golgi apparatus, two Golgi probes were used: Golgi Matrix Protein of 130 kDa (GM130), labeling cis-Golgi, and Golgin-97 labeling the trans-Golgi apparatus (22). As expected GM130 stains a compact peri-nuclear structure in round spermatids but do not co-localize with PDE8A in none of the analyzed stages (Figure 3A, inlet b).…”

ultraID: a compact and efficient enzyme for proximity-dependent biotinylation in living cells

“…The discrepancy might come from the different cell lines used in the different studies. Additional proteins specifically proximal to membrane-associated g1-COP were WWOX a protein that localizes to the Golgi but its function there is currently unknown 52,53 , ATP7A, a copper transporter that resides at the TGN 54 , TMEM165, a Golgi-localized transporter for Mn 2+ which is an important co-factor of glycosylation enzymes, and ERGIC-53. ERGIC-53 is a cargo receptor that constitutively cycles, through COPII and COPI vesicles, between the ER and the ER-Golgi intermediate compartment (ERGIC), and can be found at low concentrations at the cis-cisterna of the Golgi but not beyond 55 .…”