Ultrastructural localization of PGP 9.5 and ubiquitin immunoreactivities in rat ductus epididymidis epithelium

Ubiquitin C-terminal hydrolase L1 (UCHL1), a double-edged sword in mammalian oocyte maturation and spermatogenesis

BACKGROUND

Recent studies have shown that ubiquitin-mediated cell apoptosis can modulate protein interaction and involve in the progress of oocyte maturation and spermatogenesis. As one of the key regulators involved in ubiquitin signal, ubiquitin C-terminal hydrolase L1 (UCHL1) is considered a molecular marker associated with spermatogonia stem cells. However, the function of UCHL1 was wildly reported to regulate various bioecological processes, such as Parkinson's disease, lung cancer, breast cancer and colon cancer, how UCHL1 affects the mammalian reproductive system remains an open question.

METHODS

We identified papers through electronic searches of PubMed database from inception to July 2022.

RESULTS

Here, we summarize the important function of UCHL1 in controlling mammalian oocyte development, regulating spermatogenesis and inhibiting polyspermy, and we posit the balance of UCHL1 was essential to maintaining reproductive cellular and tissue homeostasis.

CONCLUSION

This study considers the 'double-edged sword' role of UCHL1 during gametogenesis and presents new insights into UCHL1 in germ cells.

Protein profile of Dabry's sturgeon (Acipenser dabryanus) spermatozoa and relationship to sperm quality

Knowledge of conditions affecting sperm quality is essential for efficient culture of fish for commercial purposes and conservation of species. Two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time of flight mass spectrometry were used to characterize the proteomic profile of Acipenser dabryanus spermatozoa relative to motility and fertilization capacity. There were differential amounts of protein in 313 spots in spermatozoa of males classified to have relatively greater or lesser spermatozoa quality. The functions of 43 of 50 selected proteins were identified. The proteins in 14 spots were involved in metabolism, and of these, proteins in 11 spots were highly abundant in spermatozoa of males categorized to have spermatozoa of greater quality, including pyruvate kinase, enolase B, phosphoglycerate kinase, lactate dehydrogenase, cytosolic malate dehydrogenase, brain creatine kinase b, Ckmb protein, and nucleoside diphosphate kinase. The proteins involved in mechanics of flagellum movement were identified, including the dynein intermediate chain, radial spoke head 1 homolog; ropporin-1-like, Bardet-Biedl syndrome 5, ADP-ribosylation factor-like protein 3, tektin-4, gamma-actin, and tubulin cytoskeleton proteins to be differentially abundant in spermatozoa that were classified relatively greater or lesser quality. Heat shock proteins, copper/zinc superoxide dismutase and peroxiredoxins, which are involved in stress response were of differential abundance in spermatozoa from males with spermatozoa in the two different classification groups. Proteins were also detected that are involved in protein folding and binding, or hydrolase activity. The results are valuable for the prediction of sperm quality and for reproduction management in A. dabryanus and other threatened species.

UCHL1 expression and localization on testicular development and spermatogenesis of Chinese giant salamanders

Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1), which is extensively expressed in vertebrates, is a deubiquitinating enzymes that inhibits the degradation of proteins by reversing ubiquitination modification. Herein, a 1087-bp sequence encoding UCHL1 was identified from the Chinese giant salamander (CGS; Andrias davidianus). The coding sequences (CDS) of UCHL1 encoded a putative poly peptide of 222 amino acids. The CGS UCHL1 isoforms were more related to their human and mouse counterparts. The phylogenic tree of vertebrate UCHL1 indicated that CGS UCHL1 has the closest relationship with human UCHL1 (up to 73.99 %). Before the gonads of male CGSs matured, the peak level of UCHL1 expression in testes appeared in 3-year-old CGSs according to RT-qPCR and western blot. In adult testes, the level of UCHL1 protein was lower in the breeding period than in the post-breeding period, whereas the level of UCHL1 protein in interstitial fluid of adult CGS testes was higher during the breeding period than during the post-breeding period. In testicular seminiferous lobules in the developmental stage of CGSs, immunohistochemistry displayed three kinds of localizing patterns of UCHL1, including nuclear localization at half year old, cytoplasmic localization from one year to three years old, and extracellular localization in adult. In testicular seminiferous lobules of adult CGS, the different developmental germ cells were separated by cysts containing UCHL1 protein, but UCHL1 did not localize on the mature sperm. The results showed that extracellular UCHL1 loaded on exosomes, as a component of the homogeneous germ cell cysts, could regulate the synchronous development of sperm in testes of adult CGS.

Immunofluorescence Reveals Ubiquitination of Retained Distal Cytoplasmic Droplets on Ejaculated Porcine Spermatozoa

The purpose of the present study was twofold: 1) to determine if antibodies raised against ubiquitin would recognize antigens associated with the porcine cytoplasmic droplet (CD), and 2) to determine if the same antibody would identify ubiquitinated substrates on the surface of morphologically abnormal boar spermatozoa. Permeabilization with the detergent Triton X-100 (0.05%) showed virtually all CDs to be ubiquitin positive. Distal droplets (DDs) retained in situ on boar spermatozoa were readily labeled following Triton permeabilization, whereas DDs present on nonpermeabilized cells were not. Negative control preparations lacked the ubiquitin staining on the DD. The use of microtubes for fixation and incubation provided clearer images as well as better sperm cell distribution and density than an initial slide-mounted technique. Immunoblotting indicated that larger amounts of ubiquitinated proteins were present in extracts from sperm cells from an ejaculate with an abnormally high percentage of retained DDs (52% DDs) compared to a morphologically normal sample (6% DDs). The primary antibody recognized both mono-ubiquitin of bovine origin (8.5 kd) and human ubiquitin conjugate (35 kd), as demonstrated by Western blot. Preabsorption of the anti-ubiquitin antibody with purified bovine ubiquitin was successful in preventing diaminobenzidine staining of sperm extract from the high DD ejaculate. The presence of antigens recognized by anti-ubiquitin antibodies in the boar sperm CD, coupled with the possibility that superfluous ubiquitin species are detrimental to embryonic development by targeting critical paternally contributed zygotic organelles, raises concerns that retained DDs may be more detrimental to fertility than previously suspected.

Ubiquitin C-terminal hydrolase L-1 is essential for the early apoptotic wave of germinal cells and for sperm quality control during spermatogenesis

Ubiquitination is required throughout all developmental stages of mammalian spermatogenesis. Ubiquitin C-terminal hydrolase (UCH) L1 is thought to associate with monoubiquitin to control ubiquitin levels. Previously, we found that UCHL1-deficient testes of gad mice have reduced ubiquitin levels and are resistant to cryptorchid stress-related injury. Here, we analyzed the function of UCHL1 during the first round of spermatogenesis and during sperm maturation, both of which are known to require ubiquitin-mediated proteolysis. Testicular germ cells in the immature testes of gad mice were resistant to the early apoptotic wave that occurs during the first round of spermatogenesis. TUNEL staining and cell quantitation demonstrated decreased germ cell apoptosis and increased numbers of premeiotic germ cells in gad mice between Postnatal Days 7 and 14. Expression of the apoptotic proteins TRP53, Bax, and caspase-3 was also significantly lower in the immature testes of gad mice. In adult gad mice, cauda epididymidis weight, sperm number in the epididymis, and sperm motility were reduced. Moreover, the number of defective spermatozoa was significantly increased; however, complete infertility was not detected. These data indicate that UCHL1 is required for normal spermatogenesis and sperm quality control and demonstrate the importance of UCHL1-dependent apoptosis in spermatogonial cell and sperm maturation.

Characterization of the testis in congenitally ubiquitin carboxy-terminal hydrolase-1 (Uch-L1) defective (gad) mice

The gracile axonal dystrophy (gad) mice are known to have a deletion within the gene encoding ubiquitin carboxy-terminal hydrolase-1 (Uch-L1) and show hereditary sensory deterioration and motor paresis. Expression of Uch-L1 is reported to be almost limited to the nervous system and testis. To understand whether Uch-L1, one of the major ubiquitin carboxy-terminal hydrolase (UCH) isozymes in the testis, affects spermatogenesis and other UCH isozymes (Uch-L3, L4 and L5) expression in the testis, we compared the testis between gad, hetero and wild type mice by histological, immunohistochemical analyses and RT-PCR. Histological analysis in 25-week-old gad mice showed shrinking of seminiferous tubules, decreasing total number of cells and enlargement of remaining cells in seminiferous tubules. By immunohistochemistry, a significant decrease (p < 0.05) in the number of proliferating cell nuclear antigen (PCNA) positive cells was observed. Expression of other UCH isozyme mRNAs was not apparently affected by Uch-L1 deficiency in 25-week-old gad mice. This study is the first report on the testis of gad mutant mouse.

Nature's ingenuity: bypassing the classical secretory route via apocrine secretion

Although it has been suggested that epithelial cells of the male reproductive system are involved in apocrine secretion, this method of secretion is not fully understood. In the present study, apocrine secretion was investigated in epithelial principal cells lining the epididymis and vas deferens (VD) of adult mice. The tissues were fixed by cardiac vascular perfusion with glutaraldehyde for routine electron microscope (EM) analysis and Bouin's fixative for light microscope (LM) immunocytochemistry to access functional roles. In the epididymis and VD, the apex of principal cells revealed protrusions of cytoplasm referred to as apical blebs (ABs). The latter contained solely numerous free ribosomes, 20 nm vesicles and few ER cisternae, suggesting segregation of their contents. While some ABs displayed wide areas of contact with the apical principal cell cytoplasm, others showed thin stalk-like attachment points as well as fissures at the junction of the two areas. Together with images of ABs and their contents deep in the lumen, it is suggested that ABs detach from principal cells whereupon they breakdown to release their contents therein. As ABs of the epididymis were immunoreactive for glutathione-S-transferases (GSTs) and ubiquitin, it is proposed that these proteins are synthesized on free ribosomes in ABs and that apocrine secretion represents the manner whereby they enter the lumen to effectively protect sperm from free radical injury and ubiquitinate proteins for degradation, respectively. ABs of the VD were immunoreactive for 3beta-HSD, suggesting that they are also capable of synthesis of steroids with their release via apocrine secretion. Taken together the data provide evidence for apocrine secretion in the adult mouse epididymis and VD that could play important roles in relation to sperm maturation, protection and viability.

Immunohistochemical localization of protein gene product 9.5, ubiquitin, and neuropeptide Y immunoreactivities in epithelial and neuroendocrine cells from normal and hyperplastic human prostate

This study was designed to investigate (a) the presence of protein gene product 9.5 (PGP 9.5), ubiquitin, and neuropeptide Y (NPY) in the neuroendocrine and secretory epithelium of the human normal prostate and its secretions, and (b) the changes in immunoreactivity to these proteins in men with benign prostatic hyperplasia. Western blotting and light microscopic immunohistochemistry techniques were used and the numerical density of immunoreactive neuroendocrine cells, and the volume fractions of immunostained secretory epithelium were evaluated. Western blotting revealed the presence of the three antigens in both tissue homogenates and prostate secretion. Some neuroendocrine cells immunoreacted to PGP 9.5 and NPY in all the prostate regions of control specimens. Ubiquitin immunoreactivity was detected in the nuclei from both basal cells and secretory epithelial cells. The cytoplasm of the secretory cells and the glandular lumen also showed immunostaining for the three proteins. The numerical densities of both PGP 9.5 and NPY neuroendocrine cells were lower in hyperplasia than in controls. No differences in the volume fraction occupied by epithelial immunostaining to both proteins was found between hyperplastic and control prostates. We concluded that (a) PGP 9.5 and NPY, but not ubiquitin, are common antigens in both neuroendocrine and secretory prostate cells, (b) the three immunoreactive proteins contribute to the prostate secretions, and (c) the secretion of ubiquitin is markedly diminished in the hyperplastic epithelium.(J Histochem Cytochem 48:1121-1130, 2000)

Expression of protein gene product 9.5, a neuronal ubiquitin C-terminal hydrolase, and its developing change in sertoli cells of mouse testis

Protein gene product 9.5 (PGP9.5), originally isolated as a neuron-specific protein, belongs to a family of ubiquitin carboxyl-terminal hydrolases that play important roles in the nonlysosomal proteolytic pathway. Antibodies against PGP9.5 have been used for immunohistochemical detection of neural elements, although some non-neuronal cells are also immunoreactive for PGP9.5. In the present study, developing testes of the mouse were immunostained after autoclave pretreatment of sections. In the testes of days 8 and 16, PGP9.5 was only localized on the spermatogonia, whereas on day 30 and in adults it appeared not only on spermatogonia, but also on Sertoli cells. In the testis of the male sterile W/W(v) mutant, very little, but strong, immunoreactivity was detected at some Sertoli cells, which were phagocytizing Sertoli cell aggregations that had fallen from the basal membrane. Additionally, it was confirmed that the nucleotide sequence of PGP9.5 in mice was highly conserved, like that in other mammals. These results suggest that PGP9.5 is a useful marker for activated Sertoli cells, playing an important role in degradation of abnormal proteins.

Localization of protein gene product 9.5 immunoreactivity in derivatives of the human Wolffian duct and in prostate cancer

BACKGROUND

Protein gene product 9.5 (PGP 9.5) has been considered to be a neuronal marker, but it is also present in extraneuronal tissues, e.g., the human mammary gland and rat epididymis. Its presence and distribution in the developing and adult male human genital tract have been unknown.

METHODS

Immunohistochemical reactions were performed on human embryonic and postnatal specimens of the male genital tract, using commercial monoclonal and polyclonal antibodies.

RESULTS

PGP 9.5 immunoreactivity was found in the Wolffian duct of human embryos (55-85 mm crown-rump length). Strong reactivity was observed in mesonephric tubular cells and at the apical rim of Wolffian duct cells. Owing to their PGP 9.5 immunoreactivity, these cells could also be identified on the surface of the embryonic verumontanum, extending from the orifices of the Wolffian duct to a small stretch of the urogenital sinus. There they contrasted sharply against non-Wolffian cells. In the adult human genital tract, PGP 9.5 immunoreactive material was present in the supranuclear portion of some epithelial cells of the epididymal efferent ductules, in isolated cells of the ejaculatory ducts, and in prostate cancer specimens. In the ejaculatory ducts, the PGP 9.5-immunoreactive cells were free of immunoreactivity for semenogelin, the major secretory product of the ejaculatory-vesicular-ampullary complex, and they also lacked chromogranin A-immunoreactivity. In prostate cancer specimens, PGP 9.5 immunoreactivity was never observed in secretory cells (immunoreactive for prostate-specific antigen), but was restricted to neuroendocrine cells, where it occurred either alone or coexpressed with chromogranin A-immunoreactivity.

CONCLUSIONS

PGP 9.5-immunoreactivity is prenatally distributed in the Wolffian duct and its derivations; postnatally, it is restricted to a few cells derived from the initial and terminal segment of the Wolffian duct, and to neuroendocrine cells in prostate cancer specimens.