Goliath, a ring-H2 mitochondrial protein, regulated by luteinizing hormone/human chorionic gonadotropin in rat leydig cells

We have cloned the rat homologue of the ring-H2 protein Goliath involved in Drosophila development. The rat Goliath mRNA (1.85 kb) was translated as a major ubiquitous protein species of 28-kDa and three larger isoforms (50, 46, and 36 kDa) expressed mainly in liver, lung, stomach, heart, and thymus and barely detectable in other tissues (kidney, skeletal muscle, brain, testis, intestine, and spleen). By immunohistochemistry on rat testis sections, we localized the protein in interstitial tissue and seminiferous tubules. In tubules, Goliath was expressed mainly in postmeiotic germ cells and to a much lesser extent in Sertoli cells. In the interstitium, Goliath was exclusively present in Leydig cells. Using a series of immunolabeling, cellular fractionation, and electron microscopy experiments, we established that Goliath is present in mitochondria of the R2C Leydig cell line. Using short-term hypophysectomized animals, we showed that Goliath is regulated by LH/hCG in Leydig cells but not in germ cells. This regulation in Leydig cells concerned only the 50-kDa isoform. This report is the first description of a differential regulation of the Goliath protein between germ cells and Leydig cells.

Experimental inoculation of the adult rat testis with Sendai virus: effect on testicular morphology and leukocyte population

BACKGROUND

Surprisingly little is known about the interactions between viruses and the male uro-genital tract. These are important, as viral testicular orchitis, induced by mumps or human immunodeficiency virus (HIV) infection for example, can lead to sterility. Moreover, semen is an essential vector in the propagation of sexually transmissible viral diseases. Here, we studied the effects of testicular infection with Sendai virus, a virus related to mumps virus, on the cellular distribution of viral particles and on testicular morphology, with particular attention to the testicular leukocyte population.

METHODS

At 5, 9, 11 or 24 h post-injection of Sendai virus through the scrotum, the testes were fixed for morphological and immunohistological studies. Localization of virus particles and numeration of leukocytes were performed using specific antibodies and morphological criteria.

RESULTS

As early as 5 h post-injection, a rapid and massive infiltration of leukocytes was observed in the interstitial tissue. The peritubular cell layer and the most external part of the basal portion of the seminiferous tubules were altered. The virus was diffusely located within the interstitial tissue 9 h following the injection whereas, after 24 h, viral proteins were restricted to the cytoplasm of infiltrated leukocytes. The number of leukocytes increased with time post-injection. Thus, 24 h post-injection, CD3+ T-cell number was 3-fold higher, ED1+ monocyte number was 4-fold higher and polynuclear cell number was 600-fold higher than in the control testes (P<0.001 all observations). In contrast, the population of resident macrophages was unaffected by Sendai virus.

CONCLUSIONS

Testicular viral infection causes inflammation including rapid recruitment of leukocytes. The experiments presented here provide a model for further studies on the etiopathology of viral orchitis, in particular that caused by mumps virus.

Source, catabolism and role of the tetrapeptide N-acetyl-ser-asp-lys-Pro within the testis

The tetrapeptide N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (AcSDKP) is a natural regulator of hematopoietic stem cell proliferation. The present study was aimed at investigating the presence and the role of AcSDKP in rat testis. Specific immunoreactivity was always observed in the interstitial tissue at all stages of testicular development and in elongated spermatids at 45 days of age and in adults. In accordance with the interstitial labeling, high AcSDKP levels were detected in Leydig cell and testicular macrophage culture media and cell extracts, as well as in the testicular interstitial fluid (TIF). Much lower concentrations were found in peritubular cells and Sertoli cells cultures, whereas very low concentrations were present in cultured spermatocytes and spermatids. In contrast to the slight degradation rate of AcSDKP observed in the spermatocyte and spermatid culture media, no catabolism of the peptide was seen in testicular somatic cell culture medium. Furthermore, the degradation rate of AcSDKP was much lower in TIF than in peripheral blood plasma. Despite the very strong evidence indicating that Leydig cells and testicular macrophages produce AcSDKP, the selective destruction of these cells did not result in any change in AcSDKP levels in TIF or in plasma. This suggests a compensatory mechanism ensuring constant levels of the peptide in TIF when interstitial cells are absent. Finally, in vitro, in the presence of AcSDKP, significantly more [(3)H]thymidine incorporation was found in A spermatogonia. In conclusion, this study establishes the presence of very high concentrations of AcSDKP in rat testis and demonstrates its Leydig cell and testicular macrophage origin. The presence of AcSDKP in the TIF and its stimulatory effect on thymidine incorporation in spermatogonia very strongly suggest its implication in the paracrine control of spermatogenesis.