Dazl protein expression in adult rat testis is up-regulated at meiosis and not hormonally regulated

The Y-chromosomal DAZ (deleted in azoospermia) gene and the autosomal Dazl (deleted in azoospermia-like) gene are two crucial factors for the achievement and maintenance of spermatogenesis. Whereas Y-chromosomal DAZ is present in certain primates, it is lacking in rodents and other species. We have investigated the expression of Dazl protein during spermatogenesis in the adult rat testis using immunohistochemistry. Dazl immunoreactivity was found predominantly in the cytosol of primary pachytene spermatocytes. A weaker but clearly detectable signal was present in intermediate and B spermatogonia and in early spermatocytes from preleptotene to zygotene. The highest expression patterns were observed between stages IV and VIII during the spermatogenic cycle when spermatocytes prepare for the first meiotic division. Specific staining could also be observed in step 11-19 elongating spermatids in the acrosome region. Treatment for 42 days with a potent GnRH-antagonist abolished gonadotrophin secretion and led to a regressed testis, lacking most of the advanced germ cell types such as spermatids but still bearing spermatogonia and spermatocytes. No difference in staining pattern for Dazl protein was observed in GnRH antagonist-treated rats despite the lack of gonadotrophins and substantial impairment of the spermatogenic process, indicating that Dazl expression is clearly hormone-independent. The localization and level of Dazl expression suggests an important role in the regulation of the first meiotic stages of spermatogenesis. The hormone independent onset of expression points to an autonomous cell-cycle event in which Dazl seems to be essential for the entry into meiosis. The presence of Dazl in the acrosome region of elongating spermatids might reflect an unknown role of Dazl as a morphogenetic factor during spermiogenesis.     

Cloning and characterization of temperature-related gene TRS1

To investigate the mechanism of spermatogenesis arrest derived from heat treatment and to screen temperature-related genes involved in spermatogenesis, the authors analyzed the differences in gene expression between cryptorchid and scrotal testes in rats, and cloned a full-length cDNA named TRS1. In situ hybridization showed that TRS1 mRNA was mainly expressed in spermatocyte and round spermatids in testis. The expression level decreased in cryptorchid testis, suggesting that the lower scrotal temperature is a key factor in keeping the normal expression of TRS1. At the N-terminal of TRS1, there was a plecstrin homology (PH) domain signature. This PH domain has high similarity to that in PEPP2, a homosapien protein, which has a characteristic of binding phosphatidylinositol 3-phosphate via its PH domain in vitro. These findings suggest that TRS1 may be important in spermatogenesis and give clues for further research on the function of TRS1.     

Differential expression of TLRs and AKAP3 in cigarette smoked mice testis

Toll‐like receptors (TLRs) are expressed in Sertoli cells and Leydig cells and can initiate testicular innate immune responses. The A‐kinase anchor protein 3 (AKAP3), a family of scaffolding protein, was reported to be expressed only in testis and plays important regulatory roles during spermatogenesis. Our present study aimed to investigate the differential expression of TLRs family and AKAP3 in cigarette smoked Kunming mice testis. To check the effect of cigarette smoke, mice were randomly divided (n = 5 each) and exposed to cigarette smoke (2 hr/day with 10 cigarettes) for six consecutive days followed by one exposure‐free day. The exposure lasted for zero (control), 1, 3, 5 and 7 months respectively. The IHC results showed that expression of AKAP3 protein is mainly located in sperm cells and the mean density of which was significantly lower than that of control mice. Real‐time PCR results showed that expression of AKAP3 was significantly increased at early CS exposure (1 month) and then returned to normal in subsequent months. TLR2‐7, TLR13, Myd88 and Traf6 mRNA expression are much lower compared to control, especially after 3‐month cigarette smoke exposure, the time of which is almost consistent with sperm cycle. The present study suggests that TLR signal pathway and AKAP3 may play roles in spermatogenesis.     

Human sperm membrane protein (hSMP-1): a developmental testis-specific component during germ cell differentiation

Serum was obtained from an infertile woman having antibodies with sperm agglutinating activity. The antibodies interacted with a human sperm membrane protein (hSMP-1) with an estimated Mr of 55 kD. The gene (HSD-1) coding hSMP-1 was isolated from a human testis cDNA expression library and assigned the accession number U12978. The cDNA was conjugated to a prokaryotic expression vector to construct the recombinant vector, pRSET-HSD-I, which was expressed in Escherichia coli. The recombinant hSMP-1 was isolated and used to immunize rabbits to raise polyclonal antibodies. Usingan immunocytochemical technique, hSMP-1 protein was immunolocalized in germ cells of human testis at all stages of spermatogenesis. mRNAs were prepared from 16 different human tissues and analyzed by Northern blot using HSD-1 as probe. A positive reaction was elicited only with testis mRNA. The present findings suggest that the expression of hSMP-1 gene is testis-specific and occurs during the early stages of germ cell differentiation. In a comparative study, the location of the hSMP-I protein in sperm and in germ cells of the seminiferous tubules of rats was determined. The target antigen was immunolocated on the head and tail of rat sperm and in late spermatids and spermatozoa of rat testis. These results suggest that, in the rat, the HSD-1 gene is expressed during spermiogenesis.     

Immunolocalization assessment of metastasis-associated protein 1 in human and mouse mature testes and its association with spermatogenesis

Aim： To investigate the stage-specific localization of metastasis-associated protein 1 （MTA1） during spermatogenesis in adult human and mouse testis. Methods： The immunolocalization of MTA1 was studied by immunohistochemistry and Western blot analysis. The distribution pattern of MTA1 in mouse testis was confirmed by using quantitative analysis of purified spermatogenic cells. Results： The specificity of polyclonal antibody was confirmed by Western blot analysis. MTA1 was found expressed in the nucleus of germ cells, except elongate spermatids, and in the cytoplasm of Sertoli cells; Leydig cells did not show any specific reactivity. MTA1 possessed different distribution patterns in the two species： in humans, the most intensive staining was found in the nucleus of round spermatids and of primary spermatocytes while in mice, the most intense MTA 1 staining was in the nucleus of leptotene, zygotene and pachytene spermatocytes. In both species the staining exhibited a cyclic pattern. Conclusion： The present communication initially provides new evidence for the potential role of MTA1 in mature testis. In addition, its distinctive expression in germ cells suggests a regulatory role of the peptide during spermatogenesis.     

Inhibition of mouse acrosome reaction and sperm-zona pellucida binding by anti-human sperm membrane protein 1 antibody

Aim： To investigate the possible functions of human sperm membrane protein （hSMP-1） in the process of fertilization. Methods： A 576-bp cDNA fragment of HSD-1 gene coding for the extracellular domain of hSMP-1 was cloned and expressed. The localization of this protein on human and mouse sperm was determined by indirect immunofluorescent staining by using anti-recombinant hSMP-1 （anti-rhSMP-1） antibodies. Sperm acrosome reaction and spermzona pellucida （ZP） binding assay were carried out in 10-week-old BALB/c mice. Results： Recombinant hSMP-1 was successfully cloned and expressed. The expression of the native protein was limited on the acrosome of human and mouse sperm. Treatment of anti-rhSMP-1 antibodies significantly decreased the average number of sperms bound to each egg. Meanwhile, the percentage of acrosome reaction was decreased in comparison to pre-immune control after treatment with anti-rhSMP-1 （P 〈 0.05）. Conclusion： The results suggest that anti-rhSMP-1 antibody inhibited mouse acrosome reaction and sperm-ZP binding.     

Gene functional research using polyethylenimine-mediated in vivo gene transfection into mouse spermatogenic cells

Aim:To study polyethylenimine(PEI)-mediated in vivo gene transfection into testis cells and preliminary functionalresearch of spermatogenic cell-specific gene NYD-SP12 using this method.Methods:PEI/DNA complexes wereintroduced into the seminiferous tubules of mouse testes using intratesticular injection.Transfection efficiency andspeciality were analyzed on the third day of transfection with fluorescent microscopy and hematoxylin staining.Thelong-lasting expression of the GFP-NYD-SP12 fusion protein and its subcelluar localization in spermatogenic cells atdifferent stages were analyzed with fluorescent microscopy and propidium iodide staining.Results:With the media-tion of PEI,the GFP-NYD-SP12 fusion gene was efficiently transferred and expressed in the germ cells(especially inprimary spermatocytes).Transfection into Sertoli cells was not observed.The subcellular localization of the GFP-NYD-SP2 fusion protein showed dynamic shifts in spermatogenic cells at different stages during spermatogenesis.Conclusion:PEI can efficiently mediate gene transfer into spermatocytes.Thus,it might be useful for the functionalresearch of spermatogenic-cell specific genes such as the NYD-SP12 gene.In our study,the NYD-SP12 protein wasvisualized and was involved in the formation of acrosome during spermatogenesis.Our research will continue into thedetailed function of NYD-SP12 in spermatocytes.(Asian J Androl 2006 Jan;8:53-59)     

睾丸特异性基因TSF22在小鼠中的表达研究

目的 筛选与精子发生相关的基因。方法 将4、9、18、35、54日龄和6月龄小鼠睾丸组织cDNA探针与Affymetrix全基因组芯片进行杂交，筛选出差异表达的基因。利用网络信息资源对该基因进行生物学信息分析。RT-PCR分析该基因在小鼠睾丸不同发育阶段及小鼠不同组织中的表达。结果 芯片结果分析筛选出一个差异表达杂交点（GenBank登录号：NM_199034），生物信息学分析发现该基因全长1597bp，含有570bp的完整ORF，编码190个氨基酸、分子量为22．106kDa的蛋白质，我们将其命名为TSF22。RT-PCR分析表明TSF22基因特异性表达于睾丸组织及18日龄小鼠睾丸中。结论 TSF22基因的表达与小鼠精子发生的过程一致，可能在精子发生中起重要作用。     

急性热应激对性成熟雄性小鼠睾丸、附睾、输精管中热休克蛋白70表达的影响

目的:探讨急性热应激对性成熟雄性小鼠睾丸、附睾、输精管中热休克蛋白70(heat shock protein 70,HSP70)表达的影响。方法:将32只8周龄雄性小白鼠随机均分为4组,饲养7d后,进行热应激处理,温度控制在(39±0.5)℃,时间分别为0.5、1和3h。应激后立即采血,分离血清测定谷草转氨酶(GOT)含量。一侧附睾制备精子悬液,用于计算精子密度和顶体畸形率;另一侧附睾、睾丸、输精管用于免疫组化研究。结果:应激后,小鼠体重、睾丸系数、顶体畸形率变化不显著(P>0.05),附睾系数和精子密度有不同程度的下降,GOT含量急剧升高(P<0.01)。随着应激时间的延长,小鼠精子密度呈递减趋势,顶体畸形率呈上升趋势。应激时间最短的0.5h组小鼠体重、睾丸系数、附睾系数的降幅反而最大。免疫组化法观察发现,HSP70在性成熟小鼠睾丸、附睾、输精管中均有表达。正常状态下,HSP70在睾丸组织间质细胞中少量表达,应激后分布于间质细胞核,此外在精母细胞核与精子细胞核中也有大量分布;附睾中HSP70主要分布于主细胞质,基细胞和亮细胞中没有表达,应激后附睾体的纤毛细胞中也发现大量棕色颗粒;输精管中HSP70主要定位在基细胞质,主细胞中不表达。随着应激时间的延长,HSP70在睾丸、附睾中的表达量明显升高,而在输精管中的增幅不明显。结论:急性热应激对性成熟雄性小鼠的生殖系统造成了损伤;HSP70在睾丸、附睾、输精管中的表达与定位具有区域特异性和细胞特异性,提示其可能参与精子的发生与成熟;HSP70在应激状态下表达量大幅上升的作用可能在于保护细胞免受高热损伤。     

Spermatogenesis‐associated 48 is essential for spermatogenesis in mice

Azoospermia, oligospermia and teratozoospermia all seriously impact male reproductive health. Spermatogenesis is a complex and precisely regulated process in which germ cells proliferate and differentiate and involves the regulation of multiple testis‐specific genes. Here, we identified testis‐specific gene spermatogenesis‐associated 48 (SPATA48), the expression of which was age‐dependent, indicating that it is involved in spermatogenesis. In humans and mice with azoospermia, expression of SPATA48 disappeared in the testis. Spata48?/? knockout male mice had smaller testis and defective spermatogenesis compared to wild‐type (WT) mice. This study can help in the exploration of the genetic basis of male infertility and identify new targets for the diagnosis and treatment of male infertility.     

Stage-specific expression of a protein of the acrosome of baboon sperm during spermiogenesis detected with a monoclonal antibody

A single monoclonal antibody, BSA4, raised against baboon epididymal sperm was used to study the ontogeny of the baboon sperm acrosome region during testicular spermiogenesis. This antibody is not species-specific but is restricted to the acrosome region in all other sperm examined (human, rat, and mouse). In the baboon, treatment of epididymal sperm with 0.05% Triton-X results in complete loss of anterior acrosome staining. Such treated sperm display a distinct equatorial staining. Antibody BSA4 reacts with a determinant (molecular weight, 43,000 d) that first appears in postmeiotic round spermatids during spermiogenesis. When tested for an effect on the fertilization process in vitro, the antibody BSA4 displayed significant inhibition, indicating a possible functional role for the determinant on mouse sperm. Using the avidin-biotin immunoperoxidase method, several stages of acrosome development were recognized: ie, cap, acrosome, and maturation stages of spermiogenesis. The antibody staining was restricted to the developing acrosome at all stages, indicating that the equatorial region is part of the acrosome and is expressed with temporal specificity during spermatogenesis in the baboon.     

Stage- and cell-specific expression of soluble guanylyl cyclase alpha and beta subunits, cGMP-dependent protein kinase I alpha and beta, and cyclic nucleotide-gated channel subunit 1 in the rat testis

Several studies suggest that nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) modulate testicular function. In this study, we examined the expression of cGMP-dependent protein kinase G-I (PKG-I), and cyclic nucleotide-gated channel 1 (CNG-1), 2 known mediators of cGMP action, and the expression of soluble guanylyl cyclase (sGC) subunits in the rat testis. Immunohistochemical analysis revealed that the alpha subunit of sGC was expressed in the blood vessels and Leydig cells of adult rat testes. In addition, the sGC alpha subunit was observed in the acrosomal structures of spermatids undergoing the middle and later stages of spermiogenesis, but not in mature spermatozoa. Similar localization and expression patterns were seen for the sGC beta subunit, indicating coexpression of the sGC subunits. PKG-I was expressed in blood vessels and in the acrosomal region of spermatids during the early and middle stages of spermiogenesis but was not observed in Leydig cells or in mature spermatozoa. In contrast to sGC and PKG-I, CNG-1 was expressed only in cytoplasm and the residual bodies of late-stage (17-19) spermatids, with no staining observed in blood vessels and Leydig cells. These results demonstrate that sGC, PKG-I, and CNG-1 are expressed in a stage- and cell-specific manner in the rat testis. The distinct temporal patterns of expression of these components of cGMP signaling pathways suggest different physiological roles for sGC, PKG-I, and CNG-1 in spermiogenesis and steroidogenesis.     

LM23 is a novel member of the Speedy/Ringo family at the crossroads of life and death of spermatogenic cell

LM23 is a gene specifically expressed in the testis of Rattus norvegicus, as previously reported by our laboratory. The aim of the study is to further investigate the biological function of LM23. Several bioinformatic tools were utilized, including PROSITE and BLAST. To determine the subcellullar localization of LM23, a polyclonal antibody specific for LM23 was generated via the immunization of rabbits. The LM23 gene was cloned from rat testis tissue, and LM23 protein was expressed in Escherichia coli. The biological function of LM23 was analyzed with microarray analysis and immunohistochemistry, using a rat model of LM23 gene knockdown. The results suggested that LM23 belongs to the Speedy/Ringo family. LM23 regulated the G₁/S and G₂/M transitions of the cell cycle during spermatogenesis. Downregulation of the LM23 gene during spermatogenesis could lead to the activation of both the Fas–FasL pathway and the mitochondrial pathway. These novel findings indicate that LM23 has a diverse array of functions that are important in both the life and death of the spermatogenic cell.