Molecular cloning, structure, and testis-specific expression of MFSJ1, a member of the DNAJ protein family, in the Japanese monkey (Macaca fuscata)

DnaJC18, a Novel Type III DnaJ Family Protein, is Expressed Specifically in Rat Male Germ Cells

Mammalian spermatogenesis occurs in a precise and coordinated manner in the seminiferous tubules. One of the attempts to understand the detailed biological process during mammalian spermatogenesis at the molecular level has been to identify the testis specific genes followed by study of the testicular expression pattern of the genes. From the subtracted cDNA library of rat testis prepared using representational difference analysis (RDA) method, a complimentary DNA clone encoding type III member of a DnaJ family protein, DnaJC18, was cloned (GenBank Accession No. DQ158861). The full-length DnaJC18 cDNA has the longest open reading frame of 357 amino acids. Tissue and developmental Northern blot analysis revealed that the DnaJC18 gene was expressed specifically in testis and began to express from postnatal week 4 testis, respectively. In situ hybridization studies showed that DnaJC18 mRNA was expressed only during the maturation stages of late pachy- tene, round and elongated spermatids of adult rat testis. Western blot analysis with DnaJC18 antibody revealed that 41.2 kDa DnaJC18 protein was detected only in adult testis. Immunohistochemistry study further confirmed that DnaJC18 protein, was expressed in developing germ cells and the result was in concert with the in situ hybridization result. Confocal microscopy with GFP tagged DnaJC18 protein revealed that it was localized in the cytoplasm of cells. Taken together, these results suggested that testis specific DnaJC18, a member of the type III DnaJ protein family, might play a role during germ cell maturation in adult rat testis.

Heat Shock Protein A2 (HSPA2): Regulatory Roles in Germ Cell Development and Sperm Function

Among the numerous families of heat shock protein (HSP) that have been implicated in the regulation of reproductive system development and function, those belonging to the 70 kDa HSP family have emerged as being indispensable for male fertility. In particular, the testis-enriched heat shock 70 kDa protein 2 (HSPA2) has been shown to be critical for the progression of germ cell differentiation during spermatogenesis in the mouse model. Beyond this developmentally important window, mounting evidence has also implicated HSPA2 in the functional transformation of the human sperm cell during their ascent of the female reproductive tract. Specifically, HSPA2 appears to coordinate the remodelling of specialised sperm domains overlying the anterior region of the sperm head compatible with their principle role in oocyte recognition. The fact that levels of the HSPA2 protein in mature spermatozoa tightly correlate with the efficacy of oocyte binding highlight its utility as a powerful prognostic biomarker of male fertility. In this chapter, we consider the unique structural and biochemical characteristics of HSPA2 that enable this heat shock protein to fulfil its prominent roles in orchestrating the morphological differentiation of male germ cells during spermatogenesis as well as their functional transformation during post-testicular sperm maturation.

Expression of Human DNAJ (Heat Shock Protein-40) B3 in Humanized UDP-glucuronosyltransferase 1 Mice

The human DNAJB3 gene encodes a DNAJ (Heat shock protein 40; Hsp40) homolog, subfamily B, member 3 chaperone protein (DNAJB3), which can be down-regulated in disease conditions, as observed in decreased expression of DNAJB3 mRNA in peripheral blood mononuclear cells (PBMC) of obese patients. Recently, humanized UDP-glucuronosyltransferase (UGT) 1 mice (hUGT1 mice) were developed, in which the introduced human UGT1 gene contained a gene encoding human DNAJB3. In the present study, we analyzed the expression of human DNAJB3 mRNA in hUGT1 mice. Among the examined tissues, the testis had the highest expression of human DNAJB3 mRNA, while the lowest expression was observed in the liver. We found that the pattern of tissue-specific expression of mouse Dnajb3 in hUGT1 mice was very similar to that of human DNAJB3. We further demonstrated that the expression of human DNAJB3 in the liver was significantly reduced in high-fat-diet-fed hUGT1 mice compared to the expression level in the control mice, indicating that the expression of human DNAJB3 in hUGT1 mice could be similarly regulated in disease conditions such as obesity. Humanized UGT1 mice might therefore be useful to investigate the physiological role of human DNAJB3 in vivo.

Molecular chaperones, cochaperones, and ubiquitination/deubiquitination system: involvement in the production of high quality spermatozoa

Spermatogenesis is a complex process in which mitosis, meiosis, and cell differentiation events coexist. The need to guarantee the production of qualitatively functional spermatozoa has evolved into several control systems that check spermatogenesis progression/sperm maturation and tag aberrant gametes for degradation. In this review, we will focus on the importance of the evolutionarily conserved molecular pathways involving molecular chaperones belonging to the superfamily of heat shock proteins (HSPs), their cochaperones, and ubiquitination/deubiquitination system all over the spermatogenetic process. In this respect, we will discuss the conserved role played by the DNAJ protein Msj-1 (mouse sperm cell-specific DNAJ first homologue) and the deubiquitinating enzyme Ubpy (ubiquitin-specific processing protease-y) during the spermiogenesis in both mammals and nonmammalian vertebrates.

Structure of msj-1 gene in mice and humans: a possible role in the regulation of male reproduction

Msj-1 gene encodes a DnaJ protein highly expressed in spermatids and spermatozoa of both rodents and amphibians, possibly involved in vesicle fusion and protein quality control by means of interaction with heat shock proteins. We isolated and characterized the entire murine msj-1 gene and searched for putative msj-1-like genes into the human genome. Furthermore, ultrastructural localization of MSJ-1 was analyzed in mouse germ cells by immunogold electron microscopy. The analysis of murine msj-1 genomic sequence reveals that it is an intron less gene. Putative promoter region was predicted within the 600 bp upstream the transcription start site. In mouse, msj-1 maps on chromosome 1, into an intronic region of UDP glucuronosyl-transferase 1 family cluster. At ultrastructural level, MSJ-1 marks the developing acrosomic vesicle and the sperm centriolar region. A blast search against the human genome database revealed two closed regions (Ha and Hb) on human chromosome 2 having high nucleotide identity with murine msj-1 coding region. Similarly to mouse, in human both regions map into an intronic region of UDP glycosyl-transferase 1 family polypeptide A cluster (ugt1a@). A significant ORF encoding a putative DnaJ protein of 145 aa was predicted from Ha. Finally, expression analysis, conducted by RT-PCR in human sperm cells, demonstrated that Ha mRNA is effectively present in humans; by Western blot, a specific MSJ-1 band of approximately 30kDa was detected in human sperm. Taken together, these data suggest that msj-1 gene might be conserved among vertebrates and might exert fundamental functions in reproduction.

Characteristics of 292 Testis-Specific Genes in Human

To explore their genomic and functional characteristics, 292 human testis-specific genes were obtained from a UniGene library and a full-scale analysis was made. Various bioinformatics tools were applied to analyze the gene ontology and chromosome location, and the expression profiles of eight selected candidates from the 292 genes were analyzed using RT-PCR for 12 adult human tissues. The results showed that of the total 292 genes, 153 were known (114 assigned genes and 39 named genes), and 139 were unknown. Of the 114 assigned genes, 63 were labeled to molecular function, 28 to cellular component, 23 to biological process. All 292 genes are distributed on human chromosomes at different gene density, lower gene density appears on chromosomes 21 (R=0.22), X (R=0.33), 14 (R=0.39), 10 (R=0.61), 8 (R=0.63), and 18 (R=0.67) and higher density on chromosomes 19 (R=3.65), 20 (R=1.83), 16 (R=1.74), and 17 (R=1.64). The expression profile of the eight selected genes in the 12 human tissues showed that five candidate genes: Hs.443729, Hs.115366, Hs.558087, Hs.534501, and Hs.132104 were expressed exclusively in human testis; Hs.132310, Hs.443299 were expressed highly in testis and also expressed weakly in human heart; Hs.160370 was expressed in human testis, ovary, uterus, and not expressed in other tissues. Our study can be a basis for characterization of the function of human testis-specific genes during male mammalian spermatogenesis.

Identification and characteristics of a novel testis-specific gene, Tsc21, in mice and human

Testis-specific genes are essential for spermatogenesis in mammalian male reproduction. We have identified a novel gene, Tsc21, exclusively expressed in mice and human testes from the results of the Affymetrix Genechip analysis in the six developmental stages of testis of postnatal Balb/C mice. The full cDNA length of Tsc21 was 810 bp, with a 543 bp open reading frame encoding a 180 amino acids protein with a predicted molecular weight of 21.040 kDa. A Blast search in the mouse genome database localized the Tsc21 gene to mice chromosome 6C3. Multiple amino acid sequence alignment of human, mouse, and rat homologous genes showed that mice Tsc21 protein was highly homologous with the human Tsc21 gene (70%) and rat Tsc21 gene (86%). The results of reverse transcriptase-polymerase chain reaction analysis showed that the mice Tsc21 is exclusively expressed in the testis and epididymis of mice, and its expression is only detected after the mice is 35 days old. Human Tsc21 is also exclusively expressed in testis of human. Considering the expression profile Tsc21 in mice and human, we propose that Tsc21 may play a role during mammalian male spermatogenesis. Our study should be a basis for function characterization of the Tsc21 gene, leading to the elucidation of the molecular events underlying mammalian male reproduction.

Structure of msj-1 gene: a comparative analysis

Msj-1 gene encodes a DnaJ protein highly expressed in spermatids and spermatozoa of both rodents and amphibians. We isolated and characterized the msj-1 gene in mice. A bioinformatic approach was then used to predict the putative promoter region, chromosomal localization, and its presence in the human genome. The analysis of msj-1 genomic sequence revealed that msj-1 is an intronless gene. Interestingly, two regions (A and B, separated by 10,682 bp) on human chromosome 2 having respectively 78% and 77% nucleotide identity with the murine msj-1 coding region were identified. This suggests the existence of an msj-1-like gene also in humans.

Expression of fragile X mental retardation-1 gene with nuclear export signal mutation changes the expression profiling of mouse cerebella immortal neuronal cell

Fragile X syndrome (FXS) is the most frequent cause of inherited mental retardation and is largely caused by a loss of expression of fragile X mental retardation protein (FMRP), encoded by fragile X retardation gene-1 (Fmr1). FMRP is a multifunction protein, with intrinsic RNA-binding properties, which is a component of ribonucleoprotein complex associated with polyribosomes. The properties of FMRP indicate that it might participate in post-transcriptional processes in the regulation of some mRNA species, including localization, stability and translational control. However, the function of FMRP related to the pathologenesis in FXS is largely unknown. Many efforts were undertaken to identify the putative specific RNA targets as well as the FMRP-related proteins and to identify the effect of FMRP absence on the corresponding proteins. Here we present our efforts using proteomics approach to explore the differential expression profiling of mouse cerebella immortal cell, in which we changed the expression of FMRP by expressing Fmr1 gene with nuclear export signal (NES) mutation. This mutation makes FMRP unable to shuttle from nucleus to cytoplasm and leads to nuclear instead of cytoplasmic location as usual, which was hypothesized to affect the pathways of groups of RNAs or proteins related with FMRP. In present study, 56 proteins were found to be differentially expressed in transfected R2 neuronal cells, including 16 decreased expressions and 40 increased expressions. The differentially expressed proteins play roles in diverse physiological processes, such as neuronal plasticity, spermatogenesis and craniofacial and limb development etc. In addition, the expressions of three mRNA identified as FMRP targets in fragile X cell were tested in present model cells. All these results provide new insights to the role of FMRP in the disease.

Detection of msj-1 gene expression in the frog, Rana esculenta testis, brain, and spinal cord

MSJ-1 is member of the DnaJ/heat shock protein (Hsp) 40 chaperone protein family. It is present in mouse testis and spinal cord. In particular, MSJ-1 is localized in post-meiotic cells and in motoneurones of the ventral horns. To assess whether the role of this protein is evolutionarily conserved, we have investigated if msj-1 gene is expressed in the frog, Rana esculenta. Using reverse transcription-polymerase chain reaction (RT-PCR), a msj-1-like transcript was detected in testis, brain, and spinal cord. Homology ranging from 42.3 to 46.0% was found as compared with the mammalian counterparts. Muscle did not show any signal. By Western blot analysis, a signal of the predicted size of 30 kDa was evidenced in testis, brain, and spinal cord but not in ovary, heart, liver, kidney, and muscle. MSJ-1 fluctuations in the testis reveal that it appeared in concomitance with post-meiotic events during the annual sexual cycle, as shown in a previous study. The protein is localized in spermatids and is still retained in mature spermatozoa, where it has perinuclear and centriolar localization. MSJ-1 levels did not change in brain and spinal cord. Furthermore, in the brain MSJ-1 was mainly present in diencephalon and mesencephalon, while in spinal cord MSJ-1 was localized into several motoneurones of the cervical and thoracic tract. A putative role in vesicle trafficking is briefly discussed.