RILP inhibits proliferation, migration, and invasion of PC3 prostate cancer cells.

RILP (Rab-interacting lysosomal protein) is a key regulator of lysosomal transport and a potential tumor suppressor. However, the role of RILP in prostate cancer and the underlying mechanism of RILP in regulating the proliferation, migration, and invasion of prostate cancer cells remain to be studied. In this study, we confirmed RalGDS (Ral guanine nucleotide dissociation stimulator) as the interaction partner of RILP in PC3 prostate cancer cells. Immunofluorescence microscopy showed that RILP recruits RalGDS to the lysosomal compartment. We found that RILP inhibits the activation of RalA and downstream effector RalBP1, and negatively regulates the downstream molecular phosphorylation of Ras. We showed that RILP inhibits the proliferation, migration, and invasion of PC3 prostate cancer cells, which may give rise to novel ideas for cancer treatment.

Expression profile analysis of a new testis-specifically expressed gene C17ORF64 and its association with cell apoptosis in MCF-7 cells.

With the increasing incidence of male infertility, identification and investigation the functions of new genes related to spermatogenesis are effective avenues to elucidate the decline of testicular function. In this study, a new gene, C17ORF64 (chromosome 17 open reading frame 64), was identified from mouse testes and its potential function was studied.RT-PCR and qRT-PCR assay showed that C17ORF64 mRNA was expressed exclusively in mouse testes and up-regulated from the 3-week old to 6-month old testes during postpartum development, which is consistent with C17ORF64 protein expression profile by western blotting analysis. Immunohistochemical analysis revealed that C17ORF64 protein was mainly localized in the cytoplasm of spermatogonia and spermatocytes, which is verified by GFP- labeled C17ORF64 gene expressed in GC-1 cells. C17ORF64 overexpression not only promoted cell apoptosis in MCF-7 cells, but also significantly decreased cell viability via MTT assay. Flow cytometric assay showed that C17ORF64 overexpression could inhibit cell cycle progression by arresting G1/S transition. Western blot and qRT-PCR analysis revealed that C17ORF64 overexpression inhibited the expression of anti-apoptotic protein bcl-2 and increased the expressions of pro-apoptotic protein caspase-3, caspase-8, caspase-9, Bax, P21 and P53. Taken together, our results confirmed C17ORF64 testis-specific expression pattern and, for the first time, demonstrated that C17ORF64 could inhibit cell viability and accelerate apoptosis in MCF-7 cells through caspase-3 regulatory pathways.

The testis-specific expressed gene Spata34 is not required for fertility in mice.

It is estimated that more than two thousand genes exhibit testis-predominant expression pattern. The functions of hundreds of these genes have been explored during mouse spermatogenesis. However, there are still many genes whose relevance to reproduction in vivo remains unexplored. Our previous studies, as well as the other documented study, have indicated that Spata34, an evolutionarily conserved gene in metazoan species, was exclusively expressed in mouse testes and involved in spermatogenesis by regulating cell cycle progression. The present study aims to determine the effect of Spata34 gene knockout on mouse reproduction in vivo by generating a Spata34 gene knockout model using CRISPR/Cas9-mediated genome editing technology. We found that the Spata34 gene KO mice had normal fertility compared with wild type mice, and no overt detectable difference was found in testis/body weight ratios, testicular histology, sperm counts and spermatozoa motility parameters between WT and Spata34 KO mice. Our report indicated that the testis-specific-expressed gene Spata34 was not required for male mouse fertility, which will help to avoid unnecessary expenditures and effort by other researchers.

Cloning of a new testis-enriched gene C4orf22 and its role in cell cycle and apoptosis in mouse spermatogenic cells.

Spermatogenesis is a complicated and dynamic cellular differentiation process mainly regulated by genes, steroid hormones and environmental factors. Although a number of genes involved in spermatogenesis have been identified, there are still a lot of genes underlying spermatogenesis remained unexplained. Here, a novel gene C4orf22, also known as 1700007G11Rik or Cfap299 was identified from mouse testis. C4orf22 protein contains 233 amino acid residues and is highly conserved in metazoan species. C4orf22 mRNA was predominantly expressed in mouse testis and increased from 2-week-old testes to 8-week-old testes during the developing testes by RT-PCR and qRT-PCR. Immunohistochemical analysis indicated that C4orf22 protein was mainly distributed in the cytoplasm of spermatogonia and primary spermatocytes, which was further confirmed by C4orf22-tagged with GFP in the GC-1 and GC-2 cells. Over-expression of pEGFP-C3-C4orf22 significantly inhibited GC-1 cells apoptosis and promoted cell cycle progression with an increase in the cell number of S and G2 phase. Conversely, small interfering RNA (siRNA) silencing C4orf22 in GC-1 cells could cause an increase in the number of apoptosis cells and the cell cycle was arrested at G2/M phase. Western blot analysis and qRT-PCR results showed that C4orf22 over-expression significantly increased the expressions of anti-apoptotic bcl-2 and decreased the expression of caspase-3, caspase-8 and Bax. Our results suggest that C4orf22 may be involved in spermatogenesis, and for the first time, unravels its potential role in regulating cell apoptosis through bcl-2 regulatory pathway in GC-1 cells.

Roles of MicroRNA-34a in Epithelial to Mesenchymal Transition, Competing Endogenous RNA Sponging and Its Therapeutic Potential.

MicroRNA-34a (miR-34a), a tumor suppressor, has been reported to be dysregulated in various human cancers. MiR-34a is involves in certain epithelial-mesenchymal transition (EMT)-associated signal pathways to repress tumorigenesis, cancer progression, and metastasis. Due to the particularity of miR-34 family in tumor-associated EMT, the significance of miR-34a is being increasingly recognized. Competing endogenous RNA (ceRNA) is a novel concept involving mRNA, circular RNA, pseudogene transcript, and long noncoding RNA regulating each other's expressions using microRNA response elements to compete for the binding of microRNAs. Studies showed that miR-34a is efficient for cancer therapy. Here, we provide an overview of the function of miR-34a in tumor-associated EMT. ceRNA hypothesis plays an important role in miR-34a regulation in EMT, cancer progression, and metastasis. Its potential roles and challenges as a microRNA therapeutic candidate are discussed. As the negative effect on cancer progression, miR-34a should play crucial roles in clinical diagnosis and cancer therapy.

Role of Spata34 in cell proliferation and its expression pattern in postnatal development of rat testis.

Spata34 is a testis-specific-expressed gene which exerts diverse functions in testis development. This study intends to examine the expression profiles of Spata34 in postnatal rat testis, and explore its potential roles in cell proliferation in vitro. We found that the mRNA and protein expression levels of Spata34 were developmentally upregulated in rat testes during the early 1-7 postnatal weeks using real-time polymerase chain reaction and western blotting. Immunohistochemical results indicated that Spata34 protein was mainly detected in the nuclear and cytoplasm of spermatocytes and round spermatids. The possible function of Spata34 in cellular proliferation was analyzed using cell counting kit, colony formation and flow cytometry assays. Our results showed that overexpression of Spata34 in multipotent adult germline stem cell lines (maGSC129SV) cells markedly facilitated cell proliferation with a large increase in cell numbers in S phase of cell cycle. While knockdown of Spata34 expression by specific siRNA suppressed the growth of maGSC129SV cells and triggered cell-cycle arrest at G1/S phase transition, which was related to the elevation of p21 and p27 and decrease of Cyclin D1 and Cyclin D-dependent kinase 4. Altogether, our results indicated that the Spata34 gene evokes unique expression patterns during postnatal development of the rat testis, and for the first time, unravels the function of Spata34 on regulating cell-cycle progress through p21 and p27 pathway.

Immune response of interferon-γ-inducible lysosomal thiol reductase (GILT) from Chinese sturgeon (Acipenser sinensis) to microbial invasion and its antioxdative activity in lipopolysaccharides-treated mammalian dentritic cells.

Interferon-γ-inducible lysosomal thiol reductase (GILT) plays an important role in the major histocompatibility complex-restricted antigen processing of endocytosed proteins via catalyzing the disulfide bond reduction in the endocytic pathway. Here, the cDNA of Chinese sturgeon (Acipenser sinensis) GILT (CsGILT) was cloned. It contained an open reading frame of 762 nucleotides encoding a protein of 254 amino acids with an estimated molecular weight of 28.1 kDa. The characteristic structural features, including a signature sequence CQHGX2ECX2NX4C, a CXXC motif, two potential N-glycosylation sites, and eight conserved cysteines were detected in the deduced amino acid sequence of CsGILT. CsGILT was widely expressed in Chinese sturgeon with the highest expression in the spleen, and CsGILT mRNA expression was significantly up-regulated when Chinese sturgeons were challenged with polyinosinic polycytidylic acid or Vibrio anguillarum. The recombinant CsGILT displayed obvious thiol reductase activity demonstrated by catalyzing the reduction of mouse IgG(H+L) by dithiothreitol into heavy chain and light chain. CsGILT also displayed significant antioxidant activity in mouse dentritic cells as indicated by its increasing GSH level and GSH/GSSG ratio, decreasing intracellular reactive oxygen species and nitric oxide levels and lipid peroxidation, as well as enhancing the activities of the antioxidative redox enzymes including catalase and superoxide dismutase. Our results suggested an important role for CsGILT in the immune response in Chinese sturgeon to pathogen invasion possibly via a conserved functional mechanism throughout vertebrate evolution, contributing to our understanding the immune biology and protection of Chinese sturgeon.

[Effect of ditching for drain on control of Oncomelania hupensis snail in beaches of Dongting Lake].

OBJECTIVE: To evaluate the effect of ditching for drain on the control of the breed of Oncomelania hupensis snails in beaches of Dongting Lake. METHODS: From November, 2009 to November, 2012, an 0. hupensis snail infested beach of the Yueyang jail and an O. hupensis snail infested beach of Junshan District were selected as research fields in the eastern Dongting Lake area, and the former, as the intervention field, was performed with the ditching for drain by excavators and the latter, as the control field, was not. RESULTS: Before the project implemented, the average soil moisture contents on the beaches in dry seasons of the two fields were both about 35.56%. After the project implemented, in the intervention field, the average soil moisture content was 26.53% which was significantly lower than that (35.56%) in the control field (F = 6.53, P < 0.05). The underground water levels in different heights in the intervention field were lower than those in the control field (χ2 = 33.33, P < 0.05). Before the project implemented, the natural death rates of the snails were 0.98% and 0.89% in the two research fields respectively (P > 0.05), and after the project implemented (in 2012), no adult and young snails were found in the interventional field, but in the control field, the average densities of living snails and young snails were 29.37 snails/0.1 m2 and 213 ± 108.45 snails/0.1 m2 respectively. CONCLUSION: The intervention of ditching for drain can decrease the soil moisture contents quickly and change the ecological condition, therefore, can control the breed of O. hupensis snails in the beaches of Dongting Lake.

Three ferritin subunit analogs in Chinese giant salamander (Andrias davidianus) and their response to microbial stimulation.

Ferritin, an evolutionarily conserved iron-binding protein, plays important roles in iron storage and detoxification and in host immune response to invading stimulus as well. In the present study, we identified three ferritin subunit analog cDNAs from Chinese giant salamander (Andrias davidianus). All the three ferritin subunit cDNAs had a putative iron responsive element in the 5'-untranslated region. Two deduced ferritin subunits (designated as cgsFerH and cgsFerM) had the highest identity of 90% to H type subunit of vertebrate ferritins, while another deduced ferritin subunit (designated as cgsFerL) had the highest identity of 84% to L type subunit of vertebrate ferritins. The Chinese giant salamander ferritin (cgsFer) was widely expressed in various tissues, with highest expression for cgsFerH and cgsFerL in liver and highest expression for cgsFerM in spleen. Infection of Chinese giant salamander with A. davidianus ranavirus showed significant induction of cgsFer expression. Both lipopolysaccharide and iron challenge drastically augmented cgsFer expression in the splenocytes and hepatocytes from Chinese giant salamander. In addition, recombinant cgsFers bound to ferrous iron in a dose-dependent manner, with significant ferroxidase activity. Furthermore, the recombinant cgsFer inhibited the growth of the pathogen Vibrio anguillarum. These results indicated that cgsFer was potential candidate of immune molecules involved in acute phase response to invading microbial pathogens in Chinese giant salamander possibly through its regulatory roles in iron homeostasis.

A RING finger protein 114 (RNF114) homolog from Chinese sturgeon (Acipenser sinensis) possesses immune-regulation properties via modulating RIG-I signaling pathway-mediated interferon expression.

Ubiquitin ligases play important roles in immune regulation. The human RNF114 (RING finger protein 114), an ubiquitin ligase, was recently reported to be involved in immune response to double-stranded RNA in disease pathogenesis. Here, we identified a RNF114 homolog in Chinese sturgeon (Acipenser sinensis) and investigated its potential role in immune response. The full-length cDNA of Chinese sturgeon RNF114 (csRNF114) contains an open reading frame (ORF) of 681 nucleotides coding a protein of 227 amino acids. csRNF114 shares the highest identity of 76% at amino acid level to other RNF114 homologs, clustering with bony fish RNF114s based on phylogenetic analysis. The main structural features of csRNF114, including a C3HC4 (Cys3-His-Cys4) RING domain, a C2HC (Cys2-His-Cys)-type zinc finger motif, a C2H2 (Cys2-His2)-type zinc finger motif, and a UIM (ubiquitin-interacting motif), take csRNF114 as an ubiquitin ligase. csRNF114 mRNA was widely expressed in various tissues and significantly up-regulated in poly(I:C)-treated Chinese sturgeon. Over-expression of csRNF114 in HEK293T cells significantly promoted both basal and poly(I:C)-induced activation of interferon regulatory transcription factor 3 (IRF3) and nuclear factor-κB (NF-κB) downstream retinoic acid inducible gene I (RIG-I) signaling pathway and expression of target genes type I interferon (IFN), which was nearly abolished by knockdown of RIG-I with specific human siRNA and by mutation of the C3HC4 RING domain (C28A/C31A) in csRNF114 as well. Furthermore, csRNF114 associated with ubiquitinated proteins in HEK293T cells, for which the C3HC4 RING domain was essential. These data suggested that an ubiquitin ligase RNF114 homolog with a potential role in antiviral response possibly through modulating RIG-I signaling pathway was cloned from Chinese sturgeon, which might contribute to our understanding of the immune biology of Chinese sturgeon.

Expression and identification of a novel gene Spata34 in mouse spermatogenic cells.

Leucine-rich repeat (LRR) containing proteins play an essential role in signal transduction, cell adhesion, cell development, DNA repair and RNA processing. Here we cloned a novel gene, Spata34, encoding a LRR containing protein of 415 aa. Spata34 gene consisted of 9 exons and 8 introns and mapped to chromosome 3qA3. Spata34 is conserved across species in evolution. The Spata34 gene was expressed at various levels, faintly before first weeks postpartum and strongly from 2 weeks postpartum in adult testes. Western blot analysis showed that Spata34 protein was specially expressed in mouse testis. Immunohistochemical analysis revealed that Spata34 protein was most abundant in the cytoplasm of round spermatids and elongating spermatids within seminiferous tubules of the adult testis. Overexpression of Spata34 in COS7 cells inhibited the transcriptional activity of AP-1, p53 and p21 which suggested that Spata34 protein may act as a transcriptional repressor in p53 and p21 pathway.

Analgesic effects of Huwentoxin-IV on animal models of inflammatory and neuropathic pain.

Huwentoxin-IV (HWTX-IV), a peptide with 35 amino acid residues, was discovered in the venom of spider Ornithoctonus huwena. The peptide had an inhibitory effect on a tetrodotoxin-sensitive (TTX-S) sodium channel with highly sensitive to Nav1.7, an attractive target for pain release therapy. In this study we further demonstrated the analgesic effects of HWTX-IV using mouse and rat as an inflammatory pain model and/or a neuropathic pain models. In the both cases, the analgesic effects of the peptide were dose-dependent, and statistically significant. In the inflammatory model, 100 µg/kg of HWTX-IV produced an efficient reversal of hyperalgesia up to 63.6% after injection of formalin in rats with the efficiency equivalent to that of morphine at 50 µg/kg, and 200 µg/kg of HWTX-IV produced protective effect up to 55.6% after injection of acetic acid with the efficiency equivalent to that of morphine at 100 µg/kg. In the spinal nerve model, the peptide produced the longer and higher reversal effect on allodynia than Mexiletine. These results demonstrated that HWTX-IV released efficiently the acute inflammatory pain and chronic neuropathic pain in these animals, suggesting that HWTX-IV was a potential and efficient candidate for further clinical drug development against inflammatory and neuropathic pain.

Overexpression of human SPATA17 protein induces germ cell apoptosis in transgenic male mice.

SPATA17 is a new testis-specific-expressed gene that is involved in Spermatogenesis process. Previous studies show that SPATA17 was involved in acceleration of cell apoptosis in GC-1 cell lines. To further investigate specific roles of SPATA17 in Spermatogenesis in vivo, we generated transgenic mice in which the human SPATA17 gene was expressed specifically in spermatocytes using the human phosphoglycerate kinase 2 (PGK2) promoter. The SPATA17 transgenic mice did not show any significant defect in gross testicular anatomy as well as in fertility. However, a significant increase was observed in defective spermatogenic cells, such as apoptotic cells in the SPATA17 transgenic mice. These results revealed that elevated production of the SPATA17 protein disturbed the normal development of male germ cells.

A positively charged surface patch is important for hainantoxin-IV binding to voltage-gated sodium channels.

Hainantoxin-IV (HNTX-IV), isolated from the venom of the spider Ornithoctonus hainana, is a specific antagonist of tetrodotoxin-sensitive (TTX-S) voltage-gated sodium channels in rat dorsal root ganglion (DRG) cells. It adopts an inhibitor cystine knot motif, and structural analysis revealed a positively charged patch consisting of Arg26, Lys27, His28, Arg29 and Lys32 distributed on its molecular surface. Our previous study demonstrated that Lys27 and Arg29 but not Arg26 were critical residues for HNTX-IV binding to TTX-S sodium channels. In the present study, we examined the roles of His28 and Lys32 in the interaction of HNTX-IV with its target. Two mutants, HNTX-IV-H28D and HNTX-IV-K32A, were generated by solid-phase chemical synthesis and purified by reverse-phase HPLC after refolding and oxidation, yielding two compounds of high purity with monoisotopic masses of 3962.66 and 3927.70 Da, respectively, as determined by MALDI-TOF mass spectrometry. This indicated the presence of six cysteine residues forming three disulfide bonds. Moreover, circular dichroism spectroscopy analysis demonstrated that the substitution of His28 or Lys32 did not affect the overall structure of HNTX-IV. The inhibitory activity of HNTX-IV-H28D and HNTX-IV-K32A against TTX-S sodium channels in rat DRG cells was analyzed by whole-cell patch-clamp technique. The IC(50) values for the mutants were 0.57 and 5.80 µM (17-fold and 170-fold lower than the activity of the native toxin), indicating that His28 and Lys32 may be important for the inhibitory activity of HNTX-IV. Taken together, our results suggest that the positively charged patch might be the binding site for the interaction of HNTX-IV with TTX-S sodium channels. These findings might contribute to the elucidation of the structure and function relationship of HNTX-IV.

AP-2ß enhances p53-mediated transcription of the αB-crystallin gene through stabilizing p53.

The αB-crystallin (CRYAB) is a member of the small heat shock protein family that can be induced by various stresses and pathological conditions. Aberrant expression of CRYAB has been shown to be associated with several neurological diseases and malignant neoplasms. To identify transcriptional regulators of CRYAB expression, we examined its promoter for binding sites of transcription factors and identified four potential AP-2 binding sites in addition to a p53 binding site reported previously. Although the CRYAB promoter contains four consensus binding sequences of AP-2 and can be activated by AP-2α either in the presence or absence of p53, the luciferase assay showed that AP-2ß alone does not regulate the activity of the CRYAB promoter in the absence of p53. However, in the presence of p53, AP-2ß can significantly increase the luciferase activities of both the CRYAB promoter and reporter vector pp53-TA-luc, which contains a p53-responsive element, but no AP-2 binding sites. These data suggest that AP-2ß enhances transactivation of p53 and regulates CRYAB transcription via p53. Further study demonstrated that AP-2ß interacts with p53 and augments its protein stability. Taken together, our results indicate that AP-2ß up-regulates the transcription of the CRYAB gene through stabilizing p53.

Overexpression a novel zebra fish spermatogenesis-associated gene 17 (SPATA17) induces apoptosis in GC-1 cells.

The spermatogenesis-associated 17 gene (SPATA17, previously named MSRG-11) was reported to be a candidate spermatocyte apoptosis-related gene which may play a critical role in human spermatogenesis, especially in meiosis. Analysis of SPATA17 expression and regulation in zebra fish may provide insight into the understanding of the complicated process of gonadogenesis and its potential function in spermatocyte cell apoptosis. In this study, we cloned and characterized the SPATA17 gene from zebra fish which consists of nine exons separated by eight introns. The consensus open reading frame (1258 bp) encodes a polypeptide of 357 amino acids which shares 44% identity with the human SPATA17 gene. Bioinformatic analysis reveals that SPATA17 protein contains three short calmodulin-binding motifs (IQ motif) and is considered to play a critical role in interactions with CaM proteins. Multi-tissue RT-PCR and Northern blot results demonstrated that the zebra fish SPATA17 gene was expressed strongly in testis and a slight amount of expression in ovary. Flow cytometry analysis and genomic DNA ladders result showed that the expression of SPATA17 protein in the GC-1 cell line could accelerate cell apoptosis. Analysis of the SPATA17 sequence and its spatial expression pattern indicate that this gene is highly conserved and may play an important role in the process of zebra fish gonadogenesis.

Cloning and primarily function study of two novel putative N5-glutamine methyltransferase (Hemk) splice variants from mouse stem cells.

Methylation is one of epigenetic mechanisms regulating gene expression. The methylation pattern is determined during embryogenesis and passed over to differentiating cells and tissues. Beginning with the ESTs which were highly expressed in undifferentiated human ES cells and using homology research in mouse dbEST database, we cloned two novel putative (N (5))-glutamine methyltransferase (Hemk) splice variants termed mHemk1 and mHemk2 (Genbank accession number AY456393 and AY583759). Sequence analysis revealed that mHemk1 and mHemk2 cDNAs are 1,792 bp and 1,696 bp in length respectively. The deduced proteins have 214 amino acid residues (mHemk1) and 138 residues (mHemk2) in length and both share significant homology with (N (5))-glutamine methyltransferase (Hemk proteins) in database. Northern blot and RT-PCR analysis showed that mHemk mRNAs were abundantly expressed in undifferentiated ES cells, testis and brain, weakly expressed in differentiated ES cells and kidney, and not expressed in muscle, heart, placenta, pancreas, lung and stomach. Immunohistochemical analysis further revealed that the protein was most abundant in undifferentiated ES cells. The green fluorescent protein produced by pEGFP-C3/mHemk1 was detected mainly in the nucleus of COS7 cell lines after 24 h post-transfection. RNA interference (RNAi)-mediated knock-down method was established. Cell cycle analysis suggests that the cell proliferation decreases after RNAi with mHemk1. In vitro bioactivity assay showed that no evidence for a DNA adenine-methyltransferase activity was detected. The accumulating functional information from Hemk homology proteins in bacteria and yeast suggests that it may be an uncharacterized new mammalian N(5)-glutamine methyltransferase.

RNAi-mediated knock-down of gene mN6A1 reduces cell proliferation and decreases protein translation.

Methyltransferases play essential roles in modulating important cellular and metabolic processes. A mouse putative N6-DNA methyltransferase gene (GenBank No AY456393) is a novel gene named mN6amt1(mN6A1). To investigate its function in cell fate and protein translation, RNA interference (RNAi)-mediated knock-down method was established. Cell cycle analysis suggests that the cell proliferation decreases after RNAi with mN6A1. The expression plasmid of luciferase was used to detect protein translation, and the results showed that luciferase expression decreased after RNAi with mN6A1, whereas increased after over-expression of mN6A1 or/and eRF1. The binding between mN6A1 and eRF1 was identified by co-immunoprecipitation and pull-down experiments. It might be suggested that mN6A1 participates in protein translation through interaction with eRF1.

Molecular cloning and expression profile analysis of a novel mouse testis-specific expression gene mtIQ1.

A novel testis-specific gene termed mtIQ1 (GenBank Accession No. DQ153246) was identified by digital differential display. Sequence analysis revealed that mtIQ1 protein is a new member of calmodulin (CaM) binding protein families with conserved Ile and Gln residues (IQ motif). RT-PCR and Northern blot analysis revealed that a 0.9 kb mtIQ1 transcript was only expressed in adult mouse testis and not expressed in nine other tissues. The expression of mtIQ1 mRNA was developmentally upregulated in the testes during sexual maturation and was, conversely, downregulated by experimental cryptorchidism in vivo. The green fluorescence produced by pEGFP-C3/mtIQ1 was detected mainly in the nucleus of GC-1 cells 24 h post-transfection. Results of in situ hybridization assay confirmed that mtIQ1 was expressed in seminiferous tubules, more precisely in spermatocytes. The testis-specific and time-dependent expression pattern of mtIQ1 in postnatal mouse testes suggested that it might be involved in the regulation of spermatogenesis and sperm maturation.