Impaired Blastocyst Formation in Lnx2-Knockdown Mouse Embryos.

Ligand of Numb-protein X 2 (LNX2) is an E3 ubiquitin ligase that is known to regulate Notch signaling by participating in NUMB protein degradation. Notch signaling is important for differentiation and proliferation in mammals, and plays a significant role in blastocyst formation during early embryonic development. In this study, we investigated Lnx2 in mouse preimplantation embryos. Expression analysis showed that Lnx2 is expressed in oocytes and preimplantation embryos. Lnx2-knockdown embryos normally progress to the morula stage, but the majority of them do not develop into normal blastocysts. Transcript analysis revealed that the expression levels of genes critical for cell lineage specification, including octamer-binding transcription factor 4 (Oct4), are increased in Lnx2 knockdown embryos. Furthermore, the expression levels of Notch and Hippo signaling-related genes are also increased by Lnx2 knockdown. Collectively, our results show that Lnx2 is important for blastocyst formation in mice, suggest that this may act via lineage specification of inner cell mass, and further show that Lnx2 may be involved in transcriptionally regulating various genes implicated in early embryonic development.

Analysis of mouse male germ cell-specific or -predominant Tex13 family genes encoding proteins with transcriptional repressor activity.

Mammalian spermatogenesis is a highly organized process with successive mitotic, meiotic, and postmeiotic phases. This unique developmental process is characterized by the involvement of spermatogenic cell-specific genes. In this study, we identified and investigated testis expressed gene 13 (Tex13) family genes, consisting of Tex13a, Tex13b, Tex13c1, and Tex13d, in mice. All of these genes were transcribed specifically or predominantly in male germ cells, and their transcription was developmentally regulated. Proteins encoded by the Tex13 genes were predicted to have a conserved domain of ~ 145 amino acids. Tex13a, Tex13c1, and Tex13d encode additional C-terminal regions containing a short conserved sequence termed a zinc finger-RAN binding protein 2 (zf-RanBP2) or zf-RanBP2-like domain. As TEX13B reportedly has transcriptional repressor activity, we examined the effect of the TEX13 proteins on transcriptional regulation using a reporter assay. All of the TEX13 proteins exhibited transcriptional repressor activity. This activity was revealed to reside in the TEX13B-corresponding regions of TEX13A, TEX13C1, and TEX13D. Further, we found that the C-terminal regions of TEX13A, TEX13C1, and TEX13D also have inhibitory activities. These results suggest that male germ cell-specific or -predominant TEX13 proteins commonly function in transcriptional repression as transcription cofactors and/or RNA binding proteins.

Profiling of testis-specific or testis-predominant genes expressed in mouse male germ cell lines GC-1 and GC-2.

BACKGROUND: Spermatogenesis is a tightly organized process that utilizes an intrinsic genetic program composed of germ cell-specific genes. Although mouse germ cell-related cell lines are available, few germ cell-specific genes have been comprehensively identified in such cell lines. OBJECTIVE: We aimed to profile gene expression in the male mouse germ cell-related cell lines, GC-1 and GC-2, characterize their transcriptomic nature, and identify potential testis- or germ cell-specific or -predominant genes expressed in these cell lines. METHODS: We performed profiling analysis of genes transcribed in the mouse germ cell-related cell lines, GC-1 and GC-2, using our previous microarray data together with public transcriptome information. We analyzed the expression of a number of the cell line genes predicted to be preferentially expressed in testis by RT-PCR. RESULTS: We found that most testis-specific or -predominant mRNAs are not expressed in GC-1 and GC-2 cells, implying that these cell lines have lost their testis- or germ cell-specific genetic characteristics. RT-PCR analysis of genes predicted to be expressed in the cell lines with preferential testicular expression showed the testis-specific or -predominant expression of nine genes and verified four of them as being expressed in the germ cell lines. Among them, only cyclin-dependent kinase inhibitor 3 genes (Cdkn3) showed testis and germ cell specificity. CONCLUSION: Our study provides extensive transcriptomic information to shed light on the limited testicular characteristics of the mouse male germ cell-derived cell lines, GC-1 and GC-2, and offers a list of germ cell line genes with testicular preference.

Testicular germ cell-specific lncRNA, Teshl, is required for complete expression of Y chromosome genes and a normal offspring sex ratio.

Heat shock factor 2 (HSF2) regulates the transcription of the male-specific region of the mouse Y chromosome long arm (MSYq) multicopy genes only in testes, but the molecular mechanism underlying this tissue specificity remains largely unknown. Here, we report that the testicular germ cell-specific long noncoding RNA (lncRNA), NR_038002, displays a characteristic spatiotemporal expression pattern in the nuclei of round and elongating spermatids. NR_038002-knockout male mice produced sperm with abnormal head morphology and exhibited reduced fertility accompanied by a female-biased sex ratio in offspring. Molecular analyses revealed that NR_038002 interacts with HSF2 and thereby activates expression of the MSYq genes. We designate NR_038002 as testicular germ cell-specific HSF2-interacting lncRNA (Teshl). Together, our study is the first to demonstrate that the testis specificity of HSF2 activity is regulated by the lncRNA Teshl and establishes a Teshl-HSF2-MSYq molecular axis for normal Y-bearing sperm qualities and consequent balanced offspring sex ratio.

Transcriptome Analysis of Testicular Aging in Mice.

Male reproductive aging, or andropause, is associated with gradual age-related changes in testicular properties, sperm production, and erectile function. The testis, which is the primary male reproductive organ, produces sperm and androgens. To understand the transcriptional changes underlying male reproductive aging, we performed transcriptome analysis of aging testes in mice. A total of 31,386 mRNAs and 9387 long non-coding RNAs (lncRNAs) were identified in the mouse testes of diverse age groups (3, 6, 12, and 18 months old) by total RNA sequencing. Of them, 1571 mRNAs and 715 lncRNAs exhibited changes in their levels during testicular aging. Most of these aging-related transcripts exhibited slight and continuous expression changes during aging, whereas some (9.6%) showed larger expression changes. The aging-related transcripts could be classified into diverse expression patterns, in which the transcripts changed mainly at 3-6 months or at 12-18 months. Our subsequent in silico analysis provided insight into the potential features of testicular aging-related mRNAs and lncRNAs. We identified testis-specific aging-related transcripts (121 mRNAs and 25 lncRNAs) by comparison with a known testis-specific transcript profile, and then predicted the potential reproduction-related functions of the mRNAs. By selecting transcripts that are altered only between 3 and 18 months, we identified 46 mRNAs and 34 lncRNAs that are stringently related to the terminal stage of male reproductive aging. Some of these mRNAs were related to hormonal regulation. Finally, our in silico analysis of the 34 aging-related lncRNAs revealed that they co-localized with 19 testis-expressed protein-coding genes, 13 of which are considered to show testis-specific or -predominant expression. These nearby genes could be potential targets of cis-regulation by the aging-related lncRNAs. Collectively, our results identify a number of testicular aging-related mRNAs and lncRNAs in mice and provide a basis for the future investigation of these transcripts in the context of aging-associated testicular dysfunction.