Hemicastration induced spermatogenesis-related DNA methylation and gene expression changes in mice testis.

OBJECTIVE: Hemicastration is a unilateral orchiectomy to remove an injured testis, which can induce hormonal changes and compensatory hypertrophy of the remaining testis, and may influence spermatogenesis. However, the underlying molecular mechanisms are poorly understood. Here, we investigated the impact of hemicastration on remaining testicular function. METHODS: Prepubertal mice (age 24 days) were hemicastrated, and their growth was monitored until they reached physical maturity (age 72 days). Subsequently, we determined testis DNA methylation patterns using reduced representation bisulfite sequencing of normal and hemicastrated mice. Moreover, we profiled the testicular gene expression patterns by RNA sequencing (RNA-seq) to examine whether methylation changes affected gene expression in hemicastrated mice. RESULTS: Hemicastration did not significantly affect growth or testosterone (p>0.05) compared with control. The genome-wide DNA methylation pattern of remaining testis suggested that substantial genes harbored differentially methylated regions (1,139) in gene bodies, which were enriched in process of protein binding and cell adhesion. Moreover, RNA-seq results indicated that 46 differentially expressed genes (DEGs) involved in meiotic cell cycle, synaptonemal complex assembly and spermatogenesis were upregulated in the hemicastration group, while 197 DEGs were downregulated, which were related to arachidonic acid metabolism. Integrative analysis revealed that proteasome 26S subunit ATPase 3 interacting protein gene, which encodes a protein crucial for homologous recombination in spermatocytes, exhibited promoter hypomethylation and higher expression level in hemicastrated mice. CONCLUSION: Global profiling of DNA methylation and gene expression demonstrated that hemicastration-induced compensatory response maintained normal growth and testicular morphological structure in mice.

Genome-wide profiling of gene expression and DNA methylation provides insight into low-altitude acclimation in Tibetan pigs.

Efforts have been made to characterize the high-altitude adaption in Tibetan pigs and identified vast of genes or genomic regions undergone natural selection. Nonetheless, information concerning gene expression and DNA methylation changes response to low-altitude acclimation in Tibetan pigs is long overdue. To explore the exceptional mechanisms of gene expression and DNA methylation that are induced by low altitude environments in Tibetan pigs, we performed a comparative transcriptomic and DNA methylation analysis of skeletal muscle between indigenous Tibetan pigs that reside in high altitude regions (~4000m) and their counterparts that migrated to the geographically neighboring low-altitude regions (~500m) for nearly ten generations. Many genes that related to hypoxia response (EGLN3 and FLT1) and energy metabolism (TFB2M) were differentially expressed, but without significant DNA methylation changes. We also found genes embedded in differentially methylated regions were mainly involved in 'Starch and sucrose metabolism', 'glucuronosyltransferase activity' processes. Specifically, our results showed increased SIN3A mRNA expression, with hypomethylation status of its promoter, in longissimus dorsi muscle of low-altitude Tibetan pig. Another gene, CACNG6, showed decreasing expression level with an elevated methylation in its intron 3. These results indicated DNA-methylation-mediated expression alterations in low-altitude acclimation. We envision that this study will serve as a valuable resource for mammal acclimation research and agricultural food industry.