High-Altitude Stress Orchestrates mRNA Expression and Alternative Splicing of Ovarian Follicle Development Genes in Tibetan Sheep

Mechanistic Insights into Alternative Gene Splicing in Oxidative Stress and Tissue Injury

Significance: Oxidative stress (OS) and inflammation are inducers of tissue injury. Alternative splicing (AS) is an essential regulatory step for diversifying the eukaryotic proteome. Human diseases link AS to OS; however, the underlying mechanisms must be better understood. Recent Advances: Genome‑wide profiling studies identify new differentially expressed genes induced by OS-dependent ischemia/reperfusion injury. Overexpression of RNA-binding protein RBFOX1 protects against inflammation. Hypoxia-inducible factor-1α directs polypyrimidine tract binding protein 1 to regulate mouse carcinoembryonic antigen-related cell adhesion molecule 1 (Ceacam1) AS under OS conditions. Heterogeneous nuclear ribonucleoprotein L variant 1 contains an RGG/RG motif that coordinates with transcription factors to influence human CEACAM1 AS. Hypoxia intervention involving short interfering RNAs directed to long-noncoding RNA 260 polarizes M2 macrophages toward an anti-inflammatory phenotype and alleviates OS by inhibiting IL-28RA gene AS. Critical Issues: Protective mechanisms that eliminate reactive oxygen species (ROS) are important for resolving imbalances that lead to chronic inflammation. Defects in AS can cause ROS generation, cell death regulation, and the activation of innate and adaptive immune factors. We propose that AS pathways link redox regulation to the activation or suppression of the inflammatory response during cellular stress. Future Directions: Emergent studies using molecule-mediated RNA splicing are being conducted to exploit the immunogenicity of AS protein products. Deciphering the mechanisms that connect misspliced OS and pathologies should remain a priority. Controlled release of RNA directly into cells with clinical applications is needed as the demand for innovative nucleic acid delivery systems continues to be demonstrated.

Transcriptome and Metabolome Analyses Reveal High-Altitude Adaptation Mechanism of Epididymis Sperm Maturation in Tibetan Sheep

In this study, the epididymal histology, caepididymal sperm physiological parameters, serum reproductive hormones, and antioxidant enzyme SOD levels of Tibetan sheep at a 2500 m and 3500 m altitude were compared by using a combination of transcriptome and metabolomics methods. This was conducted to investigate the effects of a high-altitude environment on spermatogenesis and the maturation of Tibetan sheep. The results showed that compared to the low-altitude group, the high-altitude group had a smaller epididymal lumen, thicker epididymal wall, significantly decreased sperm survival rate, and significantly increased sperm deformation rate, but no difference in sperm motility and sperm respiratory intensity. With increasing altitude, Tibetan sheep showed a decreasing trend in serum reproductive hormones (FSH and T), while the antioxidant enzyme SOD activity was significantly reduced. Transcriptomic analysis revealed 139 differentially expressed genes in the Tibetan sheep epididymis under high-altitude conditions. The SYCP2 gene is involved in multiple biological processes related to reproduction and plays an important role in the regulation of epididymal function and sperm quality in Tibetan sheep. Genes like ADCYAP1R1, CABP2, CALN1, and ATP6V1B1 can help maintain sperm viability and maturation by regulating the cAMP signaling pathway, calcium ion homeostasis, and cellular signaling. Metabolomic analysis found that the high-altitude group had increased adenosine content and decreased prostaglandin I2 content in the epididymis. These metabolites are involved in spermatogenesis, motility, fertilization, and early embryonic development. The integrated omics analysis suggests that Tibetan sheep adapt to the high-altitude hypoxic environment by regulating cAMP signaling pathway genes like ADCY and PRKACA, as well as metabolites like adenosine and prostaglandin I2, to maintain epididymal function and sperm motility. These genes and metabolites play an important role in maintaining normal epididymal function and sperm motility at high altitudes.

Novel prognostic alternative splicing events in colorectal Cancer: Impact on immune infiltration and therapy response

OBJECTIVE

This study aims to comprehensively analyze alternative splicing (AS) features in colorectal cancer (CRC) using integrative multi-omics and to elucidate their relationship with the CRC immune microenvironment.

METHODS

Transcriptomic data, clinical information, and Percent Spliced In (PSI) values of AS events for CRC patients were obtained from The Cancer Genome Atlas (TCGA) and TCGA SpliceSeq databases. Differentially expressed AS events were identified. Univariate Cox analysis was used to pinpoint prognosis-related AS events. A prognostic risk model was developed and validated using multivariate Cox analysis, patient survival analysis, and the area under the receiver operating characteristic (ROC) curve (AUC). Gene Set Enrichment Analysis (GSEA), immune infiltration, immunotherapy, chemotherapy sensitivity analyses, and regulatory relationships between AS events and splicing factors (SFs) were conducted. Single-cell sequencing was used to study the distribution of key factors. siRNA and overexpression vectors were utilized to silence/overexpress BCAS1 in CRC cells and evaluate their effects on cell growth, migration, and invasion. Furthermore, the interaction between BCAS1 and ANO7 pre-mRNA was investigated using RIP-PCR.

RESULTS

82 prognosis-related AS events were identified in CRC patients. A 15-AS prognostic model was constructed, which correlated with immune cell infiltration and showed differences in immunotherapy and chemotherapy sensitivity. BCAS1 was identified as a potential regulator of the ANO7|58341|AT splicing event in CRC. Single-cell sequencing analysis revealed the distribution of BCAS1 and ANO7 in cancer stem cells. In vitro experiments demonstrated that overexpression of BCAS1 and silencing of ANO7 inhibit the proliferation, migration, and invasion of CRC cells. Moreover, BCAS1 suppresses the progression of CRC by modulating ANO7 alternative splicing.

CONCLUSION

This study provides new insights into the role of alternative splicing in colorectal cancer, particularly the potential regulatory action of BCAS1 on the ANO7|58341|AT splicing event. It also identifies the impact of alternative splicing on the tumor microenvironment and potential implications for immunotherapy, highlighting its relevance for the in-depth study and treatment of CRC.

Regulation of Hair Follicle Growth and Development by Different Alternative Spliceosomes of FGF5 in Rabbits

This study investigated the regulatory effect of alternative spliceosomes of the fibroblast growth factor 5 (FGF5) gene on hair follicle (HF) growth and development in rabbits. The FGF5 alternative spliceosomes (called FGF5-X1, FGF5-X2, FGF5-X3) were cloned. The overexpression vector and siRNA of spliceosomes were transfected into dermal papilla cells (DPCs) to analyze the regulatory effect on DPCs. The results revealed that FGF5-X2 and FGF5-X3 overexpression significantly decreased LEF1 mRNA expression (p < 0.01). FGF5-X1 overexpression significantly reduced CCND1 expression (p < 0.01). FGF5-X1 and FGF5-X2 possibly downregulated the expression level of FGF2 mRNA (p < 0.05), and FGF5-X3 significantly downregulated the expression level of FGF2 mRNA (p < 0.01). The FGF5 alternative spliceosomes significantly downregulated the BCL2 mRNA expression level in both cases (p < 0.01). FGF5-X1 and FGF5-X2 significantly increased TGFβ mRNA expression (p < 0.01). All three FGF5 alternative spliceosomes inhibited DPC proliferation. In conclusion, the expression profile of HF growth and development-related genes can be regulated by FGF5 alternative spliceosomes, inhibiting the proliferation of DPCs and has an influence on the regulation of HF growth in rabbits. This study provides insights to further investigate the mechanism of HF development in rabbits via FGF5 regulation.

A comparative metabolomics analysis of domestic yak (Bos grunniens) milk with human breast milk

Yaks are tough animals living in Tibet's hypoxic stress environment. However, the metabolite composition of yak milk and its role in hypoxic stress tolerance remains largely unexplored. The similarities and differences between yak and human milk in hypoxic stress tolerance are also unclear. This study explored yak colostrum (YC) and yak mature milk (YMM) using GC-MS, and 354 metabolites were identified in yak milk. A comparative metabolomic analysis of yak and human milk metabolites showed that over 70% of metabolites were species-specific. Yak milk relies mainly on essential amino acids- arginine and essential branched-chain amino acids (BCAAs): L-isoleucine, L-leucine, and L-valine tolerate hypoxic stress. To slow hypoxic stress, human breast milk relies primarily on the neuroprotective effects of non-essential amino acids or derivates, such as citrulline, sarcosine, and creatine. In addition, metabolites related to hypoxic stress were significantly enriched in YC than in YMM. These results reveal the unique metabolite composition of yak and human milk and provide practical information for applying yak and human milk to hypoxic stress tolerance.