Alternative splicing dynamics during gastrulation in mouse embryo.

Alternative splicing (AS) plays an essential role in development, differentiation and carcinogenesis. However, the mechanisms underlying splicing regulation during mouse embryo gastrulation remain unclear. Based on spatial-temporal transcriptome and epigenome data, we detected the dynamics of AS and revealed its regulatory mechanisms across primary germ layers during mouse gastrulation, spanning developmental stages from E6.5 to E7.5. Subsequently, the dynamic expression of splicing factors (SFs) during gastrulation was characterized, while the expression patterns and functions of germ layer-specific SFs were identified. The results indicate that AS and differential alternative splicing events (DASEs) exhibit dynamic changes and are significantly abundant during the late stage of gastrulation. Similarly, SFs demonstrate stage-specific expression, with elevated levels observed during the middle and late stages of gastrulation. Epigenetic signals associated with SFs and AS sites demonstrate significant enrichment and undergo dynamic changes throughout gastrulation. Overall, this study offers a systematic analysis of AS during mouse gastrulation, identifies primary germ layer-specific AS events, and characterizes the expression patterns of SFs and the associated epigenetic signals. These findings enhance the understanding of the mechanisms underlying the formation of the three germ layers during mammalian gastrulation, with a focus on pre-mRNA AS.