Comparative Transcriptome Analysis Reveals the Role of the FST Gene in Goose Muscle Development

Muscle growth is a critical determinant of meat yield and quality in livestock. Although follistatin (FST) is recognized as a key regulator of skeletal muscle development and fat metabolism, its specific function in geese remains largely unexplored. In this study, we identified two transcript variants of goose FST (<i>gFST</i>) in Zhedong White geese: gFST-X1 (1125 bp), encoding a 343-amino acid protein with a 28-amino acid signal peptide and four conserved domains, and gFST-X2, which contains a 243 bp insertion within the gFST-X1 transcript. RT-qPCR analysis revealed that <i>gFST</i> mRNA expression varied across tissues from female embryos (25 days), adults (70 days), and laying geese (270 days), as well as in skeletal muscle satellite cells (SMSCs) at embryonic day 16 (E16d). Overexpression of gFST in SMSCs resulted in 3596 differentially expressed genes (DEGs), including 2247 upregulated and 1349 downregulated genes (<i>padj</i> < 0.01). Key stemness markers (<i>PAX7</i>, <i>PAX3</i>) and myogenic regulators (<i>MYOG</i>, <i>MYOD</i>, <i>MYF5</i>) were significantly downregulated, whereas genes associated with lipid metabolism (<i>PPARG</i>, <i>FABP5</i>, <i>ACSL5</i>) and myosin-related processes (<i>MYO1D</i>, <i>MYO1F</i>, <i>MYO1E</i>) were markedly upregulated (<i>padj</i> < 0.01). Functional enrichment analysis linked these DEGs to the TGF-β, PPAR signaling, fatty acid metabolism, and Notch signaling pathways. These transcriptomic findings were further validated by qRT-PCR. Collectively, our results demonstrate the dual regulatory role of <i>gFST</i> in skeletal muscle development and provide new mechanistic insights into muscle development in geese.