Structural and functional analysis of growth differentiation factor 8: A positive regulator of growth in the Pacific...

Growth Differentiation Factor 8 (GDF8) is a key regulator of muscle development, differentiation, and neurogenesis, known to inhibit muscle growth in vertebrates. However, its functional role in crustaceans, whether inhibitory or promotive, remains controversial. In this study, we characterized the structure, phylogeny, and expression patterns of LvGDF8 in the Pacific white shrimp (Litopenaeus vannamei). LvGDF8 exhibited the highest expression levels in the heart relative to other tissues and showed higher levels in fast-growing individuals and females, suggesting a potential role in growth regulation. Functional assays revealed that knockdown of LvGDF8 significantly suppressed increases in body length and weight, while its overexpression enhanced growth performance. These results indicated that LvGDF8, which is highly expressed in heart tissue, acts as a growth promoter in L. vannamei, contrasting with the muscle-inhibitory function of its vertebrate homologs. Integrated transcriptomic and proteomic analyses identified numerous differentially expressed genes and proteins associated with growth and molting processes. Subsequent bioinformatics analysis revealed significant alterations in key pathways, including the endoplasmic reticulum protein processing, ecdysteroid biosynthesis, Hippo, and Rap1 signaling. Collectively, these findings suggest that LvGDF8 positively regulates growth in L. vannamei and provide novel insights into GDF8-mediated molecular mechanisms in commercially important crustacean species.