Genome-Wide Identification of Laminin Family Related to Follicular Pseudoplacenta Development in Black Rockfish (Sebastes schlegelii)

As major elements of the basement membrane, laminins play a significant role in angiogenesis, migration, and adhesion of various cells. Sebastes schlegelii is a marine viviparous teleost of commercial importance. Previous research has reported abundant blood vessels and connective tissue in the ovary during gestation. In this study, 14 laminin genes of the α, β, and γ subfamilies from genomic data were identified based on zebrafish and human laminins, distributed on 9 chromosomes in S. schlegelii. Analysis of structural domains showed that coiled-coil regions and EGF domains existed in all laminin genes. Moreover, via qPCR, we found that the expression of laminin genes, including lama4, lama5, lamb4, lamc1, and lamc3, gradually increased from the phase III ovary stage and peaked in the early stage of gestation, especially lama4 and lama5 which showed dramatically increased expression at the blastula stage. Accordingly, in situ hybridization of lama4 was conducted. The results revealed that signals became stronger following the phase IV ovary stage, and the strongest signals were located on the follicular pseudoplacenta at the blastula stage. These results suggest that the high expression of laminin genes, especially lama4 after fertilization, may drive cell proliferation, migration, and tissue expansion in the S. schlegelii ovary and ultimately promote follicular pseudoplacenta formation.