Characterization and Functional Study of FAM49B Reveals Its Effect on Cell Proliferation in HEK293T Cells

FAM49B/Fam49b is a member of the Fam49 (Family with sequence similarity 49) gene family, which is characterized by the conserved domain, DUF1394 (Domain of Unknown Function 1394). It has also been named CYRI-B (CYFIP related RAC1 interactor B), implicating its important function of regulating RAC1-driven cytoskeleton remolding. In this study, to further investigate its functions and mechanisms affecting cell behaviors, HEK293T cells (where FAM49B is highly expressed) were used to establish a FAM49B knockout cell line by CRISPR/Cas9 genome editing technology. Our data have clearly revealed that there are triple alleles of FAM49B in the genome of HEK293T cells. Meanwhile, the proliferation deficiency of the FAM49B KO HEK293T cell line and the significantly changed cell proliferation related gene expression profiles, such as CCND1, have been uncovered. At the same time, the existence of isoform 3 has been confirmed in HEK293T cells. Our studies have suggested that FAM49B may also affect cell proliferation via Cyclins, besides its influence on the cytoskeleton.