Figure 1.

LRRC4 interacts with SAM68 and promotes expression of Circ_0021726

(A) 1124C cells were transfected with FLAG-LRRC4 plasmid. Co-immunoprecipitation with Flag antibody showed the interaction between LRRC4 and endogenous SAM68 in 1124C cells (left). 1124C cells were transfected with pCDNA3.1-LRRC4 plasmid, then co-immunoprecipitation with SAM68 antibody showed the interaction between SAM68 and LRRC4 in 1124C cells (right). (B) Representative western blot analysis of LRRC4, SAM68, and GAPDH in 1124C and 1216 cells, with or without transfection with LRRC4 plasmid. (C) Quantification of SAM68 protein expression in 1124C and 1216 cells, with or without transfection with LRRC4 plasmid. (D) Representative western blot analysis of LRRC4, SAM68, and GAPDH proteins in primary GBM tissues. (E) 1124C cells were transfected with green fluorescent protein (GFP)-LRRC4 plasmid. Cells were stained with anti-SAM68 antibody (red) as indicated. The nuclei were stained with DAPI (blue). Scale bar, 20 μm. (F) Quantitation of red fluorescence intensity between GFP-positive and GFP-negative cells. (G) The diagrams show how SAM68 regulated variable splicing by directly binding to the pre-mRNA of CD44, mTOR, and cyclin D1. (H) RT-qPCR analyses showed that LRRC4 increases the expression of hsa_circ_0021726 in 1124C cells. (I) RT-qPCR analyses showed that LRRC4 increases the expression of hsa_circ_0021726 in 1216 cells. ∗p<0.05; ∗∗p<0.01:∗∗∗p<0.001.