Figure 7.
Role of MTMR4. (A) Sequencing results. The analysis identified two interesting SNVs: rs2302189 (V297G), with either wild-type (A/A) or heterozygous variant (A/C) and rs2302189 (L170V), with either wild-type (G/G) or heterozygous variant (G/C). The illustration on the right illustrates the location of the two SNVs V297G and L170V on the conserved phosphatase region of the MTMR4 protein. (B) MTMR4 protein expression revealed by SDS-PAGE and immunoblot in CTR-, S-, and AS iPSC-CMs. Knock-down of MTMR4 by siRNA confirmed the role of MTMR4 on dephosphorylation of Nedd4L in iPSC-CM. (C) Co-localization of MTMR4 and Nedd4L in CTR and S cells. Confocal images of CTR-, AS-, and S-iPSC-CMs visualized with cTnT co-staining (purple). Nedd4L and MTMR4 were shown in red and green channel and the nuclei in blue (DAPI). Scale bar = 20 μm. (D) MTMR4–Nedd4L protein interaction investigated in 293T heterologous system. HEK cells transfected either with pCMV6-XL4-hMTMR4-WT, L170V (rs3744108 G to C single-nucleotide variant), V297G (rs2302189 A to C single-nucleotide variant), or double SNVs together with pcDNA3.1-hNedd4L. Forty-eight hours after transfection, whole-cell extracts were collected and subjected to immunoprecipitation and western blot with the indicated antibodies.