Fig. 2
From: Mutations in six nephrosis genes delineate a pathogenic pathway amenable to treatment
Gene products of MAGI2, TNS2, DLC1, CDK20, and CAV1 physically and functionally interact to regulate RhoA/Rac1/Cdc42 activation. a Identification of six novel monogenic causes of NS reveals a regulatory network of RhoA activation. The large rounded square symbolizes a podocyte. All six proteins MAGI2, TNS2, DLC1, CDK20, ITSN1, and ITSN2, in which recessive defects were detected herein as novel causes of pTSNS, interact physically or functionally to regulate RhoA/Rac1/Cdc42. Yellow labels highlight proteins encoded by genes, which if mutated give rise to monogenic nephrosis as shown in this study (MAGI2, TNS2, DLC1, CDK20, ITSN1, and ITSN2) or as published (EMP2, ARHGDIA). Blue frame around yellow labels indicate that there is also a monogenic mouse model of NS or a zebrafish model known, as shown in this study for ITSN2 or as published for MAGI2, TNS2, EMP2, and RhoGDI-α. For each of the proteins, MAGI2, TNS2, DLC1, CDK20, TLN1, or ITSN1, the protein domains are shown. Red circles denote positions of mutations that we found in patients. Truncation mutations are represented by “x”. By identifying novel monogenic causes of NS we discovered a cluster proteins that regulate Rho/Rac/Cdc42 activation as being central for the pathogenesis of these patients. b MAGI2 interacts with TNS2 upon co-overexpression and coimmunoprecipitation (coIP) in HEK293T cells. Both mutant MAGI2 clones, Gly39* and Tyr746* (underlined) that reflect alleles of NS patients A5146-21 and B91 respectively, abrogate this interaction. c MAGI2 interacts with DLC1 upon co-overexpression and coIP in HEK293T cells. One mutant MAGI2 clone Gly39* (underlined) reflecting a mutation of NS patient A5146-21 abrogates this interaction. d DLC1 interacts with CDK20 upon co-overexpression in HEK293T cells. e DLC1 interacts with CAV1. Two mutant DLC1 c-DNA clones, reflecting Trp10* and Lys1358Thr alleles of NS patients A548-21 and A4967-21 respectively, lack this interaction. f In IMCD3 cells, migration rate is induced in the presence of serum as compared to scrambled control. Knockdown of Dlc1 in IMCD3 cells using mouse Dlc1 siRNA #1 impairs cell migration rate (red vs. black curve with serum). The decrease in migration is rescued by transfection with full-length human DLC1 cDNA (green curve). Transfection with four out ot six mutants (Trp10*, Ala456Val, Ala1352Val, and Lys1358Thr) failed to rescue this migratory phenotype
