Missense mutations in the SH3TC2 protein causing Charcot-Marie-Tooth disease type 4C affect its localization in the plasma membrane and endocytic pathway.
Mutations in SH3TC2 (KIAA1985) cause Charcot-Marie-Tooth disease (CMT) type 4C, a demyelinating inherited neuropathy characterized by early-onset and scoliosis. Here we demonstrate that the SH3TC2 protein is present in several components of the endocytic pathway including early endosomes, late endosomes and clathrin-coated vesicles close to the trans-Golgi network and in the plasma membrane. Myristoylation of SH3TC2 in glycine 2 is necessary but not sufficient for the proper location of the protein in the cell membranes. In addition to myristoylation, correct anchoring also needs the presence of SH3 and TPR domains. Mutations that cause a stop codon and produce premature truncations that remove most of the TPR domains are expressed as the wild-type protein. In contrast, missense mutations in or around the region of the first-TPR domain are absent from early endosomes, reduced in plasma membrane and late endosomes and are variably present in clathrin-coated vesicles. Our findings suggest that the endocytic and membrane trafficking pathway is involved in the pathogenesis of CMT4C disease. We postulate that missense mutations of SH3TC2 could impair communication between the Schwann cell and the axon causing an abnormal myelin formation.
Lupo
Vincenzo
V
Genetics and Molecular Medicine Unit, Instituto de Biomedicina de Valencia (IBV), CSIC, Valencia 46010, Spain.
Galindo
Máximo I
MI
Martínez-Rubio
Dolores
D
Sevilla
Teresa
T
Vílchez
Juan J
JJ
Palau
Francesc
F
Espinós
Carmen
C
D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D022163:Clathrin-Coated Vesicles / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044465:White People / Q000235:genetics
D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C488620:SH3TC2 protein, human