Functional analysis of MITF gene mutations associated with Waardenburg syndrome type 2

• Published in: FEBS letters 2012-11, Vol.586 (23), p.4126-4131
• Main Authors: Zhang, Hua, Luo, Hunjin, Chen, Hongsheng, Mei, Lingyun, He, Chufeng, Jiang, Lu, Li, Jia-Da, Feng, Yong
• Format: Article
• Language: English
• Subjects: 1,4-dithiothreitol; 4,6-diamino-2-phenylindole; Animals; Blotting, Western; Cell Line, Tumor; DAPI; DTT; Fluorescent Antibody Technique; GFP; green fluorescence protein; Haploinsufficiency; Humans; Mice; microphthalmia-associated transcription factor; Microphthalmia-Associated Transcription Factor - genetics; Microphthalmia-Associated Transcription Factor - metabolism; MITF; Mutation; NIH 3T3 Cells; NLS; NPC; nuclear localization signal; nuclear pore complex; TYR; tyrosinase; tyrosinase-related protein-1; tyrosinase-related protein-2; TYRP1; TYRP2; Waardenburg syndrome; Waardenburg Syndrome - genetics; Waardenburg Syndrome - metabolism
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2012.10.006

► The R217I MITF retained partial activity and nuclear distribution. ► The T192fsX18 MITF was loss-of-function due to deletion of NLS. ► A sequence 213-218 (ERRRRF) of MITF is identified as the NLS for this protein. ► The two mutations result in the mild phenotypes of WS2 via haploinsufficiency. MITF mutations results in an abnormal melanocyte development and lead to Waardenburg syndrome type 2 (WS2). Here, we analyzed the in vitro activities of two recently identified WS2-associated MITF mutations (p.R217I and p.T192fsX18). The R217I MITF retained partial activity, normal DNA-binding ability and nuclear distribution, whereas the T192fsX18 MITF failed to activate TYR promoter and showed aberrant subcellular localization which may be caused by deletion of nuclear localization signal (NLS) at aa 213–218 (ERRRRF). These results suggest that haploinsufficiency may be the underlying mechanism for the mild phenotypes of WS2 caused by these two mutations.