ENPP1 Mutation Causes Recessive Cole Disease by Altering Melanogenesis

Propose: We used next-generation RNA sequencing (RNA-seq) to characterize the transcriptional changes in primary human melanocytes during recessive Cole disease. Our patient carried missense mutation in the ENPP1 gene (c.358T>C; p.C120R). RNA-seq was performed using mRNA extracted from primary hypo- and hyper-pigmented melanocytes isolated from affected patient and melanocytes from his healthy heterozygous sibling and an aged- and ethnicity-matched control. Results: A pairwise fold-change comparison was performed and genes were computationally filtered using a cutoff of more than 2 fold change and P<0.01. We first compared hyper-pigmented melanocytes to each control individually and then overlapped the results to obtain a list of 1041 up-regulated and 692 down-regulated genes. The same analysis was done for hypo-pigmented melanocytes to found that 535 genes were up-regulated and 520 were down-regulated. Finally, to obtain a profile of the overall differential gene expression, down-regulated genes in hyper and hypo-pigmented cells were overlapped to identify 143 genes that were down-regulated in patient melanocytes compared to controls regardless of pigmentation status. Similar analysis was performed to obtain the list of 172 up-regulated genes. We selected 36 deregulated genes, most of which were associated with melanocyte development and pigmentation signaling pathways, and validated 32 of them by Q-PCR, indicating that our RNA-Seq data was accurate and reliable. Conclusion: Our study represents the first analysis of hypo- and hyper-pigmented primary melanocytes isolated from affected patient versus healthy controls in recessive Cole disese pathology. Overall design: mRNA profiles of hyper- and hypo-pigmented mutant melanocytes, heterozygous and wild type melanocytes were sequenced in triplicate on the Hiseq 2500 High output 100PE

12

Chourabi M, Liew MS, Lim S, H'mida-Ben Brahim D, Boussofara L, Dai L, Wong PM, Foo JN, Sriha B, Robinson KS, Denil S, Common JE, Mamaï O, Ben Khalifa Y, Bollen M, Liu J, Denguezli M, Bonnard C, Saad A, Reversade B