Project description:<p>In order to create a melanocyte-specific eQTL resource, we obtained primary human melanocyte cultures isolated from foreskin of 106 healthy newborn males predominantly of European descent. Melanocytes were cultured in lot-matched culture medium in randomized batches to minimize variability that could be introduced by culturing conditions. RNA sequencing and direct SNP genotyping of these samples produced an average of ~87.9 million reads (paired-end, stranded, 126bps), and ~713,000 SNP genotypes, respectively.</p>
Project description:Little is known about the mechanisms underlying the localization of human melanocytes during embryogenesis, and how the characteristics of melanocytes differ in various body sites. Immunohistochemical studies of biopsy tissue obtained from four different anatomic sites (scalp, back, abdomen, and sole) of 31 aborted fetuses following the approval of the ethics committee for the study of human gene analysis revealed that the melanocyte-associated marker gp100 was expressed earlier in embryogenesis than other melanocyte markers. Human fetal melanocytes are initially localized in the epidermis, and then migrate to the hair buds from the epidermis but not the dermis. In the sole, melanocytes localize in eccrine sweat gland ducts. Cultured fetal melanocytes did not stain positively for any melanocyte markers other than MITF and nestin. When co-cultured with normal human keratinocytes and fibroblasts, fetal melanocytes stained positively for gp100. Gene expression studies indicated that fetal melanocytes were topographically diverse, especially sole-derived melanocytes compared with other melanocytes. Expression of several genes, including CHI3L1 and FGF7, was higher in sole-derived melanocytes. These findings suggest that human fetal melanocytes derived from the sole have different profiles both in vivo and in vitro compared with melanocytes from other sites.
Project description:Little is known about the mechanisms underlying the localization of human melanocytes during embryogenesis, and how the characteristics of melanocytes differ in various body sites. Immunohistochemical studies of biopsy tissue obtained from four different anatomic sites (scalp, back, abdomen, and sole) of 31 aborted fetuses following the approval of the ethics committee for the study of human gene analysis revealed that the melanocyte-associated marker gp100 was expressed earlier in embryogenesis than other melanocyte markers. Human fetal melanocytes are initially localized in the epidermis, and then migrate to the hair buds from the epidermis but not the dermis. In the sole, melanocytes localize in eccrine sweat gland ducts. Cultured fetal melanocytes did not stain positively for any melanocyte markers other than MITF and nestin. When co-cultured with normal human keratinocytes and fibroblasts, fetal melanocytes stained positively for gp100. Gene expression studies indicated that fetal melanocytes were topographically diverse, especially sole-derived melanocytes compared with other melanocytes. Expression of several genes, including CHI3L1 and FGF7, was higher in sole-derived melanocytes. These findings suggest that human fetal melanocytes derived from the sole have different profiles both in vivo and in vitro compared with melanocytes from other sites. In this study, microarray analyses were performed using cultured fetal melanocytes from 4 different sites (scalp, back, abdomen and sole) obtained at 19 WOG, and newborn normal epidermal melanocyte as a control. RNA purification was performed using an RNeasy Mini kit (Qiagen, Germany) and those 5 samples, were analyzed using GeneChip 1.0 ST Array (Affymetrix, CA, USA).
Project description:Target genes of ultraviolet stress response in cutaneous melanocytes, potentially associated with solar induced melanocarcinogenesis, were characterized by cDNA microarray technology. In cultured normal human melanocytes, 198 genes out of »9000 arrayed were found modulated > 1.9 times following artificial ultraviolet (mainly ultraviolet-B) irradiation (100 mJ per cm2).
Project description:To identify microRNAs potentially involved in melanomagenesis we compared microRNA transcription profiles between melanoma cell lines and cultured melanocytes.
Project description:Mutations in the gene encoding transcription factor TFAP2A result in pigmentation anomalies in model organisms and premature hair graying in humans. However, the pleiotropic functions of TFAP2A and its redundantly-acting paralogs have made the precise contribution of TFAP2-type activity to melanocyte differentiation unclear. Defining this contribution may help to explain why TFAP2A expression is reduced in advanced-stage melanoma compared to benign nevi. To identify genes with TFAP2A-dependent expression in melanocytes, we profile zebrafish tissue and mouse melanocytes deficient in Tfap2a, and find that expression of a small subset of genes underlying pigmentation phenotypes is TFAP2A-dependent, including Dct, Mc1r, Mlph, and Pmel. We then conduct TFAP2A ChIP-seq in mouse and human melanocytes and find that a much larger subset of pigmentation genes is associated with active regulatory elements bound by TFAP2A. These elements are also frequently bound by MITF, which is considered the “master regulator” of melanocyte development. For example, the promoter of TRPM1 is bound by both TFAP2A and MITF, and we show that the activity of a minimal TRPM1 promoter is lost upon deletion of the TFAP2A binding sites. However, the expression of Trpm1 is not TFAP2A-dependent, implying that additional TFAP2 paralogs function redundantly to drive melanocyte differentiation, which is consistent with previous results from zebrafish. Paralogs Tfap2a and Tfap2b are both expressed in mouse melanocytes, and we show that mouse embryos with Wnt1-Cre-mediated deletion of Tfap2a and Tfap2b in the neural crest almost completely lack melanocytes but retain neural crest-derived sensory ganglia. These results suggest that TFAP2 paralogs, like MITF, are also necessary for induction of the melanocyte lineage. Finally, we observe a genetic interaction between tfap2a and mitfa in zebrafish, but find that artificially elevating expression of tfap2a does not increase levels of melanin in mitfa hypomorphic or loss-of-function mutants. Collectively, these results show that TFAP2 paralogs, operating alongside lineage-specific transcription factors such as MITF, directly regulate effectors of terminal differentiation in melanocytes. In addition, they suggest that TFAP2A activity, like MITF activity, has the potential to modulate the phenotype of melanoma cells.