Microphthalmia-associated Transcription Factor Gene Research Articles

The Hoof Color of Australian White Sheep Is Associated with Genetic Variation of the MITF Gene.

Studying the characteristics of mammalian hoof colors is important for genetic improvements in animals. A deeper black hoof color is the standard for breeding purebred Australian White (AUW) sheep and this phenotype could be used as a phenotypic marker of purebred animals. We conducted a genome-wide association study (GWAS) analysis using restriction site associated DNA sequencing (RAD-seq) data from 577 Australian White sheep (black hoof color = 283, grey hoof color = 106, amber hoof color = 186) and performed association analysis utilizing the mixed linear model in EMMAX. The results of GWAS demonstrated that a specific single-nucleotide polymorphism (SNP; g. 33097911G>A) in intron 14 of the microphthalmia-associated transcription factor (MITF) gene was significantly associated with the hoof color in AUW sheep (p = 9.40 × 10-36). The MITF gene plays a key role in the development, differentiation, and functional regulation of melanocytes. Furthermore, the association between this locus and hoof color was validated in a cohort of 212 individuals (black hoof color = 122, grey hoof color = 38, amber hoof color = 52). The results indicated that the hoof color of AUW sheep with GG, AG, and AA genotypes tended to be black, grey, and amber, respectively. This study provided novel insights into hoof color genetics in AUW sheep, enhancing our comprehension of the genetic mechanisms underlying the diverse range of hoof colors. Our results agree with previous studies and provide molecular markers for marker-assisted selection for hoof color in sheep.

Anhydrous Alum Inhibits α-MSH-Induced Melanogenesis by Down-Regulating MITF via Dual Modulation of CREB and ERK.

Melanogenesis, the intricate process of melanin synthesis, is central to skin pigmentation and photoprotection and is regulated by various signaling pathways and transcription factors. To develop potential skin-whitening agents, we used B16F1 melanoma cells to investigate the inhibitory effects of anhydrous alum on melanogenesis and its underlying molecular mechanisms. Anhydrous alum (KAl(SO4)2) with high purity (>99%), which is generated through the heat-treatment of hydrated alum (KAl(SO4)2·12H2O) at 400 °C, potentiates a significant reduction in melanin content without cytotoxicity. Anhydrous alum downregulates the master regulator of melanogenesis, microphthalmia-associated transcription factor (MITF), which targets key genes involved in melanogenesis, thereby inhibiting α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. Phosphorylation of the cAMP response element-binding protein, which acts as a co-activator of MITF gene expression, is attenuated by anhydrous alum, resulting in compromised MITF transcription. Notably, anhydrous alum promoted extracellular signal-regulated kinase phosphorylation, leading to the impaired nuclear localization of MITF. Overall, these results demonstrated the generation and mode of action of anhydrous alum in B16F1 cells, which constitutes a promising option for cosmetic or therapeutic use.

Modeling of pigmentation disorders associated with MITF mutation in Waardenburg syndrome revealed an impaired melanogenesis pathway in iPS-derived melanocytes.

Waardenburg Syndrome (WS) is a rare genetic disorder that leads to congenital hearing loss and pigmentation defects. Microphthalmia-associated transcription factor (MITF) is one of its significant pathogenic genes. Despite the comprehensive investigation in animal models, the pathogenic mechanism is still poorly described in humans due to difficulties accessing embryonic tissues. In this work, we used induced pluripotent stem cells derived from a WS patient carrying a heterozygous mutation in the MITF gene c.626A>T (p.His209Leu), and differentiated toward melanocyte lineage, which is the most affected cell type involved in WS. Compared with the wild-type cell line, the MITFmut cell line showed a reduced expression of the characteristic melanocyte-related genes and a lesser proportion of mature, fully pigmented melanosomes. The transcriptome analysis also revealed widespread gene expression changes at the melanocyte stage in the MITFmut cell line. The differentially expressed genes were enriched in melanogenesis and cell proliferation-related pathways. Interestingly, ion transport-related genes also showed a significant difference in MITFmut -induced melanocytes, indicating that the MITF mutant may lead to the dysfunction of potassium channels and transporters produced by intermediate cells in the cochlea, further causing the associated phenotype of deafness. Altogether, our study provides valuable insights into how MITF mutation affects WS patients, which might result in defective melanocyte development and the related phenotype based on the patient-derived iPSC model.

Genome-Wide Identification and Characterization of MITF Genes in Ruditapes philippinarum and Their Involvement in the Immune Response to Vibrio anguillarum Infection.

Studies have shown that the shellfish have innate immune system, which is a very important immune form of shellfish, and they rely on the innate immune system to resist diseases. As a transcription factor, Microphthalmia-associated transcription factor (MITF) plays a regulatory role in immune response and the shell color is also an important index for the breeding of excellent varieties of R. philippinarum. The research on immune response mechanism of RPMITFs can provide important reference data for the breeding of excellent clam varieties. In the genome of R. philippinarum, the RPMITF genes family of shell color-related gene family was selected as the target gene of this experiment. There are 12 RpMITF genes named RpMITF1, RpMITF2, RpMITF3, RpMITF4, RpMITF5, RpMITF6, RpMITF7, RpMITF8, RpMITF9, RpMITF10, RpMITF11, and RpMITF12. The open reading frame length is 639, 1233, 996, 1239, 675, 624, 816, 1365, 612, 1614, 1122, and 486bp, encoding 212, 410, 331, 412, 224, 207, 271, 454, 203, 537, 373, and 161 aa, respectively. The predicted molecular weight range of amino acids is 18.85-62.61 kda, and the isoelectric point range is 5.26-9.44. Real-time quantitative PCR was used to detect the gene expression of RpMITF gene family in hepatopancreas tissues of two populations of Manilaclam at 6 time points (0, 3, 6, 12, 24, and 48h) after Vibrio anguillarum stress. The results show that RpMITF gene family was significantly expressed in hepatopancreas of two clam populations after V. anguillarum stress (P < 0.05).

SMILE Downregulation during Melanogenesis Induces MITF Transcription in B16F10 Cells.

SMILE (small heterodimer partner-interacting leucine zipper protein) is a transcriptional corepressor that potently regulates various cellular processes such as metabolism and growth in numerous tissues. However, its regulatory role in skin tissue remains uncharacterized. Here, we demonstrated that SMILE expression markedly decreased in human melanoma biopsy specimens and was inversely correlated with that of microphthalmia-associated transcription factor (MITF). During melanogenesis, α-melanocyte-stimulating hormone (α-MSH) induction of MITF was mediated by a decrease in SMILE expression in B16F10 mouse melanoma cells. Mechanistically, SMILE was regulated by α-MSH/cAMP/protein kinase A signaling and suppressed MITF promoter activity via corepressing transcriptional activity of the cAMP response element-binding protein. Moreover, SMILE overexpression significantly reduced α-MSH-induced MITF and melanogenic genes, thereby inhibiting melanin production in melanocytes. Conversely, SMILE inhibition increased the transcription of melanogenic genes and melanin contents. These results indicate that SMILE is a downstream effector of cAMP-mediated signaling and is a critical factor in the regulation of melanogenic transcription; in addition, they suggest a potential role of SMILE as a corepressor in skin pigmentation.

MicroRNA-183-5p regulates MITF expression in vitiligo skin depigmentation

Microphthalmia-associated transcription factor (MITF) is a master regulatory factor for melanocytes. MITF regulates multiple pigmentary genes for maintaining cellular homeostasis. MicroRNAs (miRNAs) play crucial roles in numerous biological processes however their molecular/cellular mechanisms to regulate pigmentation have not been fully explored. This study was undertaken to investigate the role of miRNAs in skin depigmentation via regulation of MITF gene. Depigmentation in C57BL/6 black mice was induced by an autoimmune response against tyrosinase. Bioinformatics approach was used to detect miRNAs conserved in 3′untraslated region (3′UTR) of MITF mRNA. The iMC23 mouse melanocytes were used for transfection experiments. The data demonstrated that the MITF mRNA/protein was markedly low in lesional skin of depigmented mice (p < 0.05). Targetscan genomic database determined that 3′UTR of mouse MITF constitutes 4819 nucleotide bases and has 23 conserved sites for different miRNAs To validate the pairing of these predicted miRNAs with MITF mRNA, five miRNAs were deregulated in lesional skin (p < 0.05). Among them, mmu-miR-181a-5p and mmu-miR-183-5p were up-regulated, whereas mmu-miR-26a-5p, mmu-miR-26b-5p and mmu-miR-32-5p were down-regulated (p < 0.05). To verify these results, the iMC23 mouse melanocytes were used. Transfection of iMC23 cells with specific miRNAs mimics or inhibitors or with 3’UTR reporter clone of MITF, showed only mmu-miR-183-5p binds to 3’UTR of MITF mRNA and regulates its expression in iMC23 melanocytes. In conclusions, this is the first study shows that miR-183-5p is a direct regulator of MITF in iMC23 melanocytes. Thus, miR-183-5p is an important regulator of melanocytes homeostasis and may be a novel target for autoimmune depigmentation therapy.

PD-L1 expression is regulated by microphthalmia-associated transcription factor (MITF) in nodular melanoma

Malignant melanoma (MM) is known to avoid the host’s immune response. Studies on in vitro melanoma cell lines link the microphthalmia-associated transcription factor (MITF) with the regulation of the PD-L1 expression. It seems that MITF affects the activation of the gene responsible for PD-L1 protein expression. Several proteins, including Bcl-2 and Cyclin D1, play major roles in malignant melanoma cell cycle regulation and survival. Our study aims to assess the relationship between MITF, Bcl-2, and cyclin D1 protein expression and the expression of the PD-L1 molecule. Additionally, we examined the association of BRAF mutation, MITF, and CCND1 gene amplification with PD-L1 protein expression. We performed immunohistochemical staining on fifty-two tumour samples from patients diagnosed with nodular melanoma (NM). BRAF V600 mutation, MITF, and CCND1 gene amplification analyses were analyzed by the Sanger sequencing and QRT-PCR methods, respectively. Statistical analyses confirmed the significant inverse correlation between cyclin D1 and PD-L1 expression (p = 0.001) and correlation between PD-L1 and MITF protein expression (p = 0.023). We found a statistically significant inverse correlation between the present MITF gene amplification and PD-L1 (p = 0.007) and MITF protein expression (p = 3.4 ×10–6), respectively. Our study, performed on clinical NM materials, supports the in vitro study findings providing a rationale for the potential MITF-dependent regulation of PD-L1 expression in malignant melanoma.

Expanding the phenotype of E318K (c.952G\u2009>\u2009A) MITF germline mutation carriers: case series and review of the literature

BackgroundThe microphthalmia-associated transcription factor gene (MITF) belongs to the MYC supergene family and plays an important role in melanocytes’ homeostasis. Individuals harboring MITF germline pathogenic variants are at increased risk of developing cancer, most notably melanoma and renal cell carcinoma.Case presentationWe describe a cohort of ten individuals who harbor the same MITF c.952G > A (p.Glu 318Lys), or p.E318K, germline pathogenic variant. Six carriers developed at least one malignancy (4 cases of breast cancer; 1 cervical cancer; 1 colon cancer; 1 melanoma; 1 ovarian/fallopian tube cancer). A significant phenotypic heterogeneity was found among these individuals and their relatives. Breast cancer was, overall, the most frequent malignancy observed in this case series, with 13 occurrences of 60 (21.67 %) total cancer cases described among the probands and their relatives.ConclusionsOur retrospective analysis data raise the hypothesis of a possible association of the MITF p.E318K pathogenic variant with an increased risk of breast cancer.

Inhibitory Effects of Cycloheterophyllin on Melanin Synthesis.

This study was performed to clarify the inhibitory effects of cycloheterophyllin on melanin synthesis. In order to elucidate the inhibitory effects of cycloheterophyllin on the B16F10 cell line, cell viability, messenger ribonucleic acid (mRNA) expressions, tyrosinase activity assay, and melanin production assay were measured. The effects of cycloheterophyllin on tyrosinase-related protein 1 (TYRP1)/TYRP2/tyrosinase (TYR)/microphthalmia-associated transcription factor (MITF) mRNA expressions and melanin content were determined. Quantitative real-time RT-PCR showed that cycloheterophyllin decreased the mRNA expression level of TYRP1/TYRP2/TYR/MITF genes and melanin production contents than α-MSH-treated B16F10 cells. The tyrosinase activity assay revealed that cycloheterophyllin decreased the melanin production in the B16F10 cells. These data show that cycloheterophyllin increases the whitening effects in the B16F10 cells; thus, cycloheterophyllin is a potent ingredient for skin whitening. Thus, further research on the mechanism of action of cycloheterophyllin for the development of functional materials should be investigated.

Expression of MITF Gene in Melanogenesis with Psoralea corylifolia, Zingiber officinale, Terminalia chebula, Punica granatum and Eclipta alba Based on Poly-Herbal Formulation

Pigmentation is an important physical characteristic of human beings due to the presence of a biopolymer molecule called melanin. Melanin pigment in the human skin and several other tissues were due to the activation and inhibition of different genes at the downstream signaling pathway like Tyrosinase-related protein 1 (TYRP1) and Tyrosinase-related protein 2 (TYRP2) and Microphthalmia-associated transcription factor (MITF) genes. In this study, we tried to deliver the molecular approach of TYRP1, TYRP2, and MITF by activating kinases in the process of Melanogenesis by treating with Unani formulations on the B16F10 murine melanoma cell line. RNA isolation of B16F10 cells was performed followed by cDNA conversion and expression studies at mRNA levels by RT-PCR method. To explore further western blot was performed at the protein level for the significant results which we obtained with UNIM regimes in the expression studies. The bioactive ingredient of UNIM-004 and UNIM-005 of Methanolic extracts up-regulates the expression and protein levels of the MITF gene which leads to the synthesis of melanin pigment in human beings. Therefore from this study, it indicates that the application and administration of UNIM-004 and UNIM-005 of methanolic extract will result in activating melanin in B16F10 cells by increasing mRNA expression levels in the MITF gene when compared with TYRP1and TYRP2 genes followed by Western blot experiment and found to be producing melanocytes in the progression of Melanogenesis in a dose-dependent manner at 10 μg and 100 μg concerning for to GAPDH control gene at mRNA expression level in Vitiligo patients.

Genomic variability of Cirneco dell’Etna and the genetic distance with other dog breeds

Cirneco dell’Etna is an old Italian breed of scent hunting dogs. Commonly used genomic measures such as heterozygosity, fixation indexes, and runs of homozygosity can help to improve knowledge about its genetic diversity. This study aimed to: (i) investigate Cirneco’s genomic background, (ii) quantify its genomic inbreeding, and (iii) detect genomic regions differentiating the Cirneco’s two allowed coat colours, self-coloured fawn and tan and white. Canine 230 K SNP BeadChips was used to investigate 24 Cirneco (19 self-coloured fawn, and 5 tan and white) and other 106 dogs from eight phylogenetically and historically related breeds. The genetic distance, ancestry, and relationship among breeds were explored by multidimensional scaling, Reynolds distances, phylogenetic tree, and admixture analysis. The genomic inbreeding (F ROH) was calculated for each breed. Averaged Wright’s fixation index ST was used to identify the genes that most differentiated the two groups of Cirneco. All analyses highlighted that Segugio Italiano and Kelb tal Fenek are the closest breeds to Cirneco. Within the breed, tan and white subjects showed a more heterogeneous genetic background and a lower inbreeding in comparison with self-coloured fawn ones, even though more than half of the latter presented a superimposable admixture. The gene that most differentiated these two groups is Microphthalmia-Associated Transcription Factor (MITF), previously associated with white spotting in other breeds. Given the small size of the Cirneco population and its open registry, its management should carefully combine morphological and genealogical evaluations with genetic tools to identify the best breeders while maintaining an acceptable genetic pool. Highlights The genomic analysis demonstrated that Segugio Italiano and Kelb tal Fenek are genetically related to the Cirneco. The MITF gene is responsible for white blazing in Cirneco as in many other dog breeds. Genomic tools should be integrated with phenotypic and genealogic evaluations in the management of Italian autochthonous dog breeds to safeguard their welfare and biodiversity.

Expression and contribution of microphthalmia-associated transcription factor to the melanin deposition in Liancheng white ducks

The present study investigates the expression of microphthalmia-associated transcription factor (MITF) and its contribution to the melanin deposition in Liancheng white ducks. Nested PCR was used to clone the MITF gene sequence from the skin tissue of female Liancheng white ducks. Ultraviolet spectrophotometry was used to detect the melanin deposition. MITF mRNA expression and melanin deposition in different tissues and organs were detected and their correlation was analyzed. The MITF gene (GenBank number: MG516570) was 1 323 bp in length, contains a complete CDS region (34–1 323 bp) and codes 429 amino acids with 100% homology to the MITF of Anas platyrhynchos and over 95% homology to those of Gallus gallus and Coturnix japonica. Genetic evolution analysis reveals a close relationship of Liancheng white ducks with A. platyrhynchos, and also to lesser extents with Anser cygnoides, silky fowl and G. gallus, as well as Sus scrofa, Ovis aries and other mammals. Real-time quantitative PCR (qPCR) analysis demonstrated that MITF was expressed in skin, gizzard, liver, kidney and muscle, and of these tissues, its expression was the highest in the skin tissue (skin>gizzard>liver>kidney>muscle). Ultraviolet spectrophotometry showed that melanin deposition was positively correlated with the MITF expression level in these five tissues and organs (P<0.05). Together, these results demonstrated a tissue-specific pattern of MITF expression and a positive correlation between MITF expression and melanin deposition, indicating that MITF expression may contribute to the melanin deposition in Liancheng white ducks.

Melanogenic Effects of Maclurin Are Mediated through the Activation of cAMP/PKA/CREB and p38 MAPK/CREB Signaling Pathways

Melanogenesis is the biological process which the skin pigment melanin is synthesized to protect the skin against ultraviolet irradiation and other external stresses. Abnormal biology of melanocytes is closely associated with depigmented skin disorders such as vitiligo. In this study, we examined the effects of maclurin on melanogenesis and cytoprotection. Maclurin enhanced cellular tyrosinase activity as well as cellular melanin levels. We found that maclurin treatment increased the expression of microphthalmia-associated transcription factor (MITF), tyrosinase-related protein- (TRP-) 1, TRP-2, and tyrosinase. Mechanistically, maclurin promoted melanogenesis through cyclic adenosine monophosphate (cAMP) response element binding (CREB) protein-dependent upregulation of MITF. CREB activation was found to be mediated by p38 mitogen-activated protein kinase (MAPK) or cAMP-protein kinase A (PKA) signaling. In addition, maclurin-induced CREB phosphorylation was mediated through the activation of both the cAMP/PKA and the p38 MAPK signaling pathways. Maclurin-induced suppression of p44/42 MAPK activation also contributed to its melanogenic activity. Furthermore, maclurin showed protective effects against H2O2 treatment and UVB irradiation in human melanocytes. These findings indicate that the melanogenic effects of maclurin depend on increased MITF gene expression, which is mediated by the activation of both p38 MAPK/CREB and cAMP/PKA/CREB signaling. Our results thus suggest that maclurin could be useful as a protective agent against hypopigmented skin disorders.

Integrated Analysis of mRNA Expression, CpG Island Methylation, and Polymorphisms in the MITF Gene in Ducks (Anas platyrhynchos).

Microphthalmia-associated transcription factor (MITF) is a key regulator for the development and function of melanocytes in skin, eye, and plumage pigmentations. Thus, the MITF was selected as a candidate gene associated with plumage coloration in ducks. This study analyzed the mRNA expression, promoter methylation, and polymorphisms in the MITF gene in ducks with different plumage colors (Putian Black, Putian White, Liancheng White, and Longsheng Jade-green). No expression of the MITF melanin-specific isoform (MITF-M) was detected in white feather bulbs. By contrast, the mRNA expression levels of MITF-M were high in black feather bulbs. Bioinformatics analysis showed that two CpG islands were present in the promoter region of the MITF gene. The methylation level of the second CpG island was significantly lower in black feather bulbs than in white feather bulbs. However, the methylation level of the first CpG island was not different among the feather bulbs with various colors except Liancheng White feather bulbs. The methylation status of the whole CpG island significantly and negatively correlated with the mRNA expression of MITF-M (P < 0.05). Furthermore, four novel SNPs (single nucleotide polymorphisms) were identified in the 5′UTR, exon 4, intron 7, and intron 8 of the MITF gene. Allele T in g.39807T>G and allele G in g.40862G>A were the predominant alleles only found in Putian White, whereas the variant A allele in g.32813G>A exhibited a high allele frequency in Liancheng White. Collectively, these results contributed to the understanding of the function of the MITF gene in duck plumage coloration.

The recessive C locus in the MITF gene plays a key regulatory role in the plumage colour pattern of duck (Anas platyrhynchos)

ABSTRACT1. The c/c alleles are responsible for the white plumage colour of ducks; however, the gene corresponding to this locus is still unclear. In order to identify the locus-related candidate gene associated with duck’s plumage colour pattern, it was necessary to analyse the whole genome resequencing data.2. A total of 929,465 SNPs in chromosome 13 and 1,688 SNPs in the region of the Microphthalmia-Associated Transcription Factor (MITF) gene were identified from whole genome resequencing data analysis. After construction of an FST plot from chromosome 13, MITF was highlighted as a candidate gene, possessing the highest FST value (0.811) on chromosome 13.3. Six novel SNPs were discovered, located in the intronic region of the MITF gene. F2 progeny of Kaiya × Liancheng ducks (N = 1,061) were selected for genotyping by the Restriction Fragment Length Polymorphism (RFLP) technique. Association analysis using Haploview software was used for validation of the results.4. Association results between SNPs and phenotypes showed significant association with corresponding phenotypes. All the significantly associated SNPs were located in the identified candidate gene.5. The identified candidate gene provided novel information which is important in marker-assisted selection and breeding of duck and for the investigation of the C locus recessive white genetic mechanisms underlying plumage colour pattern.

Genome-wide identification, characterization and expression analysis of the MITF gene in Yesso scallops (Patinopecten yessoensis) with different shell colors

The microphthalmia-associated transcription factor (MITF) is the center of the regulator network of melanin synthesis in vertebrates. However, the role of MITF in shell color formation is poorly studied in mollusks. In the present study, an MITF gene, PyMITF, was first identified at the whole-genome level in Yesso scallop (Patinopecten yessoensis), an evolutionarily and economically important species, the shell color of which shows polymorphism. The PyMITF is a large gene spanning ~37 kb in the genome with 7 introns and 8 exons. A basic helix-loop-helix leucine zipper (bHLH-LZ) domain was detected in the PyMITF protein sequence, which can bind the canonical E-box sequence in the promoter region of the downstream genes. Phylogenetic analysis of the MITFs among vertebrates and invertebrates revealed that the molecular evolution of MITFs was consistent with the species taxonomy. Different expression levels of PyMITF were detected among different shell color strains, indicating the important role of PyMITF involved in shell pigmentation. Besides, PyMITF was expressed at a significantly higher level in the central mantle than that in the edge mantle, proving the participation of the central mantle in shell color formation in molecular level for the first time. The work provides valuable information for the molecular mechanism study of shell color formation.

Cloning of a microphthalmia-associated transcription factor gene and its functional analysis in nacre formation and melanin synthesis in Hyriopsis cumingii

Microphthalmia-associated transcription factor (MITF) is an essential transactivator in melanin synthesis. To characterize the role of MITF in the pearl mussel Hyriopsis cumingii, the MITF homolog of H. cumingii was isolated. The full-length HcMitf cDNA consisted of a 1332-bp with an open reading frame that encode for a 443 amino acid protein that contain a conserved basic helix-loop-helix zipper domain. The HcMitf was found to widespread tissue distribution but expression was higher in purple mussels than in white mussels, mostly in mantle, liver, kidney, gill, and foot with the exception of the adductor mussel. HcMitf and its downstream gene tyrosinase (HcTyr) were highly expressed at the nacre deposition stage after implantation of mantle tissue to produce pearls. Using RNA interference, the expression of HcMitf was reduced by 78% (P < 0.01) and expression of HcTyr was also significantly suppressed and consequently total melanin content was decreased (P < 0.05). The results suggest that HcMitf plays an important role in melanin synthesis, nacre formation and shell pigmentation in the H. cumingii.

Comparative genomics and transcriptomics of Chrysolophus provide insights into the evolution of complex plumage coloration.

BackgroundAs one of the most recognizable characteristics in birds, plumage color has a high impact on understanding the evolution and mechanisms of coloration. Feather and skin are ideal tissues to explore the genomics and complexity of color patterns in vertebrates. Two species of the genus Chrysolophus, golden pheasant (Chrysolophus pictus) and Lady Amherst's pheasant (Chrysolophus amherstiae), exhibit brilliant colors in their plumage, but with extreme phenotypic differences, making these two species great models to investigate plumage coloration mechanisms in birds.ResultsWe sequenced and assembled a genome of golden pheasant with high coverage and annotated 15,552 protein-coding genes. The genome of Lady Amherst's pheasant is sequenced with low coverage. Based on the feather pigment identification, a series of genomic and transcriptomic comparisons were conducted to investigate the complex features of plumage coloration. By identifying the lineage-specific sequence variations in Chrysolophus and golden pheasant against different backgrounds, we found that four melanogenesis biosynthesis genes and some lipid-related genes might be candidate genomic factors for the evolution of melanin and carotenoid pigmentation, respectively. In addition, a study among 47 birds showed some candidate genes related to carotenoid coloration in a broad range of birds. The transcriptome data further reveal important regulators of the two colorations, particularly one splicing transcript of the microphthalmia-associated transcription factor gene for pheomelanin synthesis.ConclusionsAnalysis of the golden pheasant and its sister pheasant genomes, as well as comparison with other avian genomes, are helpful to reveal the underlying regulation of their plumage coloration. The present study provides important genomic information and insights for further studies of avian plumage evolution and diversity.

Identification of a gene encoding microphthalmia-associated transcription factor and its association with shell color in the clam Meretrix petechialis.

The microphthalmia-associated transcription factor (MITF) is a master regulator of melanocyte development through the direct transcriptional control of related genes, e.g., the phenoloxidase gene. In this study, an MITF gene, MpMITF2, was identified in the clam Meretrix petechialis. The full-length cDNA of MpMITF2 was 2026 bp, and the molecular mass of the predicted protein was 42.6 kDa. A basic helix-loop-helix leucine zipper domain was detected in the deduced protein sequence, which can bind the E-box motif within the promoter of the downstream genes. The mRNA of MpMITF2 was more highly expressed in the mantle compared to the other four tissues. Furthermore, there was a significant difference in the mRNA expression of MpMITF2 among three clam strains with different shell colors. The protein level of MpMITF2 was also different among these strains. These results implied that MpMITF2 was associated with shell color formation in the clam M. petechialis. When the mRNA expression of MpMITF2 was knocked down, the new shell showed discontinuous pigment distribution, suggesting that the reduced expression of MpMITF2 influenced pigment synthesis. A gene encoding phenoloxidase (MpPO) was identified as related to the shell color of the clam and was also a putative downstream gene of MITF. Both the mRNA and protein levels of MpPO decreased significantly at 12 h post-MpMITF-suppression, suggesting that MpMITF2 is required for the expression of MpPO. Our results indicate the close relationships among MpMITF2, MpPO and shell color. This study implicates the role of MITF in shell color formation in the clam M. petechialis.

Downregulation of α-Melanocyte-Stimulating Hormone-Induced Activation of the Pax3-MITF-Tyrosinase Axis by Sorghum Ethanolic Extract in B16F10 Melanoma Cells.

Ultraviolet irradiation-induced hyperpigmentation of the skin is associated with excessive melanin production in melanocytes. Tyrosinase (TYR) is a key enzyme catalyzing the rate-limiting step in melanogenesis. TYR expression is controlled by microphthalmia-associated transcription factor (MITF) expression. Sorghum is a cereal crop widely used in a variety of foods worldwide. Sorghum contains many bioactive compounds and is beneficial to human health. However, the effects of sorghum in anti-melanogenesis have not been well characterized. In this study, the biological activity of sorghum ethanolic extract (SEE) on α-melanocyte-stimulating hormone (α-MSH)-induced TYR expression was evaluated in B16F10 melanoma cells. SEE attenuated α-MSH-induced TYR gene promoter activity through the downregulation of the transcription factor MITF. We found that paired box gene 3 (Pax3) contributes to the maximal induction of MITF gene promoter activity. Further analysis demonstrated that SEE inhibited α-MSH-induced Pax3 expression. The collective results indicate that SEE attenuates α-MSH-induced TYR expression through the suppression of Pax3-mediated MITF gene promoter activity. Targeting the Pax3-MITF axis pathway could be considered a potential strategy to increase the efficacy of anti-melanogenesis.