Protein melan-A also known as melanoma antigen recognized by T cells 1 or MART-1 is a protein that in humans is encoded by the MLANA o "MALENA" gene.[1] A fragment of the protein, usually consisting of the nine amino acids 27 to 35, is bound by MHC class I complexes which present it to T cells of the immune system. These complexes can be found on the surface of melanoma cells. Decameric peptides (26-35) are being investigated as cancer vaccines.
The names MART-1 and melan-A were coined by two groups of researchers who independently sequenced the gene for this antigen in 1994. Both names are currently in common use. Kawakami et al. at the National Cancer Institute coined the term MART-1, which stands for "melanoma antigen recognized by T-cells."[2] Coulie et al. of Belgium called the gene melan-A, presumably an abbreviation for "melanocyte antigen."[3]
Clinical significance
MART-1/melan-A is a protein antigen that is found on the surface of melanocytes. Antibodies against the antigen are used in the medical specialty of anatomic pathology in order to recognize cells of melanocytic differentiation, useful for the diagnosis of a melanoma. The same name is also used to refer to the gene which codes for the antigen.
The MART-1/melan-A antigen is specific for the melanocyte lineage, found in normal skin, the retina, and melanocytes, but not in other normal tissues. It is thus useful as a marker for melanocytic tumors (melanomas) with the caveat that it is normally found in benign nevi as well.
In many immunological studies melan-A peptides serve as a positive control for T-cell priming experiments. This is due to the fact that its high precursor frequency of about 1/1000 among cytotoxic T-cells makes it easy for antigen presenting cells to evoke peptide-specific responses.[4]
Structure
MART-1/melan-A is a putative 18 kDa transmembrane protein consisting of 118 amino acids. It has a single transmembrane domain.
Mandelcorn-Monson RL, Shear NH, Yau E, et al. (2003). "Cytotoxic T lymphocyte reactivity to gp100, MelanA/MART-1, and tyrosinase, in HLA-A2-positive vitiligo patients". J. Invest. Dermatol. 121 (3): 550–6. doi:10.1046/j.1523-1747.2003.12413.x. PMID12925214.
Ghorab Z, Jorda M, Ganjei P, Nadji M (2004). "Melan A (A103) is expressed in adrenocortical neoplasms but not in renal cell and hepatocellular carcinomas". Appl. Immunohistochem. Mol. Morphol. 11 (4): 330–3. doi:10.1097/00129039-200312000-00009. PMID14663359.
Murer K, Urosevic M, Willers J, et al. (2005). "Expression of Melan-A/MART-1 in primary melanoma cell cultures has prognostic implication in metastatic melanoma patients". Melanoma Res. 14 (4): 257–62. doi:10.1097/01.cmr.0000136713.21029.56. PMID15305155.
Kucher C, Zhang PJ, Pasha T, et al. (2005). "Expression of Melan-A and Ki-67 in desmoplastic melanoma and desmoplastic nevi". The American Journal of Dermatopathology. 26 (6): 452–7. doi:10.1097/00000372-200412000-00002. PMID15618925.
Hoashi T, Watabe H, Muller J, et al. (2005). "MART-1 is required for the function of the melanosomal matrix protein PMEL17/GP100 and the maturation of melanosomes". J. Biol. Chem. 280 (14): 14006–16. doi:10.1074/jbc.M413692200. PMID15695812.
Godefroy E, Scotto L, Souleimanian NE, et al. (2006). "Identification of two Melan-A CD4+ T cell epitopes presented by frequently expressed MHC class II alleles". Clin. Immunol. 121 (1): 54–62. doi:10.1016/j.clim.2006.05.007. PMID16814609.
Kono M, Dunn IS, Durda PJ, et al. (2007). "Role of the mitogen-activated protein kinase signaling pathway in the regulation of human melanocytic antigen expression". Mol. Cancer Res. 4 (10): 779–92. doi:10.1158/1541-7786.MCR-06-0077. PMID17050671.
Bioley G, Jandus C, Tuyaerts S, et al. (2007). "Melan-A/MART-1-specific CD4 T cells in melanoma patients: identification of new epitopes and ex vivo visualization of specific T cells by MHC class II tetramers". J. Immunol. 177 (10): 6769–79. doi:10.4049/jimmunol.177.10.6769. PMID17082590.
Roma AA, Magi-Galluzzi C, Zhou M (2007). "Differential expression of melanocytic markers in myoid, lipomatous, and vascular components of renal angiomyolipomas". Arch. Pathol. Lab. Med. 131 (1): 122–5. doi:10.1043/1543-2165(2007)131[122:DEOMMI]2.0.CO;2 (inactive 2018-08-30). PMID17227112.