Abstract
Ocular albinism type 1 (OA1) is an inherited disorder characterized by severe reduction of visual acuity, photophobia, and retinal hypopigmentation. Ultrastructural examination of skin melanocytes and of the retinal pigment epithelium reveals the presence of macromelanosomes, suggesting a defect in melanosome biogenesis. The gene responsible for OA1 is exclusively expressed in pigment cells and encodes a predicted protein of 404 aa displaying several putative transmembrane domains and sharing no similarities with previously identified molecules. Using polyclonal antibodies we have identified the endogenous OA1 protein in retinal pigment epithelial cells, in normal human melanocytes and in various melanoma cell lines. Two forms of the OA1 protein were identified by Western analysis, a 60-kDa glycoprotein and a doublet of 48 and 45 kDa probably corresponding to unglycosylated precursor polypeptides. Upon subcellular fractionation and phase separation with the nonionic detergent Triton X-114, the OA1 protein segregated into the melanosome-rich fraction and behaved as an authentic integral membrane protein. Immunofluorescence and immunogold analyses on normal human melanocytes confirmed the melanosomal membrane localization of the endogenous OA1 protein, consistent with its possible involvement in melanosome biogenesis. The identification of a novel melanosomal membrane protein involved in a human disease will provide insights into the mechanisms that control the cell-specific pathways of subcellular morphogenesis.
Full text
PDF![9055](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/49a8a5745436/pnas01521-0268.png)
![9056](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/3fff4615f24d/pnas01521-0269.png)
![9057](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/2c6746064289/pnas01521-0270.png)
![9058](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/0aa8cbecf2b6/pnas01521-0271.png)
![9059](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/7631eb180a89/pnas01521-0272.png)
![9060](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/df4f/38594/8e33aef53013/pnas01521-0273.png)
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adema G. J., de Boer A. J., Vogel A. M., Loenen W. A., Figdor C. G. Molecular characterization of the melanocyte lineage-specific antigen gp100. J Biol Chem. 1994 Aug 5;269(31):20126–20133. [PubMed] [Google Scholar]
- Adema G. J., de Boer A. J., van 't Hullenaar R., Denijn M., Ruiter D. J., Vogel A. M., Figdor C. G. Melanocyte lineage-specific antigens recognized by monoclonal antibodies NKI-beteb, HMB-50, and HMB-45 are encoded by a single cDNA. Am J Pathol. 1993 Dec;143(6):1579–1585. [PMC free article] [PubMed] [Google Scholar]
- Aroca P., Martinez-Liarte J. H., Solano F., García-Borrón J. C., Lozano J. A. The action of glycosylases on dopachrome (2-carboxy-2,3-dihydroindole-5,6-quinone) tautomerase. Biochem J. 1992 May 15;284(Pt 1):109–113. doi: 10.1042/bj2840109. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Barsh G. S. Pigmentation, pleiotropy, and genetic pathways in humans and mice. Am J Hum Genet. 1995 Oct;57(4):743–747. [PMC free article] [PubMed] [Google Scholar]
- Bassi M. T., Schiaffino M. V., Renieri A., De Nigris F., Galli L., Bruttini M., Gebbia M., Bergen A. A., Lewis R. A., Ballabio A. Cloning of the gene for ocular albinism type 1 from the distal short arm of the X chromosome. Nat Genet. 1995 May;10(1):13–19. doi: 10.1038/ng0595-13. [DOI] [PubMed] [Google Scholar]
- Bordier C. Phase separation of integral membrane proteins in Triton X-114 solution. J Biol Chem. 1981 Feb 25;256(4):1604–1607. [PubMed] [Google Scholar]
- De Luca M., D'Anna F., Bondanza S., Franzi A. T., Cancedda R. Human epithelial cells induce human melanocyte growth in vitro but only skin keratinocytes regulate its proper differentiation in the absence of dermis. J Cell Biol. 1988 Nov;107(5):1919–1926. doi: 10.1083/jcb.107.5.1919. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gardner J. M., Nakatsu Y., Gondo Y., Lee S., Lyon M. F., King R. A., Brilliant M. H. The mouse pink-eyed dilution gene: association with human Prader-Willi and Angelman syndromes. Science. 1992 Aug 21;257(5073):1121–1124. doi: 10.1126/science.257.5073.1121. [DOI] [PubMed] [Google Scholar]
- Garner A., Jay B. S. Macromelanosomes in X-linked ocular albinism. Histopathology. 1980 May;4(3):243–254. doi: 10.1111/j.1365-2559.1980.tb02919.x. [DOI] [PubMed] [Google Scholar]
- Green H., Kehinde O., Thomas J. Growth of cultured human epidermal cells into multiple epithelia suitable for grafting. Proc Natl Acad Sci U S A. 1979 Nov;76(11):5665–5668. doi: 10.1073/pnas.76.11.5665. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hearing V. J., Tsukamoto K. Enzymatic control of pigmentation in mammals. FASEB J. 1991 Nov;5(14):2902–2909. [PubMed] [Google Scholar]
- Imokawa G., Mishima Y. Loss of melanogenic properties in tyrosinases induced by glucosylation inhibitors within malignant melanoma cells. Cancer Res. 1982 May;42(5):1994–2002. [PubMed] [Google Scholar]
- Jackson I. J., Chambers D. M., Tsukamoto K., Copeland N. G., Gilbert D. J., Jenkins N. A., Hearing V. A second tyrosinase-related protein, TRP-2, maps to and is mutated at the mouse slaty locus. EMBO J. 1992 Feb;11(2):527–535. doi: 10.1002/j.1460-2075.1992.tb05083.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jiménez M., Tsukamoto K., Hearing V. J. Tyrosinases from two different loci are expressed by normal and by transformed melanocytes. J Biol Chem. 1991 Jan 15;266(2):1147–1156. [PubMed] [Google Scholar]
- Kobayashi T., Urabe K., Orlow S. J., Higashi K., Imokawa G., Kwon B. S., Potterf B., Hearing V. J. The Pmel 17/silver locus protein. Characterization and investigation of its melanogenic function. J Biol Chem. 1994 Nov 18;269(46):29198–29205. [PubMed] [Google Scholar]
- Kobayashi T., Urabe K., Winder A., Jiménez-Cervantes C., Imokawa G., Brewington T., Solano F., García-Borrón J. C., Hearing V. J. Tyrosinase related protein 1 (TRP1) functions as a DHICA oxidase in melanin biosynthesis. EMBO J. 1994 Dec 15;13(24):5818–5825. doi: 10.1002/j.1460-2075.1994.tb06925.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Luo D., Chen H., Jimbow K. Cotransfection of genes encoding human tyrosinase and tyrosinase-related protein-1 prevents melanocyte death and enhances melanin pigmentation and gene expression of Lamp-1. Exp Cell Res. 1994 Jul;213(1):231–241. doi: 10.1006/excr.1994.1195. [DOI] [PubMed] [Google Scholar]
- O'Donnell F. E., Jr, Hambrick G. W., Jr, Green W. R., Iliff W. J., Stone D. L. X-linked ocular albinism. An oculocutaneous macromelanosomal disorder. Arch Ophthalmol. 1976 Nov;94(11):1883–1892. doi: 10.1001/archopht.1976.03910040593001. [DOI] [PubMed] [Google Scholar]
- Orlow S. J., Boissy R. E., Moran D. J., Pifko-Hirst S. Subcellular distribution of tyrosinase and tyrosinase-related protein-1: implications for melanosomal biogenesis. J Invest Dermatol. 1993 Jan;100(1):55–64. doi: 10.1111/1523-1747.ep12354138. [DOI] [PubMed] [Google Scholar]
- Orlow S. J., Zhou B. K., Boissy R. E., Pifko-Hirst S. Identification of a mammalian melanosomal matrix glycoprotein. J Invest Dermatol. 1993 Aug;101(2):141–144. doi: 10.1111/1523-1747.ep12363626. [DOI] [PubMed] [Google Scholar]
- Rinchik E. M., Bultman S. J., Horsthemke B., Lee S. T., Strunk K. M., Spritz R. A., Avidano K. M., Jong M. T., Nicholls R. D. A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism. Nature. 1993 Jan 7;361(6407):72–76. doi: 10.1038/361072a0. [DOI] [PubMed] [Google Scholar]
- Rosemblat S., Durham-Pierre D., Gardner J. M., Nakatsu Y., Brilliant M. H., Orlow S. J. Identification of a melanosomal membrane protein encoded by the pink-eyed dilution (type II oculocutaneous albinism) gene. Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):12071–12075. doi: 10.1073/pnas.91.25.12071. [DOI] [PMC free article] [PubMed] [Google Scholar]
- SEIJI M., SHIMAO K., BIRBECK M. S., FITZPATRICK T. B. Subcellular localization of melanin biosynthesis. Ann N Y Acad Sci. 1963 Feb 15;100:497–533. [PubMed] [Google Scholar]
- Schiaffino M. V., Bassi M. T., Galli L., Renieri A., Bruttini M., De Nigris F., Bergen A. A., Charles S. J., Yates J. R., Meindl A. Analysis of the OA1 gene reveals mutations in only one-third of patients with X-linked ocular albinism. Hum Mol Genet. 1995 Dec;4(12):2319–2325. doi: 10.1093/hmg/4.12.2319. [DOI] [PubMed] [Google Scholar]
- Spritz R. A. Molecular genetics of oculocutaneous albinism. Hum Mol Genet. 1994;3(Spec No):1469–1475. doi: 10.1093/hmg/3.suppl_1.1469. [DOI] [PubMed] [Google Scholar]
- Tsukamoto K., Jackson I. J., Urabe K., Montague P. M., Hearing V. J. A second tyrosinase-related protein, TRP-2, is a melanogenic enzyme termed DOPAchrome tautomerase. EMBO J. 1992 Feb;11(2):519–526. doi: 10.1002/j.1460-2075.1992.tb05082.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vijayasaradhi S., Doskoch P. M., Houghton A. N. Biosynthesis and intracellular movement of the melanosomal membrane glycoprotein gp75, the human b (brown) locus product. Exp Cell Res. 1991 Oct;196(2):233–240. doi: 10.1016/0014-4827(91)90256-t. [DOI] [PubMed] [Google Scholar]
- Vijayasaradhi S., Xu Y., Bouchard B., Houghton A. N. Intracellular sorting and targeting of melanosomal membrane proteins: identification of signals for sorting of the human brown locus protein, gp75. J Cell Biol. 1995 Aug;130(4):807–820. doi: 10.1083/jcb.130.4.807. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wagner S. N., Wagner C., Höfler H., Atkinson M. J., Goos M. Expression cloning of the cDNA encoding a melanoma-associated Ag recognized by mAb HMB-45. Identification as melanocyte-specific Pmel 17 cDNA. Lab Invest. 1995 Aug;73(2):229–235. [PubMed] [Google Scholar]
- Winder A. J., Wittbjer A., Rosengren E., Rorsman H. The mouse brown (b) locus protein has dopachrome tautomerase activity and is located in lysosomes in transfected fibroblasts. J Cell Sci. 1993 Sep;106(Pt 1):153–166. doi: 10.1242/jcs.106.1.153. [DOI] [PubMed] [Google Scholar]
- Yoshiike T., Manabe M., Hayakawa M., Ogawa H. Macromelanosomes in X-linked ocular albinism (XLOA). Acta Derm Venereol. 1985;65(1):66–69. [PubMed] [Google Scholar]
- Zambruno G., Marchisio P. C., Marconi A., Vaschieri C., Melchiori A., Giannetti A., De Luca M. Transforming growth factor-beta 1 modulates beta 1 and beta 5 integrin receptors and induces the de novo expression of the alpha v beta 6 heterodimer in normal human keratinocytes: implications for wound healing. J Cell Biol. 1995 May;129(3):853–865. doi: 10.1083/jcb.129.3.853. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhou B. K., Kobayashi T., Donatien P. D., Bennett D. C., Hearing V. J., Orlow S. J. Identification of a melanosomal matrix protein encoded by the murine si (silver) locus using "organelle scanning". Proc Natl Acad Sci U S A. 1994 Jul 19;91(15):7076–7080. doi: 10.1073/pnas.91.15.7076. [DOI] [PMC free article] [PubMed] [Google Scholar]