Humans with Hermansky-Pudlak Syndrome (HPS) or ocular albinism (OA1) display abnormal aspects of organelle biogenesis. The multigenic disorder HPS displays broad defects in biogenesis of lysosome-related organelles including melanosomes, platelet dense granules, and lysosomes. A phenotype of ocular pigmentation in OA1 is a smaller number of macromelanosomes, in contrast to HPS, where in many ca...

PURPOSE Ocular Albinism type 1 (OA1) is a disease caused by mutations in the OA1 gene and characterized by the presence of macromelanosomes in the retinal pigment epithelium (RPE) as well as abnormal crossing of the optic axons at the optic chiasm. We showed in our previous studies in mice that Oa1 activates specifically Gαi3 in its signaling pathway and thus, hypothesized that a constitutively...

Skin color is one of the most distinct features in the human race. To assess the mechanisms of skin color variation, human skin substitutes (HSS) were constructed by grafting mixtures of cultured keratinocytes and melanocytes from a combination of donor skin types, together with light skin derived fibroblasts, into chambers inserted onto the back skin of severe combined immunodeficient (SCID) m...

Selective dispersion of melanosomes was often observed after iontophoretic injection of cyclic adenosine monophosphate (AMP) from a glass microelectrode positioned in a target melanophore in frog skin (as viewed from above through a microscope), with other melanophores in the field serving as controls. Because the skin has orderly arrays of several types of closely spaced cells, it is probable ...

A mutation in the small GTPase Rab38 gives rise to the mouse coat color phenotype "chocolate" (cht), implicating Rab38 in the regulation of melanogenesis. However, its role remains poorly characterized. We report that cht Rab38(G19V) is inactive and that the nearly normal pigmentation in cht melanocytes results from functional compensation by the closely related Rab32. In cht cells treated with...

The protein product of the ocular albinism type 1 gene, named OA1, is a pigment cell-specific G protein-coupled receptor exclusively localized to intracellular organelles, namely lysosomes and melanosomes. Loss of OA1 function leads to the formation of macromelanosomes, suggesting that this receptor is implicated in organelle biogenesis, however the mechanism involved in the pathogenesis of the...

Lysosome-related organelles (LROs) exist in specialized cells to serve specific functions and typically co-exist with conventional lysosomes. The biogenesis of LROs is known to utilize much of the common protein machinery used in the transport of integral membrane proteins to lysosomes. Consequently, an outstanding question in the field has been how specific cargoes are trafficked to LROs inste...