Rab27a: A key to melanosome transport in human melanocytes.
Normal pigmentation depends on the uniform distribution of melanin-containing vesicles, the melanosomes, in the epidermis. Griscelli syndrome (GS) is a rare autosomal recessive disease, characterized by an immune deficiency and a partial albinism that has been ascribed to an abnormal melanosome distribution. GS maps to 15q21 and was first associated with mutations in the myosin-V gene. However, it was demonstrated recently that GS can also be caused by a mutation in the Rab27a gene. These observations prompted us to investigate the role of Rab27a in melanosome transport. Using immunofluorescence and immunoelectron microscopy studies, we show that in normal melanocytes Rab27a colocalizes with melanosomes. In melanocytes isolated from a patient with GS, we show an abnormal melanosome distribution and a lack of Rab27a expression. Finally, reexpression of Rab27a in GS melanocytes restored melanosome transport to dendrite tips, leading to a phenotypic reversion of the diseased cells. These results identify Rab27a as a key component of vesicle transport machinery in melanocytes.
Bahadoran
P
P
Unité de Recherches sur la Biologie et la Physiopathologie de la Peau, Institut National de la Santé et de la Recherche Médicale U385, Faculté de Médecine, 06107 Nice Cedex 2, France.
Aberdam
E
E
Mantoux
F
F
Buscà
R
R
Bille
K
K
Yalman
N
N
de Saint-Basile
G
G
Casaroli-Marano
R
R
Ortonne
J P
JP
Ballotti
R
R
D001692:Biological Transport; D002148:Calmodulin-Binding Proteins / Q000302:isolation & purification; D002451:Cell Compartmentation; D005455:Fluorescent Antibody Technique; D006801:Humans; D017496:Hypopigmentation / Q000378:metabolism*; D007153:Immunologic Deficiency Syndromes / Q000378:metabolism*; D008544:Melanocytes / Q000378:metabolism* / Q000648:ultrastructure; D020460:Melanosomes / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D020409:Molecular Motor Proteins; D024701:Myosin Type V; D009419:Nerve Tissue Proteins / Q000302:isolation & purification; D013577:Syndrome; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D000075745:rab27 GTP-Binding Proteins
D002148:Calmodulin-Binding Proteins; D020409:Molecular Motor Proteins; D009419:Nerve Tissue Proteins; C078829:chicken brain myosin-V p190; D000075745:rab27 GTP-Binding Proteins; D024701:Myosin Type V; C066694:RAB27A protein, human; D020691:rab GTP-Binding Proteins