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Reprogramming of endolysosomes for melanogenesis in BLOC-1-deficient melanocytes
Philip S Goff1, Shyamal Patel1, Dawn C Harper2
1School of Health and Medical Sciences, City St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
Current Biology : CB
|July 19, 2025
Summary
Defects in BLOC-1 cause hypopigmentation by mistargeting melanin synthesis proteins. However, these cells can still produce melanin in endolysosomes, which can be enhanced by modulating pH.
Area of Science:
- Cell Biology
- Biochemistry
- Genetics
Background:
- Melanins, synthesized in melanosomes, provide skin photoprotection.
- Melanocytes utilize specific trafficking pathways to deliver cargo to melanosomes or lysosomes.
- Mutations in BLOC-1 disrupt cargo delivery, leading to hypopigmentation.
Purpose of the Study:
- To investigate the melanogenic capacity of BLOC-1-deficient melanocytes.
- To explore mechanisms for enhancing melanin production in these cells.
- To understand the role of endolysosomal pH in melanogenesis.
Main Methods:
- Analysis of BLOC-1-deficient melanocytes.
- Treatment with cyclic adenosine monophosphate (cAMP)-elevating agents.
- Genetic manipulation and treatment with lysosomotropic agents to modulate pH.
- Assessment of melanin content and tyrosinase activity.
Main Results:
- BLOC-1-deficient melanocytes retain melanogenic capacity despite protein mislocalization.
- Melanin is formed in late endosomes/lysosomes with a neutral pH, not melanosomes.
- Modulating endolysosomal pH significantly enhances melanin production.
- Upregulated mistargeted cargoes contribute to increased tyrosinase expression and activity.
Conclusions:
- Endolysosomes in BLOC-1-deficient cells can be reprogrammed for melanogenesis via pH modulation.
- Targeting endolysosomal pH offers a therapeutic strategy for hypopigmentation disorders.
- This study reveals novel insights into melanosome biogenesis and pigment production.
