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Updated: Mar 21, 2026
06:08
Quantification of Hypopigmentation Activity In Vitro
Published on: March 6, 2019
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TPC2 controls pigmentation by regulating melanosome pH and size
Andrea L Ambrosio1, Judith A Boyle1, Al E Aradi1
1Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870.
Summary
The two-pore segment channel 2 (TPC2) protein regulates skin and hair pigmentation by controlling melanosome pH and size. Loss of TPC2 function increases melanin production by altering these critical factors.
Area of Science:
- Cell Biology
- Genetics
- Biochemistry
Background:
- Melanin, the pigment in skin and hair, is produced in melanosomes within melanocytes.
- The two pore segment channel 2 (TPCN2) gene is associated with pigmentation variations, but its role in melanin synthesis is unclear.
- TPCN2 encodes the TPC2 protein, a cation channel found in melanocytes.
Purpose of the Study:
- To investigate the function of the TPC2 protein in melanocytes and its role in regulating pigmentation.
- To determine the localization and function of TPC2 within melanosomes and related organelles.
Main Methods:
- Confocal fluorescence and immunogold electron microscopy to determine TPC2 localization.
- TPCN2 gene editing (CRISPR/Cas9) and siRNA-mediated knockdown to study TPC2 function.
- Genetically encoded pH and Ca(2+) sensors to measure melanosome lumen acidity and calcium levels.
- Analysis of melanosome size and number using fluorescence and electron microscopy.
Main Results:
- TPC2 is localized to the melanosome-limiting membrane and endolysosomal compartments.
- TPCN2 knockout or TPC2 knockdown significantly increased melanin content in melanocytic cells.
- Melanosomes in TPC2-deficient cells exhibited less acidic lumens and increased size.
- TPC2 mediates Ca(2+) release from melanosomes, which is reduced upon TPC2 loss.
Conclusions:
- TPC2 plays a critical role in regulating pigmentation by controlling melanosome pH and size.
- TPC2 influences melanosome function through calcium ion release.
- Understanding TPC2's role provides insights into the molecular mechanisms of pigmentation control.
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