Fig 1

IP₃R2 is a positive regulator of pigmentation.
(A) Pictorial representation and cell pellet image demonstrating increased pigmentation of B16 cells over seven days, from day0 to day7. Created in BioRender. Motiani, R. (2026) https://BioRender.com/o9pmka1. (B) qRT-PCR analysis showing quantification of IP₃R1, IP₃R2, and IP₃R3 mRNA in B16 cells (N = 3). (C) Microarray analysis of IP₃R2 in primary human melanocyte showing pictorial representation of microarray stimulated with L-tyrosine and Phenylthiourea. Created in BioRender. Motiani, R. (2026) https://BioRender.com/07kdt7i. (D) qRT-PCR analysis showing increase in IP₃R2 mRNA expression after 72 h of treatment with 1mM L-Tyrosine (N = 4). (E) qRT-PCR analysis showing decrease in IP₃R2 mRNA expression after 72 h of treatment with 200 µM Phenylthiourea (N = 4). (F) Representative image of pellet pictures demonstrates B16 cells of LD day6, transfected with either non-targeted siRNA or siRNA specifically targeting IP₃ receptor type1, type2, and type3 on LD day3. (G) Bar graph showing melanin content estimation of B16 cells harvested 72 h post siRNA transfection at LD day6 (N = 4). (H) Representative image of pellet pictures shows B16 cells 72 h after transfection with either non-targeted siRNA or siRNA specifically targeting IP₃R2, along with a 48 h exposure to 1 μM αMSH. (I) Bar graph showing mean pixel intensity of B16 cells harvested 72 h post-siRNA transfection in addition to 48 h exposure to 1 μM αMSH (N = 4). (J) Representative image of pellet picture showing primary human melanocytes 72 h post-transfection with either non-targeted siRNA or siRNA specifically targeting IP₃R2. (K) Bar graph showing mean pixel intensity of lightly pigmented primary human melanocytes harvested 72 h post-siRNA transfection (N = 3). (L) Heatmap highlighting the expression pattern of the IP₃R2 gene in African vs. White skin (GSE54638). (M) Representative traces of Fura2AM-based Ca²⁺ imaging in B16 cells stimulated with the Histamine followed by Tg after 72 h of siRNA transfection. (N) Bar graph showing the quantification of Ca²⁺ imaging traces stimulated with 50 µM Histamine, where ‘N’ denotes the total number of cells imaged. (O) Bar graph showing the quantification of Ca²⁺ imaging traces stimulated with 2 µM Tg, where ‘N’ denotes the total number of cells imaged. (P) Representative image of pellet picture showing B16 cells transfected with IP₃R2 and IP₃R2-M in the LD model system. (Q) Bar graph showing the melanin content in B16 cells transfected with IP₃R2 and IP₃R2-M (N = 4). (R) Representative image of pellet picture showing B16 cells overexpressed with IP₃R2 and IP₃R2-M in stable IP₃R2 knockdown background. (S) Bar graph showing the melanin content in B16 cells overexpressed with IP₃R2 and IP₃R2-M in stable IP₃R2 knockdown background (N = 3). Data presented are mean ± SEM. For statistical analysis, Dunnett’s multiple comparisons test was performed for panels G, Q, S, while one-sample t test was performed for panels D, E, I, K and an Unpaired t test was performed for panels N, O using GraphPad Prism software. Here, ‘ns’ means non-significant; * p < 0.05, ** p < 0.01 and *** p < 0.001.