Figure 2: RAB6 controls the biogenesis of melanosomes in vitro and in vivo.
From: Routing of the RAB6 secretory pathway towards the lysosome related organelle of melanocytes
(a) WB of control (siControl) or RAB6 (siRAB6) depleted MNT-1 cell lysates probed with RAB6 or Tubulin antibodies. (b) Melanin content estimation of siControl or siRAB6 depleted MNT-1 cells (9 independent experiments). (c) Quantification of immature (stages-I/-II) and mature (stages-III/-IV) melanosomes (n), presented as mean percentage of the total number±s.e.m. (siControl, n=725; siRAB6, n=395, 8–10 cells per condition, four independent experiments). (d) Conventional EM analysis of control or RAB6-depleted MNT-1 cells (stages-I/ -II, arrowheads; stages-III/ -IV, arrows). (e) Conventional EM on NMM isolated from Rosa26CreERT2- TG-/+or+/+; Rab6F/F mouse treated (RAB6 KO) or not (RAB6 Flox/Flox; control) with 4-OHT to extinguish RAB6 expression. (f) Quantification of immature (stages-I/ -II) and mature (stages-III/-IV) melanosomes (n) in NMM. Data are means±s.e.m. (RAB6 Flox/Flox, n=1468; RAB6 KO, n=826; 4 independent mice). (g) Conventional EM analysis of RPE from 2 independent conditional RAB6 KO (Tyr::Cre/°; Rab6F/F) mice showed a reduction in pigmented melanosomes (arrows) relative to RAB6 HET mice (Tyr::Cre/°; Rab6F/+). (h) Quantification of the number of pigmented melanosomes (n) per 100 μm2 of RPE in RAB6 HET and conditional RAB6 KO mice. Data are means±s.e.m. (RAB6 HET, n=526; RAB6 KO#1, n=74; RAB6 KO#2, n=204) from 10 random electron micrographs. Scale bars: 500 nm (d), 5 μm (e), 1 μm (g); M.W. in KDa; Two tailed, Unpaired t test (b,h), Sidak’s multiple comparisons test (c); *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.
