Fig. 2: March5 deficiency reduces insulin expression and secretion by inhibiting Ca²⁺ release and MafA expression.

a In vitro GSIS. Islets isolated from 10-week-old male mice were treated with 2.8- or 16.7-mM glucose. N = 3 biologically independent samples. b, c Biphasic GSIS determined by the perifusion assays (b) using isolated islets from 10-week-old CON and cKO mice, along with corresponding area under the curve (AUC) analyses (c) for first phase (6–12 min) and second phase (14–36 min) of insulin secretion. N = 3 biologically independent samples. d Ca²⁺ influx. Representative results from CON and cKO mice islets are provided. N = 15 islets per group. The quantification of 16.7 mM glucose and 25 mM KCl stimulation in islets. N = 3 biologically independent samples. e Representative electron micrographs of islets showing β-cell insulin granules. Dotted lines indicate the plasma membrane. Docked granules are marked by arrowheads. Upper scale bar 1 μm. Bottom scale bar, 0.2 μm. f Insulin granules density and Number of docked insulin granules in the plasma membrane. N = 5 mice per group. g QPCR analyses of total RNA isolated from islets of 2-month-old male cKO and CON mice. h Western blot analyses using isolated islets from 2-month-old male cKO and CON mice with indicated antibodies. N = 3 biologically independent samples (g, h). i, j IHC staining and quantitative data for MafA. Scale bar, 50 μm. N = 5 per group. k, l Western blot analyses of INS1 cells. Quantitative data from three independent experiments (l). m In vitro GSIS. Islets isolated from 12-week-old male mice were treated with 2.8- or 16.7-mM glucose. n QPCR analyses of total RNA isolated from islets of 12-week-old male mice. N = 3 biologically independent samples (m, n). o, p Western blot analyses using isolated islets from 12-week-old male CON and M5OE mice with indicated antibodies. Quantitative data from three independent experiments (p). q, r Western blot analyses of INS1 cells. Quantitative data from three independent experiments (q). All mRNA levels were normalized to Gapdh mRNA level. Data are expressed as mean ± s.d. Data were analyzed by two-tailed unpaired Student’s t-tests for comparisons between two groups and one-way ANOVA for multiple groups, followed by Tukey’s post hoc test. Source data are provided as a Source Data file.