Fig. 4.
Downregulation of L-type CaV channels in CaVγ4-silenced beta cells. a Correlation of mRNA expression (Microarray) between CaVγ4 (CACNG4) and L-type CaV channels in human islets. n = 128 donors. Pearson correlation coefficient (R) was tested (t-test) and labeled alongside with p values. b CaV1.2 (CACNA1C) and CaV1.3 (CACNA1D) mRNA expression (qPCR) in CaVγ4-silenced human islets. n = 3 donors, *p = 0.032 (CaV1.2), *p = 0.011 (CaV1.3). c As in b but in CaVγ4-overexpressed human islets. n = 3 donors, **p = 0.005 (CaV1.2), *p = 0.039 (CaV1.3). d CaV channel immunoblotting and means of expression in CaVγ4-silenced INS-1 cells. n = 4, ***p < 0.001. e Decreased CaV1.2 expression in Wistar islets cultured at 5 or 20 mM glucose (72 h). n = 3, **p = 0.003. f As in e but cultured with 1 mM palmitate (48 h). n = 4, **p = 0.003. g Interaction between CaVγ4 and CaV1.3 in INS-1 cells treated with 5 or 20 mM glucose (24 h). Visualization by proximity ligation assay as fluorescent spots. h Calculation of fluorescent intensity. n = 25 cells each, ***p < 0.001. Data are presented as mean ± SEM and were analyzed with two-tailed unpaired Student’s t-test; and the significance in b, c was corrected by the Holm–Bonferroni method. OE overexpression, KD knockdown