Fig. 4

SLC38A5 Is Upregulated in α Cells and Required for Expansion of α Cells in Response to Interrupted Glucagon Signaling

(A and B) Representative images of pancreatic islet α cell SLC38A5 expression are shown in (A) control Gcgr^Hep+/+ and (B) Gcgr^Hep−/− mouse pancreas. Glucagon (green), SLC38A5 (red), and insulin (blue) are shown. White scale bars represent 50 μm. White dashed boxes indicate region selected for insets.

(C) Quantification of SLC38A5+ α cells in Gcgr^Hep+/+ (white) and Gcgr^Hep−/− (red) mouse pancreas; ^∗∗p < 0.01; n = 3.

(D–I) Representative images of pancreatic islet α cell SLC38A5 expression in Gcgr^+/+ and Gcgr^−/− islets from subcapsular renal transplantation into Gcgr^+/+ and Gcgr^−/− mice (n = 3). SLC38A5 expression is shown at (D and E) 1 week and (F–I) 8 weeks post-transplantation.

(J–L) Representative images of pancreatic islet α cell SLC38A5 expression are shown in dispersed islets cultured in in (J) low AA, (K) high AA low Q, or (L) high AA media for 4 days. Glucagon (green), SLC38A5 (red), and DAPI (blue) are shown. White arrows indicate SLC38A5⁺ α cells.

(M and N) Quantification of (M) α cell proliferation and (N) SLC38A5⁺ α cells in isolated islets cultured in low AA, high AA low Q, or high AA media for 4 days. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus high AA treated; n = 3.

(O) α cell number after knockdown of slc38a5 genes in 6 dpf wild-type (white) and gcgra^−/−gcgrb^−/− (green, control) zebrafish larvae primary islet. α cell number in slc38a5a single guide RNA (sgRNA)-treated gcgra^−/−gcgrb^−/− (yellow with green left-hashed), slc38a5b sgRNA-treated gcgra^−/−gcgrb^−/− (yellow with green right-hashed), or slc38a5a/slc38a5b sgRNA-treated gcgra^−/−gcgrb^−/− (yellow with green double-hatched) are also shown. ^∗∗∗p < 0.001 versus wild-type, ^###p < 0.001 versus control gcgra^−/−gcgrb^−/−, and ^$$$p < 0.001 versus slc38a5a sgRNA-treated gcgra^−/−gcgrb^−/−; n = 7–23. Data are mean ± SEM.