Fig 2: Gamma-aminobutyric acid type B receptor subunit 2 (GABBR2) expression increased in hypoxia-treated endothelial cells in vitro and mouse ischemic hindlimb in vivo. (A) Prediction of an endothelial-specific expression of GABBR2 by RNA-seq data. (B) Re-speculation of the role of GABBR2 in angiogenesis. (C,D) Expression changes of GABBR2 in human umbilical vein endothelial cells (HUVECs) after hypoxia treatment for 1, 3, and 6 h. (E,F) Expression changes of GABBR2 in the muscle of mouse ischemic hindlimb on days 1, 3, and 7. *p <0.05; **p <0.01.

Fig 3: Effect of gamma-aminobutyric acid type B receptor subunit 2 (GABBR2) knockdown on the glycolysis capacity of human umbilical vein endothelial cells (HUVECs) after hypoxia treatment. (A) Extracellular acidification rate (ECAR) changes induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. WT, normal mice; KD, GABBR2-downregulated mice; WT-H, wild-type (WT) mice with hindlimb ischemia; KD-H, GABBR2 knockdown (KD) mice with hindlimb ischemia. (B) ATP production changes induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. (C–E) Expression changes of HKII, PFKFB3, and PKM1 induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. *p < 0.05.

Fig 4: Effect of gamma-aminobutyric acid type B receptor subunit 2 (GABBR2) knockdown on the proliferation, migration, and angiogenesis of human umbilical vein endothelial cells (HUVECs). (A) Downregulation of GABBR2 in HUVECs by lentivirus transfection. (B) Cellular proliferation changes induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. (C) EdU staining induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. (D) Wound healing distance changes induced by 6 h of hypoxic treatment in normal and GABBR2-downregulated HUVECs. (E) Tube-like construction formation induced by 6 h of hypoxic treatment in normal and GABBR2 downregulated HUVECs. *p < 0.05; **p < 0.01; ****p < 0.0001.

Fig 5: Effect of gamma-aminobutyric acid type B receptor subunit 2 (GABBR2) knockdown on endothelial progenitor cell (EPC) mobilization in peripheral blood in hindlimb post-ischemia. (A) Representative images of CD34+/CD133+ cells in the peripheral blood of mice analyzed by flow cytometry. WT, normal mice; KD, GABBR2-downregulated mice; WT-H, wild-type (WT) mice with hindlimb ischemia; KD-H, GABBR2 knockdown (KD) mice with hindlimb ischemia. (B) Ratio of CD34+ cells in the peripheral blood of normal and ischemic mice. (C) Ratio of CD133+ cells in the peripheral blood of normal and ischemic mice. (D) Ratio of CD34+ and CD133+ cells in the peripheral blood of normal and ischemic mice. *p < 0.05; ***p < 0.001; ****p < 0.0001.