Fig. 6. A specific therapeutic peptide blocks the FUNDC1–IP3R1 interaction and angiogenesis.

a Transduction efficiency of peptides 1, 2, and a control peptide in Human umbilical vein endothelial cells (HUVECs) (n = 5 independent experiments). b HUVECs were treated with different peptides (20 μM) for 24 h, then subjected to immunoprecipitation with antibody against FUNDC1(HA) to quantify the interaction of FUNDC1 and IP3R1 (n = 3 independent experiments). c HUVECs were treated with different peptides (20 μM) for 24 h, then cytosolic Ca²⁺ was detected using the fluorescent probe Fluo-4, AM (n = 5 independent experiments). d HUVECs were treated with different peptides. After 24 h, the cell lysates were collected and subjected to western blot assays to detect the expression of VEGFR2, IP3R1, SRF, and phosphorylated SRF at Ser103 (pSRF) (n = 5 independent experiments). e Three-dimensional spheroids and representative images of spheroid-sprouting were analyzed (n = 5 independent experiments). Scale bar, 100 µm. f Matrigel containing vascular endothelial growth factor (VEGF) was injected subcutaneously into 6-week-old wild-type mice, then the mice received an intravenous injection of the indicated peptides. After 10 days, matrigel plugs were removed for analysis of new vessel formation by histological and Hb assay (n = 5 mice/group). Quantification of Hb extracted from matrigel plugs of different groups. g C57BL/6 mice with LLC tumors that were approximately 90 mm³ in size were treated with intravenous injections of different peptides (10 mg/kg/3 days). After 28 days, the tumors were harvested and quantified. Representative images of tumors (n = 5 mice/group). h Immunostaining of LLC tumor sections and quantification of relative CD31-positive area. (n = 5 mice/group). Scale bar, 100 µm. Statistical significance was assessed using one-way ANOVA with post hoc multiple comparisons test for multiple groups. *p < 0.05 vs Ctrl peptide. All values are mean ± S.D.