Expression variations of different VEGFA isoforms in ARPE-19 cells under high glucose conditions

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Objective  To explore expression changes of different vascular endothelial growth factor A (VEGFA) isoforms in human retinal pigment epithelial cell line ARPE-19 cells under high glucose conditions.

Methods  ARPE-19 cells were divided into blank control group, control group 1, control group 2, HG1 group, and HG2 group treated with 5.5 mmol/L glucose, 5.5 mmol/L glucose+ 19.5 mmol/L mannitol, 5.5 mmol/L glucose+ 44.5 mmol/L mannitol, 25.0 mmol/L glucose, and 50.0 mmol/L glucose, respectively.The blank control group, control group 1, and control group 2 were treated for 72 hours, while HG1 and HG2 groups were treated for 24, 48, and 72 hours.The relative expression of VEGFA isoforms was detected by fluorescent quantitative PCR.Total VEGFA, SERPINF1 (pigment epithelium-derived factor, PEDF), a negative regulator of VEGF signaling, and VEGF165 (V4, 5, 10) protein expression was measured by Western blot.

Results  Total VEGFA mRNA and protein expression in ARPE-19 cells showed statistically significant differences at both 25 mmol/L and 50 mmol/L glucose concentrations across different culture periods (mRNA: F=114.60, 143.60; both P<0.05.protein: F=10.00, 8.04; both P<0.05). Compared to the respective controls, the relative expression of total VEGFA mRNA and protein increased significantly at 24, 48, and 72 hours after treatment (all P<0.05). There was no significant difference in SERPINF1 (PEDF) mRNA or protein expression in ARPE-19 cells across different time points at 25 mmol/L or 50 mmol/L glucose concentrations (mRNA: F=0.86, 0.32; both P>0.05.protein: F=1.25, 0.08; both P>0.05). The mRNA expression levels of VEGFA isoforms in ARPE-19 cells from highest to lowest were VEGF165(V4, 5, 10), VEGF121(V6), VEGF189(V2), VEGF111(V8) and VEGF165b(V7). The relative VEGF111(V8) mRNA expression level was significantly lower in HG1-24 hour group than in control group 1, the relative VEGF189(V2) and VEGF121(V6) mRNA expression levels were significantly higher in HG1-48 hour group than in control group 1, the relative VEGF121(V6) and VEGF165b(V7) mRNA expression levels were significantly higher in HG1-72 hour group than in control group 1, with statistically significant differences (all P<0.05). The relative VEGF111(V8) and VEGF165(V4, 5, 10) mRNA expression levels were significantly higher in the HG2-24 hour group than in control group 2, the relative VEGF165(V4, 5, 10) and VEGF165b(V7) mRNA expression levels were significantly higher in HG2-48 hour group than control group 2, and the relative VEGF189(V2), VEGF111(V8), VEGF165(V4, 5, 10), and VEGF165b(V7) mRNA expression levels were significantly higher in HG2-72 hour group than in control group 2, with statistically significant differences (all P<0.05). The relative VEGF165(V4, 5, 10) protein expression levels in blank control group, control group 1, HG1-24 hour group, HG1-48 hour group, and HG1-72 hour group were 1.01±0.07, 1.05±0.07, 1.16±0.06, 1.37±0.08, and 1.28±0.05, respectively, with a statistically significant overall difference ( F=10.36, P<0.05). The relative VEGF165(V4, 5, 10) protein expression level was significantly higher in HG1-48 hour group than in control group 1 ( P<0.05). The relative protein expression levels of VEGF165(V4, 5, 10) in blank control group, control group 2, HG2-24 hour group, HG2-48 hour group, and HG2-72 hour group were 1.02±0.05, 1.12±0.00, 1.22±0.05, 1.53±0.21, and 1.77±0.04, respectively, with a statistically significant overall difference ( F=16.55, P<0.001). The relative VEGF165(V4, 5, 10) protein levels were significantly higher in HG2-48 hour group and HG2-72 hour group than in control group 2 (both P<0.05).

Conclusions  In ARPE-19 cells, mRNA abundance of VEGFA isoforms from highest to lowest were VEGF165(V4, 5, 10), VEGF121(V6), VEGF189(V2), VEGF111(V8), VEGF165b(V7). VEGF121(V6) mRNA expression level is significantly increased at 25 mmol/L high glucose concentration, whereas VEGF165(V4, 5, 10) mRNA expression level shows significant elevation only at 50 mmol/L high glucose.Under both high glucose conditions, isoforms with significantly elevated mRNA expression levels are VEGF189(V2) and VEGF165b(V7), while SERPINF1 (PEDF) expression level does not change significantly.

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