高糖及糖基化终末产物对视网膜Müller细胞缺氧诱导因子-1α介导缺氧信号通路的影响

Effects of high glucose and AGEs on hypoxia signal pathway mediated by HIF-1α of retinal Müller cells

目的探讨高糖以及糖基化终末产物(advanced glycationend products,AGEs)对体外培养的视网膜Müller细胞低氧诱导因子(hypoxia-inducible factor,HIF)-1α介导缺氧信号通路的影响。方法采用改进的酶消化法培养新生5-7 d SD大鼠视网膜Müller细胞,纯化培养至第2代后,以2×106mL-1密度接种于48孔培养板中,根据培养液中葡萄糖及AGEs含量不同,分为正常组、模拟高糖组(葡萄糖终浓度为50 mmol·L-1)、低AGEs及高AGEs组(培养液AGEs终浓度分别为50 mg·L-1、100 mg·L-1),每组设6个复孔,干预48 h后,以ELISA法测定细胞培养上清液中HIF-1α、血管内皮生长因子(vascular endothelial growth factor,VEGF)蛋白表达量以及脯氨酸羟化酶(proline hydroxylase domain,PHD)1、2、3的活性;以RT-PCR测定Müller细胞HIF-1αmRNA及VEGF mRNA相对内参的表达量。结果高AGEs组HIF-1α蛋白表达量为(3.248±0.404)μg·L-1,明显高于正常组的(2.577±0.158)μg·L-1及高糖组的(2.600±0.131)μg·L-1,差异均有统计学意义(均为P<0.05);低AGEs组HIF-1αmRNA相对表达量为3.205±0.865,明显高于高糖组的2.438±0.444及高AGEs组的1.935±0.191,差异均有统计学意义(均为P<0.05);正常组VEGF蛋白含量和VEGF mRNA的相对表达量分别为(532.249±19.922)μg·L-1和1.348±0.314,均低于高糖组的(566.661±24.979)μg·L-1和2.265±0.677、低AGEs组的(590.565±29.725)μg·L-1和2.001±0.574及高AGEs组的(593.646±16.339)μg·L-1和2.063±0.759,差异均有统计学意义(均为P<0.05)。正常组PHD1活性为(99.969±11.066)μg·L-1,高于高糖组的(80.987±5.910)μg·L-1、低AGEs组的(88.809±6.303)μg·L-1及高AGEs组的(75.519±4.914)μg·L-1,而低AGEs组PHD1活性高于高AGEs组,差异均有统计学意义(均为P<0.05);PHD2活性正常组为(131.266±2.614)μg·L-1,低于低AGEs组的(142.896±8.323)μg·L-1及高AGEs组的(149.998±15.013)μg·L-1,差异均有统计学意义(均为P<0.05);PHD3在各组之间差异均无统计学意义(P=0.066)。结论 AGEs比高糖更能诱导视网膜Müller细胞HIF-1α的高表达,且HIF-1α的表达强度与AGEs浓度有关。

Objective To investigate the effects of high glucose and advanced glycosylation end products(AGEs)on hypoxia signal pathway mediated by hypoxia-inducible factor-1α(HIF-1α)in purified retinal M(u|¨)ller cells.Methods The retinal M(u|¨)ller cells of 5-7 days postnatal SD rats were cultured with modified enzyme-digestion method.After twice passage for a further purified population,M(u|¨)ller cells were taken in 48-well culture plates at 2×10~6 cells·mL^(-1)and divided into four groups based on the different concentration of glucose and AGEs:Normal control group,high glucose group(cultured in DMEM containing 50 mmol·L^(-1)glucose),low AGEs dose group(cultured in cultured in DMEM containing 50 mg·L^(-1)AGEs),high AGEs dose group(cultured in DMEM containing 100 mg·L^(-1)AGEs),and 6 parallel holes were set in each group.After 48 hours' culture,HIF-1α expression,vascular endothelial growth factor(VEGF)expression and proline hydroxylase 1,2,3(PHD1,2,3)activity of the culture cells were measured by ELISA.In addition,the HIF-1α and VEGF mRNA expression were tested by RT-PCR.Results Compared with the normal control group and high glucose group, the expression of HIF-1α in high dose AGEs group was obviously increased[normal control group(2.577±0.158)μg·L^(-1),high glucose group(2.600±0.131)μg· L^(-1),high dose AGEs group(3.248±0.404)μg·L^(-1);all P<0.05].The expression of HIF-1α mRNA in low dose AGEs group(3.205±0.865)was significantly increased compared with high glucose group(2.438±0.444)and high dose AGEs group(1.935 ±0.191)(all P<0.05).The expressions of VEGF(532.249±19.922)μg·L^(-1)and VEGF mRNA(1.348±0.314)in the normal control group were respectively reduced compared with high glucose group[(566.661±24.979)μg·L^(-1),2.265±0.677],low dose AGEs group[(590.565±29.725)μg·L^(-1),2.001±0.574]and high dose AGEs group [(593.646±16.339)μg·L^(-1)2.063±0.759](all P<0.05).The activity of PHD1 in the normal control group(99.969±11.066)μg·L^(-1)was significantly increased compared with high glucose group(80.987±5.91)μg·L^(-1),low dose AGEs group(88.809±6.303)μg· L^(-1)and high dose AGEs group(75.519±4.914)μg·L^(-1)(all P<0.05).The activity of PHD1 in low dose AGEs group was also obviously higher than that of high dose AGEs group(P<0.05).The activity of PHD2 in the normal control group(131.266±2.614)μg·L^(-1) was significantly lower compared with low dose AGEs group(142.896±8.323)μg·L^(-1)and high dose AGEs group(149.998±15.013)μg·L^(-1)(all P<0.05).The differences of activity of PHD3 was not statistically significant among the four groups(P=0.066).Conclusion The up-expression of HIF-1α in culture M(u|¨)ller cells can be induced by AGEs or high glucose,but AGEs is stronger than high glucose.The expressive level of HIF-1α is correlated Objective T o investigate the effects of high glucose and advanced glycosylation end products( AG Es) on hypoxia signal pathw ay m ediated by hypoxia-inducible factor-1 α(H IF-1 α)in purified retinal M üller cells. Methods T he retinal M üller cells of 5- 7 days postnatal SD rats w ere cultured w ith m odified enzym e-digestion m ethod. After tw ice passage for a further purified population,M üller cells w ere taken in 48-w ell culture plates at 2 × 106cells·m L- 1and divided into four groups based on the different concentration of glucose and AG Es: Normal control group,high glucose group( cultured in D M EM containing 50 m m ol·L- 1glucose),low AG Es dose group( cultured in cultured in D M EM containing 50 m g·L- 1AG Es),high AG Es dose group( cultured in D M EM containing 100 m g · L- 1AG Es),and 6 parallel holes w ere set in each group. After 48 hours' culture,H IF-1 α expression,vascular endothelial grow th factor( V EG F) expression and proline hydroxylase 1,2,3( PH D 1,2,3) activity of the culture cells w ere m easured by ELISA. In addition,the HIF-1α and VEGF mRNA expression were tested by RT-PC R. Results C om pared w ith the norm al control group and high glucose group, the expression of H IF-1 α in high dose AG Es group w as obviously increased[norm al control group(2. 577 ± 0. 158) μg·L- 1,high glucose group( 2. 600 ± 0. 131) μg · L- 1,high dose AGEs group(3. 248 ± 0. 404)μg·L- 1;all P < 0. 05]. T he expression of H IF-1 α m RN A in low dose AG Es group(3. 205 ± 0. 865) w as significantly increased com pared w ith high glucose group( 2. 438 ± 0. 444) and high dose AG Es group( 1. 935 ± 0. 191)( all P < 0. 05). T he expressions of V EG F( 532. 249 ± 19. 922) μg · L- 1and V EG F m RN A( 1. 348 ± 0. 314) in the norm al control group w ere respectively reduced com pared w ith high glucose group[(566. 661 ± 24. 979) μg·L- 1,2. 265 ± 0. 677],low dose AGEs group [( 590. 565 ± 29. 725) μg · L- 1,2. 001 ± 0. 574] and high dose AGEs group [(593. 646 ±16.339)μg·L- 1,2. 063 ± 0. 759〗(all P < 0. 05). T he activity of PHD1 in the normal control group(99. 969 ± 11. 066)μg·L- 1w as significantly increased compared w ith high glucose group(80. 987 ± 5. 91) μg·L- 1,low dose AGEs group(88. 809 ±6. 303)μg· L- 1and high dose AGEs group(75. 519 ± 4. 914) μg ·L- 1(all P < 0. 05). T he activity of PHD1 in low dose AGEs group w as also obviously higher than that of high dose AGEs group(P < 0. 05). T he activity of PHD2 in the normal control group(131. 266 ± 2. 614)μg·L- 1 w as significantly low er compared w ith low dose AGEs group(142. 896 ± 8. 323)μg·L- 1and high dose AGEs group(149. 998 ± 15. 013) μg·L- 1(all P < 0. 05). T he differences of activity of PHD3 w as not statistically significant among the four groups( P = 0. 066). Conclusion T he up-expression of HIF-1α in culture M üller cells can be induced by AGEs or high glucose,but AGEs is stronger than high glucose. T he expressive level of HIF-1α is correlated with the concentration of AGEs.