Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intro...Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development.PPR21 is a typical P-type PPR protein targeted to mitochondria.The ppr21 mutants are arrested in embryogenesis and endosperm development,leading to embryo lethality.Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1,2,and 4 and impair the assembly and activity of mitochondrial complex I.Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns.However,our protein interaction analyses reveal that PPR21 does not interact with EMP12.Instead,both PPR21 and EMP12 interact with the small MutS-related(SMR)domain-containing PPR protein 1(PPR-SMR1)and the short P-type PPR protein 2(SPR2).PPR-SMR1 interacts with SPR2,and both proteins are required for the splicing of many introns in mitochondria,including nad2 intron 1,2,and 4.These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.展开更多
目的探索酮还原酶家族1成员C3(aldo-keto reductase family 1 member C3,AKR1C3)对乳腺癌恶性细胞生物学行为的干预作用及对程序性细胞死亡蛋白/程序性死亡-配体1(programmed cell death protein1/programmed death-ligand1,PD-1/PD-L)...目的探索酮还原酶家族1成员C3(aldo-keto reductase family 1 member C3,AKR1C3)对乳腺癌恶性细胞生物学行为的干预作用及对程序性细胞死亡蛋白/程序性死亡-配体1(programmed cell death protein1/programmed death-ligand1,PD-1/PD-L)通路的影响。方法把MCF-7人乳腺癌细胞中NC组和AKR1C3组分别转染空质粒和AKR1C3质粒,采用MTT法检测转染后24 h、48 h、72 h细胞活力;采用流式细胞技术测定各组细胞的存活率以及早期、晚期凋亡比例;通过Transwell实验对各组细胞的迁移和侵袭能力进行检测;通过Western blot检测各组细胞PD-1、PD-L1、蛋白激酶B(protein kinase b,AKT)蛋白表达水平。使用C57BL/6小鼠构建荷瘤模型,将采用人乳腺癌MCF-7细胞转染NC质粒和AKR1C3质粒进行细胞荷瘤,每3 d测量瘤体积,持续21 d,绘制两组小鼠肿瘤生长曲线,并于实验终点测量肿瘤质量。结果相较于NC组,AKR1C3组细胞活力降低(P<0.05),并且具有时间依赖效应(P<0.05),迁移和侵袭能力降低(P<0.05),早期凋亡和晚期凋亡比例升高(P<0.05),PD-1、PD-L1、AKT蛋白表达水平降低(P<0.05)。动物实验表明,AKR1C3组小鼠肿瘤体积降低,肿瘤质量下降(P<0.05)。结论AKR1C3可以抑制人乳腺癌细胞恶性生物学行为,抑制PD-1/PDL1信号通路蛋白表达。展开更多
基金supported by the National Natural Science Foundation of China(32072126 and 32230075)the Shandong Provincial Natural Science Foundation(ZR2019MC005).
文摘Pentatricopeptide repeat(PPR)proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression.Here,we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development.PPR21 is a typical P-type PPR protein targeted to mitochondria.The ppr21 mutants are arrested in embryogenesis and endosperm development,leading to embryo lethality.Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1,2,and 4 and impair the assembly and activity of mitochondrial complex I.Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns.However,our protein interaction analyses reveal that PPR21 does not interact with EMP12.Instead,both PPR21 and EMP12 interact with the small MutS-related(SMR)domain-containing PPR protein 1(PPR-SMR1)and the short P-type PPR protein 2(SPR2).PPR-SMR1 interacts with SPR2,and both proteins are required for the splicing of many introns in mitochondria,including nad2 intron 1,2,and 4.These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.
