基因可变剪接调控植物响应非生物胁迫研究进展
Advances in the Regulation of Alternative Splicing of Genes in Plants in Response to Abiotic Stress
(A) 植物正常发育情况下进行的组成型剪接模式图(在正常条件下, 热响应基因(heat-responsive genes, HRG)未被激活或几乎不表达, 生长相关基因(genes responding for growth, GRG)正常表达。SR蛋白发生磷酸化(例如, 由剪接因子复合物(splicing factor complex, SFC)中的SR蛋白激酶(SR protein kinase, SRPK)进行磷酸化), 从而参与组成型剪接, 产生大量发育相关蛋白); (B) 植物在轻度热胁迫下可变剪接模式图(在轻度热胁迫(例如, 32°C持续6小时)下, 包括热诱导SR基因在内的HRGs在转录水平被激活, 磷酸化的SR蛋白参与HRGs的组成型剪接或可变剪接, 同时GRGs在转录水平上被抑制。部分来自GRGs的转录本片段也由磷酸化SR蛋白剪接, 产生不同功能的剪接变体。植物细胞通过该机制产生大量的热耐受蛋白进而响应热胁迫); (C) 植物在重度热胁迫下的可变剪接模式图(在重度热胁迫(例如, 45°C持续90分钟)下, 包括热诱导SR基因在内的HRGs在转录水平被激活。然而, 在重度热胁迫下SR蛋白去磷酸化(例如, 由SRPK缺乏引起), 导致功能性剪接因子短缺, 从而使HRGs和GRGs内含子保留的转录本在细胞核中积累, 最终导致功能性转录本数量显著减少。因此, 植物细胞中的热耐受蛋白和发育相关蛋白短缺)。ASF: 可变剪接片段; ×: 该过程被抑制。
(A) Schematic diagram of constitutive splicing in plants under normal development (under normal conditions, heat-responsive genes (HRG) are not activated or are barely expressed, while growth-related genes (GRGs) are actively transcribed. SR proteins are efficiently phosphorylated (e.g., phosphorylated by SR protein kinase (SRPK) in the splicing factor complex (SFC)), thus participating in constitutive splicing and generating many development-related proteins); (B) Schematic diagram of alternative splicing in plants under mild heat stress (under mild heat stress (e.g., 32°C for 6 hours), HRGs including heat-inducible SR genes are transcriptionally activated. Phosphorylated SR proteins participate in constitutive or alternative splicing of HRGs. GRGs are suppressed at the transcriptional level, but their pre-mRNAs may still be alternative spliced by phosphorylated SR proteins to produce functionally distinct isoforms. Through this mechanism, plant cells produce a large number of heat-tolerant proteins to cope with heat stress); (C) Schematic diagram of alternative splicing in plants under severe heat stress (under severe heat stress (e.g., 45°C for 90 minutes), HRGs including heat-inducible SR genes are activated at the transcriptional level. However, under severe heat stress, the dephosphorylation of SR proteins (e.g., caused by the deficiency of SRPK) leads to a deficiency of active splicing factors, resulting in the accumulation of intron-retained transcripts of HRGs and GRGs in the nucleus, and leads to an extremely low number of functional transcripts. Therefore, there is a shortage of heat-tolerant proteins and development-related proteins in plant cells). ASF: Alternative spliced fragment; ×: The process is inhibited.
