The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE...The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE as a protein undergoing major redox-dependent conformational changes. Its transcript was strongly induced under cold and salt stress in a time-dependent manner similar to SAP10, with high levels after 6 h and decreasing levels after 24 and 48 h. The tran- script regulation resembled those of the stress marker peroxiredoxin PrxllD at 24 and 48 h. Recombinant SAP12 protein showed redox-dependent changes in quaternary structure as visualized by altered electrophoretic mobility in non-reducing SDS polyacrylamide gel electrophoresis. The oxidized oligomer was reduced by high dithiothreitol concentrations, and also by E. coli thioredoxin TrxA with low dithiothreitol （DTF） concentrations or NADPH plus NADPH-dependent thioredoxin reductase. From Western blots, the SAP12 protein amount was estimated to be in the range of 0.5 ngμg^-1 leaf protein. SAP12 protein decreased under salt and cold stress. These data suggest a redox state-linked function of SAP12 in plant cells particularly under cold and salt stress.展开更多
KAP1/TRIM28/TIF1β was identified nearly twenty years ago as a universal transcriptional co-repressor because it interacts with a large KRAB-containing zinc finger protein(KRAB-ZFP) transcription factor family. Many s...KAP1/TRIM28/TIF1β was identified nearly twenty years ago as a universal transcriptional co-repressor because it interacts with a large KRAB-containing zinc finger protein(KRAB-ZFP) transcription factor family. Many studies demonstrate that KAP1 affects gene expression by regulating the transcription of KRAB-ZFP-specific loci, trans-repressing as a transcriptional co-repressor or epigenetically modulating chromatin structure. Emerging evidence suggests that KAP1 also functions independent of gene regulation by serving as a SUMO/ubiquitin E3 ligase or signaling scaffold protein to mediate signal transduction. KAP1 is subjected to multiple post-translational modifications(PTMs), including serine/tyrosine phosphorylation, SUMOylation, and acetylation, which coordinately regulate KAP1 function and its protein abundance. KAP1 is involved in multiple aspects of cellular activities, including DNA damage response, virus replication, cytokine production and stem cell pluripotency. Moreover, knockout of KAP1 results in embryonic lethality, indicating that KAP1 is crucial for embryonic development and possibly impacts a wide-range of(patho)physiological manifestations. Indeed, studies from conditional knockout mouse models reveal that KAP1-deficiency significantly impairs vital physiological processes, such as immune maturation, stress vulnerability, hepatic metabolism, gamete development and erythropoiesis. In this review, we summarize and evaluate current literatures involving the biochemical and physiological functions of KAP1. In addition, increasing studies on the clinical relevance of KAP1 in cancer will also be discussed.展开更多
文摘The stress-associated protein SAP12 belongs to the stress-associated protein （SAP） family with 14 members in Arabidopsis thaliana. SAP12 contains two AN1 zinc fingers and was identified in diagonal 2D redox SDS-PAGE as a protein undergoing major redox-dependent conformational changes. Its transcript was strongly induced under cold and salt stress in a time-dependent manner similar to SAP10, with high levels after 6 h and decreasing levels after 24 and 48 h. The tran- script regulation resembled those of the stress marker peroxiredoxin PrxllD at 24 and 48 h. Recombinant SAP12 protein showed redox-dependent changes in quaternary structure as visualized by altered electrophoretic mobility in non-reducing SDS polyacrylamide gel electrophoresis. The oxidized oligomer was reduced by high dithiothreitol concentrations, and also by E. coli thioredoxin TrxA with low dithiothreitol （DTF） concentrations or NADPH plus NADPH-dependent thioredoxin reductase. From Western blots, the SAP12 protein amount was estimated to be in the range of 0.5 ngμg^-1 leaf protein. SAP12 protein decreased under salt and cold stress. These data suggest a redox state-linked function of SAP12 in plant cells particularly under cold and salt stress.
文摘KAP1/TRIM28/TIF1β was identified nearly twenty years ago as a universal transcriptional co-repressor because it interacts with a large KRAB-containing zinc finger protein(KRAB-ZFP) transcription factor family. Many studies demonstrate that KAP1 affects gene expression by regulating the transcription of KRAB-ZFP-specific loci, trans-repressing as a transcriptional co-repressor or epigenetically modulating chromatin structure. Emerging evidence suggests that KAP1 also functions independent of gene regulation by serving as a SUMO/ubiquitin E3 ligase or signaling scaffold protein to mediate signal transduction. KAP1 is subjected to multiple post-translational modifications(PTMs), including serine/tyrosine phosphorylation, SUMOylation, and acetylation, which coordinately regulate KAP1 function and its protein abundance. KAP1 is involved in multiple aspects of cellular activities, including DNA damage response, virus replication, cytokine production and stem cell pluripotency. Moreover, knockout of KAP1 results in embryonic lethality, indicating that KAP1 is crucial for embryonic development and possibly impacts a wide-range of(patho)physiological manifestations. Indeed, studies from conditional knockout mouse models reveal that KAP1-deficiency significantly impairs vital physiological processes, such as immune maturation, stress vulnerability, hepatic metabolism, gamete development and erythropoiesis. In this review, we summarize and evaluate current literatures involving the biochemical and physiological functions of KAP1. In addition, increasing studies on the clinical relevance of KAP1 in cancer will also be discussed.
