The Ikaros gene encodes a zinc finger,DNA-binding protein that regulates gene transcription and chromatin remodeling.Ikaros is a master regulator of hematopoiesis and an established tumor suppressor.Moderate alteratio...The Ikaros gene encodes a zinc finger,DNA-binding protein that regulates gene transcription and chromatin remodeling.Ikaros is a master regulator of hematopoiesis and an established tumor suppressor.Moderate alteration of Ikaros activity (e.g.haploinsufficiency) appears to be sufficient to promote malignant transformation in human hematopoietic cells.This raises questions about the mechanisms that normally regulate Ikaros function and the potential of these mechanisms to contribute to the development of leukemia.The focus of this review is the regulation of Ikaros function by phosphorylation/dephosphorylation.Site-specific phosphorylation of Ikaros by casein kinase 2 (CK2) controls Ikaros DNA-binding ability and subcellular localization.As a consequence,the ability of Ikaros to regulate cell cycle progression,chromatin remodeling,target gene expression,and thymocyte differentiation are controlled by CK2.In addition,hyperphosphorylation of Ikaros by CK2 leads to decreased Ikaros levels due to ubiquitinmediated degradation.Dephosphorylation of Ikaros by protein phosphatase 1 (PP1) acts in opposition to CK2 to increase Ikaros stability and restore Ikaros DNA binding ability and pericentromeric localization.Thus,the CK2 and PP1 pathways act in concert to regulate Ikaros activity in hematopoiesis and as a tumor suppressor.This highlights the importance of these signal transduction pathways as potential mediators of leukemogenesis via their role in regulating the activities of Ikaros.展开更多
【目的】观察苦瓜皂苷G对糖尿病肾病(DN)大鼠的治疗作用及机制。【方法】从55只大鼠中随机抽取45只采用一次性腹腔注射链脲佐菌素(STZ)法诱导DN模型。将造模成功的38只大鼠随机分为模型组9只、苦瓜皂苷G低剂量组9只、苦瓜皂苷G中剂量组1...【目的】观察苦瓜皂苷G对糖尿病肾病(DN)大鼠的治疗作用及机制。【方法】从55只大鼠中随机抽取45只采用一次性腹腔注射链脲佐菌素(STZ)法诱导DN模型。将造模成功的38只大鼠随机分为模型组9只、苦瓜皂苷G低剂量组9只、苦瓜皂苷G中剂量组10只、苦瓜皂苷G高剂量组10只。剩余10只大鼠设为正常组。对应灌胃给药4周后,酶联免疫吸附分析(ELISA)检测大鼠24 h尿蛋白水平,血糖仪检测空腹血糖(FBG),全自动生化分析仪检测血肌酐(SCr)、血尿素氮(BUN)水平,苏木素-伊红染色(HE)法观察大鼠肾组织病理学变化,采用实时定量聚合酶链反应(RT-qPCR)和Western Blot法分别检测E-钙黏蛋白(E-cad)、α-平滑肌肌动蛋白(α-SMA)、Notch1、锌指蛋白转录因子1(Snail1)、Jagged1 m RNA及蛋白表达情况。【结果】与正常组比较,模型组24 h尿蛋白、FBG、血清SCr和BUN水平及肾组织α-SMA、Notch1、Snail1、Jagged1 mRNA及蛋白水平显著升高,肾组织E-cad m RNA及蛋白水平降低,肾组织可见肾小球萎缩、肾小管扩张及间质纤维化;与模型组比较,苦瓜皂苷G低、中、高剂量组24 h尿蛋白、FBG、血清SCr和BUN水平及肾组织α-SMA、Notch1、Snail1、Jagged1 mRNA及蛋白水平显著降低,肾组织E-cad m RNA及蛋白水平升高,肾组织病理损伤得到改善。【结论】苦瓜皂苷G可有效改善DN大鼠肾功能障碍、减轻肾脏纤维化,其机制可能与通过调控Notch/Snail1信号通路,抑制α-SMA和Jagged1 mRNA及蛋白表达,增强E-cad mRNA及蛋白表达有关。展开更多
基金Supported by (in part) An NIH R01 HL095120 grant,a St.Baldrick’s Foundation Career Development Award,the Four Diamonds Fund of the Pennsylvania State University College of Medicine,and the John Wawrynovic Leukemia Research Scholar Endowment (SD)
文摘The Ikaros gene encodes a zinc finger,DNA-binding protein that regulates gene transcription and chromatin remodeling.Ikaros is a master regulator of hematopoiesis and an established tumor suppressor.Moderate alteration of Ikaros activity (e.g.haploinsufficiency) appears to be sufficient to promote malignant transformation in human hematopoietic cells.This raises questions about the mechanisms that normally regulate Ikaros function and the potential of these mechanisms to contribute to the development of leukemia.The focus of this review is the regulation of Ikaros function by phosphorylation/dephosphorylation.Site-specific phosphorylation of Ikaros by casein kinase 2 (CK2) controls Ikaros DNA-binding ability and subcellular localization.As a consequence,the ability of Ikaros to regulate cell cycle progression,chromatin remodeling,target gene expression,and thymocyte differentiation are controlled by CK2.In addition,hyperphosphorylation of Ikaros by CK2 leads to decreased Ikaros levels due to ubiquitinmediated degradation.Dephosphorylation of Ikaros by protein phosphatase 1 (PP1) acts in opposition to CK2 to increase Ikaros stability and restore Ikaros DNA binding ability and pericentromeric localization.Thus,the CK2 and PP1 pathways act in concert to regulate Ikaros activity in hematopoiesis and as a tumor suppressor.This highlights the importance of these signal transduction pathways as potential mediators of leukemogenesis via their role in regulating the activities of Ikaros.
文摘【目的】观察苦瓜皂苷G对糖尿病肾病(DN)大鼠的治疗作用及机制。【方法】从55只大鼠中随机抽取45只采用一次性腹腔注射链脲佐菌素(STZ)法诱导DN模型。将造模成功的38只大鼠随机分为模型组9只、苦瓜皂苷G低剂量组9只、苦瓜皂苷G中剂量组10只、苦瓜皂苷G高剂量组10只。剩余10只大鼠设为正常组。对应灌胃给药4周后,酶联免疫吸附分析(ELISA)检测大鼠24 h尿蛋白水平,血糖仪检测空腹血糖(FBG),全自动生化分析仪检测血肌酐(SCr)、血尿素氮(BUN)水平,苏木素-伊红染色(HE)法观察大鼠肾组织病理学变化,采用实时定量聚合酶链反应(RT-qPCR)和Western Blot法分别检测E-钙黏蛋白(E-cad)、α-平滑肌肌动蛋白(α-SMA)、Notch1、锌指蛋白转录因子1(Snail1)、Jagged1 m RNA及蛋白表达情况。【结果】与正常组比较,模型组24 h尿蛋白、FBG、血清SCr和BUN水平及肾组织α-SMA、Notch1、Snail1、Jagged1 mRNA及蛋白水平显著升高,肾组织E-cad m RNA及蛋白水平降低,肾组织可见肾小球萎缩、肾小管扩张及间质纤维化;与模型组比较,苦瓜皂苷G低、中、高剂量组24 h尿蛋白、FBG、血清SCr和BUN水平及肾组织α-SMA、Notch1、Snail1、Jagged1 mRNA及蛋白水平显著降低,肾组织E-cad m RNA及蛋白水平升高,肾组织病理损伤得到改善。【结论】苦瓜皂苷G可有效改善DN大鼠肾功能障碍、减轻肾脏纤维化,其机制可能与通过调控Notch/Snail1信号通路,抑制α-SMA和Jagged1 mRNA及蛋白表达,增强E-cad mRNA及蛋白表达有关。
