Cytokine Signaling in Renal Fibrosis

肾纤维化中的细胞因子信号转导

• 批准号: 7393667
• 负责人: Erwin P. Bottinger
• 金额: $ 34.65万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-15 至 2010-03-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7393667
• 关键词: Apoptosis; Characteristics; Chronic; Clinical; Cytokine Signaling; Diabetic mouse; Disease; Doxycycline; Fibrosis; Focal Segmental Glomerulosclerosis; Funding; Grant; Growth; Hepatocyte; In Vitro; Injury; Kidney; Kidney Diseases; Knockout Mice; Lesion; MAP Kinase Gene; MAPK14 gene; Mediating; Modeling; Molecular; Mus; Outcome; Pathway interactions; Phenotype; Physiological; Proteins; Publishing; Regulation; Reporting; Research; Research Personnel; Role; Signal Transduction; Staging; Testing; Therapeutic; To specify; Transforming Growth Factor beta; Transgenic Organisms; Up-Regulation; Work; autocrine; cell type; derepression; glomerulosclerosis; in vitro Model; in vivo Model; interstitial; kidney cell; mouse model; non-diabetic; novel; podocyte; prevent; programs; response

DESCRIPTION (provided by applicant): With funding from this grant, we have achieved several key discoveries in TGF-beta signaling that redirected our research focus from well-documented, glomerular and interstitial fibrosis outcomes in advanced renal disease to novel proapoptotic and growth inhibitory TGF-beta signaling in podocytes. In this revised renewal application, we propose that TGF-beta contributes to podocyte depletion during early stages of glomerular injury. Our new hypothesis states that negative regulation of Gadd45b by Smad2 silences proapoptotic p38 MARK in the context of moderate physiological TGF-0 activity. In contrast, when TGF-(3 activity exceeds a critical threshold, negative regulation of Gadd45b by Smad2 becomes suppressed resulting in derepression of Gadd45b. Gadd45b selectively activates the proapoptotic p38 MARK pathway if its intracellular concentrations exceed a critical signaling threshold. To test this hypothesis, we propose three SPECIFIC AIMS: 1) Determine whether Smad2 functions as negative regulator of proapoptotic Gadd45b and p38/JNK MARK and podocyte apoptosis, and examine whether Smad2 thereby protects against podocyte depletion and glomerulosclerosis. 2) Determine whether Gadd45b mediates activation of proapoptotic p38/JNK MARK signaling and podocyte apoptosis, and examine whether Gadd45b-deficiency prevents podocyte depletion and FSGS in Cd2ap-/- mice. 3) Determine whether an abundance threshold of Gadd45b protein in podocytes is sufficient to specify effective activation of proapoptotic p38/JNK pathways to mediate apoptosis, using doxycycline-inducible tritation of abundance of Gadd45b protein in conditionally-immortalized podocytes. In the long-term, this work will elucidate molecular signaling mechanisms determining specific, contextdependent cellular responses, such as apoptosis and growth arrest, that may be triggered by different concentrations of TGF-beta in different cell types subject to injury in chronic progressive renal disease.

描述(申请人提供)：在这笔赠款的资助下，我们在转化生长因子-β信号方面取得了几项关键发现，将我们的研究重点从有充分记录的晚期肾脏疾病的肾小球和间质纤维化结果转向足细胞中新的促凋亡和生长抑制转化生长因子-β信号。在这项修订的更新应用中，我们认为转化生长因子-β在肾小球损伤的早期阶段有助于足细胞的耗竭。我们的新假设表明，Smad2对Gadd45b的负调控在适度的生理转化生长因子-0活性的背景下沉默了促凋亡的p38标记。相反，当转化生长因子-3活性超过临界阈值时，Smad2对Gadd45b的负调控受到抑制，导致Gadd45b的去抑制。如果Gadd45b的细胞内浓度超过一个关键的信号阈值，它会选择性地激活促凋亡的p38Mark通路。为了验证这一假说，我们提出了三个特定的目标：1)确定Smad2是否作为促凋亡的Gadd45b和p38/JNK Mark和足细胞凋亡的负调节因子，并检测Smad2是否因此保护足细胞枯竭和肾小球硬化。2)确定Gadd45b是否介导促凋亡的p38/JNK标记信号的激活和足细胞的凋亡，并检测Gadd45b缺乏是否能阻止CD2AP-/-小鼠足细胞的耗竭和FSGS。3)通过多西环素诱导条件永生化足细胞中Gadd45b蛋白的丰度滴定，确定足细胞中Gadd45b蛋白的丰度阈值是否足以指定促凋亡p38/JNK通路的有效激活以介导细胞凋亡。 从长远来看，这项工作将阐明决定特定的、上下文相关的细胞反应的分子信号机制，如细胞凋亡和生长停滞，这些反应可能由不同浓度的转化生长因子-β在慢性进行性肾脏疾病中不同类型的细胞损伤中触发。