P53 and cell cycle checkpoint by p38 MAP kinase

p53 和 p38 MAP 激酶的细胞周期检查点

• 批准号: 6986142
• 负责人: Mercedes Rincon
• 金额: $ 36.98万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-15 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6986142
• 关键词: P53; cell; cycle; checkpoint; p38

DESCRIPTION (provided by the applicant): Early thymocyte development (prior to the CD4+CD8 + stage) is critical for the generation of T cells. Genetic alterations that cause several human immunodeficiencies have been mapped in genes that play a key role in these early stages of thymocyte development. Several important processes occur during the differentiation of immatureCD25¿CD44 - thymocytes into CD25-CD44- thymocytes, such as V(D)J recombination, expression of the T cell receptor (TcR) and expression of the pre-TcR complex. In addition to pre-TcR-mediated signals, inactivation of p53 appears to be required for differentiation of CD25+CD44 thymocytes. We have demonstrated that activation of p38 MAP kinase arrests cell cycle progression and differentiation ofCD25+CD44- thymocytes. Moreover, we have also shown that p38 MAP kinase induces an accumulation of p53 in these thymocytes. It has been shown that p38 MAP kinase activates p53 in response to DNA damage to induce a cell cycle checkpoint for repair of mutations. We propose that the activation of p38 MAP kinase by IL-7 in CD25+CD44 -thymocytes phosphorylates and activates p53 to promote a G2/M checkpoint, a/lowing the repair of deleterious mutations that could be caused by V(D)J rearrangement. Later, the expression of pre-TcR on CD25+CD44 - thymocytes triggers signals that inactivate p38 MAP kinase and, thereby, p53 to allow cell cycle progression and further differentiation. To test this hypothesis we propose to demonstrate that:- p38 MAP kinase activates p53 at the CD25 +CD44- stage to induce a cell cycle checkpoint. We will examine: a) p53 phosphorylation and expression of 14-3-3 sigma (a p53 target at the G2/M checkpoint) in thymocytes arrested at theCD25+CD44 - stage by activation of p38 MP kinase in vivo, and b) the effect of p53 inactivation in cell cycle progression and differentiation of these cells.- pre-TcR signals inactivate p38 MAP kinase and p53 to end the cell cycle checkpoint and allow differentiation of CD25+CD44 - thymocytes. We will examine p38 MAP kinase and p53 activity in CD25+CD44 - thymocytes in the presence or absence of pre-TcR or pre-TcR-signals.- IL-7 activates p38 MAP kinase and, thereby, p53 in CD25+CD44 thymocytes to induce a cell cycle checkpoint.- pre-TcR provides survival signals during the cell cycle checkpoint of CD25+CD44 - thymocytes to prevent death of these cells while DNA repairs takes place.

描述（由申请方提供）：早期胸腺细胞发育（在CD 4 + CD 8+阶段之前）对于T细胞的生成至关重要。导致几种人类免疫缺陷的遗传改变已经在胸腺细胞发育的早期阶段发挥关键作用的基因中被定位。在未成熟的CD 25 → CD 44-胸腺细胞分化为CD 25-CD 44-胸腺细胞的过程中，发生了几个重要的过程，如V（D）J重组、T细胞受体（TcR）的表达和前TcR复合物的表达。除了前TcR介导的信号外，p53的失活似乎是CD 25 + CD 44胸腺细胞分化所需的。我们已经证明p38 MAP激酶的激活可以阻止CD 25 + CD 44-胸腺细胞的细胞周期进程和分化。此外，我们还表明，p38 MAP激酶诱导p53在这些胸腺细胞的积累。研究表明，p38 MAP激酶激活p53以响应DNA损伤，从而诱导细胞周期检查点以修复突变。我们认为，在CD 25 + CD 44-胸腺细胞中，IL-7激活p38 MAP激酶磷酸化并激活p53，以促进G2/M检查点，降低可能由V（D）J重排引起的有害突变的修复。随后，前TcR在CD 25 + CD 44-胸腺细胞上的表达触发信号，使p38 MAP激酶活化，从而使p53活化，以允许细胞周期进展和进一步分化。为了验证这一假设，我们建议证明：- p38 MAP激酶激活p53在CD 25 + CD 44-阶段诱导细胞周期检查点。我们将研究：a）在体内通过激活p38 MP激酶而停滞在CD 25 + CD 44-期的胸腺细胞中p53磷酸化和14-3-3 σ（G2/M检查点处的p53靶点）的表达，和B）p53失活在这些细胞的细胞周期进展和分化中的作用。pre-TcR信号转导p38 MAP激酶和p53以结束细胞周期检查点并允许CD 25 + CD 44-胸腺细胞的分化。我们将在存在或不存在前TcR或前TcR信号的情况下，检测CD 25 + CD 44-胸腺细胞中的p38 MAP激酶和p53活性。IL-7激活p38 MAP激酶，从而激活CD 25 + CD 44胸腺细胞中的p53，以诱导细胞周期检查点。pre-TcR在CD 25 + CD 44-胸腺细胞的细胞周期检查点期间提供存活信号，以防止这些细胞在DNA修复发生时死亡。