Integrin splicing and cancer stem cell fate

整合素剪接和癌症干细胞命运

• 批准号: 9055381
• 负责人: Arthur M Mercurio
• 金额: $ 38.32万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-28 至 2020-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9055381
• 关键词: Address; Alternative Splicing; Antigen-Antibody Complex; BMI1 gene; Binding; Biology; Breast Carcinoma; Breast Epithelial Cells; Cell Adhesion; Cell membrane; Cells; Complex; Cytoplasmic Tail; Data; Deposition; Development; Event; Feedback; Gap Junctions; Gene Targeting; Genetic Transcription; Growth; Integrin alpha6; Integrin alpha6beta1; Integrins; Laminin; Lead; Ligands; Malignant Epithelial Cell; Mediating; Messenger RNA; Nuclear; Pathway interactions; Phosphorylation; Phosphotransferases; Property; RNA Splicing; Repression; Resistance development; Role; Serine; Signal Repression; Signal Transduction; Stem cells; Testing; Therapeutic; Therapeutic Intervention; Transducers; Tumor Suppressor Proteins; Variant; Vascular Endothelial Growth Factors; Work; adhesion receptor; base; cancer initiation; cancer stem cell; effective therapy; feeding; innovation; kinase inhibitor; malignant breast neoplasm; novel; prevent; public health relevance; stem cell fate; targeted treatment; tumor

 DESCRIPTION (provided by applicant): This proposal will examine the novel hypothesis the genesis and function of breast cancer stem cells (CSCs) are governed by a feed forward loop that sustains activation of the Hippo transducer TAZ. The nexus of this loop is a splice variant of the α6β1 integrin, α6Bβ1. Two variants of the α6 subunit exist (α6A and α6B) that differ onl in their cytoplasmic domains. Alternative splicing of a common mRNA generates these variants. α6Aβ1 integrin signaling prevents TAZ activation. The first aim will pursue the mechanism involved based on the findings that α6Aβ1 interacts with the polarity/tumor suppressor protein Scribble and that Scribble associates with TAZ and prevents its nuclear localization. Thus, the first aim will test the hypothesis that the α6Aβ1 integrin interacts with Scribble on the surfaceof mammary epithelial cells and contributes to its anchoring on the plasma membrane, an interaction mediated by the PDZ-binding domain present in the α6A cytoplasmic domain. It is postulated that the α6A integrin/Scribble complex sequesters TAZ preventing its nuclear localization and activation. The second aim will assess the hypothesis that one mechanism by which TAZ promotes the genesis of CSCs is to repress the mRNA splicing factor ESRP1 resulting in the genesis of α6Bβ1 and loss of α6Aβ1, and the formation of a LM511 matrix. Moreover, it is postulated that TAZ regulates VEGF transcription and induces VEGF signaling, and that VEGF signaling enables the BMI1-mediated repression of ESRP1. TAZ also promotes the formation of a LM511 matrix that functions as the ligand for α6Bβ1. Consequently, a feed forward loop is established involving TAZ and LM511/α6Bβ1 signaling that sustains CSCs. The third specific aim will determine how α6Aβ1 and α6Bβ1 signaling differ in their ability to actiate TAZ focusing on the role of Jun-terminal kinase (JNK). The specific hypothesis to be addressed is that α6Aβ1 signaling promotes JNK activation and JNK-mediated phosphorylation of TAZ on a novel serine (S90), which contributes to TAZ inactivation. LM511/α6Bβ1 signaling, in contrast, prevents JNK activation and JNK-mediated TAZ phosphorylation enabling TAZ activation. This hypothesis infers that JNK inhibition has a causal role in TAZ activation and the acquisition of stem cell properties, which will be evaluated. This proposal is rich in innovation and significance and the results to be obtained will have a major impact on our understanding of the biology of breast CSCs and reveal new mechanisms for therapeutic intervention.

 描述（由申请人提供）：本提案将检查新假设，即乳腺癌干细胞（CSC）的发生和功能由维持Hippo换能器TAZ激活的前馈回路控制。这个环的连接点是一个剪接变体， α6β1整合素，α 6 B β1。α6亚基存在两种变体（α6A和α 6 B），仅胞质结构域不同。共同mRNA的选择性剪接产生这些变体。α 6 A β1整合素信号传导阻止TAZ活化。第一个目标将根据α 6 A β1与极性/肿瘤抑制蛋白Scribble相互作用以及Scribble与TAZ结合并阻止其核定位的发现来探索相关机制。因此，第一个目标将检验以下假设：α6Aβ1整合素与乳腺上皮细胞表面的Scribble相互作用，并有助于其锚定在质膜上，这种相互作用由α6A胞质结构域中存在的PDZ结合结构域介导。据推测，α6A整联蛋白/Scribble复合物螯合TAZ，阻止其核定位和活化。第二个目的是评估TAZ促进CSC发生的一种机制是抑制mRNA剪接因子ESRP 1，导致α 6 B β1的发生和α 6 A β1的丢失，以及LM 511基质的形成。此外，据推测，TAZ调节VEGF转录并诱导VEGF信号传导，并且VEGF信号传导使得BMI 1介导的ESRP 1抑制成为可能。TAZ还促进LM 511基质的形成，该基质作为α 6 B β1的配体发挥作用。因此，建立了一个前馈回路，涉及TAZ和LM 511/α 6 β1信号传导，维持CSC。第三个具体目标是确定α 6 A β1和α 6 B β1信号转导在激活TAZ的能力方面的差异，重点是Jun-terminal kinase（JNK）的作用。要解决的具体假设是，α 6 A β1信号转导促进JNK激活和JNK介导的TAZ在新丝氨酸（S90）上的磷酸化，这有助于TAZ失活。相反，LM 511/α 6 B β1信号传导阻止JNK活化和JNK介导的TAZ磷酸化，从而使TAZ活化。该假设推断JNK抑制在TAZ激活和获得干细胞特性中具有因果作用，将对其进行评价。这一建议富有创新性和意义 并且所获得的结果将对我们理解乳腺CSC的生物学产生重大影响，并揭示治疗干预的新机制。