Molecular Roles of Cdk5 in Neuronal Functions and Pain Signaling

Cdk5 在神经元功能和疼痛信号传导中的分子作用

• 批准号: 8553333
• 负责人: Ashok Kulkarni
• 金额: $ 87.25万
• 依托单位: NATIONAL INSTITUTE OF DENTAL & CRANIOFACIAL RESEARCH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8553333
• 关键词: Adult; Affect; Age; Agonist; Alzheimer' s Disease; Astrocytes; Attenuated; Behavioral; Brain; Calcium; Capsaicin; Carrageenan; Cells; Cyclin-Dependent Kinase 5; Deposition; Development; Disease; Extracellular Matrix; Future; Genes; Growth; Heart; Infiltration; Inflammation; Inflammatory Response; Injection of therapeutic agent; Injury; Lead; Lung; Lymphocyte; Mediating; Messenger RNA; Molecular; Mus; Nerve Tissue; Nervous system structure; Neuraxis; Neuroblastoma; Neurons; Nociception; Oral; Organ; Pain; Pathology; Pathway interactions; Peripheral; Phenotype; Phosphorylation; Phosphotransferases; Play; Proline; Protein-Serine-Threonine Kinases; Proteins; Rattus; Reporting; Role; Salivary Glands; Signal Transduction; Spinal Cord; Spinal Ganglia; TGF Beta Signaling Pathway; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Vanilloid; Wasting Syndrome; Work; craniofacial; enzyme activity; human TGFB1 protein; human TNF protein; inflammatory neuropathic pain; inhibitor/antagonist; macrophage; nervous system disorder; novel; receptor; response

Cdk5 regulates pain signaling: We have recently reported a novel role of Cdk5 in pain signaling. We previously reported that expression of Cdk5 and p35, as well as Cdk5 kinase activity, was increased in the dorsal root ganglia (DRG) and the spinal cord (SC) after peripheral inflammation. Inflammation induced by carrageenan injection in the hind paws of mice increased the mRNA and protein levels of Cdk5/p35 in nociceptive neurons, with a subsequent increase in Cdk5 kinase activity. Furthermore, we identified that the elevated Cdk5 activity phosphorylates transient receptor potential vanilloid 1 (TRPV1), a key receptor that modulates agonist-induced calcium influx in neurons. Additionally, we found that inflammation triggers an increase in Cdk5 activity through activation of early growth response 1 (Egr-1) and p35 expression by TNF-alpha. These findings suggest that Cdk5 plays an important role in the molecular mechanisms involved in pain signaling. Crosstalk between Cdk5 and TGF-beta pathways affects nociceptive signaling: Our earlier studies on the characterization of the TGF-beta1-/- mouse phenotype confirmed TGF-beta1 as a key regulator of inflammation. TGF-beta1-/- mice develop a rapid wasting syndrome and die by 3-4 weeks of age. These mice display an excessive inflammatory response with massive infiltration of lymphocytes and macrophages into many organs, principally the heart, lungs, and salivary glands. TGF-beta1 is normally present at low levels in healthy adult CNS cells, but its level is rapidly up-regulated following injury and induces expression of several injury-related genes. TGF-beta1 is also known to promote the survival of neurons, although the mechanism is still not clear. TGF-beta1 has also been implicated in the pathology of Alzheimer's disease. TGF-beta1 over-expression in astrocytes can lead to excessive deposition of extracellular matrix components in the brain, resulting in neurological disease. Recent reports indicate that TGF-beta1 may participate in neuropathic and inflammatory pain; however, the molecular mechanisms underlying its involvement in pain signaling are still far from clear. Therefore, the main objective of our study was to explore possible crosstalk between Cdk5 and TGF-beta signaling pathways, and the influence of this crosstalk on inflammation-induced pain. Our studies revealed that the protein levels of Cdk5, p35, and p39 are reduced in the nervous tissues of TGF-beta1-/- mice, resulting in decreased Cdk5 activity. Moreover, TGF-beta1-/- mice showed decreased Cdk5-mediated phosphorylation of TRPV1 in the TG and DRG, with concomitant attenuated behavioral responses to noxious thermal stimulation. This was associated with decreased activity of PKC-delta, a known regulator of p35. Most importantly, we found that TGF-betaR1f/f; SNS-Cre mice also displayed decreased Cdk5 expression in DRGs along with hypoalgesia. In addition, TGF-beta1 treatment of rat neuroblastoma B104 cells increased Cdk5 activity, whereas treatment with SB-431542, an inhibitor of TGF-beta1 signaling, decreased Cdk5 activity. Treatment with TGF-beta1 potentiated capsaicin-induced Ca+2 influx in DRG primary cultures. These findings indicate that active crosstalk between TGF-beta and Cdk5 pathways regulate inflammation-induced pain signaling.

Cdk5 调节疼痛信号： 我们最近报道了 Cdk5 在疼痛信号传导中的新作用。我们之前报道，外周炎症后背根神经节（DRG）和脊髓（SC）中 Cdk5 和 p35 的表达以及 Cdk5 激酶活性增加。在小鼠后爪注射角叉菜胶诱导的炎症增加了伤害感受神经元中 Cdk5/p35 的 mRNA 和蛋白质水平，随后 Cdk5 激酶活性增加。此外，我们还发现，升高的 Cdk5 活性会磷酸化瞬时受体电位香草酸 1 (TRPV1)，TRPV1 是调节神经元中激动剂诱导的钙流入的关键受体。此外，我们发现炎症通过 TNF-α 激活早期生长反应 1 (Egr-1) 和 p35 表达，引发 Cdk5 活性增加。这些发现表明 Cdk5 在涉及疼痛信号传导的分子机制中发挥着重要作用。 Cdk5 和 TGF-β 通路之间的串扰影响伤害感受信号传导： 我们早期对 TGF-β1-/- 小鼠表型特征的研究证实 TGF-β1 是炎症的关键调节因子。 TGF-β1-/- 小鼠会出现快速消耗综合征，并在 3-4 周龄时死亡。这些小鼠表现出过度的炎症反应，淋巴细胞和巨噬细胞大量浸润到许多器官，主要是心脏、肺和唾液腺。 TGF-β1 通常在健康成人中枢神经系统细胞中水平较低，但其水平在损伤后迅速上调，并诱导多种损伤相关基因的表达。 TGF-β1 也被认为可以促进神经元的存活，尽管其机制仍不清楚。 TGF-β1 也与阿尔茨海默病的病理有关。星形胶质细胞中TGF-β1过度表达可导致细胞外基质成分在大脑中过度沉积，从而导致神经系统疾病。最近的报告表明，TGF-β1 可能参与神经性疼痛和炎性疼痛；然而，其参与疼痛信号传导的分子机制仍远未明确。因此，我们研究的主要目的是探索 Cdk5 和 TGF-β 信号通路之间可能的串扰，以及这种串扰对炎症引起的疼痛的影响。 我们的研究表明，TGF-β1-/-小鼠神经组织中Cdk5、p35和p39的蛋白水平降低，导致Cdk5活性降低。此外，TGF-β1-/-小鼠在TG和DRG中表现出Cdk5介导的TRPV1磷酸化减少，同时对有害热刺激的行为反应减弱。这与 PKC-delta（一种已知的 p35 调节因子）活性降低有关。最重要的是，我们发现 TGF-betaR1f/f； SNS-Cre 小鼠还表现出 DRG 中 Cdk5 表达降低以及痛觉减退。此外，用TGF-β1处理大鼠神经母细胞瘤B104细胞会增加Cdk5活性，而用TGF-β1信号抑制剂SB-431542处理会降低Cdk5活性。在 DRG 原代培养物中，用 TGF-β1 处理可增强辣椒素诱导的 Ca+2 流入。这些发现表明 TGF-β 和 Cdk5 通路之间的主动串扰调节炎症诱导的疼痛信号传导。