Annexins and Osteoarthritis

描述(申请人提供)：Annexins成为治疗各种疾病的有吸引力的治疗靶点，包括癌症、心血管疾病和糖尿病，因为它们能够调节与疾病病理有关的重要信号通路的活动。膜联蛋白(ANX)A5和AnxA6在骨关节炎(OA)软骨中高度表达；然而，关于它们在OA病理中的作用尚不清楚。在骨性关节炎中起作用的两个主要信号通路是核因子-κB和WNT/？连环蛋白(WNT)，这促使我们研究AnxA5和AnxA6与这些信号通路之间的潜在相互作用。在关节软骨细胞中，包括白介素1在内的多种细胞因子激活的核因子-κB信号通路是骨性关节炎的主要分解代谢信号通路之一，而Wnt信号通路在人类关节软骨细胞中具有抗分解代谢作用，而在小鼠软骨细胞中具有分解代谢作用。我们的初步研究结果表明，AnxA5和AnxA6在刺激NF-κB信号的同时抑制Wnt信号。此外，我们的研究结果表明，AnxA5通过与半胱氨酸蛋白酶calain的抑制剂calastatin直接相互作用来调节NF-κB和Wnt信号，从而刺激calain的活性。CaPain刺激NF-κB信号，而抑制Wnt信号。另一方面，AnxA6通过直接与NF-κB复合体的p65单位结合来刺激NF-κB信号转导，而通过干扰Wnt信号复合体的膜结合来抑制Wnt信号转导，而Wnt信号转导是Wnt信号激活所必需的。基于这些发现，我们推测，在OA病理过程中，AnxA5和AnxA6通过不同的机制来调节NF-κB和Wnt信号，从而刺激软骨破坏。为了验证我们的假设，我们提出了两个目标。在第一个目标中，我们将确定AnxA5/Calastatin和AnxA6/P65相互作用的性质，以及这些相互作用如何影响NF-κB信号活性。此外，我们将确定AnxA5/calastatin相互作用如何影响Wnt信号，以及AnxA6依赖于钙的质膜结合如何干扰Wnt信号复合体的膜结合，最终干扰Wnt信号活性。此外，我们将在AnxA5和AnxA6单基因和双基因敲除小鼠中，确定AnxA5和AnxA6单独和共同影响衰老、膝关节注射IL-1或手术诱导的骨关节炎过程中的NF-κB和Wnt信号转导。在目标2中，我们将确定膜联蛋白介导的这些信号通路对人关节软骨细胞功能和表型的影响。最后，我们将确定膜联蛋白介导的Wnt信号抑制如何影响OPG在AnxA5和AnxA6单、双基因敲除的关节软骨细胞中的表达，以及AnxA5和AnxA6过表达的软骨细胞，最终在骨关节炎病理中发生破骨细胞生成和软骨下骨的变化。我们期望这项提案的成功完成将为OA病理过程中刺激软骨破坏提供新的机制，并为OA的治疗提供新的治疗靶点。

DESCRIPTION (provided by applicant): Annexins became attractive therapeutic targets for the treatment of various diseases, including cancer, cardiovascular diseases and diabetes, because of their ability to modulate the activities of important signaling pathways involved in disease pathology. Annexin (Anx) A5 and AnxA6 are highly expressed in osteoarthritic (OA) cartilage; however, nothing is known about their role in OA pathology. Two major signaling pathways with roles in OA are NF-κB and the Wnt/ß-catenin (Wnt), encouraging us to examine the potential interaction between AnxA5 and AnxA6 and these signaling pathways. NF-κB signaling pathway, which is being activated in articular chondrocytes by various cytokines, including interleukin (IL)-1, is one of the major catabolic signaling pathways in OA, whereas the Wnt signaling pathway has been recently shown to act anti-catabolically in human articular chondrocytes while acting catabolically in mouse chondrocytes. Our preliminary findings show that AnxA5 and AnxA6 stimulate NF-κB signaling while inhibiting Wnt signaling. In addition, our findings suggest that AnxA5 modulates NF-κB and Wnt signaling via direct interaction with calpastatin, an inhibitor of the cysteine protease calpain, thereby stimulating calpain activity. Calpain stimulates NF-κB signaling, while inhibiting Wnt signaling. AnxA6, on the other hand, stimulates NF-κB signaling via direct binding to the p65 unit of the NF-κB complex, while it inhibits Wnt signaling via interfering with membrane association of the Wnt signaling complex, which is required for Wnt signaling activation. Based on these findings, we hypothesize that AnxA5 and AnxA6 act via different mechanisms, to modulate NF-κB and Wnt signaling to stimulate cartilage destruction during OA pathology. To test our hypothesis, we are proposing two aims. In the first aim we will determine the nature of the AnxA5/calpastatin and AnxA6/p65 interactions, and how these interactions affect NF-κB signaling activity. In addition, we will determine how the AnxA5/calpastatin interaction affect Wnt signaling and how Ca2+-dependent plasma membrane association of AnxA6 interferes with the membrane association of the Wnt signaling complex and ultimately Wnt signaling activity. Furthermore, we will determine how AnxA5 and AnxA6 individually and together affect NF-κB and Wnt signaling during aging, IL-1 injection in the knee joint or surgically induced OA in AnxA5 and AnxA6 single and double knockout mice. In Aim 2, we will determine the effect of annexin-mediated modulation of these signaling pathways on the function and phenotype of human articular chondrocytes. Finally, we will determine how annexin-mediated inhibition of Wnt signaling affects OPG expression in AnxA5 and AnxA6 single and double knockout articular chondrocytes and AnxA5 and AnxA6 overexpressing chondrocytes and ultimately osteoclastogenesis and subchondral bone changes in OA pathology. We expect that the successful completion of this proposal will provide novel mechanisms stimulating cartilage destruction during OA pathology and novel therapeutic targets for the treatment of OA.