BIOLOGICAL EFFECTS OF BASIC CALCIUM PHOSPHATE CRYSTALS

碱式磷酸钙晶体的生物效应

• 批准号: 6603864
• 负责人: HERMAN S CHEUNG
• 金额: $ 24.87万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-30 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6603864
• 关键词: arthritis; biological signal transduction; calcium phosphate; cell membrane; cellular pathology; citrates; connective tissue; enzyme biosynthesis; fibroblasts; genetic regulatory element; metalloendopeptidases; physical chemical interaction; prostaglandin E; tissue /cell culture; tissue inhibitor of metalloproteinases; transcription factor

The US Census Bureau estimated that 35 million American will be 65 years or older by the Year 2000. Osteoarthritis [OA] and pseudogout are the most common afflictions of aging. Crystalline calcium pyrophosphate dihydrate [CPPD] and basic calcium phosphate [BCP] are the 2 most common forms of pathologic articular mineral. Each occurs frequently in OA joints, and each may be phlogistic, causing acute attacks of pseudogout (CPPD) and acute calcific periarthritis (BCP). The incidence of both calcium crystal arthritides significantly increases with age. The overall objective of this proposal is to determine the pathogenesis of the degenerative arthropathies associated with the deposition of CPPD and BCP crystals in articular tissues with the eventual goal of developing a rational means of preventing or reversing the consequences of such deposition. The paradigm of our work is that crystals can cause the degeneration of articular tissues. Crystals induce fibroblast-like synoviocytes to proliferate and produce metalloproteinases [MMP] and prostaglandins [PG], which eventually cause the degeneration of articular tissues. Phosphocitrate, a specific inhibitor of calcium crystals, reverses the degenerative effects of crystals. We are requesting funding to elucidate the mechanism of interaction of crystals and plasma membrane and the subsequent signal pathways leading the activation of various transcription factors and ultimately MMP synthesis and mitogenesis. The overall Hypothesis is that the interaction of crystals with specific components in plasma membrane resulted in MMP expression primarily through a Ras/ERK 1 and 2 Mitogen-activated Protein Kinase (MAPK)/Serum Response Factor (SRF)/c-fos /AP-1 dependent signaling pathway. New treatment strategies that might ameliorate the degenerative process may ensue from new information about how crystals form and how they exert their biologic effects. We shall test 5 inter-related sub-hypothesis: Hypothesis 1: Cell activation by crystals is due to the physical interaction of crystal surface with specific components of the cell membrane e.g. phospholipid. Hypothesis 2: SRF mediates BCP crystal- induced cell activation. Hypothesis 3: BCP crystals induce MMP-1 via a Ras-dependent p42/44 MAPK signal transduction pathway. Hypothesis 4: There are specific cis elements in the promoter of MMP-1 and -13 that regulates crystal-induced MAP synthesis. Hypothesis 5: There are specific cis elements in the promotor of Tissue Inhibitor of Metalloproteinase (TIMP)-2 that regulate crystal inhibition of TIMP- 2 expression.

美国人口普查局估计，到2000年，美国将有3500万人年满65岁。 骨关节炎[OA]和假性痛风是最常见的疾病老化。 结晶焦磷酸钙二水合物（CPPD）和碱性磷酸钙（BCP）是两种最常见的病理性关节矿物质，它们都是OA关节的常见病，都可能引起炎性反应，引起假性痛风（CPPD）和急性钙化性关节周围炎（BCP）。 两种钙结晶性关节炎的发病率均随年龄增长而显著增加。本提案的总体目标是确定与关节组织中CPPD和BCP晶体沉积相关的退行性关节病的发病机制，最终目标是开发预防或逆转此类沉积后果的合理方法。 我们工作的范例是，晶体可以导致关节组织的退化。 晶体诱导成纤维细胞样滑膜细胞增殖并产生金属蛋白酶（MMP）和胰蛋白酶（PG），最终导致关节组织的退变。 磷酸柠檬酸盐是钙晶体的特异性抑制剂，可逆转晶体的退行性作用。我们正在申请资金，以阐明晶体和质膜的相互作用机制，以及随后导致各种转录因子活化并最终导致MMP合成和有丝分裂的信号通路。 总的假设是晶体与质膜中特定组分的相互作用主要通过Ras/ERK 1和2丝裂原活化蛋白激酶（MAPK）/血清反应因子（SRF）/c-fos /AP-1依赖的信号通路导致MMP表达。 可能改善退行性过程的新治疗策略可能会从晶体如何形成以及它们如何发挥生物学作用的新信息中产生。我们将测试5个相互关联的子假设：假设1：晶体激活细胞是由于晶体表面与细胞膜的特定组分（如磷脂）的物理相互作用。 假说2：SRF介导BCP晶体诱导的细胞活化. 假设3：BCP晶体通过Ras依赖性p42/44 MAPK信号转导途径诱导MMP-1。假设4：在MMP-1和-13的启动子中存在特异性顺式元件，其调节晶体诱导的MAP合成。假设五：金属蛋白酶组织抑制剂（TIMP-2）启动子中存在特异性顺式元件，调控TIMP- 2表达的晶体抑制。