REGULATION OF PHOSPHATE TRANSPORT IN THE OSTEOCLAST

破骨细胞中磷酸盐运输的调节

• 批准号: 2769671
• 负责人: ANANDA GUPTA
• 金额: $ 9.39万
• 依托单位: BARNES-JEWISH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2769671
• 关键词: MDCK cell; biological signal transduction; biological transport; chickens; genetic library; homeostasis; immunofluorescence technique; laboratory mouse; laboratory rabbit; membrane transport proteins; microinjections; mixed tissue /cell culture; molecular cloning; nucleic acid hybridization; nucleic acid probes; osteoclasts; osteoporosis; pathologic bone resorption; phosphates; polymerase chain reaction; protein isoforms; transfection; western blottings

DESCRIPTION (Adapted from the Applicant's Abstract): Phosphate (Pi) is the basic anionic component of the mineralized bone matrix, which is primarily hydroxyapatite. During bone resorption, the osteoclast is exposed to high concentrations of Pi released through demineralization of the bone matrix. Therefore, it is conceivable that the osteoclasts possess specific transport mechanisms for Pi uptake into the intracellular free Pi pool. Furthermore, Pi transport may be linked to maintenance of the ATP content of the osteoclast during the cyclical processes of migration, attachment and resorption. In this application, the principal investigator proposes that the activity of a NaPi-cotransporter plays a key role in maintaining substrate levels necessary for the energy requirements of the osteoclast. The applicant has evidence that the Na-dependent Pi cotransporter in the osteoclast localizes within a recycling endosomal pool which rapidly redistributes to the plasma membrane upon contact with bone. The goal of this proposal is to answer several questions which have arisen during the initial characterization of the Na-dependent phosphate (NaPi)-cotransporter in the osteoclast. These include: (1) what is the molecular identify of the NaPi-cotransporter in the osteoclast; (2) what is the nature of the recycling endosomal pool which contains the NaPi cotransporter; 3) what are the signals initiated by the attachment of osteoclasts to bone, leading to stimulation of Pi uptake; and (4) what is the contribution of the Na:Pi-cotransporter to normal osteoclast function. To address these issues, the Specific Aims of this application are: (1) to determine the molecular identify of the NaPi-cotransporter in the osteoclast; the applicant postulates that it is related, but not identical to the renal NaPi-2 isoform (rat, Type II family); (2) to determine the mechanisms of vesicular trafficking of the NaPi-cotransporter in the osteoclast. The applicant will focus on the initial signaling pathways which trigger the stimulatory responses and differential targeting of the NaPi-cotransporter; and (3) to determine the role of the NaPi-cotransporter in normal osteoclast function. The applicant proposes that phosphate transport is a process critical to normal osteoclast function. The efficacy of "knocking out" the function and expression of the NaPi-cotransporter will be assessed, both in vitro and in vivo. It is suggested by the applicant that the NaPi-cotransporter in the osteoclast may provide a potential target for novel therapeutic interventions in the treatment of osteoporosis.

描述（改编自申请人的摘要）：磷酸盐（Pi）是磷酸盐。 矿化骨基质的碱性阴离子成分，主要是 羟基磷灰石 在骨吸收过程中，破骨细胞暴露于高浓度的 通过骨基质脱矿释放的Pi浓度。 因此，可以想象破骨细胞具有特异性转运 Pi摄取到细胞内游离Pi池的机制。 此外，委员会认为， Pi运输可能与维持细胞膜ATP含量有关。 破骨细胞在迁移，附着和 再吸收 在本申请中，主要研究者提出， NaPi协同转运蛋白的活性在维持 破骨细胞能量需求所必需的底物水平。 申请人有证据表明，在细胞中的Na依赖性Pi协同转运蛋白 破骨细胞定位于再循环的内体库中， 在与骨接触时重新分布到质膜。 的目标 这一建议是为了回答在会议期间提出的几个问题。 钠依赖性磷酸盐（NaPi）协同转运蛋白的初步表征 在破骨细胞中。 这些问题包括：（1）什么是 破骨细胞中的NaPi协同转运蛋白;（2）破骨细胞中的NaPi协同转运蛋白的性质是什么？ 再循环内体池含有NaPi协同转运蛋白; 3）什么是 由破骨细胞附着于骨骼而引发的信号，导致 刺激Pi摄取;和（4）什么是贡献的 Na：Pi-协同转运蛋白对正常破骨细胞功能的影响。 为了解决这些问题， 本申请的具体目的是：（1）测定分子量 破骨细胞中NaPi协同转运蛋白的鉴定;申请方 假设它与肾脏NaPi-2亚型相关，但不相同 (rat II型家族）;（2）确定囊泡形成的机制 破骨细胞中NaPi协同转运蛋白的运输。 申请人将 聚焦于触发刺激性信号的初始信号通路， NaPi协同转运蛋白的应答和差异靶向;以及（3） 确定NaPi协同转运蛋白在正常破骨细胞功能中的作用。 申请人提出，磷酸盐转运是一个关键过程， 破骨细胞功能正常。 “敲除”功能的功效和 将在体外和体外评估NaPi-协同转运蛋白的表达。 vivo. 申请人建议，在细胞中的NaPi-共转运蛋白 破骨细胞可能为新的治疗方法提供潜在的靶点， 骨质疏松症的治疗方法