The Role of Mucolipin 1 Block in Transition Metal Toxicity

Mucolipin 1 嵌段在过渡金属毒性中的作用

基本信息

批准号：
7816743
负责人：
KIRILL KISELYOV
金额：
$ 18.12万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-05-01 至 2012-04-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Transition metals such as Cu, Fe, Co have well known toxic effects. A large fraction of the transition metal uptake occurs through lysosomes and accumulation of transition metals in lysosomes was shown in the overload models. The effects of transition metals on lysosomal digestive machinery are not very well established. The preliminary data obtained for this project show that transition metals block ion channel mucolipin 1 (TRPML1). TRPML1 was previously identified as the lysosomal ion channel mutations in which cause lysosomal storage disease mucolipidosis type IV (MLIV). Similar to the effects of TRPML1 downregulation in MLIV, TRPML1 block by transition metals is associated with formation of cytoplasmic storage bodies, mitochondrial fragmentation and the loss of Ca2+ buffering by mitochondria. By analogy with the lysosome-mitochondria axis model of aging and cell death in lysosomal storage diseases, these data suggest that TRPML1 block by transition metals affects lysosomal function and, therefore autophagy. Suppressed autophagy results in accumulation of dysfunctional mitochondria that cannot take up cytoplasmic Ca2+ and guard cells against pro-apoptotic effects of Ca2+ spikes. The central premise of this proposal is: if TRPML1 block contributes to transition metals toxicity, then all transition metals that block TRPML1 should induce the same MLIV-like phenotype. This novel model of the lysosomal contribution to transition metal toxicity will be tested using several approaches. First, the range of transition metals that block TRPML1 will be established in order to correlate TRPML1 block by metals and lysosomal storage phenotype induced by such block. Whether or not all transition metals that block TRPML1 induce autophagy suppression and accumulation of mitochondria that are compromised in their Ca2+ buffering function will be established. Structural determinants of TRPML1 block by transition metals will be established and transition metal resistant mutants will be created. Such mutants will be used to replace native TRPML1 and establish the relative contribution of TRPML1 block into lysosomal toxicity of transition metals. The results obtained in the course of this project are expected to identify a novel link between lysosomal buildup of transition metals and cell death and may provide a rationale for novel pharmacological approaches to transition metals toxicity. The basic biological implications of this project include better understanding of the effect of toxic metals, structure and function of ion channels and housekeeping role of lysosomes. PUBLIC HEALTH RELEVANCE: The present project aims to answer whether the block of the lysosomal ion channel TRPML1 contributes to transition metal toxicity. Delineating the chain of events that connects lysosomal accumulation of transition metals to cell death will pave way for a detailed inquiry into lysosomal aspects of transition metal toxicity and may suggest novel pharmacological approaches to complement the existing treatments for metal toxicity. Since lysosomes are involved in the organism-level functions such as antigen processing, proving that transition metals affect lysosomal function may have even broader biological impact.

描述（由申请人提供）：Cu，Fe，Co等过渡金属具有众所周知的毒性作用。过渡金属通过溶酶体发生很大一部分，并且在过载模型中显示了溶酶体中过渡金属的积累。过渡金属对溶酶体消化机械的影响不是很好。该项目获得的初步数据表明，过渡金属阻断离子通道粘液蛋白1（TRPML1）。先前将TRPML1鉴定为溶酶体离子通道突变，其中引起溶酶体储存疾病粘脂脂异常IV型（MLIV）。与MLIV中TRPML1下调的影响相似，TRPML1通过过渡金属块与细胞质储存体的形成，线粒体碎片和线粒体的Ca2+缓冲损失有关。通过类似于溶酶体储存疾病中溶酶体 - 单向体轴模型，这些数据表明，过渡金属的TRPML1阻断会影响溶酶体功能，因此会影响自噬。抑制自噬会导致无法占用细胞质Ca2+的线粒体功能失调的积累，并防止守卫细胞抵抗Ca2+尖峰的凋亡作用。该提案的中心前提是：如果TRPML1块有助于过渡金属毒性，则所有阻断TRPML1的过渡金属都应诱导相同的MLIV样表型。这种对过渡金属毒性贡献的新型模型将使用多种方法进行测试。首先，将建立块TRPML1的过渡金属范围，以通过金属和该块诱导的溶酶体存储表型将TRPML1块相关联。是否所有阻断TRPML1的过渡金属都会诱导自噬抑制和在其Ca2+缓冲函数中受损的线粒体的积累。将通过过渡金属建立TRPML1块的结构决定因素，并将创建过渡金属抗性突变体。此类突变体将用于替代天然TRPML1并建立TRPML1块对过渡金属溶酶体毒性的相对贡献。预计在该项目过程中获得的结果有望确定过渡金属和细胞死亡之间的溶酶体积累之间的新联系，并可能为新型的过渡金属毒性的药理方法提供理由。该项目的基本生物学含义包括更好地了解有毒金属的影响，离子通道的结构和功能以及溶酶体的管家作用。公共卫生相关性：本项目旨在回答溶酶体离子通道TRPML1的块是否有助于过渡金属毒性。描述将过渡金属与细胞死亡的溶酶体积累联系起来的事件链将铺平方法，以详细探究过渡金属毒性的溶酶体方面，并可能提出新型的药理方法来补充现有的金属毒性治疗方法。由于溶酶体参与了诸如抗原加工之类的生物水平功能，因此证明过渡金属影响溶酶体功能可能会产生更广泛的生物学影响。