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

• 批准号: 7658637
• 负责人: KIRILL KISELYOV
• 金额: $ 22.11万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7658637
• 关键词: Affect; Aging; Air; Apoptotic; Autophagocytosis; Biological; Brain; Buffers; Cell Death; Cells; Complement; Cytoplasm; Data; Down-Regulation; Event; Food; Functional disorder; Ganglioside Sialidase Deficiency Disease; Housekeeping; Ion Channel; Kidney; Link; Liver; Lysosomal Storage Diseases; Lysosomes; Metals; Mitochondria; Modeling; Mutation; Organism; Outcome; Oxidative Stress; Phenotype; Play; Process; Publishing; Relative (related person); Resistance; Role; Structure; Testing; Tissues; Toxic effect; Transition Elements; Water Pollution; aged; antigen processing; metal poisoning; mutant; novel; public health relevance; research study; toxic metal; uptake

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）：过渡金属如Cu、Fe、Co具有众所周知的毒性作用。大部分的过渡金属摄取通过溶酶体发生，并且在超负荷模型中显示了过渡金属在溶酶体中的积累。过渡金属对溶酶体消化机制的影响尚未完全确定。该项目获得的初步数据表明，过渡金属阻断离子通道粘磷脂1（TRPML 1）。TRPML 1以前被鉴定为溶酶体离子通道突变，其中导致溶酶体贮积病IV型粘脂沉积症（MLIV）。与MLIV中TRPML 1下调的作用类似，过渡金属对TRPML 1的阻断与细胞质储存体的形成、线粒体碎片化和线粒体对Ca 2+缓冲的丧失有关。通过与溶酶体贮积病中衰老和细胞死亡的溶酶体-线粒体轴模型类比，这些数据表明过渡金属对TRPML 1的阻断影响溶酶体功能，因此影响自噬。抑制的自噬导致功能障碍的线粒体的积累，其不能摄取细胞质Ca 2+并保护细胞免受Ca 2+尖峰的促凋亡作用。该建议的中心前提是：如果TRPML 1阻断有助于过渡金属毒性，那么阻断TRPML 1的所有过渡金属都应诱导相同的MLIV样表型。将使用几种方法测试溶酶体对过渡金属毒性的贡献的这种新模型。首先，将建立阻断TRPML 1的过渡金属的范围，以将金属对TRPML 1的阻断与由这种阻断诱导的溶酶体储存表型相关联。是否所有阻断TRPML 1的过渡金属都诱导自噬抑制和线粒体的积累，这些线粒体在其Ca 2+缓冲功能方面受到损害，将被确定。将建立过渡金属阻断TRPML 1的结构决定簇，并产生过渡金属抗性突变体。这些突变体将用于替代天然TRPML 1，并确定TRPML 1阻断对过渡金属溶酶体毒性的相对贡献。在本项目过程中获得的结果预计将确定过渡金属的溶酶体积聚和细胞死亡之间的新联系，并可能为过渡金属毒性的新药理学方法提供理论基础。该项目的基本生物学意义包括更好地理解有毒金属的影响，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：本项目的目的是回答溶酶体离子通道TRPML 1的阻断是否有助于过渡金属毒性。描述连接过渡金属的溶酶体蓄积与细胞死亡的事件链，将为过渡金属毒性的溶酶体方面的详细调查铺平道路，并可能提出新的药理学方法来补充现有的金属毒性治疗方法。由于溶酶体参与生物体水平的功能，如抗原加工，证明过渡金属影响溶酶体功能可能具有更广泛的生物学影响。