Discovery and function of ion channels in liver epithelia.

肝上皮离子通道的发现和功能。

• 批准号: 153111-2012
• 负责人: Hill, Ceredwyn
• 金额: $ 1.89万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=522522
• 关键词: Discovery; function; ion; channels; liver

My research program is focused on the identification and roles of ion channels in the physiology of the liver. Our current focus is on a Transient Receptor Potential Melastatin (TRPM) channel, isoform 7. TRPM7, a ubiquitously expressed channel-kinase, is associated with survival of many proliferating cells; knock-out is embryonic lethal. Recent studies support a significant role for TRPM7 in organogenesis. We showed that TRPM7 channel activity is significantly higher in dividing liver cells than in terminally differentiated, non-dividing adult hepatocytes. Channel block caused higher death rates in dividing as compared with adult cells, implying a fundamental role for Mg2+ influx in supporting liver cell proliferation. We also localized TRPM7 to the nuclear envelope in all liver cells in addition to the established cytosolic, punctate expression seen in other cells. TRPM7 expression was higher in the nuclear envelope of non-dividing adult hepatocytes as compared with dividing cells. Differentiating conditions reduced channel activity and increased nuclear envelope TRPM7 in dividing cells. During mitosis TRPM7 associates with the mitotic spindle. Thus TRPM7 channel activity seems to be important in embryonic hepatocyte expansion and hepatoma cell survival, whereas nuclear envelope accumulation is associated with terminal differentiation. Over the next five years we will define how TRPM7 supports embryonic hepatocyte expansion and de-differentiated growth, and terminal differentiation. A spectrum of rat hepatocytes from dividing embryonic and hepatoma cells to non-dividing adult cells will be used. These cells provide unique opportunities to study TRPM 7 expression and function in dividing and non-dividing cells from the same tissue and species and to study its role in liver development. Gene disruption and over-expression techniques and channel mutant constructs will be used to complement electrophysiological and molecular approaches to identify the molecular events linking TRPM7 expression, localization and activity to embryonic expansion, unregulated proliferation and terminal differentiation. Four aims are described providing the basis for 5-6 graduate theses and numerous undergraduate projects.

我的研究项目集中在肝脏生理学中离子通道的识别和作用。我们目前的重点是短暂受体电位美拉他汀（TRPM）通道，异构体7。TRPM7是一种普遍表达的通道激酶，与许多增殖细胞的存活有关；基因敲除是胚胎致命的。最近的研究支持TRPM7在器官发生中的重要作用。我们发现TRPM7通道活性在分裂的肝细胞中明显高于在终末分化的非分裂的成人肝细胞中。与成体细胞相比，通道阻断导致的分裂死亡率更高，这意味着Mg2+内流在支持肝细胞增殖方面发挥了重要作用。我们还将TRPM7定位在所有肝细胞的核膜上，除了在其他细胞中发现的细胞质点状表达外。TRPM7在未分裂成肝细胞核膜中的表达高于分裂成肝细胞。分化条件降低了分裂细胞的通道活性，增加了核膜TRPM7。在有丝分裂过程中，TRPM7与有丝分裂纺锤体结合。因此，TRPM7通道活性似乎在胚胎肝细胞扩增和肝癌细胞存活中很重要，而核膜积累与终末分化有关。在接下来的五年里，我们将确定TRPM7如何支持胚胎肝细胞扩增、去分化生长和终末分化。将使用从分裂的胚胎细胞和肝癌细胞到未分裂的成年细胞的大鼠肝细胞谱。这些细胞为研究TRPM 7在同一组织和物种的分裂和非分裂细胞中的表达和功能以及研究其在肝脏发育中的作用提供了独特的机会。基因破坏和过表达技术以及通道突变体构建将用于补充电生理学和分子方法，以确定将TRPM7的表达、定位和活性与胚胎扩张、不调节增殖和终末分化联系起来的分子事件。描述了四个目标，为5-6篇研究生论文和众多本科项目提供了基础。