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Calcium and lipid signalling in Drosophila photoreceptors

果蝇光感受器中的钙和脂质信号传导

基本信息

批准号：
BB/D007585/1
负责人：
Roger Hardie
金额：
$ 49.09万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FD007585%2F1
关键词：
Calcium lipid signalling Drosophila photoreceptors

项目摘要

Photoreceptors in the eye respond to light by converting it into electrical signals. This process of 'phototransduction' involves a sequence of biochemical steps, ending with the opening of specialised proteins known as 'ion channels', embedded in the membrane surrounding the cell. Once opened, ion channels allow charged ions, such as sodium and calcium, into the cell, thereby generating electrical signals that are transmitted along nerves to the brain. This process can be particularly well studied in the fruitfly Drosophila for several reasons. Firstly, we now know the entire genetic code of the fruitfly, and can manipulate its genes so that individual genes (and hence proteins) can be altered, deleted or introduced into the fly. Secondly, we can isolate fly photoreceptors and record their electrical signals with extreme precision using a technique known as 'patch clamp'. The biochemical events responsible for vision in the fly are essentially the same as in a widespread transduction cascade found throughout the body. This cascade is characterised by an enzyme (phospholipase C) that splits a specific chemical in the membrane into two small '2nd messenger' molecules. This results in the opening of specific ion channels known as TRP channels. An important feature of TRP channels is that they allow calcium ions (Ca2+) to enter the cell. Ca2+ itself is also an important 2nd messenger in cells - e.g. in photoreceptors it adjusts sensitivity according to light levels, allowing us to see both at night and during the day - a process known as adaptation. In fly eyes, TRP channels generate the electrical signals responsible for vision and the Ca2+ influx required for adaptation. TRP channels were in fact first discovered, because mutant flies without these channels were blind. Because most genes in vertebrates are similar to those in flies, this led to the discovery of similar channels in humans, found in virtually every tissue of the body. They are important in a wide range of processes including hormonal responses, regulation of blood pressure, cancer, taste and hearing, pain and sensations of hot and cold. Because these channels have only been recently discovered, exactly how they function and how their activity is regulated is still not well known. However, it is central to understanding of all these different processes, and not only scientists, but also many drug companies are interested in finding out as much as possible about them. In our research, we measure the activity of these channels with 'patch clamp' recordings from fly photoreceptors, often using genetically engineered flies with alterations to the channels themselves or components (enzymes, etc) suspected of being important for their function. Our study has several aims: which include. 1) Use genetic engineering to work out the molecular structure of the 'pore' of the channel and to find out what makes it permeable to Ca2+ 2) Directly measure the amount of Ca2+ that the channel allows into the cell and then generate flies in which this is altered by rearranging the molecular structure of the pore, to test the importance of Ca2+ , e.g. for adaptation. 3) Study how Ca2+ controls other components of the cascade by specifically altering individual proteins so that Ca2+ can no longer affect them. 4) Identify the small 2nd messenger molecules that regulate the channels; different enzymes are responsible for generating different messenger substances, and we will generate mutant flies defective in candidate enzymes to test which is important. The knowledge we gain from these studies will not only give us a detailed molecular understanding of how photoreceptors see, but because the basic underlying biochemical mechanisms are so widely found, will provide new insight into many other, often clinically important processes in the body.

眼睛中的感光器通过将光转换成电信号来响应光。这一“光转导”过程涉及一系列生化步骤，最终以嵌入细胞周围膜中的称为“离子通道”的特殊蛋白质打开为结束。一旦打开，离子通道就会允许带电离子（例如钠和钙）进入细胞，从而产生沿着神经传输到大脑的电信号。由于多种原因，这个过程可以在果蝇中得到特别好的研究。首先，我们现在知道果蝇的整个遗传密码，并且可以操纵其基因，以便可以改变、删除或将单个基因（以及蛋白质）引入果蝇中。其次，我们可以分离苍蝇的光感受器，并使用一种称为“膜片钳”的技术极其精确地记录它们的电信号。果蝇中负责视觉的生化事件本质上与遍布全身的广泛转导级联相同。该级联的特征是一种酶（磷脂酶 C）将膜中的特定化学物质分解成两个小的“第二信使”分子。这会导致特定离子通道（称为 TRP 通道）的打开。 TRP 通道的一个重要特征是它们允许钙离子 (Ca2+) 进入细胞。 Ca2+ 本身也是细胞中重要的第二信使 - 例如在光感受器中，它根据光线水平调整敏感度，使我们能够在夜间和白天看到东西——这一过程称为适应。在果蝇眼睛中，TRP 通道产生负责视觉的电信号和适应所需的 Ca2+ 流入。事实上，TRP 通道是最先被发现的，因为没有这些通道的突变果蝇是失明的。由于脊椎动物的大多数基因与果蝇的基因相似，这导致在人类中发现了类似的通道，几乎在身体的每个组织中都发现了这种通道。它们在许多过程中都很重要，包括荷尔蒙反应、血压调节、癌症、味觉和听力、疼痛和冷热感觉。由于这些通道最近才被发现，因此它们的具体功能及其活动如何受到调节仍不清楚。然而，它对于理解所有这些不同的过程至关重要，不仅科学家，而且许多制药公司都有兴趣尽可能多地了解它们。在我们的研究中，我们通过果蝇光感受器的“膜片钳”记录来测量这些通道的活性，通常使用基因工程果蝇，对通道本身或怀疑对其功能很重要的成分（酶等）进行改变。我们的研究有几个目标：其中包括。 1) 使用基因工程计算出通道“孔”的分子结构，并找出使 Ca2+ 渗透的因素 2) 直接测量通道允许进入细胞的 Ca2+ 量，然后生成果蝇，通过重新排列孔的分子结构来改变果蝇的量，以测试 Ca2+ 的重要性，例如为了适应。 3) 研究Ca2+如何通过特异性改变单个蛋白质来控制级联的其他成分，使Ca2+不再影响它们。 4) 识别调节通道的第二信使小分子；不同的酶负责产生不同的信使物质，我们将产生候选酶有缺陷的突变果蝇来测试哪个是重要的。我们从这些研究中获得的知识不仅能让我们对光感受器如何观察有一个详细的分子理解，而且由于基本的生化机制被广泛发现，将为我们体内许多其他通常具有临床意义的过程提供新的见解。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Electrophysiological Method for Whole-cell Voltage Clamp Recordings from $\textit{Drosophila}$ Photoreceptors

$ extit{果蝇}$光感受器全细胞电压钳记录的电生理学方法

DOI：
10.17863/cam.10824
发表时间：
2017
期刊：
影响因子：
0
作者：
Katz B
通讯作者：
Katz B

Ca2+-dependent metarhodopsin inactivation mediated by calmodulin and NINAC myosin III.

Ca2+依赖性的元视丁蛋白失活由钙调蛋白和尼纳克肌球蛋白III介导。

DOI：
10.1016/j.neuron.2008.07.007
发表时间：
2008-09-11
期刊：
NEURON
影响因子：
16.2
作者：
Liu, Che-Hsiung;Satoh, Akiko K.;Postma, Marten;Huang, Jiehong;Ready, Donald F.;Hardie, Roger C.
通讯作者：
Hardie, Roger C.

Phototransduction and the evolution of photoreceptors.