The role of PDZ scaffold CASK and CaMKII signaling in synaptic plasticity and learning

PDZ支架CASK和CaMKII信号在突触可塑性和学习中的作用

• 批准号: BB/G008973/1
• 负责人: James Hodge
• 金额: $ 55.15万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FG008973%2F1
• 关键词: role; PDZ; scaffold; CASK; CaMKII

The aim of this proposal is to better understand the molecular mechanisms by which memories are formed in the brain. Research into memory is particularly important as it gives us our sense of identity. Deficits in learning and memory occur in many diseases, injuries and during aging. Identifying the key molecules involved in these processes, will help reveal targets for new therapeutic interventions to reverse the devastating consequences of memory loss, this research is particularly important for our aging population. The brain consists of many cells or neurons that communicate via connections called synapses. Information flows through neurons via small electrical impulses, a bit like a computer. At most synapses these electrical impulses cause release of chemicals that bind to the output neuron causing it to become more excitable and propagate the electrical impulse to the next neuron in the circuit. The brain also stores information during learning and retrieves it as memory. There are special parts of the brain for learning e.g. the hippocampus. When an animal experiences learning stimuli there is a persistent increase in synaptic transmission between hippocampal neurons called Long Term Potentiation (LTP), this increase continues after the original stimulus is removed and is a synaptic mechanism for learning. These long-term changes in synaptic activity can cause increases in synaptic growth and connections between neurons, a process called synaptic plasticity that is thought to be a synaptic mechanism of memory. LTP and learning is initiated by calcium (Ca2+) entering the neuron and activating an enzyme called Ca2+ responsive kinase (CaMKII). CaMKII is abundant in the brain, constituting 1-2% of its total protein and is one of the main synaptic proteins. Once activated by increased Ca2+, CaMKII is able to cause a switch in its own activity so that it remains active even after Ca2+ has gone down. This special ability of CaMKII to maintain its own activity has been termed 'the molecular memory switch' and is required for both LTP and learning. CaMKII then regulates the activity of other proteins at the synapse that together maintain the increased synaptic transmission of LTP. In addition CaMKII activity can lead to many of the other changes occurring during synaptic plasticity and memory formation. These CaMKII mediated changes in synaptic plasticity are required for learning and memory in most animals including Drosophila. Although fruitflies are small they are smart, for instance they can land on the ceiling and detect that fruit in your fruit bowl has gone off before you can. In this proposal we wish to study CaMKII-mediated synaptic mechanisms of learning and memory further taking advantage of powerful genetics of Drosophila. One important question we wish to answer is: How is CaMKII's activity regulated and localised at synapses during learning? We have found that in flies like in mammals, at inactive synapses with low levels of Ca2+, CaMKII can regulate its own activity by a second mechanism that tends to inactivate CaMKII. We found a novel protein that interacts with CaMKII at fly synapses called CASK that tends to inactivate CaMKII thereby disrupting the ability of CaMKII to undergo the molecular memory switch. These changes would be predicted to interfere with LTP-like events and learning and memory. Therefore in this proposal we wish to determine the direct role of CASK and CaMKII activity in synaptic plasticity underlying learning and memory using flies. To achieve this we will make new fly CaMKII and CASK mutants and determine the effect of these together or alone on a range of synaptic events in parts of the fly brain that mediate learning and memory. Finally we will determine the role of CaMKII and CASK in the fly's learning and memory behaviour. This will provide important insight into how brains have evolved their huge capacity to acquire and store information.

这项提议的目的是为了更好地理解记忆在大脑中形成的分子机制。对记忆的研究尤其重要，因为它给了我们身份认同感。学习和记忆的缺陷发生在许多疾病、损伤和衰老过程中。确定参与这些过程的关键分子，将有助于揭示新的治疗干预的目标，以扭转记忆丧失的破坏性后果，这项研究对我们的老龄化人口尤其重要。大脑由许多细胞或神经元组成，这些细胞或神经元通过称为突触的连接进行交流。信息通过小的电脉冲在神经元间流动，有点像电脑。在大多数突触中，这些电脉冲会释放出与输出神经元结合的化学物质，使其变得更容易兴奋，并将电脉冲传播给回路中的下一个神经元。在学习过程中，大脑也会储存信息，并将其作为记忆提取出来。大脑中有专门负责学习的部分，比如海马体。当动物经历学习刺激时，海马神经元之间的突触传递持续增加，称为长期增强（LTP），这种增加在原始刺激被移除后仍会继续，这是一种学习的突触机制。这些突触活动的长期变化会导致突触生长和神经元之间连接的增加，这一过程被称为突触可塑性，被认为是记忆的突触机制。LTP和学习是由钙（Ca2+）进入神经元并激活一种叫做Ca2+反应激酶（CaMKII）的酶启动的。CaMKII在大脑中含量丰富，占其总蛋白的1-2%，是主要的突触蛋白之一。一旦被增加的Ca2+激活，CaMKII能够引起其自身活性的开关，因此即使在Ca2+下降后它仍保持活性。CaMKII维持自身活动的这种特殊能力被称为“分子记忆开关”，这是LTP和学习所必需的。然后，CaMKII调节突触中其他蛋白质的活性，这些蛋白质共同维持LTP突触传递的增加。此外，CaMKII活性可以导致突触可塑性和记忆形成过程中发生的许多其他变化。这些CaMKII介导的突触可塑性变化是包括果蝇在内的大多数动物学习和记忆所必需的。虽然果蝇很小，但它们很聪明，例如，它们可以降落在天花板上，在你之前发现你水果盘里的水果已经变质了。在本提案中，我们希望利用果蝇强大的遗传学进一步研究camkii介导的学习和记忆突触机制。我们希望回答的一个重要问题是：在学习过程中，CaMKII的活动是如何被调节和定位在突触上的？我们发现，在果蝇中，像在哺乳动物中一样，在Ca2+水平低的非活性突触中，CaMKII可以通过第二种机制来调节其自身的活性，这种机制往往会使CaMKII失活。我们在果蝇突触中发现了一种与CaMKII相互作用的新蛋白，称为CASK，它倾向于使CaMKII失活，从而破坏CaMKII进行分子记忆开关的能力。预计这些变化会干扰ltp样事件以及学习和记忆。因此，在本研究中，我们希望确定CASK和CaMKII活性在果蝇学习和记忆突触可塑性中的直接作用。为了实现这一目标，我们将制造新的果蝇CaMKII和CASK突变体，并确定它们共同或单独对果蝇大脑中介导学习和记忆的部分突触事件的影响。最后，我们将确定CaMKII和CASK在果蝇学习和记忆行为中的作用。这将为了解大脑获取和存储信息的巨大能力是如何进化而来提供重要的见解。

项目成果

Ion channels to inactivate neurons in Drosophila.

• DOI: 10.3389/neuro.02.013.2009
• 发表时间: 2009
• 期刊: Frontiers in molecular neuroscience
• 影响因子: 4.8
• 作者: Hodge JJ

KCNQ channels show conserved ethanol block and function in ethanol behaviour.

• DOI: 10.1371/journal.pone.0050279
• 发表时间: 2012
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Cavaliere S;Gillespie JM;Hodge JJ
• 通讯作者: Hodge JJ

CASK regulates CaMKII autophosphorylation in neuronal growth, calcium signaling, and learning.

• DOI: 10.3389/fnmol.2013.00027
• 发表时间: 2013
• 期刊: Frontiers in molecular neuroscience
• 影响因子: 4.8
• 作者: Gillespie JM;Hodge JJ
• 通讯作者: Hodge JJ

Drosophila KCNQ channel displays evolutionarily conserved electrophysiology and pharmacology with mammalian KCNQ channels.

• DOI: 10.1371/journal.pone.0023898
• 发表时间: 2011
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Cavaliere S;Hodge JJ
• 通讯作者: Hodge JJ

Drosophila adult olfactory shock learning.

• DOI: 10.3791/50107
• 发表时间: 2014-08-07
• 期刊: Journal of visualized experiments : JoVE
• 作者: Malik BR;Hodge JJ
• 通讯作者: Hodge JJ