Symposium

Symposium 33 Next generation symposium by alumni of the Educational Seminars for Young Researchers physiology and pathology of the brain シンポジウム33 日本神経化学会若手育成セミナー出身者によるシンポジウム脳の病態生理

SY33-1 Brain Regulatory T cells accumulated in the chronic phase of ischemic brain injury 脳梗塞慢性期における制御性T細胞の役割 Ito Minako（伊藤美菜子），吉村昭彦 Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan Foxp3+ regulatory T cells (Tregs) are critical components of immune tolerance1,2. In addition, Tregs residing in non-immune tissues perform specialized functions in tissue homeostasis and remodeling3. The characteristics and functions of brain Tregs, however, are not well understood, in part because the number of Tregs in the brain under normal conditions is very low. However, during the chronic phase two weeks after ischemic stroke, a massive accumulation of Tregs occurs in the brain4. Here we show that brain Tregs relate to Tregs in other tissues such as adipose tissue (VAT) and muscle5, however, brain Tregs are apparently different from them and express several unique genes related to the nerve system including the serotonin receptor. The amplification of brain Tregs is dependent on interleukin (IL)-2, IL-33, serotonin and T cell receptor (TCR) recognition, and infiltration into the brain is driven by chemokines, CCL1 and CCL20. Brain Tregs suppress astrocyte activation (astrogliosis) and reduce neural damages via the production of amphiregulin (Areg), a low-affinity epidermal growth factor receptor (EGFR) ligand. Stroke is a leading cause of neurological disability, and there is currently no effective method for recovery other than rehabilitation in the chronic phase of cerebral infarction. Our findings suggest that Tregs and their products may provide new therapeutic opportunities for neuronal protection against stroke as well as various other neuroinflammatory diseases.		SY33-2 Phospho-Tau Bar Code: Analysis of Phosphoisotypes of Tau and Its Application to Tauopathy リン酸化Tauバーコード ~Tauのリン酸化解析とタウオパチーへの応用~ Kimura Taeko（木村妙子）¹，久永眞市² ¹National institutes for QST ²Dept. of Biol., Grad. of sch. of sci. and Eng., Tokyo Metropolitan Univ. Tau is a microtubule-associated protein which regulates the assembly and stability of microtubules in the axons of neurons. Tau is also a major component of neurofibrillary tangles, a pathological hallmark in Alzheimer's disease (AD). A characteristic of AD tau is hyperphosphorylation with more than 40 phosphorylation sites. Aggregates of hyperphosphorylated tau are also found in other neurodegenerative diseases which are called tauopathies. Although a large number of studies have been performed on the phosphorylation of AD tau, it is not known if there is disease-specific phosphorylation among tauopathies. This is due to the lack of a proper method for analyzing tau phosphorylation in vivo. Most previous phosphorylation studies were conducted using a range of phosphorylation site-specific antibodies. These studies describe relative changes of different phosphorylation sites, however, it is hard to estimate total, absolute and collective changes in phosphorylation. To overcome these problems, we have recently applied the Phos-Tag technique to the analysis of tau phosphorylation in vitro and in vivo. This method separates tau into many bands during SDS-PAGE depending on its phosphorylation states, creating a bar code appearance. We propose calling this banding pattern of tau the "phospho-tau bar code." In this symposium, I describe what is newly discovered regarding tau phosphorylation through the use of the Phos-Tag. We would like to propose its use for the postmortem diagnosis of tauopathy which is presently done by immunostaining diseased brains with anti-phospho-antibodies. While Phos-tag SDS-PAGE, like other biochemical assays, will lose morphological information, it could provide other types of valuable information such as disease-specific phosphorylation.

SY33-3 The role of astrocytes in blood-brain barrier function after cerebral ischemia アストロサイトによる脳梗塞後の血液脳関門制御 Takarada-Iemata Mika（宝田美佳），堀修 Dept. of Neuroanat., Med., Kanazawa Univ. Disruption of the blood-brain barrier (BBB) following cerebral ischemia is closely related to the infiltration of peripheral cells into the brain, progression of lesion formation, and clinical exacerbation. However, the mechanism that regulates BBB integrity, especially after permanent ischemia, remains unclear. Here, we demonstrate that astrocytic N-myc downstream-regulated gene 2 (NDRG2), a differentiation- and stress-associated molecule, may function as a modulator of BBB permeability following ischemic stroke, using a mouse model of permanent cerebral ischemia. Genetic deletion of NDRG2 exhibited enhanced levels of infarct volume and accumulation of immune cells into the ipsilateral brain hemisphere following permanent middle cerebral artery occlusion (MCAO). Extravasation of serum proteins including fibrinogen and immunoglobulin was enhanced at the ischemic core and perivascular region of the peri-infarct area in the ipsilateral cortex of NDRG2-deficient mice. Furthermore, we identified matrix metalloproteinase-3 as a target molecule of NDRG2 using gene array analysis, and the expression of matrix metalloproteinases after MCAO markedly increased in NDRG2-deficient mice. These findings suggest that NDRG2, expressed in astrocytes, may play a critical role in the regulation of BBB permeability and immune cell infiltration through the modulation of MMP expression following cerebral ischemia.		SY33-4 Brain remodeling by astrocytic phagocytosis 貪食性アストロサイトによる脳内再編 Morizawa Yosuke（森澤陽介） Super-network Brain Physiology. Life Sciences. Tohoku Univ. Remodeling of the brain by clearance of unnecessary neuronal network and debris is essential for the maintenance of brain function and microenvironment. Recent evidence has shown that not only microglia but astrocytes also contribute to the remodeling under pathological conditions via phagocytosis. Previously, we found that astrocytes have highly phagocytic capacity after stroke with different spatiotemporal patterns of microglia. We identified that ABCA1 phagocytic pathway molecules are responsible for astrocytic phagocytosis after stroke. In addition, we recently found that this key molecule ABCA1 in astrocytes may not only contribute to remodeling of the damaged tissues. It could also play a vital role in the rewiring of functional or malfunctional neuronal circuit in diseased brain. Together, astrocytes are active regulators in brain remodeling through phagocytosis in diseased state.

SY33-5 The function of the ventral hippocampus in goal-directed behavior 目的指向型行動における腹側海馬の機能解明 Yoshida Keitaro（吉田慶多朗），三村將，田中謙二 Department of Physiology School of Medicine, Keio University Motivation has been defined as a fundamental element which enable organisms to execute actions and provides the vigor to overcome obstacles and achieve goals. In rodents, it can be defined as the activation goal-directed behavior, which involves a directional component that select a behavior leading to the current goal, and an activational component that initiates and maintains actions to achieve the goal. Research over the last several decades has suggested that the nucleus accumbens (NAc) plays a key role in various aspects of motivated, goal-directed behaviors. This is based on complex array of sensory, context and reward information from cortical, limbic and dopaminergic inputs. The ventral CA1 (vCA1) sends dense projection to the NAc and this pathway involved in goal-directed behavior based on spatial learning task. However, it is unknown that how the vCA1 contribute aspect of directional and activational component in goal-directed behavior. Here we show that activities of vCA1, not dorsal area, were suppressed during lever press actions in a food-seeking discrimination task. Optogenetic counter-activation when mice press the lever increased time spent to complete the goal and failure, whereas optogenetic inhibition during this period increased the number of lever presses to obtain a food. Furthermore, we found that microinjection of serotonin receptor 3A (Htr3A) antagonist into the vCA1 also increased time spent to complete the goal and failure. These findings causally implicate that suppression of the vCA1 activities via Htr3A interneuron drives sustainment of goal-directed actions.