Chemical labelling for visualizing native AMPA receptors in live neurons

The location and number of neurotransmitter receptors are dynamically regulated at postsynaptic sites. However, currently available methods for visualizing receptor trafficking require the introduction of genetically engineered receptors into neurons, which can disrupt the normal functioning and processing of the original receptor. Here we report a powerful method for visualizing native α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) which are essential for cognitive functions without any genetic manipulation. This is based on a covalent chemical labelling strategy driven by selective ligand-protein recognition to tether small fluorophores to AMPARs using chemical AMPAR modification (CAM) reagents. The high penetrability of CAM reagents enables visualization of native AMPARs deep in brain tissues without affecting receptor function. Moreover, CAM reagents are used to characterize the diffusion dynamics of endogenous AMPARs in both cultured neurons and hippocampal slices. This method will help clarify the involvement of AMPAR trafficking in various neuropsychiatric and neurodevelopmental disorders

Endothelial PI3K-C2α, a class II PI3K, has an essential role in angiogenesis and vascular barrier function

The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) is localized in endosomes, the trans-Golgi network and clathrin-coated vesicles; however, its functional role is not well understood. Global or endothelial-cell-specific deficiency of PI3K-C2α resulted in embryonic lethality caused by defects in sprouting angiogenesis and vascular maturation. PI3K-C2α knockdown in endothelial cells resulted in a decrease in the number of PI3-phosphate-enriched endosomes, impaired endosomal trafficking, defective delivery of VE-cadherin to endothelial cell junctions and defective junction assembly. PI3K-C2α knockdown also impaired endothelial cell signaling, including vascular endothelial growth factor receptor internalization and endosomal RhoA activation. Together, the effects of PI3K-C2α knockdown led to defective endothelial cell migration, proliferation, tube formation and barrier integrity. Endothelial PI3K-C2α deficiency in vivo suppressed postischemic and tumor angiogenesis and diminished vascular barrier function with a greatly augmented susceptibility to anaphylaxis and a higher incidence of dissecting aortic aneurysm formation in response to angiotensin II infusion. Thus, PI3K-C2α has a crucial role in vascular formation and barrier integrity and represents a new therapeutic target for vascular disease.In Press / 2013-03-18公開予定

神経細胞グルタミン酸受容体の機能解析を指向した新規ケミカルラベル化法の開発

京都大学0048新制・課程博士博士(工学)甲第20583号工博第4363号新制||工||1678(附属図書館)京都大学大学院工学研究科合成・生物化学専攻(主査)教授 浜地 格, 教授 森 泰生, 教授 白川 昌宏学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDGA

Alpha-determinant cyclic modules and Jacobi polynomials

MI: Global COE Program Education-and-Research Hub for Mathematics-for-IndustryグローバルCOEプログラム「マス･フォア･インダストリ教育研究拠点」For positive integers n and l, we study the cyclic GL(n)-module generated by the l-th power of the α-determinant. This cyclic module is isomorphic to the n-th tensor space of the symmetric l-th tensor space of the vector representation of GL(n) for all but finite exceptional values of α. If αa is exceptional, then the multiplicities of several irreducible subrepresentations in the cyclic module are smaller than those in the aforementioed tensor space. The degeneration of each isotypic component of the cyclic module is described by a matrix whose size is given by a Kostka number and entries are polynomials in αa with rational coefficients. Especially, we determine explicitly the matrix when n equals 2. In that case, the matrix becomes a scalar and is essentially given by the classical Jacobi polynomial. Moreover, we prove that these polynomials are unitary