Mammalian septin Sept2 modulates the activity of GLAST, a glutamate transporter in astrocytes.
Sept2 is a member of the septin family of GTPases. Septins form filaments in a GTP-form dependent manner, and are involved in cytokinesis from yeast to mammals; however, some mammalian septins, including Sept2, are expressed in the brain, a tissue in which almost all the cells are postmitotic. Recently, some functions of mammalian septin other than cytokinesis such as vesicle transport have been reported. However, mammalian septin's physiological functions are still unclear. The present study revealed that Sept2 co-localizes with the astrocyte glutamate transporter GLAST in the Bergmann glial processes facing axons and synapses. Biochemical analyses demonstrated that Sept2 bound directly to the carboxy-terminal region of GLAST in a GDP-form dependent manner. Expression of constitutive GDP-form Sept2 mutant reduced the glutamate uptake activity of GLAST via internalization of GLAST from cell surface. Thus Sept2 may regulate GLAST-mediated glutamate uptake by astrocytes, which is important for appropriate transmitter signalling in the cerebellum.
Kinoshita
Nagatoki
N
Department of Anatomy and Neurobiology, Kyoto University Graduate School of Medicine, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. n-kinoshita@cdb.riken.jp
Kimura
Kazushi
K
Matsumoto
Naoya
N
Watanabe
Masahiko
M
Fukaya
Masahiro
M
Ide
Chizuka
C
D027322:Amino Acid Transport System X-AG / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D051379:Mice; D009928:Organ Specificity; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*
D027322:Amino Acid Transport System X-AG; D006153:Guanosine Diphosphate; D018698:Glutamic Acid; D006160:Guanosine Triphosphate; D010744:Phosphoric Monoester Hydrolases