Subtype switching of vesicular glutamate transporters at parallel fibre-Purkinje cell synapses in developing mouse cerebellum.
Two subtypes of the vesicular glutamate transporter are expressed differentially in two excitatory afferents synapsing on to Purkinje cells: VGluT1 (BNPI) in axon terminals of cerebellar granule cells (i.e. parallel fibres; PFs) and VGluT2 (DNPI) in those of the inferior olivary neurons (climbing fibres; CFs). In the present study, we examined their expression in the developing mouse cerebellum. By in situ hybridization, the inferior olivary nucleus selectively expressed VGluT2 mRNA through postnatal life. In the cerebellum, both subtypes were transcribed in the external and internal granular layers during the first postnatal week. Thereafter, VGluT1 mRNA showed marked upregulation in the internal granular layer, whereas VGluT2 mRNA disappeared from the external and internal granular layers by the end of the third postnatal week. By immunohistochemistry, CF terminals consistently exhibited VGluT2 immunoreactivity in the postnatal cerebellum. By contrast, in the first 10 days of postnatal life, VGluT2 predominated in PF terminals, despite the transcription of both transporters in developing granule cells. During the second 10 days, VGluT2 in PF terminals was replaced with VGluT1 from deep regions of the molecular layer upwards, correlating with dendritic translocation of CFs. This replacement was accomplished by postnatal day 30. Taking that late-borne PFs are laid down successively on earlier ones in the molecular layer, the deep-to-superficial replacement represents maturation-linked switching from VGluT2 to VGluT1 in individual PFs, and is likely to be regulated at both the transcription and translation levels.
Miyazaki
Taisuke
T
Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan.
Fukaya
Masahiro
M
Shimizu
Hidemi
H
Watanabe
Masahiko
M
D000818:Animals; D000831:Animals, Newborn; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002531:Cerebellum / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D006168:Guinea Pigs; D015151:Immunoblotting; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization; D026901:Membrane Transport Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D016253:Microscopy, Immunoelectron; D009434:Neural Pathways / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D009847:Olivary Nucleus / Q000378:metabolism / Q000648:ultrastructure; D011689:Purkinje Cells / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C493477:Slc17a6 protein, mouse; C493475:Slc17a6 protein, rat; C493465:Slc17a7 protein, mouse; C493466:Slc17a7 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins