RRC ID 1441
Author Hinoi E, Wang L, Takemori A, Yoneda Y.
Title Functional expression of particular isoforms of excitatory amino acid transporters by rodent cartilage.
Journal Biochem Pharmacol
Abstract In the present study, we have attempted to demonstrate functional expression by the rodent cartilage of particular isoforms of excitatory amino acid transporters (EAATs) essentially required for central glutamatergic signal termination. Constitutive expression of mRNA was shown for the first time with the neuronal EAAT subtype excitatory amino acid carrier-1 (EAAC1), in addition to glial subtypes such as glutamate aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1), in rat costal chondrocytes cultured for 7-21 days on reverse transcription polymerase chain reaction (RT-PCR). Western blotting analysis confirmed the expression of corresponding proteins for both GLAST and GLT-1 in cultured chondrocytes. The accumulation of [(3)H]glutamate (Glu) occurred in a temperature- and sodium-dependent manner with biochemical and pharmacological profiles similar to those seen for brain EAATs in chondrocytes cultured for 7 days, while [(3)H]Glu accumulation consisted of a single component with a K(m) of 39.1+/-2.3 microM and a V(max) of 1320+/-120pmol/mg protein/min, respectively. In organotypic cultured metatarsals isolated before vascularization from embryonic mice, where cells underwent maturational development from resting to proliferating, prehypertrophic, hypertrophic and calcified chondrocytes in a progressive order of cellular differentiation, moreover, mRNA expression was seen for GLAST, GLT-1 and EAAT4 but not for EAAC1 subtypes. Immunohistochemical analysis revealed distribution profiles different from each other with GLAST, GLT-1 and EAAT4 isoforms in sections of cultured metatarsals and isolated tibiae. These results suggest that extracellular Glu could be cleared up into intracellular locations through particular glial and/or neuronal EAAT isoforms functionally expressed by the rodent cartilage.
Volume 70(1)
Pages 70-81
Published 2005-7-1
DOI 10.1016/j.bcp.2005.04.025
PII S0006-2952(05)00225-X
PMID 15894296
MeSH Amino Acid Transport System X-AG / genetics Animals Carrier Proteins / genetics* Cells, Cultured Chondrocytes / metabolism* Excitatory Amino Acid Transporter 1 / genetics Excitatory Amino Acid Transporter 2 / genetics Excitatory Amino Acid Transporter 3 Excitatory Amino Acid Transporter 4 Female Glutamate Plasma Membrane Transport Proteins Glutamic Acid / metabolism* Mice Protein Isoforms RNA, Messenger / analysis Rats Rats, Wistar Symporters / genetics
IF 4.96
Times Cited 30
Human and Animal Cells ATDC5(RCB0565)