Metal binding of metallothioneins in human astrocytomas (U87 MG,IPDDC-2A) |
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Authors: | Magda Tu?ek ?nidari? Anja Pucer Tanja Fatur Metka Filipi? Janez ??an?ar Ingrid Falnoga |
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Institution: | (1) National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia;(2) Department of Environmental Sciences, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;(3) Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia |
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Abstract: | Astroglia cells structurally and nutritionally support neurons in the central nervous system. They play an important role
in guiding the construction of the nervous system and controlling the chemical and ionic environment of neurons. They also
represent the major sites for accumulation and immobilisation of toxic metal ions most probably connected with metallothioneins.
For this reason astroglia cells possess high cytosolic levels of metallothioneins I, II and III (MT-I,II,III). Our aim was
to establish the inducibility and metal binding of MTs in two human astrocytoma cell lines, U87 MG (astrocytoma–glioblastoma,
grade IV) and IPDDC-2A (astrocytoma, grade II), on exposure to cadmium chloride (1 μM). MTs were identified by molecular weight (size exclusion chromatography) and their metal content (Cd, Zn and Cu) to follow
the interactions between metals. We showed that MTs are constitutively expressed in both human astrocytoma cell lines. In
accordance with the higher malignancy grade of U87 MG, the amount of MTs was higher in U87 MG than in IPDDC-2A cells. After
24 hours of exposure to Cd their expression greatly increased in both cell lines and they were capable of immobilising almost
all water soluble Cd. Induction of MTs in U87 MG cells was additionally followed up to 48 hours with exposure to different
concentrations of CdCl2 (1, 10 μM). Induction was a time dependent process throughout the period. Isoform III (identified by chromatographic separation of
isoform III from I/II) was present at all exposure times, but only in traces with respect to the prevailing amounts of MT-I/II
isoforms. So induction can be attributed to isoform I/II only. |
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Keywords: | metallothioneins (MTs) isoforms I II III cadmium astrocytomas U87 MG IPDDC-2A human |
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