Metallothionein induction in neonatal rat primary astrocyte cultures protects against methylmercury cytotoxicity

L. Rising, D. Vitarella, H. K. Kimelberg, Michael Aschner

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Metallothionein (MT) protein and mRNA levels were monitored following exposure of rat neonatal primary astrocyte cultures to methylmercury (MeHg). MT-I and MT-II mRNAs were probed on northern blots with an [α-32P]dCTP- labeled synthetic cDNA probe specific for rat MT mRNA. MT-I and MT-II mRNAs were detected in untreated cells, suggesting constitutive MT expression in these cells. The probes hybridize to a single mRNA with a size appropriate for MT, ~550 and 350 bp for MT-I and MT-II, respectively. Expression of MT- I and MT-II mRNA in astrocyte monolayers exposed to 2 x 16-6 M MeHg for 6 h was increased over MT-I and MT-II mRNA levels in controls. Western blot analysis revealed a time-dependent increase in MT protein synthesis through 96 h of exposure to MeHg. Consistent with the constitutive expression of MTs at both the mRNA level and the protein level, we have also demonstrated a time-dependent increase in MT immunoreactivity in astrocytes exposed to MeHg. The cytotoxic effects of MeHg were measured by the rate of astrocytic D- [3H]aspartate uptake. Preexposure of astrocytes to CdCl2, a potent inducer of MTs, completely reversed the inhibitory effect of MeHg on D[3H]aspartate uptake that occurs in MeHg-treated astrocytes with constitutive MT levels. Associated with CdCl2 treatment was a time-dependent increase in astrocytic MT levels. In summary, astrocytes constitutively express MTs; treatment with MeHg increases astrocytic MT expression, and increased MT levels (by means of CdCl2 pretreatment) attenuate MeHg-induced toxicity. Increased MT expression may represent a generalized response to heavy metal exposure, thus protecting astrocytes and perhaps also, indirectly, juxtaposed neurons from the neurotoxic effects of heavy metals.

Original languageEnglish (US)
Pages (from-to)1562-1568
Number of pages7
JournalJournal of Neurochemistry
Volume65
Issue number4
StatePublished - 1995
Externally publishedYes

Fingerprint

Metallothionein
Cytotoxicity
Cell culture
Astrocytes
Rats
Messenger RNA
Cadmium Chloride
D-Aspartic Acid
Heavy Metals
Aspartic Acid
Proteins

Keywords

  • Astrocytes
  • Cadmium chloride
  • D- Aspartate
  • Metallothionein
  • Methylmercury
  • Rat

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Metallothionein induction in neonatal rat primary astrocyte cultures protects against methylmercury cytotoxicity. / Rising, L.; Vitarella, D.; Kimelberg, H. K.; Aschner, Michael.

In: Journal of Neurochemistry, Vol. 65, No. 4, 1995, p. 1562-1568.

Research output: Contribution to journalArticle

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abstract = "Metallothionein (MT) protein and mRNA levels were monitored following exposure of rat neonatal primary astrocyte cultures to methylmercury (MeHg). MT-I and MT-II mRNAs were probed on northern blots with an [α-32P]dCTP- labeled synthetic cDNA probe specific for rat MT mRNA. MT-I and MT-II mRNAs were detected in untreated cells, suggesting constitutive MT expression in these cells. The probes hybridize to a single mRNA with a size appropriate for MT, ~550 and 350 bp for MT-I and MT-II, respectively. Expression of MT- I and MT-II mRNA in astrocyte monolayers exposed to 2 x 16-6 M MeHg for 6 h was increased over MT-I and MT-II mRNA levels in controls. Western blot analysis revealed a time-dependent increase in MT protein synthesis through 96 h of exposure to MeHg. Consistent with the constitutive expression of MTs at both the mRNA level and the protein level, we have also demonstrated a time-dependent increase in MT immunoreactivity in astrocytes exposed to MeHg. The cytotoxic effects of MeHg were measured by the rate of astrocytic D- [3H]aspartate uptake. Preexposure of astrocytes to CdCl2, a potent inducer of MTs, completely reversed the inhibitory effect of MeHg on D[3H]aspartate uptake that occurs in MeHg-treated astrocytes with constitutive MT levels. Associated with CdCl2 treatment was a time-dependent increase in astrocytic MT levels. In summary, astrocytes constitutively express MTs; treatment with MeHg increases astrocytic MT expression, and increased MT levels (by means of CdCl2 pretreatment) attenuate MeHg-induced toxicity. Increased MT expression may represent a generalized response to heavy metal exposure, thus protecting astrocytes and perhaps also, indirectly, juxtaposed neurons from the neurotoxic effects of heavy metals.",
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T1 - Metallothionein induction in neonatal rat primary astrocyte cultures protects against methylmercury cytotoxicity

AU - Rising, L.

AU - Vitarella, D.

AU - Kimelberg, H. K.

AU - Aschner, Michael

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N2 - Metallothionein (MT) protein and mRNA levels were monitored following exposure of rat neonatal primary astrocyte cultures to methylmercury (MeHg). MT-I and MT-II mRNAs were probed on northern blots with an [α-32P]dCTP- labeled synthetic cDNA probe specific for rat MT mRNA. MT-I and MT-II mRNAs were detected in untreated cells, suggesting constitutive MT expression in these cells. The probes hybridize to a single mRNA with a size appropriate for MT, ~550 and 350 bp for MT-I and MT-II, respectively. Expression of MT- I and MT-II mRNA in astrocyte monolayers exposed to 2 x 16-6 M MeHg for 6 h was increased over MT-I and MT-II mRNA levels in controls. Western blot analysis revealed a time-dependent increase in MT protein synthesis through 96 h of exposure to MeHg. Consistent with the constitutive expression of MTs at both the mRNA level and the protein level, we have also demonstrated a time-dependent increase in MT immunoreactivity in astrocytes exposed to MeHg. The cytotoxic effects of MeHg were measured by the rate of astrocytic D- [3H]aspartate uptake. Preexposure of astrocytes to CdCl2, a potent inducer of MTs, completely reversed the inhibitory effect of MeHg on D[3H]aspartate uptake that occurs in MeHg-treated astrocytes with constitutive MT levels. Associated with CdCl2 treatment was a time-dependent increase in astrocytic MT levels. In summary, astrocytes constitutively express MTs; treatment with MeHg increases astrocytic MT expression, and increased MT levels (by means of CdCl2 pretreatment) attenuate MeHg-induced toxicity. Increased MT expression may represent a generalized response to heavy metal exposure, thus protecting astrocytes and perhaps also, indirectly, juxtaposed neurons from the neurotoxic effects of heavy metals.

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