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High levels of MeCP2 depress MHC class I expression in neuronal cells.

Miralvès J, Magdeleine E, Kaddoum L, Brun H, Peries S, Joly E - PLoS ONE (2007)

Bottom Line: The molecular basis of this regulation is poorly understood, but the genes are particularly rich in CpG islands.We show here that transiently transfected cells expressing high levels of MeCP2 specifically downregulate cell-surface expression of MHC class I molecules in the neuronal cell line N2A and they prevent the induction of MHC class I expression in response to interferon in these cells, supporting our first hypothesis.Immunohistological analyses of brain slices from MECP2 knockout mice (the MeCP2(tm1.1Bird) strain) demonstrated a small but reproducible increase in MHC class I when compared to their wild type littermates, but we found no difference in MHC class I expression in primary cultures of mixed glial cells (mainly neurons and astrocytes) from the knockout and wild-type mice.

View Article: PubMed Central - PubMed

Affiliation: Institut de Pharmacologie et Biologie Structurale, Centre National de Recherche Scientifique (CNRS), Toulouse, France.

ABSTRACT

Background: The expression of MHC class I genes is repressed in mature neurons. The molecular basis of this regulation is poorly understood, but the genes are particularly rich in CpG islands. MeCP2 is a transcriptional repressor that binds to methylated CpG dinucleotides; mutations in this protein also cause the neurodevelopmental disease called Rett syndrome. Because MHC class I molecules play a role in neuronal connectivity, we hypothesised that MeCP2 might repress MHC class I expression in the CNS and that this might play a role in the pathology of Rett syndrome.

Methodology: We show here that transiently transfected cells expressing high levels of MeCP2 specifically downregulate cell-surface expression of MHC class I molecules in the neuronal cell line N2A and they prevent the induction of MHC class I expression in response to interferon in these cells, supporting our first hypothesis. Surprisingly, however, overexpression of the mutated forms of MeCP2 that cause Rett syndrome had a similar effect on MHC class I expression as the wild-type protein. Immunohistological analyses of brain slices from MECP2 knockout mice (the MeCP2(tm1.1Bird) strain) demonstrated a small but reproducible increase in MHC class I when compared to their wild type littermates, but we found no difference in MHC class I expression in primary cultures of mixed glial cells (mainly neurons and astrocytes) from the knockout and wild-type mice.

Conclusion: These data suggest that high levels of MeCP2, such as those found in mature neurons, may contribute to the repression of MHC expression, but we find no evidence that MeCP2 regulation of MHC class I is important for the pathogenesis of Rett syndrome.

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Evaluation of MHC class I expression in adult mouse brain slices.Serial frozen sections of adult male wild-type and MeCP2−/y littermates were analysed for expression of MHC class I by immunohistochemistry using the rat R1-21.2 monoclonal antibody and EnVision detection technology (Dako). For the negative control, the same staining process was used omitting the primary antibody. Similar results were obtained with the M1/42 monoclonal antibody. Similar results were obtained in independent experiments on brains from three different pairs of mice.
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pone-0001354-g004: Evaluation of MHC class I expression in adult mouse brain slices.Serial frozen sections of adult male wild-type and MeCP2−/y littermates were analysed for expression of MHC class I by immunohistochemistry using the rat R1-21.2 monoclonal antibody and EnVision detection technology (Dako). For the negative control, the same staining process was used omitting the primary antibody. Similar results were obtained with the M1/42 monoclonal antibody. Similar results were obtained in independent experiments on brains from three different pairs of mice.

Mentions: Our data from experiments with cells in culture (above) suggest that the genes encoding MHC class I and β2-microglobulin are controlled by MeCP2; overexpression of normal MeCP2 downregulates their expression. To find out whether this is the case in vivo, we investigated whether neuronal cells from MeCP2 knockout mice (MeCP2tm1.1Bird) contained elevated levels of MHC class I by performing immunohistochemistry on frozen brain sections of MECP2 knockout hemizygous male (-/y) mice and of their wild-type littermates using two different rat monoclonal antibodies directed against mouse MHC class I molecules. The results we obtained suggest that there are slightly higher levels of MHC class I expression in some regions of the brains of MeCP2 knockout mice than in the same regions of the wild-type control brains (Figure 4). Although these differences were not always seen for all brain areas of MECP2 knockout mice compared to their control littermates, when a difference was seen, it was always for higher expression in MECP2 knockout animals.


High levels of MeCP2 depress MHC class I expression in neuronal cells.

Miralvès J, Magdeleine E, Kaddoum L, Brun H, Peries S, Joly E - PLoS ONE (2007)

Evaluation of MHC class I expression in adult mouse brain slices.Serial frozen sections of adult male wild-type and MeCP2−/y littermates were analysed for expression of MHC class I by immunohistochemistry using the rat R1-21.2 monoclonal antibody and EnVision detection technology (Dako). For the negative control, the same staining process was used omitting the primary antibody. Similar results were obtained with the M1/42 monoclonal antibody. Similar results were obtained in independent experiments on brains from three different pairs of mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2131781&req=5

pone-0001354-g004: Evaluation of MHC class I expression in adult mouse brain slices.Serial frozen sections of adult male wild-type and MeCP2−/y littermates were analysed for expression of MHC class I by immunohistochemistry using the rat R1-21.2 monoclonal antibody and EnVision detection technology (Dako). For the negative control, the same staining process was used omitting the primary antibody. Similar results were obtained with the M1/42 monoclonal antibody. Similar results were obtained in independent experiments on brains from three different pairs of mice.
Mentions: Our data from experiments with cells in culture (above) suggest that the genes encoding MHC class I and β2-microglobulin are controlled by MeCP2; overexpression of normal MeCP2 downregulates their expression. To find out whether this is the case in vivo, we investigated whether neuronal cells from MeCP2 knockout mice (MeCP2tm1.1Bird) contained elevated levels of MHC class I by performing immunohistochemistry on frozen brain sections of MECP2 knockout hemizygous male (-/y) mice and of their wild-type littermates using two different rat monoclonal antibodies directed against mouse MHC class I molecules. The results we obtained suggest that there are slightly higher levels of MHC class I expression in some regions of the brains of MeCP2 knockout mice than in the same regions of the wild-type control brains (Figure 4). Although these differences were not always seen for all brain areas of MECP2 knockout mice compared to their control littermates, when a difference was seen, it was always for higher expression in MECP2 knockout animals.

Bottom Line: The molecular basis of this regulation is poorly understood, but the genes are particularly rich in CpG islands.We show here that transiently transfected cells expressing high levels of MeCP2 specifically downregulate cell-surface expression of MHC class I molecules in the neuronal cell line N2A and they prevent the induction of MHC class I expression in response to interferon in these cells, supporting our first hypothesis.Immunohistological analyses of brain slices from MECP2 knockout mice (the MeCP2(tm1.1Bird) strain) demonstrated a small but reproducible increase in MHC class I when compared to their wild type littermates, but we found no difference in MHC class I expression in primary cultures of mixed glial cells (mainly neurons and astrocytes) from the knockout and wild-type mice.

View Article: PubMed Central - PubMed

Affiliation: Institut de Pharmacologie et Biologie Structurale, Centre National de Recherche Scientifique (CNRS), Toulouse, France.

ABSTRACT

Background: The expression of MHC class I genes is repressed in mature neurons. The molecular basis of this regulation is poorly understood, but the genes are particularly rich in CpG islands. MeCP2 is a transcriptional repressor that binds to methylated CpG dinucleotides; mutations in this protein also cause the neurodevelopmental disease called Rett syndrome. Because MHC class I molecules play a role in neuronal connectivity, we hypothesised that MeCP2 might repress MHC class I expression in the CNS and that this might play a role in the pathology of Rett syndrome.

Methodology: We show here that transiently transfected cells expressing high levels of MeCP2 specifically downregulate cell-surface expression of MHC class I molecules in the neuronal cell line N2A and they prevent the induction of MHC class I expression in response to interferon in these cells, supporting our first hypothesis. Surprisingly, however, overexpression of the mutated forms of MeCP2 that cause Rett syndrome had a similar effect on MHC class I expression as the wild-type protein. Immunohistological analyses of brain slices from MECP2 knockout mice (the MeCP2(tm1.1Bird) strain) demonstrated a small but reproducible increase in MHC class I when compared to their wild type littermates, but we found no difference in MHC class I expression in primary cultures of mixed glial cells (mainly neurons and astrocytes) from the knockout and wild-type mice.

Conclusion: These data suggest that high levels of MeCP2, such as those found in mature neurons, may contribute to the repression of MHC expression, but we find no evidence that MeCP2 regulation of MHC class I is important for the pathogenesis of Rett syndrome.

Show MeSH
Related in: MedlinePlus