title: Epigenetics of Epileptogenesis-Evoked Upregulation of Matrix Metalloproteinase-9 in Hippocampus.
abstract: Enhanced levels of Matrix Metalloproteinase-9 (MMP-9) have been implicated in the pathogenesis of epilepsy in humans and rodents. Lack of Mmp-9 impoverishes, whereas excess of Mmp-9 facilitates epileptogenesis. Epigenetic mechanisms driving the epileptogenesis-related upregulation of MMP-9 expression are virtually unknown. The aim of this study was to reveal these mechanisms. We analyzed hippocampi extracted from adult and pediatric patients with temporal lobe epilepsy as well as from partially and fully pentylenetetrazole kindled rats. We used a unique approach to the analysis of the kindling model results (inclusion in the analysis of rats being during kindling, and not only a group of fully kindled animals), which allowed us to separate the molecular effects exerted by the epileptogenesis from those related to epilepsy and epileptic activity. Consequently, it allowed for a disclosure of molecular mechanisms underlying causes, and not consequences, of epilepsy. Our data show that the epileptogenesis-evoked upregulation of Mmp-9 expression is regulated by removal from Mmp-9 gene proximal promoter of the two, interweaved potent silencing mechanisms-DNA methylation and Polycomb Repressive Complex 2 (PRC2)-related repression. Demethylation depends on a gradual dissociation of the DNA methyltransferases, Dnmt3a and Dnmt3b, and on progressive association of the DNA demethylation promoting protein Gadd45β to Mmp-9 proximal gene promoter in vivo. The PRC2-related mechanism relies on dissociation of the repressive transcription factor YY1 and the dissipation of the PRC2-evoked trimethylation on Lys27 of the histone H3 from the proximal Mmp-9 promoter chromatin in vivo. Moreover, we show that the DNA hydroxymethylation, a new epigenetic DNA modification, which is localized predominantly in the gene promoters and is particularly abundant in the brain, is not involved in a regulation of MMP-9 expression during the epileptogenesis in the rat hippocampus as well as in the hippocampi of pediatric and adult epileptic patients. Additionally, we have also found that despite of its transient nature, the histone modification H3S10ph is strongly and gradually accumulated during epileptogenesis in the cell nuclei and in the proximal Mmp-9 gene promoter in the hippocampus, which suggests that H3S10ph can be involved in DNA demethylation in mammals, and not only in Neurospora. The study identifies MMP-9 as the first protein coding gene which expression is regulated by DNA methylation in human epilepsy. We present a detailed epigenetic model of the epileptogenesis-evoked upregulation of MMP-9 expression in the hippocampus. To our knowledge, it is the most complex and most detailed mechanism of epigenetic regulation of gene expression ever revealed for a particular gene in epileptogenesis. Our results also suggest for the first time that dysregulation of DNA methylation found in epilepsy is a cause rather than a consequence of this condition.
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Katarzyna
authors: K
authors: Zybura-Broda
authors: Laboratory of Neurobiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
authors: Renata
authors: R
authors: Amborska
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Magdalena
authors: M
authors: Ambrozek-Latecka
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Joanna
authors: J
authors: Wilemska
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Agnieszka
authors: A
authors: Bogusz
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Joanna
authors: J
authors: Bucko
authors: Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
authors: Anna
authors: A
authors: Konopka
authors: Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland.
authors: Wieslawa
authors: W
authors: Grajkowska
authors: Department of Neurosurgery, The Children's Memorial Health Institute, Warsaw, Poland.
authors: Marcin
authors: M
authors: Roszkowski
authors: Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
authors: Andrzej
authors: A
authors: Marchel
authors: Department of Neurosurgery, Medical University of Warsaw, Warsaw, Poland.
authors: Andrzej
authors: A
authors: Rysz
authors: Department of Pathology, Medical University of Warsaw, Warsaw, Poland.
authors: Lukasz
authors: L
authors: Koperski
authors: Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
authors: Grzegorz M
authors: GM
authors: Wilczynski
authors: Laboratory of Neurobiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
authors: Leszek
authors: L
authors: Kaczmarek
authors: Department of Clinical Cytology, Centre of Postgraduate Medical Education, Warsaw, Poland.
authors: Marcin
authors: M
authors: Rylski
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics; D000090205:DNA Methyltransferase 3A; D044127:Epigenesis, Genetic; D004827:Epilepsy / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D020780:Matrix Metalloproteinase 9 / Q000235:genetics*; D008875:Middle Aged; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D015533:Transcriptional Activation / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics*; D050986:YY1 Transcription Factor / Q000378:metabolism; D055815:Young Adult; D000097642:GADD45 Proteins
chemical_list: D000943:Antigens, Differentiation; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D020780:Matrix Metalloproteinase 9; D050986:YY1 Transcription Factor; C000717967:DNMT3A protein, human; C086470:GADD45B protein, human; D000097642:GADD45 Proteins; C494698:YY1 protein, human