Maternal Cocaine Administration Causes an Epigenetic Modification of Protein Kinase Cϵ Gene Expression in Fetal Rat Heart

Abstract

Protein kinase Cepsilon (PKCepsilon) plays a pivotal role in cardioprotection during cardiac ischemia and reperfusion injury. Recent studies demonstrated that prenatal cocaine exposure caused a decrease in PKCepsilon expression and increased heart susceptibility to ischemic injury in adult offspring, suggesting an in utero programming of PKCepsilon gene expression pattern in the heart. The present investigation aimed to elucidate whether an epigenetic mechanism, DNA methylation, accounts for cocaine-mediated repression of the PKCepsilon gene in the heart. Pregnant rats were administered either saline or cocaine intraperitoneally (15 mg/kg) twice daily from days 15 to 20 of gestational age, and term fetal hearts were studied. Cocaine treatment significantly decreased PKCepsilon mRNA and protein levels in the heart. CpG dinucleotides found in cAMP response element-binding protein (CREB), CREB/c-Jun1, and CREB/c-Jun2 binding sites at the proximal promoter region of the PKCepsilon gene were densely methylated and were not affected by cocaine. In contrast, methylation of CpGs in the activator protein 1 (AP-1) binding sites was low but was significantly increased by cocaine. Reporter gene assays showed that the AP-1 binding site played a strong stimulatory role of PKCepsilon gene transcription. Methylation of the AP-1 binding sites significantly decreased AP-1 binding to the PKCepsilon promoter. Supershift analyses implicated c-Jun homodimers binding to the AP-1 binding sites. Cocaine did not affect nuclear c-Jun levels or the binding of c-Jun to the unmethylated AP-1 binding sites. The results indicate a role for DNA methylation in cocaine-mediated PKCepsilon gene repression in the developing heart and suggest an epigenetic mechanism affecting this gene linked with vulnerability of ischemic injury in the heart of adult offspring.

Prenatal Nicotine Exposure Increases Heart Susceptibility to Ischemia/Reperfusion Injury in Adult Offspring

“…Our previous studies demonstrated that prenatal insults caused an epigenetic modification of the PKC gene in the fetal heart resulting in a down-regulation of PKC expression in the heart of adult offspring (Li et al, 2004;Bae et al, 2005;Zhang et al, 2007). A similar finding has been obtained in the present study showing that prenatal nicotine exposure significantly decreased cardiac PKC protein expression in adult offspring.…”

Effect of chronic heroin and cocaine administration on global DNA methylation in brain and liver

“…For instance, increased DNA methylation was observed in the OPRM1 gene in lymphocytes of former heroin users currently on methadone maintenance (Nielsen et al, 2009). Maternal exposure to cocaine was found to cause methylation of the AP-1 and SP1 binding sites and hyper-methylation of the promoter region of PKCε in the fetal rat heart Zhang et al, 2007Zhang et al, , 2009, as well as changes in the global methylation status of hippocampal pyramidal neurons (Novikova et al, 2008). Direct exposure to cocaine was found to cause hyper-methylation of the CDKL5 gene in the striatum (Carouge et al, 2010).…”

Primary Prevention of Atherosclerosis

“…40 In addition, prenatal exposure to cocaine or to hypoxia causes methylation of the activator protein-1 binding site of the protein kinase C-⑀ gene (PKC-⑀); this, in turn, leads to decreased expression of the kinase, which has a cardioprotective function after cardiac ischemia-reperfusion injury. 89,90 However, this evidence was obtained in rats; the same issues must be studied in humans before the epigenetic modifications of PKC-⑀ can be used to identify people eligible for primary prevention measures.…”