7A). decreased by a treatment of ethanol (100 M) in Park2 siRNA-transfacted PC12 cells (5 M). Moreover, the exacerbating effects of Park2 deletion on ethanol-induced ROS generation, mitophagy, mitochondrial dysfunction as well as cell death were reduced by p38 specific inhibitor (SB203580) in in vitro (10 M) and in vivo 10 mg/kg). Park2 deficiency exacerbates ethanol-induced dopaminergic neuron damage through p38 kinase dependent inhibition of autophagy and mitochondrial function. Keywords: Autophagy, Mitochondrial function, Neurodegeneration, Park2, Parkinson disease (PD) == Highlights == EtOH consumption can induce the ROS formation through activation of p38 MAPK. ROS can cause the neurodegeneration through inhibition of the autophagy system. Park2 knock down amplifies EtOH-induced decrement of autophagy. Park2 knock down amplifies EtOH-induced mitochondrial dysfunction. Park2 has a neuroprotective effect against ROS mediated damage of neuron. == 1 . Introduction == Park2, which encodes Parkin, is the most frequently mutated gene that has casually been linked to autosomal recessive early onset familial Parkinson’s disease (PD)[1]. Abnormalities of Parkin have also been described in sporadic PD[2]. Parkin is an E3 ubiquitin ligase that provides specificity for the process of tagging proteins with ubiquitin for degradation in the ubiquitin proteasome system[3]. Evidence implicating a direct role intended for the ubiquitination in PD came from the association of genetic mutations in the parkin gene with familial parkinsonism[1], and several studies demonstrated that parkin acts as a ubiquitin ligase associated with proteasomal degradation[4],[5],[6]. This property of parkin thus directly related with ubiquitination for dopaminergic neuronal survival[7]. The exact mechanism SERPINF1 by which Parkin causes PD-like syndromes and why dopaminergic neurons are primarily affected by a ubiquitously expressed mutation remain unclear[8],[9]. However , several studies suggest that Parkin interacts with PINK1 (PTEN-induced putative kinase 1; also known as PARK6), another gene mutated in autosomal recessive familial form of PD[10]to regulate mitochondrial biology, and alters mitochondrial dynamics[11]. Recently, a study performed Elastase Inhibitor with cultured cells has shown that Parkin can mediate autophagy on damaged mitochondria[12]. The relation between Parkin and mitochondrial biology was first established in Drosophila, which displayed impairment in mitochondrial function and neuronal loss in an age-dependent manner when rendered deficient for Elastase Inhibitor Parkin[13]. Likewise, similar mitochondrial defects were exhibited in Park2 knockout (KO) mouse models although only mice with conditional KO of Park2 recapitulate parkinsonian phenotype and striatonigral degeneration[14]. More recently, post-mortem brain tissues of PD patients also confirmed the involvement of altered mitochondrial pathologies in the disease process[15]. Parkin Elastase Inhibitor has a protective effect against a diversity of insults. More importantly, viral over-expression of parkin protected midbrain dopaminergic neurons against acute a-synuclein damage in primary culture[16]and rat brain[17]as well as in Drosophila melanogaster[18]. It was also found that parkin expression was protective against 6-hydroxydopamine neurotoxicity in rat brain[19]. Parkin over-expression also protected SH-SY5Y human neuroblastoma cells against oxidative dopamine neurotoxicity[20]. The neuroprotective function of parkin has also been suggested to result from its selective recruitment to damaged mitochondria, where it promotes the autophagic removal of the reactive oxygen species (ROS)-generating organelles[12]. ROS are chemically reactive chemical species containing oxygen such as peroxides, superoxide, hydroxyl radical, and singlet oxygen[21]. In a biological context, ROS have important roles in cell signaling and homeostasis[22]. However , during times of environmental stress, ROS levels can increase, and this may result in significant damage to cell structures[22]. It has been reported that hydrogen peroxide (H2O2) is able to trigger the p38 kinase to induce apoptosis[23]. In PD conditions, oxidative stress is a major cause of neuronal death. Studies with PD-like symptoms elicited animal models have shown that extracellular superoxideO2production results in the activation of microglial cells which subsequently attack neighboring dopaminergic neurons[24]. Many studies have already demonstrated that several kinds of ROS can induce Elastase Inhibitor the activation of the mitogen-activated.
