Two Sodium/Calcium Exchanger Gene Products, NCX1 and NCX3, Play a Major Role in the Development of Permanent Focal Cerebral Ischemia

Abstract

Background and Purpose— The Na + /Ca 2+ exchanger, by mediating Ca 2+ and Na + fluxes in a bidirectional way across the synaptic plasma membrane, may play a pivotal role in the events leading to anoxic damage. In the brain, there are 3 different genes coding for 3 different proteins: NCX1, NCX2, and NCX3. The aim of this study was to determine whether NCX1, NCX2, and NCX3 might play a differential role in the development of cerebral injury induced by permanent middle cerebral artery occlusion (pMCAO). Methods— By means of Western blotting, NCX1, NCX2, and NCX3 protein expression was evaluated in the ischemic core and in the remaining nonischemic area of the slice at different time intervals starting from ischemia induction. The role of each isoform was also assessed with antisense oligodeoxynucleotides (ODNs) targeted for each isoform. These ODNs were continuously intracerebroventricularly infused with an osmotic minipump (1 μL/h) for 48 hours, 24 hours before pMCAO. Results— The results showed that after pMCAO all 3 NCX proteins were downregulated in ischemic core; NCX3 decreased in periinfarctual area whereas NCX1 and NCX2 were unchanged. The ODNs for NCX1 and NCX3 gene products were capable of inducing an increase in the ischemic lesion and to worsen neurological scores. Conclusions— The results of this study suggest that in the neuroprotective effect exerted by NCX during ischemic injury, the major role is prevalently exerted by NCX1 and NCX3 gene products.

Silencing or knocking out the Na+/Ca2+ exchanger-3 (NCX3) impairs oligodendrocyte differentiation

“…Indeed, mice lacking NCX3 by silencing or transgenic approaches, show an enhanced cellular vulnerability to hypoxic-ischemic insults 30 and a worsening of the infarct area after stroke. 12,14 More recently, NCX3 has also been proposed as a new molecular effector involved in the neuroprotective effect of ischemic post-conditioning. 31 In agreement with the beneficial role of this exchanger, it has been demonstrated that NCX3-deficient mice show skeletal muscle fiber necrosis and impaired neuromuscular transmission, which is clinically associated with reduced motor activity, weakness of forelimb muscles, and fatigability.…”

“…[5][6][7] The Na þ /Ca 2 þ exchanger (NCX), 8 a transmembrane domain protein, which, by operating in a bidirectional way, couples the efflux of Ca 2 þ to the influx of Na þ into the cell or, vice versa, the influx of Ca 2 þ to the efflux of Na þ , is involved in the regulation of diverse neuronal and glial cell functions. 8,9 Furthermore, NCX is involved in regulating intracellular Ca 2 þ concentration under pathological conditions and has been proposed as a potential therapeutic target in different disorders of the nervous system, including de-myelinating conditions such as MS, 10,11 ischemia-reperfusion injury, [12][13][14] and spinal cord injury. 15,16 Three different ncx1, ncx2, and ncx3 genes have been identified in mammals.…”

Targeted Disruption of Na+/Ca2+Exchanger 3 (NCX3) Gene Leads to a Worsening of Ischemic Brain Damage

“…Furthermore, NCX3 mRNA and protein downregulation, induced by the overexpression of DREAM (downstream regulatory element antagonist modulator), increases the mortality rate of cerebellar granule cells (Gomez-Villafuertes et al, 2005). In addition, ischemic rats treated with NCX3 antisense displayed a remarkable broadening of the infarct volume (Pignataro et al, 2004b). In agreement with this vicarious function proposed for NCX3, our recent in vivo experiments, entailing the induction of permanent MCAo in rats, have demonstrated that NCX3 mRNA is upregulated 24 h after the injury in brain regions belonging to the periinfarct area (Boscia et al, 2006b).…”

“…Another element of complexity in the role played by NCX in the events leading to anoxic neurodegeneration is the existence of three different gene products, NCX1, NCX2, and NCX3 (Philipson and Nicoll, 2000;Annunziato et al, 2004), which indeed display different expression patterns in the brain under physiological (Papa et al, 2003) and pathophysiological (Boscia et al, 2006b) conditions. Particularly, in the ischemic core region, NCX1, NCX2, and NCX3 mRNAs and proteins are downregulated in those areas surviving the ischemic insult (Pignataro et al, 2004b;Boscia et al, 2006b). In contrast, in the periischemic area, NCX2 is downregulated, whereas NCX3 is upregulated (Boscia et al, 2006b).…”

Disruption of ionic and cell volume homeostasis in cerebral ischemia: The perfect storm

“…The protective effect of KB-R7943 has been explained by its potent hypothermic actions [108]. Importantly, in vivo downregulation of NCX1 and NCX3, but not NCX2, using phosphorothioated antisense oligonucleotides, strongly increased infarction volumes and neurological deficits in a rat permanent focal ischemia model [110]. Consistent with the latter data, two NCX blockers, bepridil and the more selective CB-DMB, produced an irreversible loss of electrical activity in striatal spiny neurons in the penumbra of focal ischemia, as compared to untreated ischemic controls [111].…”