Neuronal overexpression of IP3 receptor 2 is detrimental in mutant SOD1 mice

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease causing progressive paralysis of the patient followed by death on average 3-5 years after diagnosis. Disease pathology is multi-factorial including the process of excitotoxicity that induces cell death by cytosolic Ca2+ overload. In this study, we increased the neuronal expression of an endoplasmic reticulum (ER) Ca2+ release channel, inositol 1,4,5-trisphosphate receptor 2 (IP(3)R2), to assess whether increased cytosolic Ca2+ originating from the ER is detrimental for neurons. Overexpression of IP(3)R2 in N2a cells using a Thy1.2-IP(3)R2 construct increases cytosolic Ca2+ concentrations evoked by bradykinin. In addition, mice generated from this construct have increased expression of IP(3)R2 in the spinal cord and brain. This overexpression of IP(3)R2 does not affect symptom onset, but decreases disease duration and shortens the lifespan of the ALS mice significantly. These data suggest that ER Ca2+ released by IP3 receptors may be detrimental in ALS and that motor neurons are vulnerable to impaired Ca2+ metabolism. (C) 2012 Elsevier Inc. All rights reserved.