Endoplasmic reticulum stress-related deficits in calcium clearance promote neuronal dysfunction that is prevented by SERCA2 gene augmentation

Abstract

Disruption of calcium (Ca²⁺) homeostasis in neurons is a hallmark of neurodegenerative diseases. Here, we investigate the mechanisms leading to Ca²⁺ dysregulation and ask whether altered Ca²⁺ dynamics impinge on neuronal stress and circuit dysfunction. Using two-photon microscopy, we show that ocular hypertension, a major risk factor in glaucoma, and optic nerve crush injury disrupt the capacity of retinal neurons to clear cytosolic Ca²⁺ leading to impaired light-evoked responses. Gene- and protein expression analysis reveal the loss of the sarco-endoplasmic reticulum (ER) Ca²⁺-ATPase2 pump (SERCA2/ATP2A2) in injured retinal neurons from mice and patients with primary open-angle glaucoma. Pharmacological activation or neuron-specific gene delivery of SERCA2 is sufficient to rescue single-cell Ca²⁺ dynamics and promote robust survival of damaged neurons. Furthermore, SERCA2 gene supplementation reduces ER stress, reestablishes circuit balance, and restores visual behaviors. Our findings reveal that enhancing the Ca²⁺ clearance capacity of vulnerable neurons alleviates organelle stress and promotes neurorecovery.

Keywords: calcium homeostasis; endoplasmic reticulum stress; gene therapy; glaucoma; in vivo imaging; neurodegeneration; organelle stress; retinal ganglion cell; sarco-endoplasmic reticulum (ER) calcium-ATPase2 pump (SERCA2/ATP2A2); traumatic optic neuropathy.