Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by homozygous mutation or deletion of the survival motor neuron 1 (SMN1) gene. A second copy, SMN2, is similar to SMN1 but produces ∼10% SMN protein because of a single-point mutation that causes splicing defects. Chronic low levels of SMN cause accumulation of co-transcriptional R-loops and DNA damage leading to genomic instability and neurodegeneration in SMA. Severity of SMA disease correlates inversely with SMN levels. SMN2 is a promising target to produce higher levels of SMN by enhancing its expression. Mechanisms that regulate expression of SMN genes are largely unknown. We report that zinc finger protein ZPR1 binds to RNA polymerase II, interacts in vivo with SMN locus and upregulates SMN2 expression in SMA mice and patient cells. Modulation of ZPR1 levels directly correlates and influences SMN2 expression levels in SMA patient cells. ZPR1 overexpression in vivo results in a systemic increase of SMN levels and rescues severe to moderate disease in SMA mice. ZPR1-dependent rescue improves growth and motor function and increases the lifespan of male and female SMA mice. ZPR1 reduces neurodegeneration in SMA mice and prevents degeneration of cultured primary spinal cord neurons derived from SMA mice. Further, we show that the low levels of ZPR1 associated with SMA pathogenesis cause accumulation of co-transcriptional RNA-DNA hybrids (R-loops) and DNA damage leading to genomic instability in SMA mice and patient cells. Complementation with ZPR1 elevates senataxin levels, reduces R-loop accumulation and rescues DNA damage in SMA mice, motor neurons and patient cells. In conclusion, ZPR1 is critical for preventing accumulation of co-transcriptional R-loops and DNA damage to avert genomic instability and neurodegeneration in SMA. ZPR1 enhances SMN2 expression and leads to SMN-dependent rescue of SMA. ZPR1 represents a protective modifier and a therapeutic target for developing a new method for the treatment of SMA.

Ahmad S, et al. Exp Neurobiol. 2019 Apr;28(2):216-228. https://doi.org/10.5607/en.2019.28.2.216

Background and Purpose: Neuroprotective strategies for stroke remain inadequate. Nanoliposomes comprised of phosphatidylcholine, cholesterol, and monosialogangliosides (nanoliposomes) induced an antioxidant protective response in endothelial cells exposed to amyloid insults. We tested the hypotheses that nanoliposomes will preserve human neuroblastoma (SH-SY5Y) and human brain microvascular endothelial cells viability following oxygen-glucose deprivation (OGD)–reoxygenation and will reduce injury in mice following middle cerebral artery occlusion. Methods: SH-SY5Y and human brain microvascular endothelial cells were exposed to oxygen-glucose deprivation–reoxygenation (3 hours 0.5%–1% oxygen and glucose-free media followed by 20-hour ambient air/regular media) without or with nanoliposomes (300 µg/mL). Viability was measured (calcein-acetoxymethyl fluorescence) and protein expression of antioxidant proteins HO-1 (heme oxygenase-1), NQO1 (NAD[P]H quinone dehydrogenase 1), and SOD1 (superoxide dismutase 1) were measured by Western blot. C57BL/6J mice were treated with saline (n=8) or nanoliposomes (10 mg/mL lipid, 200 µL, n=7) while undergoing 60-minute middle cerebral artery occlusion followed by reperfusion. Day 2 postinjury neurological impairment score and infarction size were compared. Results: SH-SY5Y and human brain microvascular endothelial cells showed reduced viability post–oxygen-glucose deprivation–reoxygenation that was reversed by nanoliposomes. Nanoliposomes increased protein expressions of HO-1, NQO1 in both cell types and SOD1 in human brain microvascular endothelial cells. Nanoliposomes-treated mice showed reduced neurological impairment and brain infarct size (18.8±2% versus 27.3±2.3%, P =0.017) versus controls. Conclusions: Nanoliposomes reduced stroke injury in mice subjected to middle cerebral artery occlusion likely through induction of an antioxidant protective response. Nanoliposome is a candidate novel agent for stroke.