Zinc Finger Protein 746 is a Driver of Neuronal Death Following Cerebral Ischemia

Sunday, May 5, 2024

4:09 PM – 4:13 PM CT

Location: S405a

Presenting Author(s)

Jaimin C. Patel, BS

Medical Student
Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
Baltimore, MD, US

Co-Author(s)

SC

Suyi Cao, MD

Research Associate
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA, Maryland, United States
RC

Rong Chen, PhD

Senior Research Specialist
Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA, Maryland, United States
TD

Ted M. Dawson, MD PhD

Director
Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
Baltimore, Maryland, United States
VD

Valina L. Dawson, PhD

Director
Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
Baltimore, Maryland, United States
BK

Bong Gu Kang, PhD

Research Associate
Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, John Hopkins University
Baltimore, Maryland, United States
MK

Mohammed F. Khan, PhD

Research Associate
Johns Hopkins University School of Medicine
Baltimore, Maryland, United States
HW

Hu Wang, PhD

Research Associate
Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine
Baltimore, Maryland, United States

Disclosure(s):

Jaimin C. Patel, BS: No financial relationships to disclose

Introduction: Parkin is an E3 ubiquitin ligase that decreases in expression following cerebral ischemia. However, the mechanism of its downregulation and the contributions of its substrates toward neuronal death in ischemic stroke is unknown. Zinc Finger Protein 746, also known as parkin interacting substrate (PARIS), is a parkin substrate that drives neurodegeneration in Parkinson’s disease through transcriptional repression of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α). In this study, we explore the mechanisms by which parkin downregulation occurs and whether PARIS is a driver of neuronal death in cerebral ischemia.

Methods: Wildtype and PARIS gene knockout (KO) mice aged 3-4 months underwent a sham procedure or middle cerebral artery occlusion (MCAO) for 45 minutes. A blinded observer scored mice on a five-point scale after MCAO, with zero being no deficit and five being comatose. Brain samples were subsequently isolated for infarct volume assessment, western blot, or immunofluorescence at prespecified time points.

Results: PARIS expression is increased at 6 hours following ischemia (p < 0.001), and parkin (p=0.0050) as well as PGC-1α (p=0.031) expression are decreased at 24 hours following ischemia. Parkin becomes increasingly autoubiquitinated at 4 hours post-MCAO (p=0.0080). PARIS KO mice had diminished neurological deficit (WT = 3.6, KO = 1.4, p = 0.0015) and infarct volume at 1 day following focal ischemia (WT = 86.7 mm^3, KO = 22.6 mm^3, p < 0.001). Gamma phosphorylation of the histone H2A.X variant (yH2AX) in neuronal nuclei was attenuated in the peri-infarct region of PARIS KO mice (p = 0.0087).

Conclusion : Our data suggests parkin becomes downregulated by its own proteasomal degradation, and, consequently, PARIS is dramatically upregulated following cerebral ischemia, driving neuronal death. PARIS KO is markedly neuroprotective and reduces neuronal double-stranded DNA break burden, as quantified by yH2AX levels. PARIS inhibition may, therefore, be a viable neuroprotective strategy in patients experiencing an ischemic stroke.