Modification of ubiquitin-C-terminal hydrolase-L1 by cyclopentenone prostaglandins exacerbates hypoxic injury

Cyclopentenone prostaglandins (CyPGs), such as 15-deoxy-Δ12,14 -prostaglandin J2 (15d-PGJ2), are active prostaglandin metabolites exerting a variety of biological effects that may be important in the pathogenesis of neurological diseases. Ubiquitin-C-terminal hydrolase L1 (UCH-L1) is a brain specific deubiquitinating enzyme whose aberrant function has been linked to neurodegenerative disorders. We report that [15d-PGJ2] detected by quadrapole mass spectrometry (MS) increases in rat brain after temporary focal ischemia, and that treatment with 15d-PGJ2 induces accumulation of ubiquitinated proteins and exacerbates cell death in normoxic and hypoxic primary neurons. 15d-PGJ2 covalently modifies UCH-L1 and inhibits its hydrolase activity. Pharmacologic inhibition of UCH-L1 exacerbates hypoxic neuronal death while transduction with a TAT–UCH-L1 fusion protein protects neurons from hypoxia. These studies indicate that UCH-L1 function is important in hypoxic neuronal death and that excessive production of CyPGs after stroke may exacerbate ischemic injury by modification and inhibition of UCH-L1.

Research Highlights►The cyclopentenone prostaglandin 15-deoxy-∆ 12, 14 prostaglandin J2 concentration is increased in rat brain after temporary focal ischemia. ►Treatment with 15-deoxy-∆ 12, 14 prostaglandin J2 increases accumulation of ubiquitinated proteins and exacerbates hypoxic cell death in primary neurons. ►15-deoxy-∆ 12, 14 prostaglandin J2 and other prostaglandin D metabolites bind to UCH-L1 and affect the enzyme's activity. This modification is increased after hypoxia in primary neurons. ►Restoring UCH-L1 activity by transduction of primary neurons with a TAT UCH-L1 fusion protein protected neurons, while inhibition of UCH-L1 exacerbated hypoxic injury.