title: Small molecule activation of adaptive gene expression: tilorone or its analogs are novel potent activators of hypoxia inducible factor-1 that provide prophylaxis against stroke and spinal cord injury.
abstract: A major challenge for neurological therapeutics is the development of small molecule drugs that can activate a panoply of downstream pathways without toxicity. Over the past decade our group has shown that a family of enzymes that regulate posttranscriptional and transcriptional adaptive responses to hypoxia are viable targets for neuronal protection and repair. The family is a group of iron, oxygen, and 2-oxoglutarate-dependent dioxygenases, known as the HIF prolyl 4-hydroxylases (HIF PHDs). We have previously shown that pluripotent protection offered by iron chelators is mediated, in part, via the ability of these agents to inhibit the HIF PHDs. Our group and others have implicated the transcriptional activator HIF-1 in some of the salutary effects of iron chelation-induced PHD inhibition. While some iron chelators are currently employed in humans for conditions such as hemochromatosis, the diverse utilization of iron in physiological processes in the brain makes the development of HIF activators that do not bind iron a high priority. Here we report the development of a high throughput screen to develop novel HIF activators and/or PHD inhibitors for therapeutic use in the central nervous system (CNS). We show that tilorone, a low-molecular weight, antiviral, immunomodulatory agent is the most effective activator of the HIF pathway in a neuronal line. We also show that tilorone enhances HIF protein levels and increases the expression of downstream target genes independent of iron chelation and HIF PHD inhibition in vitro. We further demonstrate that tilorone can activate an HIF-regulated reporter gene in the CNS. These studies confirm that tilorone can penetrate the blood-brain barrier to activate HIF in the CNS. As expected from these findings, we show that tilorone provides effective prophylaxis against permanent ischemic stroke and traumatic spinal cord injury in male rodents. Altogether these findings identify tilorone as a novel and potent modulator of HIF-mediated gene expression in neurons with neuroprotective properties.
authors.affiliation: Burke-Cornell Medical Research Institute, Weill Medical College of Cornell University, White Plains, NY 10605, USA. rratan@burke.org
authors.forename: Rajiv R
authors.initials: RR
authors.lastname: Ratan
authors.forename: Ambreena
authors.initials: A
authors.lastname: Siddiq
authors.forename: Leila
authors.initials: L
authors.lastname: Aminova
authors.forename: Brett
authors.initials: B
authors.lastname: Langley
authors.forename: Stephen
authors.initials: S
authors.lastname: McConoughey
authors.forename: Ksenia
authors.initials: K
authors.lastname: Karpisheva
authors.forename: Hsin-Hwa
authors.initials: HH
authors.lastname: Lee
authors.forename: Thomas
authors.initials: T
authors.lastname: Carmichael
authors.forename: Harley
authors.initials: H
authors.lastname: Kornblum
authors.forename: Giovanni
authors.initials: G
authors.lastname: Coppola
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Geschwind
authors.forename: Ahmet
authors.initials: A
authors.lastname: Hoke
authors.forename: Natalya
authors.initials: N
authors.lastname: Smirnova
authors.forename: Cameron
authors.initials: C
authors.lastname: Rink
authors.forename: Sashwati
authors.initials: S
authors.lastname: Roy
authors.forename: Chandan
authors.initials: C
authors.lastname: Sen
authors.forename: Michael S
authors.initials: MS
authors.lastname: Beattie
authors.forename: Ron P
authors.initials: RP
authors.lastname: Hart
authors.forename: Martin
authors.initials: M
authors.lastname: Grumet
authors.forename: Dongming
authors.initials: D
authors.lastname: Sun
authors.forename: Robert S
authors.initials: RS
authors.lastname: Freeman
authors.forename: Gregg L
authors.initials: GL
authors.lastname: Semenza
authors.forename: Irina
authors.initials: I
authors.lastname: Gazaryan
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D015870:Gene Expression / Q000187:drug effects*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000819:agonists*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000517:prevention & control*; D020521:Stroke / Q000517:prevention & control*; D013994:Tilorone / Q000494:pharmacology*
chemical_list: C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D013994:Tilorone