Small Molecule Activation of Adaptive Gene Expression

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.

Machine learning models identify molecules active against the Ebola virus in vitro

“…Tilorone is an investigational agent that has been known for over 40 years as an antiviral 56 and is an inducer of interferon in mice 57 . It has been shown to possess a broad array of biological activities including cell growth inhibition in PC3 CDK5dn prostate cancer cells (IC 50 8–12 μM) 58 , inhibition of Primase DnaG from Bacillus anthracis (IC 50 7.1 μM) 59 , in a mouse model of pulmonary fibrosis it decreased lung hydroxyproline content and the expression of collagen genes 60 , α7 nicotinic receptor (nAChR) agonist activity (K i 56 nM) 61 , activated human alpha7 nAChR with an EC 50 value of 2.5 μM 62 , radioprotective activity 63 , potent modulation of HIF-mediated gene expression in neurons with neuroprotective properties 64 and induction of the accumulation of glycosaminoglycans, delay infectious prion clearance, and prolong prion disease incubation time 65 . Quinacrine is an old antimalarial drug now more widely used as an antiprotozoal for the treatment of giardiasis 66 and as an anthelmintic.…”

Efficacy of Tilorone Dihydrochloride against Ebola Virus Infection

“…Other biologically important activities include ␣7 nicotinic receptor (nAChR) agonist activity (K i , 56 nM) (16) and activated human alpha7 nAChR with an EC 50 of 2.5 M (17), which is a target for various central nervous system diseases. Tilorone was also shown to have radioprotective activity (18), potent modulation of HIF-mediated gene expression in neurons with neuroprotective properties (19), induction of the accumulation of glycosaminoglycans, delayed infectious prion clearance, and prolonged prion disease incubation time (20).…”

“…Sold under the trade name Amixin or Lavomax, tilorone is approved for use in Russia, Ukraine, Kazakhstan, Belarus, Armenia, Georgia, Kyrgyzstan, Moldova, Turkmenistan, and Uzbekistan for multiple viral disease indications (i.e., influenza, acute respiratory viral infection, viral hepatitis, viral encephalitis, myelitis, and others) and is included in the list of vital and essential medicines of the Russian Federation. Tilorone has a broad array of biological activities (13)(14)(15)(16)(17)(18)(19)(20) and was first reported to be a small-molecule interferon (IFN) inducer with broad-spectrum antiviral activities (21)(22)(23). IFNs are pleiotropic cytokines with a long history of involvement in the development and treatment of viral infections and can inhibit viral replication by direct or indirect means such that combining IFNs with other antiviral drugs is a proven clinical strategy.…”

Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by “antioxidant” metal chelators: From ferroptosis to stroke

“…For example, HRE-luciferase expressed in an immortalized mouse striatal neuron cell line, HT22, was used for high-throughput screening of drugs that activate HIF-mediated transcription [116]. These constructs are valuable tools for assaying an endpoint of HIF activation, but do not provide mechanistic insight regarding HIF regulation.…”