Background: Elevation of cerebral cholesterol turnover in mice due to increased CYP46A1 expression has palliative effects on hallmarks of Alzheimer disease. Results: CYP46A1 could also be activated post-translationally by drugs in vitro and in vivo. Conclusion: CYP46A1 is a viable therapeutic target. Significance: Pharmacologic stimulation of CYP46A1 and cerebral cholesterol turnover may lead to new therapeutic strategies for the treatment of brain disorders.

Cytochrome P450 46A1 (cholesterol 24-hydroxylase) is an important brain enzyme that may be inhibited by structurally distinct pharmaceutical agents both in vitro and in vivo. To identify additional inhibitors of CYP46A1 among U.S. Food and Drug Administration-approved therapeutic agents, we used in silico and intuitive predictions and evaluated some of the predicted binders in the enzyme and spectral binding assays. We tested a total of 298 marketed drugs for the inhibition of CYP46A1-mediated cholesterol hydroxylation in vitro and found that 13 of them reduce CYP46A1 activity by Ͼ50%. Of these 13 inhibitors, 7 elicited a spectral response in CYP46A1 with apparent spectral K d values in a low micromolar range. One of the identified tight binders, the widely used antidepressant fluvoxamine, was cocrystallized with CYP46A1. The structure of this complex was determined at a 2.5 Å resolution and revealed the details of drug binding to the CYP46A1 active site. The NH 2 -containing arm of the Y-shaped fluvoxamine coordinates the CYP46A1 heme iron, whereas the methoxy-containing arm points away from the heme group and has multiple hydrophobic interactions with aliphatic amino acid residues. The CF 3 -phenyl ring faces the entrance to the substrate access channel and has contacts with the aromatic side chains. The crystal structure suggests that only certain drug conformers can enter the P450 substrate access channel and reach the active site. Once inside the active site, the conformer probably further adjusts its configuration and elicits the movement of the protein side chains.

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We report 2 episodes of potential SARS-CoV-2 transmission from infected van drivers to passengers despite masking and physical distancing. Whole-genome sequencing confirmed relatedness of driver and passenger SARS-CoV-2. With the heater operating, fluorescent microspheres were transported by airflow >3 meters from the front to the back of the van.