Thursday, April 25, 2024
4/25/2024
The last step in the cholesterol biosynthesis pathway is conversion of 7-dehydrocholesterol (7-DHC) to cholesterol, catalyzed by a single enzyme, 7-dehyrocholesterol reductase (DHCR7). To date, >150 DHCR7 loss-of-function mutations have been identified, with >1% heterozygous carriers in the human population. Heterozygous carriers have elevated 7-DHC levels. It has been well documented that 7-DHC is toxic, and its numerous spontaneous oxidative products (oxysterols) have disruptive effects on normal cell division and differentiation. 7-DHC levels can also markedly increase as a result of drug treatment. We recently performed a high throughput drug screening and found that aripiprazole (ARI- an atypical antipsychotic) and trazodone (TRZ - an antidepressant) both strongly increased 7-DHC levels. Further literature review revealed that ARI- and TRZ-treated patients have elevated 7-DHC levels, misclassifying some them as SLOS patients - even when they had two intact copies of the Dchr7 gene. In a follow-up experiments we observed that peripheral dermal fibroblasts from human DHCR7+/- mutation carriers also had elevated 7-DHC levels at baseline, which worsened as a result of ARI exposure. Our newest data indicate that ARI treatment of pregnant Dhcr7+/- mice have deleterious effects on the development of the offspring. Based on these data, we hypothesize that ARI/TRZ exposure and DHCR7+/- mutations potentiate each other, elevating 7-DHC levels into a pathological range. As a result, the spontaneous, toxic metabolites of 7-DHC will alter neural development and/or brain function, especially when DHCR7+/- mutation carrier mothers have DHCR7+/- offspring exposed to ARI or TRZ. We will test this central hypothesis in a patient-derived fibroblast model (Aim 1) and neurodevelopmental transgenic mouse models (Aims 2-3) at two different time points using a maternal genotype*offspring genotype*treatment paradigm. Aripiprazole, marketed under the name of Ablilify® is the most prescribed drug in the US, and the possibility that heterocyclic cationic amphiphile exposure might be deleterious to >1% of the human DHCR7+/- mutation carriers warrants further investigation. Developing personalized medicine approaches requires understanding Gene*Treatment interactions, and knowing the interaction between maternal genotype*offspring genotype*treatment is necessary to precisely define the population that is potentially vulnerable to ARI/TRZ exposure.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).
