Thursday, April 3, 2025
4/3/2025
Nicotinic receptor selective cell penetrating peptide for brain cargo delivery - ABSTRACT. In the U.S., major depressive disorder (MDD) is the most common mental disorder, with depression prevalence approaching 20% among adolescents and young adults. Current pharmacological treatments are unsatisfactory in that 33-55% of people suffering from MDD are non-responsive. MDD is associated with alterations in neurotransmitter systems including hypercholinergic tone modulated by nicotinic acetylcholine receptors (nAChRs) and decreased brain-derived neurotrophic factor (BDNF) expression. nAChRs are abundant in the central nervous system, and hypercholinergic tone, in part caused by α7-nAChR activation, is associated with depression. Pharmacologically desensitizing α7-nAChRs improves depressive symptoms in mice. Common serotonin and norepinephrine reuptake inhibitor therapies antagonize nAChRs non-selectivity (off target effect) and enhance BDNF levels at clinically effective doses. Excitingly, reducing expression of programmed cell death 4 (Pdcd4) protein, a translation inhibitor, by small interfering RNA (siRNA) delivered by a cell penetrating peptide (CPP), enhances BDNF expression to reverse depressive-like behaviors in mice. However, caution must be taken as CPPs interact broadly with cellular macromolecules and lipid bilayers resulting in uncontrolled cargo delivery. To begin to combat this issue, we developed an α7-nAChR selective CPP. Our preliminary data show that the lead CPP is not cytotoxic and can transport a fluorophore into neuronal-like cells by an α7-nAChR dependent mechanism. These underlying findings led us to our hypothesis that the novel lead CPP, a selective α7-nAChR antagonist, coupled with Pdcd4 siRNA may be able to achieve our important goal to help those suffering from MDD. Defining if the lead CPP can move siRNA cargo into cells and mammalian brain will remove critical barriers that stymie scientific and clinical MDD work, in addition to other conditions affected by α7-nAChR dysregulation. We will pursue the aims of this proposal by comparing cell culture and in vivo application of the lead CPP complexed with fluorophore-tagged siRNA to determine if the siRNA can be delivered to cause a cellular effect. We will combine live-cell confocal microscopy, brain imaging, western blot, and ELISA assays. Anticipated outcomes may also reveal potential utility of the lead CPP as a research tool. Application funding will provide foundational support for PI Weltzin’s progress towards becoming an independent researcher by demonstrating project feasibility, assay advancement, preliminary data generation, and a senior-author publication.
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