The Antidepressant Sertraline Targets Intracellular Vesiculogenic Membranes in Yeast

Abstract

Numerous studies have shown that the clinical antidepressant sertraline (Zoloft) is biologically active in model systems, including fungi, which do not express its putative protein target, the serotonin/5-HT transporter, thus demonstrating the existence of one or more secondary targets. Here we show that in the absence of its putative protein target, sertraline targets phospholipid membranes that comprise the acidic organelles of the intracellular vesicle transport system by a mechanism consistent with the bilayer couple hypothesis. On the basis of a combination of drug-resistance selection and chemical-genomic screening, we hypothesize that loss of vacuolar ATPase activity reduces uptake of sertraline into cells, whereas dysregulation of clathrin function reduces the affinity of membranes for sertraline. Remarkably, sublethal doses of sertraline stimulate growth of mutants with impaired clathrin function. Ultrastructural studies of sertraline-treated cells revealed a phenotype that resembles phospholipidosis induced by cationic amphiphilic drugs in mammalian cells. Using reconstituted enzyme assays, we also demonstrated that sertraline inhibits phospholipase A 1 and phospholipase D, exhibits mixed effects on phospholipase C, and activates phospholipase A 2 . Overall, our study identifies two evolutionarily conserved membrane-active processes-vacuolar acidification and clathrin-coat formation-as modulators of sertraline's action at membranes. S ERTRALINE, whose trade name is Zoloft, is a Food and Drug Administration (FDA) approved drug that belongs to the pharmacological class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) (Koe et al. 1983). The putative therapeutic target of SSRIs is the human serotonin/5-HT transporter (hSERT/5-HTT/SLC6A4), an integral membrane protein that mediates sodium-dependent reuptake of the monoamine neurotransmitter serotonin at presynaptic nerve terminals in the brain (Tatsumi et al. 1997;Mortensen et al. 2001;Meyer et al. 2004). Indeed, the recent crystal structure of sertraline bound to a bacterial leucine transporter, LeuT-a homolog of mammalian monoamine transporters-has led to the proposal of a corresponding high-affinity binding site for sertraline in hSERT (Zhou et al. 2009). Inhibition of hSERT-dependent reuptake by sertraline is thought to underlie its antidepressant effect in people, as documented extensively over the last two decades in the clinical psychiatric literature (reviewed in Cipriani et al. 2009).However, there are numerous examples of sertraline's effects on cellular physiology, including, most curiously, cytotoxicity in yeast (Lass-Flö rl et al. 2001a,b), by an unknown mechanism that does not involve hSERT, suggesting the existence of one or more heretofore unrecognized secondary drug targets that may be evolutionarily conserved (Levkovitz et al. 2007;Reddy et al. 2008). Those observations, coupled with reports that antidepressants can accumulate in the brains of people to concentrations at which ''off-target'' effects are see...

The Antidepressant Sertraline Provides a Promising Therapeutic Option for Neurotropic Cryptococcal Infections

“…Sertraline displays extremely broad antiproliferation activity against evolutionarily diverse organisms (10, 12-15, 19, 20, 23). Recent studies indicate the influence of sertraline on membrane stability or vesicle transport in fungi (27,30). The results of our S. cerevisiae mutant screens are consistent with these discoveries.…”

“…Gene ontology analyses indicated that these genes are enriched for those with roles in intracellular vesicle transport and membrane organization (Fig. 4), which is consistent with the findings of two recent studies of the effects of sertraline on yeast (27,30). Interestingly, genes related to protein synthesis are highly enriched in the resistant group; the most sensitive mutant selected from our screen was strain ⌬tif3, in which an important translation initiation factor Tif3 was disrupted.…”

“…One report attributed the antifungal activity of sertraline to a nonspecific cytotoxicity due to its lipophilicity (37). However, findings of two recent studies suggested membrane organization and vesicle-mediated transport as its antifungal targets (27,30). Sertraline was also shown to possess antitumor activity (15,16,32).…”

In Vitro Antifungal Activity of Sertraline and Synergistic Effects in Combination with Antifungal Drugs against Planktonic Forms and Biofilms of Clinical Trichosporon asahii Isolates

“…A genetic study suggests that SRT may exert antifungal effect by perturbing translation and inhibiting protein synthesis of fungi [16]. Rainey et al demonstrated that SRT may exhibit antifungal activity by targeting intracellular vesiculogenic phospholipid membranes in fungi [37]. Another study demonstrated that SRT can perturb membrane permeability and inhibit sphingolipid biosynthesis in fungi [38].…”

Sertraline demonstrates fungicidal activity in vitro for Coccidioides immitis

“…Sertraline was again identified as an antifungal drug using in vitro screens for off-label antifungal activity of medications currently approved for other clinical uses (Zhai et al 2012; Butts et al 2013). The mechanism of fungicidal action of sertraline may include both inhibition of intracellular vesicular transport (Rainey et al 2010) and inhibition of protein translation (Zhai et al 2012). Interestingly, sertraline and other serotonin reuptake inhibitors are also being actively investigated for both intrinsic antimicrobial activity and combination treatment of antibiotic-resistant bacteria (Ayaz et al 2015a, 2015b).…”