Jensen, A. A. | bioRxiv Science

bioRxiv2024

The selective 5-HT2A receptor agonist LPH-5 induces persistent and robust antidepressant-like effects in rodents

Psychedelic-assisted psychotherapy has over the last decade emerged as a promising treatment strategy for mental health disease, and the therapeutic potential in classical psychedelics such as psilocybin, LSD and 5-MeO-DMT is presently being pursued in a plethora of clinical trials. However, the resurgent interest in the drugs as therapeutics has also prompted a search for novel agents with more specific pharmacological activities than the rather promiscuous classical psychedelics. Here we present the results of an elaborate preclinical characterization of one such compound, LPH-5 [(S)-3-(2,5-dimethoxy-4-(trifluoromethyl)phenyl)piperidine]. LPH-5 was found to be a potent partial agonist at the 5-HT2A receptor (5-HT2AR) and to exhibit pronounced selectivity for this receptor over the related 5-HT2B and 5-HT2C receptors in a range of functional assays. LPH-5 (0.375 - 12.0 mg/kg, i.p.) dose-dependently induced head-twitch responses (HTR) in Sprague Dawley rats, with substantial 5-HT2AR engagement being observed at 0.5-1.0 mg/kg. Acute administration of LPH-5 (1.5 mg/kg, i.p.) induced robust antidepressant-like effects in Flinders Sensitive Line rats and adrenocorticotropic hormone-treated Sprague Dawley rats, and LPH-5 (0.3 and 1.5 mg/kg, i.p.) induced significant effects in a recently developed Wistar Kyoto rat model proposed to reflect the long-term antidepressant-like effects produced by psychedelics in humans. In conclusion, selective 5-HT2AR activation, as mediated here by LPH- 5, seems to hold antidepressant potential, suggesting that this activity component is key for the beneficial effects of classical psychedelics. Hence, we propose that LPH-5 and other 5-HT2AR- selective agonists could hold potential as therapeutics in psychiatric disease as a new generation of psychedelic-derived antidepressant.

neuroscience↗

bioRxiv2022

In vivo and In vitro Characterization of the ClpC AAA+ ATPase of Chlamydia trachomatis

Bacterial AAA+ unfoldases are crucial for bacterial physiology by recognizing specific substrates and, typically, unfolding them for degradation by a proteolytic component. The caseinolytic protease (Clp) system is one example where a hexameric unfoldase (e.g., ClpC) interacts with the tetradecameric proteolytic core ClpP. Unfoldases can have both ClpP-dependent and ClpP-independent roles in protein homeostasis, development, virulence, and cell differentiation. ClpC is an unfoldase predominantly found in Gram-positive bacteria and mycobacteria. Intriguingly, the obligate intracellular Gram-negative pathogen Chlamydia, an organism with a highly reduced genome, also encodes a ClpC ortholog, implying an important function for ClpC in chlamydial physiology. Here, we used a combination of in vitro and in vivo approaches to gain insight into the function of chlamydial ClpC. ClpC exhibits intrinsic ATPase and chaperone activities, with a primary role for the Walker B motif in the first nucleotide binding domain (NBD1). Furthermore, ClpC binds ClpP1P2 complexes via ClpP2 to form the functional protease ClpCP2P1 in vitro, which degraded arginine-phosphorylated {beta}-casein. In vivo experiments confirmed that higher order complexes of ClpC are present in chlamydial cells. Importantly, the in vivo data further revealed severe negative effects of both overexpression and depletion of ClpC in Chlamydia as revealed by a significant reduction in chlamydial growth. Here again, NBD1 was critical for ClpC function. Hence, we provide the first mechanistic insight into the molecular and cellular function of chlamydial ClpC, which supports its essentiality in Chlamydia. ClpC is, therefore, a potential novel target for the development of anti-chlamydial agents. SignificanceChlamydia trachomatis is an obligate intracellular pathogen and the worlds leading cause of preventable infectious blindness and bacterial sexually transmitted infections. Due to the high prevalence of chlamydial infections along with negative effects of current broad-spectrum treatment strategies, new anti-chlamydial agents with novel targets are desperately needed. In this context, bacterial Clp proteases have emerged as promising new antibiotic targets, since they often play central roles in bacterial physiology and, for some bacterial species, are even essential for survival. Here, we report on the chlamydial AAA+ unfoldase ClpC, its functional reconstitution and characterization, individually and as part of the ClpCP2P1 protease, and establish an essential role for ClpC in chlamydial growth and intracellular development, thereby identifying ClpC as a potential target for anti-chlamydial compounds.

microbiology↗