Biology subjects

Lee, J. I.

Publications and source records attributed to Lee, J. I..

5 recordsLinked to original sources

bioRxiv2026

Contribution of the novel oxazolidinone TBD09 (MK-7762) to regimens with bedaquiline and pretomanid in a mouse model of tuberculosis

Linezolid is a key component of the bedaquiline, pretomanid, linezolid (BPaL) regimen for rifampin-resistant tuberculosis, but dose- and duration-dependent mitochondrial toxicity frequently limits its use. TBD09 (formerly MK-7762) is a novel oxazolidinone developed to maintain antitubercular potency comparable to linezolid while reducing related adverse events. We evaluated the contribution of TBD09 to the bactericidal and sterilizing activities of BPa-based regimens in a murine tuberculosis model. BALB/c mice were aerosol-infected with Mycobacterium tuberculosis H37Rv and treated starting 2 weeks post-infection. In Experiment 1, dose-ranging bactericidal activity of TBD09 (50, 100, 200 mg/kg) was assessed alone and in combination with BPa, with comparison to linezolid and sutezolid. In Experiment 2, the sterilizing activity of TBD09 (200 mg/kg) in combination with BPa and BPa plus moxifloxacin (M) was assessed by evaluating relapse after treatment durations of 4-22 weeks. TBD09 monotherapy was bacteriostatic, similar to linezolid over the first 4 weeks of treatment. The addition of TBD09 to BPa significantly enhanced bactericidal activity comparable to the addition of linezolid. In relapse assessments, BPa+TBD09 resulted in significantly fewer relapses compared to BPa alone after 14 weeks of treatment, and BPaM+TBD09 resulted in significantly fewer relapses compared to BPaM after 10 weeks. Model-based analysis estimated the treatment duration to 95% cure for BPa+TBD09 at 2.7 weeks, compared to 3.2 weeks for BPaL, although the time to 50% cure was similar. These results demonstrate that TBD09 provides bactericidal and sterilizing activity similar to linezolid in combination with BPa(M), supporting further clinical development of TBD09 for tuberculosis.

microbiology↗

bioRxiv2026

Microgravity affects the nervous system and aging in C. elegans through reduced tactile stimulation

Space travel is becoming accessible, yet our understanding of how space environment and microgravity ({micro}G) affect biology, physiology, and health remains incomplete. We investigated {micro}G effects on neuromuscular development and aging in Caenorhabditis elegans. Nematodes in {micro}G showed downregulation of genes related to synaptic signaling, dopamine response, locomotion, and cuticle development, with impaired synaptic vesicle dynamics, reduced motility, and shorter body lengths. Aged worms in {micro}G showed decreased collagen gene expression, increased motor neuron defects, synaptic vesicle accumulation and decreased release, and mitochondrial morphology collapse in body wall muscles, indicating accelerated aging. MEC-4 mechanoreceptor was identified as a key mediator of {micro}G-induced body length reduction and changes in extracellular matrix gene expression. {micro}G conditions suppressed mechanoreceptor genes, suggesting multiple mechanosensory systems are affected. Physical stimulation through culture medium with small beads in space mitigated many {micro}G-induced expression changes, including mechanoreceptors, neuromuscular defects, and aging-related phenotypes. These results highlight mechanical stimulis role in maintaining neuromuscular integrity during spaceflight and suggest restoring tactile input could counter health risks from reduced stimulation in long-term space missions. SIGNIFICACEWe found that microgravity ({micro}G) conditions suppress the expression of multiple mechanoreceptor genes in Caenorhabditis elegans, indicating that several mechanosensory systems are affected during spaceflight. Importantly, reintroducing physical stimulation by adding small beads to the culture medium in space partially reversed many of these {micro}G-induced gene expression changes. This intervention also mitigated neuromuscular defects and aging-related phenotypes observed under {micro}G conditions. Collectively, these findings underscore the essential role of mechanical stimuli in preserving neuromuscular integrity during space missions and suggest that restoring tactile input may be a promising strategy to counteract the health risks associated with reduced tactile stimulation during prolonged spaceflights.

systems biology↗

bioRxiv2024

In vitro and in vivo validation of cwlM and pbpB essentiality for viability and resistance to imipenem in Mycobacterium abscessus

Mycobacterium abscessus lung infection is notoriously difficult to treat due, in part, to the intrinsic resistance of this pathogen to most marketed antibiotics. {beta}-Lactams, namely imipenem and cefoxitin, are first-line drugs in combination regimens used to treat this infection; and there is growing interest in dual-{beta}-lactam-based regimens. Better understanding of the molecular basis of {beta}-lactam activity through study of the genetic determinants of {beta}-lactam susceptibility and tolerance would enable more rational drug combinations and guide discovery of novel drug targets to complement {beta}-lactams. We recently used an inducible CRISPR interference (CRISPRi) system to silence cwlM and pbpB and confirm their essentiality for in vitro growth and resistance to sub-MIC concentrations of imipenem. Here, we extend those findings to show that silencing either gene alone is bactericidal and augments the bactericidal activity of imipenem in vitro. Furthermore, using CRISPRi in a mouse model of M. abscessus lung infection for the first time, we confirm the essentiality of each gene for in vivo survival. These results validate cwlM and pbpB as essential genes and promising drug targets in this pathogen, including for potentiation of carbapenem activity. The results further establish CRISPRi as a powerful method for validating drug targets and studying gene-gene and gene-drug interactions in vitro and in vivo.

microbiology↗

bioRxiv2022

The neuropeptide FLP-17 regulates an oviposition behavior in the nematode Caenorhabditis elegans that increases maternal reproductive fitness in low oxygen environments

SUMMARYThe ability for animals to adapt their behaviors to specific environments is imperative to increase their evolutionary success. This is particularly true for behaviors such as parental behaviors that directly affect reproductive fitness. Here, we identified an oviposition behavior in the nematode C. elegans that increases the survival of the young. In standard laboratory culture, the bacterivorous hermaphrodite mothers lay eggs across a 2D E. coli lawn with no discernable pattern. However, in 3D culture they display a stereotypical behavior in which they temporarily leave the bacteria to lay eggs far away from the E. coli colony, resulting in a scattered ring of eggs located outside the bacteria. This oviposition behavior requires low oxygen levels and is regulated by the neuropeptide FLP-17 and its cognate receptor EGL-6. We confirm that a circuitry involving the oxygen-sensing BAG neurons and the vulva muscle-controlling HSN motor neurons regulates oviposition behavior. We show that loss of proper oviposition behavior results in lower reproductive fitness for the mothers and embryonic lethality for the eggs laid in bacteria under hypoxic conditions. Finally, we show that the degree of oviposition behavior varies among wild strains of C. elegans found in nature. The ability for C. elegans mothers to sense their environments and adjust their behaviors in adverse conditions is likely an adaptation that has allowed the worm to thrive in diverse and often hazardous habitats.

neuroscience↗

bioRxiv2020

Lopinavir-ritonavir is not an effective inhibitor of the main protease activity of SARS-CoV-2 in vitro

COVID-19 has caused over 900,000 deaths worldwide as of September 2020, and effective medicines are urgently needed. Lopinavir was identified as an inhibitor of the HIV protease, and a lopinavir-ritonavir combination therapy was reported to be beneficial for the treatment of SARS and MERS. However, recent clinical tests could not prove that lopinavir-ritonavir therapy was an effective treatment for COVID-19. In this report, we examined the effect of lopinavir and ritonavir to the activity of the purified main protease (Mpro) protein of SARS- CoV-2, the causative virus of COVID-19. Unexpectedly, lopinavir and ritonavir did not inhibit Mpro activity. These results will aid the drug candidate selection for ongoing and future COVID-19 clinical trials.

microbiology↗