Biology subjects

Sim, T.

Publications and source records attributed to Sim, T..

3 recordsLinked to original sources

bioRxiv2024

Targeted Degradation of METTL3 Against Acute Myeloid Leukemia and Gastric Cancer.

Accumulating evidence reveals the oncogenic role of methyltransferase-like 3 (METTL3) in a variety of cancer types, either dependent or independent of its m6A methyl transferase activity. We have designed proteolysis-targeting chimeras (PROTACs) targeting METTL3 and identified KH12 as a potent METTL3 degrader. Treatment of KH12 on MOLM-13 cells causes more than 80% degradation of METTL3 with a half-maximal degradation concentration (DC50) of 220 nM in a dose-, time- and ubiquitin-dependent fashion. In addition, KH12 reverses differentiation and possesses anti-proliferative effects surpassing the reported inhibitors in MOLM-13 cells. Furthermore, KH12 significantly suppresses the growth of various gastric cancer (GC) cells, where the m6A-independent activity of METTL3 plays a crucial role in tumorigenesis. The anti-GC effect of KH12 was further confirmed in patient-derived organoids (PDOs). This study highlights the therapeutic potential of targeted degradation of epitranscriptomic writer METTL3 as an anti-cancer strategy.

biochemistry↗

bioRxiv2022

Targeted Kinase Degradation via the KLHDC2 Ubiquitin E3 Ligase

Chemically induced protein degradation is a powerful strategy for perturbing cellular biochemistry. The predominant mechanism of action for protein degrader drugs involves induced proximity between the cellular ubiquitin conjugation machinery and the target. Unlike traditional small molecule enzyme inhibition, targeted protein degradation can clear an undesired protein from cells. We demonstrate here the use of peptide ligands for Kelch-Like Homology Domain Containing protein 2 (KLHDC2), a substrate adaptor protein and member of the cullin-2 (CUL2) ubiquitin ligase complex, for targeted protein degradation. Peptide-based bivalent compounds that can induce proximity between KLHDC2 and target proteins cause degradation of the targeted factors. The cellular activity of these compounds depends on KLHDC2 binding. This work demonstrates the utility of KLHDC2 for targeted protein degradation and exemplifies a strategy for the rational design of new peptide-based ligands useful for this purpose.

biochemistry↗

bioRxiv2022

Mushroom body output neurons MBONa1/a2 define an odor intensity channel that regulates behavioral odor discrimination learning in larval Drosophila

The sensitivity of animals to sensory input must be regulated to ensure that signals are detected and also discriminable. However, how circuits regulate the dynamic range of sensitivity to sensory stimuli is not well understood. A given odor is represented in the insect mushroom bodies (MBs) by sparse combinatorial coding by Kenyon cells (KCs), forming an odor quality representation. To address how intensity of sensory stimuli is processed at the level of the MB input region, the calyx, we characterized a set of novel mushroom body output neurons that respond only to high odor concentrations. We show that a pair of MB calyx output neurons, MBONa1/2, are postsynaptic in the MB calyx, where they receive extensive synaptic inputs from KC dendrites, the inhibitory feedback neuron APL, and octopaminergic sVUM1 neurons, but relatively few inputs from projection neurons. This pattern is broadly consistent in the third instar larva as well as in the first instar connectome. MBONa1/a2 presynaptic terminals innervate a region immediately surrounding the MB medial lobe output region in the ipsilateral and contralateral brain hemispheres. By monitoring calcium activity using jRCamP1b, we find that MBONa1/a2 responses are odor-concentration dependent, responding only to ethyl acetate (EA) concentrations higher than a 200-fold dilution, in contrast to MB neurons which are relatively concentration-invariant and respond to EA dilutions as low as 10-4. Optogenetic activation of the calyx-innervating sVUM1 modulatory neurons originating in the SEZ (Subesophageal zone), did not show a detectable effect on MBONa1/a2 odor responses. Optogenetic activation of MBONa1/a2 using CsChrimson impaired odor discrimination learning compared to controls. We propose that MBONa1/a2 form an output channel of the calyx, summing convergent sensory and modulatory input, firing only to high odor concentration, and might affect the activity of downstream MB targets.

neuroscience↗