Molecular mechanism of glutaminase activation through filamentation and the role of filaments in mitophagy protection.

Glutaminase (GLS), which deaminates glutamine to form glutamate, is a mitochondrial tetrameric protein complex. Although inorganic phosphate (Pi) is known to promote GLS filamentation and activation, the molecular basis of this mechanism is unknown. Here we aimed to determine the molecular mechanism of Pi-induced mouse GLS filamentation and its impact on mitochondrial physiology.

An Intestine/Liver Microphysiological System for Drug Pharmacokinetic and Toxicological Assessment.

The recently introduced microphysiological systems (MPS) cultivating human organoids are expected to perform better than animals in the preclinical tests phase of drug developing process because they are genetically human and recapitulate the interplay among tissues. In this study, the human intestinal barrier (emulated by a co-culture of Caco-2 and HT-29 cells) and the liver equivalent (emulated by spheroids made of differentiated HepaRG cells and human hepatic stellate cells) were integrated into a two-organ chip (2-OC) microfluidic device to assess some acetaminophen (APAP) pharmacokinetic (PK) and toxicological properties. The MPS had three assemblies: Intestine only 2-OC, Liver only 2-OC, and Intestine/Liver 2-OC with the same media perfusing both organoids.

Dual inhibition of glutaminase and carnitine palmitoyltransferase decreases growth and migration of glutaminase inhibition-resistant triple-negative breast cancer cells.

Triple-negative breast cancers (TNBCs) lack progesterone and estrogen receptors and do not have amplified human epidermal growth factor receptor 2, the main therapeutic targets for managing breast cancer. TNBCs have an altered metabolism, including an increased Warburg effect and glutamine dependence, making the glutaminase inhibitor CB-839 therapeutically promising for this tumor type. Accordingly, CB-839 is currently in phase I/II clinical trials.

Glutaminase Affects the Transcriptional Activity of Peroxisome Proliferator-Activated Receptor γ (PPARγ) via Direct Interaction.

Phosphate-activated glutaminases catalyze the deamidation of glutamine to glutamate and play key roles in several physiological and pathological processes. In humans, GLS encodes two multidomain splicing isoforms: KGA and GAC. In both isoforms, the canonical glutaminase domain is flanked by an N-terminal region that is folded into an EF-hand-like four-helix bundle.

Guanylate-binding protein-1 is a potential new therapeutic target for triple-negative breast cancer.

Background: Triple-negative breast cancer (TNBC) is characterized by a lack of estrogen and progesterone receptor expression (ESR and PGR, respectively) and an absence of human epithelial growth factor receptor (ERBB2) amplification. Approximately 15-20% of breast malignancies are TNBC. Patients with TNBC often have an unfavorable prognosis.

Active glutaminase C self-assembles into a supratetrameric oligomer that can be disrupted by an allosteric inhibitor.

The phosphate-dependent transition between enzymatically inert dimers into catalytically capable tetramers has long been the accepted mechanism for the glutaminase activation. Here, we demonstrate that activated glutaminase C (GAC) self-assembles into a helical, fiber-like double-stranded oligomer and propose a molecular model consisting of seven tetramer copies per turn per strand interacting via the N-terminal domains. The loop (321)LRFNKL(326) is projected as the major regulating element for self-assembly and enzyme activation.