Alpha B-crystallin (CryAB) is a small heat-shock protein highly expressed in cardiac tissue, where it functions as a molecular chaperone that helps prevent protein aggregation, particularly under stress conditions. A missense mutation in CryAB (R120G) causes autosomal dominant cardiomyopathy in humans and is characterized by extensive protein aggregation in cardiomyocytes. To better understand the pathogenic mechanisms underlying CryABR120G-associated cardiomyopathy, appropriate in vivo models are essential. Genetic mouse models are valuable tools for investigating disease pathogenesis and evaluating potential therapeutic strategies. In this study, we characterized a homozygous CryABR120G knock-in (KI) mouse model to assess the impact of this mutation on cardiac function. CryABR120G KI mice exhibited no overt changes in cardiac structure and function up to 12 months of age, with minimal changes in cardiac and proteotoxic stress markers, except for an increased atrial natriuretic peptide expression at 12 months. Protein quality control pathways remained largely unchanged. Although mitochondrial respiration was normal in young CryABR120G KI mice, it was reduced at 12 months of age. Despite the presence of insoluble protein aggregates, homozygous CryABR120G KI mice did not develop overt structural or functional cardiomyopathy through 12 months of age. These findings indicate that, within the age range examined, the CryABR120G KI model does not reproduce the overt cardiomyopathic phenotype associated with the CRYABR120G mutation in patients.
The structure of the catalytic subunit of cAMP-dependent protein kinase (PKA-C), a prototype for the protein kinase superfamily, laid the foundation for the development of targeted kinase inhibitors. Here we describe the structure and biophysical characterization of a PKA-C complex with BLU0588, a small PKA-selective inhibitor. The high-resolution crystal structure not only captures the inhibitor's unusual T-shaped geometry, but also shows how the four rings of BLU0588 serve as surrogates for ATP's adenosine and phosphate-organizing sites. Each site contains two subsites. BLU0588's planar azaindole and pyridine rings, which are buried beneath the glycine-rich loop in a hydrophobic shell at the base of the active site cleft, fill the adenine and ribose subsites. In contrast, BLU0588's indane and pyrrolidine rings fill the phosphate-organizing site. The indane ring occupies the α/β-phosphate organizing site while the pyrrolidine ring fills the Mg/γ-phosphate organizing site. The structure also shows how BLU0588 nucleates an open but stable conformation of the entire hydrophobic architecture of the N- and C-lobes. In addition to potently blocking phosphoryl transfer activity, BLU0588 also abolishes the synergistic high-affinity binding of the physiological pseudosubstrate inhibitor, protein kinase inhibitor. The residence time of BLU0588, measured by surface plasmon residence, contributes to its picomolar affinity and is distinct from H89, a commonly used but more promiscuous PKA inhibitor. These molecular insights provide a valuable framework for dissecting the organization of the active site cleft as well as different strategies for the rational design of more potent and selective kinase inhibitors in general.
BACKGROUND: End-of-life HIV research places emotional demands on staff, yet evidence for brief compassion training to enhance resilience is limited. OBJECTIVES: To assess the feasibility and impact of a four-week compassion training program on self-compassion and professional well-being. DESIGN: Prospective, single-group, repeated-measures pilot with surveys at baseline (T1), post-program (T2), and 12-week follow-up (T3). SETTING/PARTICIPANTS: Twenty-four professionals from the UC San Diego Last Gift program (83% women, 63% aged 25-44 years). MEASUREMENTS: Validated scales assessed self-compassion, compassion for others, professional quality of life, and work climate; changes were analyzed with Friedman and Bonferroni-adjusted Wilcoxon tests. RESULTS: Over-identification (p = 0.002), workplace joy (p = 0.005), and supportive work environment (p = 0.003) improved. Meditation frequency increased from T1 to T2 (p < 0.001) and remained higher at T3 (p = 0.006). CONCLUSIONS: A brief compassion program was feasible and improved over-identification and work-climate measures, supporting further evaluation of compassion support training in palliative and end-of-life research settings.
The intrinsic drug resistance of Mycobacterium tuberculosis (Mtb) is a major barrier to effective tuberculosis (TB) treatment and is largely due to its complex, impermeable cell envelope. We identified a periplasmic protein complex comprising FecB and Rv3035 that is essential for maintaining envelope integrity and mediating intrinsic multidrug resistance in Mtb. FecB interacts with Rv3035, forming a stable heterodimer that associates with the cell envelope biosynthesis protein AftB. We report the structures of Rv3035 alone and in complex with FecB and identify critical residues for complex formation and function. Coessentiality and genetic interaction analyses support a functional link between FecB, Rv3035, and AftB, an arabinofuranosyltransferase that synthesizes arabinogalactan and lipoarabinomannan. Loss of FecB or Rv3035 disrupted AftB-mediated arabinan synthesis, suggesting that these proteins support AftB's enzymatic activity. FecB is required for Mtb virulence in mice, underscoring its physiological relevance. These findings highlight FecB, Rv3035, and AftB as promising therapeutic targets.
Cyanobacteria are prolific producers of biologically active compounds that are important in influencing ecology, behavior of interacting organisms, and as leads in drug discovery efforts. Here we discuss the challenges faced by all natural product researchers, especially those that focus on cyanobacteria, and then describe progress that has been made in these areas. We also propose some solutions, paths forward, and thoughts for consideration on these challenges.
Over 95% of pancreatic ductal adenocarcinomas (PDACs) harbor oncogenic mutations in KRAS. However, upon treatment with KRAS inhibitors, PDAC cells undergo rapid metabolic reprogramming toward an oxidative phosphorylation (OXPHOS)-dependent, drug-resistant state. Here, we demonstrate that this metabolic shift is associated with upregulation of the transcription factor ZBTB11 and both the metabolic state and resistance to KRAS inhibitors can be attenuated by ZBTB11 depletion. We develop molecular glue degraders of ZBTB11 and demonstrate that they reprogram the aberrant transcriptome, proteome, metabolome and bioenergetics of KRAS inhibitor-resistant PDAC, resensitizing them to KRAS inhibition. ZBTB11 degradation leverages cell-type-specific and cell-state-specific differences in gene-regulatory mechanisms controlling OXPHOS pathway transcripts to selectively target the KRAS inhibitor-resistant state in PDAC while sparing neurons derived from human induced pluripotent stem cells. Together, this work establishes ZBTB11 as a druggable vulnerability in KRAS inhibitor-resistant PDAC and provides a suite of molecular glue degrader tool compounds to investigate its function.
Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia/hypercapnia (IHC), affects predominantly obese individuals, and increases atherosclerosis risk. Since we and others have implicated gut microbiota and metabolites in atherogenesis, we dissected their contributions to OSA-induced atherosclerosis. Atherosclerotic lesions were compared between conventionally-reared specific pathogen free (SPF) and germ-free (GF) Apoe-/- mice following a high fat high cholesterol diet (HFHC), with and without IHC conditions. The fecal microbiota and metabolome were profiled using 16S rRNA gene amplicon sequencing and untargeted tandem mass spectrometry (LC-MS/MS) respectively. Phenotypic data showed that HFHC significantly increased atherosclerosis as compared to regular chow (RC) in both aorta and pulmonary artery (PA) of SPF mice. IHC exacerbated lesions in addition to HFHC. Differential abundance analysis of gut microbiota identified an enrichment of Akkermansiaceae and a depletion of Muribaculaceae (formerly S24-7) family members in the HFHC-IHC group. LC-MS/MS showed a dysregulation of bile acid profiles with taurocholic acid, taurodeoxycholic acid, and 12-ketodeoxycholic acid enriched in the HFHC-IHC group, long-chain N-acyl amides, and phosphatidylcholines. Interestingly, GF Apoe-/- mice markedly reduced atherosclerotic formation relative to SPF Apoe-/- mice in the aorta under HFHC/IHC conditions. In contrast, microbial colonization did not show a significant impact on the atherosclerotic progression in PA. In summary, this research demonstrated that (1) IHC acts cooperatively with HFHC to induce atherosclerosis; (2) gut microbiota modulate atherogenesis, induced by HFHC/IHC, in the aorta not in PA; (3) different analytical methods suggest that a specific imbalance between Akkermansiaceae and Muribaculaceae bacterial families mediate OSA-induced atherosclerosis; and (4) derived bile acids, such as deoxycholic acid and lithocholic acid, regulate atherosclerosis in OSA. The knowledge obtained provides novel insights into the potential therapeutic approaches to prevent and treat OSA-induced atherosclerosis.
The constant emergence of SARS-CoV-2 resistance drives the search for new antivirals. We screened the SARS-CoV-2 cysteine proteases, the main protease (Mpro) and papain-like protease (PLpro), with 141 peptidyl and peptidomimetic inhibitors designed to target a trypanosome cysteine protease. Five compounds (1a-5a) inhibited Mpro (IC50 of 0.1601-16.42 µM), whereas none inhibited PLpro. Compounds 1a-4a inhibited human cathepsin L (hCatL; 0.184-10.74 µM), which is important for viral entry into human cells. Compounds 1a and 5a, and its synthesised (R,S) enantiomer, 5b, which share a benzyl carbamate moiety, inhibited the Mpro of SARS-CoV/MERS-CoV (0.0732-0.8295 µM). The three compounds were biochemically characterised as covalent reversible inhibitors. Compounds 5a and 5b, which contain vinyl ketone warheads, were specific for Mpro, and this behaviour was supported by covalent and noncovalent computational simulations. This study highlights the importance of revisiting legacy assets to identify starting points for new antiviral drugs.
