Recent Advances in IRAK1: Pharmacological and Therapeutic Aspects.

Interleukin receptor-associated kinase (IRAK) proteins are pivotal in interleukin-1 and Toll-like receptor-mediated signaling pathways. They play essential roles in innate immunity and inflammation. This review analyzes and discusses the physiological functions of IRAK1 and its associated diseases. IRAK1 is involved in a wide range of diseases such as dry eye, which highlights its potential as a therapeutic target under various conditions. Various IRAK1 inhibitors, including Pacritinib and Rosoxacin, show therapeutic potential against malignancies and inflammatory diseases. The covalent IRAK1 inhibitor JH-X-119-01 shows promise in B-cell lymphomas, emphasizing the significance of covalent bonds in its activity. Additionally, the emergence of selective IRAK1 degraders, such as JNJ-101, provides a novel strategy by targeting the scaffolding function of IRAK1. Thus, the evolving landscape of IRAK1-targeted approaches provides promising avenues for increasingly safe and effective therapeutic interventions for various diseases.

Characterization of an Hsp90-Independent Interaction between Co-Chaperone p23 and Transcription Factor p53.

Cancer-suppressing transcription factor p53 is regulated by a wide variety of cellular factors, including many chaperones. The DNA-binding domain (DBD) of p53 is known to interact with the chaperone Hsp90, but the role of other members of the chaperone network, including co-chaperones such as p23, is unknown. Using a combination of nuclear magnetic resonance (NMR) titration, isothermal titration calorimetry, fluorescence anisotropy, and native agarose gel electrophoresis, we have identified a direct interaction between the p53 DBD and Hsp90 co-chaperone p23 that occurs in the absence of Hsp90. The affinity is relatively weak and largely determined by electrostatic interactions between the acidic C-terminal disordered tail of p23 and the two DNA-binding regions of the p53 DBD. We show by NMR and native agarose gel electrophoresis that a p53-specific double-stranded DNA sequence competes successfully with p23 for binding to the p53 DBD. The Hsp90 independence of the interaction between p23 and p53 DBD, together with the competition of p23 versus DNA for p53, raises the intriguing possibility that p23, like other small charged proteins, may affect p53 in hitherto unknown ways.

The Smad7-Skp2 complex orchestrates Myc stability, impacting on the cytostatic effect of TGF-ß.

In most human cancers the Myc proto-oncogene is highly activated. Dysregulation of Myc oncoprotein contributes to tumorigenesis in numerous tissues and organs. Thus, targeting Myc stability could be a crucial step for cancer therapy. Here we report Smad7 as a key molecule regulating Myc stability and activity by recruiting the F-box protein, Skp2. Ectopic expression of Smad7 downregulated the protein level of Myc without affecting the transcription level, and significantly repressed its transcriptional activity, leading to inhibition of cell proliferation and tumorigenic activity. Furthermore, Smad7 enhanced ubiquitylation of Myc through direct interaction with Myc and recruitment of Skp2. Ablation of Smad7 resulted in less sensitivity to the growth inhibitory effect of TGF-ß by inducing stable Myc expression. In conclusion, these findings that Smad7 functions in Myc oncoprotein degradation and enhances the cytostatic effect of TGF-ß signaling provide a possible new therapeutic approach for cancer treatment.

Effect of Divalent Metal Ions on the Ribonuclease Activity of the Toxin Molecule HP0894 from Helicobacter pylori.

Bacteria and archaea respond and adapt to environmental stress conditions by modulating the toxin-antitoxin (TA) system for survival. Within the bacterium Helicobacter pylori, the protein HP0894 is a key player in the HP0894-HP0895 TA system, in which HP0894 serves as a toxin and HP0895 as an antitoxin. HP0894 has intrinsic ribonuclease (RNase) activity that regulates gene expression and translation, significantly influencing bacterial physiology and survival. This activity is influenced by the presence of metal ions such as Mg2+. In this study, we explore the metal-dependent RNase activity of HP0894. Surprisingly, all tested metal ions lead to a reduction in RNase activity, with zinc ions (Zn2+) causing the most significant decrease. The secondary structure of HP0894 remained largely unaffected by Zn2+ binding, whereas structural rigidity was notably increased, as revealed using CD analysis. NMR characterized the Zn2+ binding, implicating numerous His, Asp, and Glu residues in HP0894. In summary, these results suggest that metal ions play a regulatory role in the RNase activity of HP0894, contributing to maintaining the toxin molecule in an inactive state under normal conditions.

Structural Deformation of MTX Induced by Nanodrug Conjugation Dictate Intracellular Drug Transport and Drug Efficacy.

BACKGROUND: Understanding structural interactions between the active drug and conjugated nanoparticles is critical for optimizing intracellular drug transport and for increasing nano drug efficacy. In this regard, analyzing the conformational deformation of conjugated drugs surrounding nanoparticles is essential to understand the corresponding nanodrug efficacy. PURPOSE: The objective of this study is to present an optimal synthesis method for efficient drug delivery through a clear structural analysis of nanodrugs according to the type of conjugation. METHODS AND RESULTS: In this study, the structural variation of methotrexate (MTX) surrounding carbon nanotubes, depending on the type of conjugation style, such as covalent and non-covalent (PEGylation) bonds, was investigated. Specifically, covalent bonds of MTX surrounding CNTs induced greater structural deformation compared to non-covalent bonds (ie, PEGylated CNT). CONCLUSION: Greater changes in the structural variations of MTX analyzed by nuclear magnetic resonance (NMR) significantly improved the anti-inflammatory drug efficacy of human fibroblast-like synovial cells (FLS) via stable drug release in the extracellular environment and burst drug release under intracellular conditions.

Structural ensemble-based docking simulation and biophysical studies discovered new inhibitors of Hsp90 N-terminal domain.

Heat shock protein 90 (Hsp90) is one of the most abundant cellular proteins and plays a substantial role in the folding of client proteins. The inhibition of Hsp90 has been regarded as an attractive therapeutic strategy for treating cancer because many oncogenic kinases are Hsp90 client proteins. In this study, we report new inhibitors that directly bind to N-terminal ATP-binding pocket of Hsp90. Optimized structure-based virtual screening predicted candidate molecules, which was followed by confirmation using biophysical and cell-based assays. Among the reported crystal structures, we chose the two structures that show the most favourable early enrichments of true-positives in the receiver operating characteristic curve. Four molecules showed significant changes in the signals of 2D [1H, 15N] correlation NMR spectroscopy. Differential scanning calorimetry analysis supported the results indicating direct binding. Quantified dissociation constant values of the molecules, determined by a series of 2D NMR experiments, lie in the range of 0.1-33 µM. Growth inhibition assay with breast and lung cancer cells confirmed the cellular activities of the molecules. Cheminformatics revealed that the molecules share limited chemical similarities with known inhibitors. Molecular dynamics simulations detailed the putative binding modes of the inhibitors.

Metabolomic profiling of CSF in multiple sclerosis and neuromyelitis optica spectrum disorder by nuclear magnetic resonance.

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are inflammatory diseases of the central nervous system. Although several studies have characterized the metabolome in the cerebrospinal fluid (CSF) from MS and NMOSD patients, comparative analyses between them and between the relapse and the remission of each disease have not been performed. Both univariate and multivariate analyses were used to compare 1H-NMR spectra of CSF from MS, NMOSD, and healthy controls (HCs). The statistical analysis showed alterations of eight metabolites that were dependent on the disease. Levels of 2-hydroxybutyrate, acetone, formate, and pyroglutamate were higher and levels of acetate and glucose were lower in both MS and NMOSD. Citrate was lower in MS patients, whereas lactate was higher in only NMOSD specifically. The shared feature of metabolic changes between MS and NMOSD may be related to altered energy metabolism and fatty acid biosynthesis in the brain. Another analysis to characterize relapse and remission status showed that isoleucine and valine were down-regulated in MS relapse compared to MS remission. The other metabolites identified in the disease comparison showed the same alterations regardless of disease activity. These findings would be helpful in understanding the biological background of these diseases, and distinguishing between MS and NMOSD, as well as determining the disease activity.

TCEA3 binds to TGF-beta receptor I and induces Smad-independent, JNK-dependent apoptosis in ovarian cancer cells.

TFIIS is a transcription elongation factor conserved in frog, mouse and human. Recently, knockdown of TCEA1, the most well-characterized isoform of TFIIS, by RNA silencing was reported to inhibit cancer cell proliferation and induce apoptosis in breast, lung and pancreatic cancer cell lines through activation of p53 (Hubbard et al., 2008 [1]). However, the functions of other TFIIS isoforms are poorly defined. The present study shows that TCEA3, an isoform of TFIIS, can trigger ovarian cancer-specific cell death by activating the JNK signaling pathway. TCEA3 expression is low in ovarian cancer cell lines compared to noncancerous ovarian epithelial cells. Suppression of TCEA3 in noncancerous ovarian epithelial cells promotes cell growth whereas ectopic expression of TCEA3 in ovarian cancer cell lines induces the caspase-dependent mitochondrial cell death pathway. Molecular and chemical inhibition assays show that the interaction of TCEA3 with TGFß receptor I induces cell death in ovarian cancer cell through Smad-independent activation of the JNK pathway. These results reveal that TCEA3 induces a novel apoptotic mechanism in OEC, which provides TCEA3 as a novel target to develop therapeutics of ovarian cancer.

DRAK2 participates in a negative feedback loop to control TGF-ß/Smads signaling by binding to type I TGF-ß receptor.

TGF-ß1 is a multifunctional cytokine that mediates diverse biological processes. However, the mechanisms by which the intracellular signals of TGF-ß1 are terminated are not well understood. Here, we demonstrate that DRAK2 serves as a TGF-ß1-inducible antagonist of TGF-ß signaling. TGF-ß1 stimulation rapidly induces DRAK2 expression and enhances endogenous interaction of the type I TGF-ß receptor with DRAK2, thereby blocking R-Smads recruitment. Depletion of DRAK2 expression markedly augmented the intensity and the extent of TGF-ß1 responses. Furthermore, a high level of DRAK2 expression was observed in basal-like and HER2-enriched breast tumors and cell lines, and depletion of DRAK2 expression suppressed the tumorigenic ability of breast cancer cells. Thus, these studies define a function for DRAK2 as an intrinsic intracellular antagonist participating in the negative feedback loop to control TGF-ß1 responses, and aberrant expression of DRAK2 increases tumorigenic potential, in part, through the inhibition of TGF-ß1 tumor suppressor activity.