Journal of cellular biochemistry最新文献

LRRK2 has gained prominence in treating Parkinson's disease as a potential drug target. Mutations in the WD40 domain, like G2294R, are notable for their influence on the stability and dimerisation of the LRRK2. Studies have shown that G2294R could result in the WD40 distortion and destabilised LRRK2 protein. However, the underlying mechanism remains unclear. To elucidate how the G2294R mutation in the WD40 domain affects the structural and functional conformation of LRRK2, the structure of WD40 G2294R was constructed using homology modelling, and the molecular dynamics simulations on G2294R and wild-type dimers and monomers were carried out. The results show that distortion mainly occurs in the areas of β3, L1, β5, L2, and β7. The dimerisation was enhanced through the conformational changes in the G2294R variant, while the domains show different contributions towards the dimerisation. Our study reveals the effects of G2294R on the WD40. It explores its role in dimerisation and distortion, which could contribute to developing novel WD40 inhibitors and elucidate the molecular mechanism of WD40 dimerisation-monomerisation equilibrium.

The main protease (M^pro) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) plays a crucial role in viral replication. In this study, the binding modes and inhibitory mechanisms of eight condensed amino thiourea scaffold inhibitors of M^pro in proteins were investigated using a combination of molecular docking, molecular dynamics simulations, and MM/PBSA binding free energy calculations. The results indicated that the para-hydroxyl group on the benzene ring at the head of the inhibitor has a decisive influence on the initial docking pose and binding free energy strength of the inhibitor. Additionally, the position and length of the hydrophobic side chain on the tail six-membered ring significantly impacted the final binding pose of the inhibitor. The presence of a long hydrophobic side chain in the ortho position of this ring, through its interaction with the P4 hydrophobic pocket, led to an opposite binding mode in the protein compared with when it was present with or without the para-side chain. Different lengths of para-substituted side chains affected the positioning of the inhibitors in the enzyme. These different binding modes led to variations in the binding free energy between the inhibitor and the protein, which in turn gave rise to differences in inhibitory capability.

Lythrum anceps (Koehne) Makino (Japanese common name: “Misohagi”) is an edible plant belonging to the Lythraceae family. It is mainly distributed in Asia, Northern Africa, and Europe. Plants of the genus Lythrum exhibit a broad range of biological activities including anti-inflammatory and antimicrobial activities. Because of this, the plants are used in traditional medicine to treat hemorrhage, infected wounds, and dysentery. The activation of peroxisome proliferator-activated receptor-gamma (PPARγ) is an effective target for improving insulin resistance and anti-inflammatory activity. However, PPARγ activation by the genus Lythrum remains unclear. Aiming to evaluate PPARγ activation by L. anceps, we generated a reporter cell line using an artificial chromosome vector that stably expresses dual-color beetle luciferases. Dual-color real-time bioluminescence monitoring revealed marked PPARγ activation in L. anceps extracts. Moreover, ellagic acid was identified as a PPARγ activator present in L. anceps by a bioassay-guided fractionation approach.

Glioblastoma multiforme (GBM), a highly heterogeneous CNS tumor known for its highest incidence rates and poor prognosis has shown limited success in the therapies due to hypoxia—driving immune-suppression in the tumor microenvironment (TME). Emerging evidence highlights the involvement of tumor cell-derived exosomes in tumor-associated microglia polarization via transfer of exosomal onco-proteins and miRNAs. Although the regulatory role of long noncoding RNAs (lncRNAs) in immune signaling are known, its mechanism in microglial polarization via exosomes in GBM still remains poorly understood. In our study, we found that in comparison to the normoxic GBM-derived exosomes lncRNA H19 was significantly upregulated in hypoxic GBM-derived exosomes. Hypoxic GBM-derived exosomes and secretome (conditioned media) caused the reduction in the % phagocytosis of microglia as compared with the control group. Moreover, GBM secretome caused increase in the M2-specific genes (IL10, STAT-3, CD163, CD206) in microglia indicating its polarization to the protumorigenic (M2) phenotype. LncRNA H19 knocked down GBM-secretome treatment in microglia further reduced the STAT-3 expression indicating H19 mediated signaling. Overall, our results suggest the involvement of hypoxic exosomes and lncRNA H19 in microglial polarization and H19 as a potential target.

Proteasomes are the catalytic complexes in eukaryotic cells that decide the fate of proteins involved in various cellular processes in an energy-dependent manner. The proteasomal system performs its function by selectively destroying the proteins labelled with the small protein ubiquitin. Dysfunctional proteasomal activity is allegedly involved in various clinical disorders such as cancer, neurodegenerative disorders, ageing, and so forth, making it an important therapeutic target. Notably, compared to healthy cells, cancer cells have a higher protein homeostasis requirement and a faster protein turnover rate. The ubiquitin-proteasome system (UPS) helps cancer cells increase rapidly and experience less apoptotic cell death. Therefore, understanding UPS is essential to design and discover some effective inhibitors for cancer therapy. Hereby, we have focused on the role of the 26S proteasome complex, mainly the UPS, in carcinogenesis and seeking potential therapeutic targets in treating numerous cancers.

We previously reported that ferroptosis interplays with apoptosis through the integration of two independent pathways: the endoplasmic reticulum (ER) stress signaling pathway and the mitochondria-dependent apoptotic signaling pathway. In this study, we investigated a potential gatekeeper molecule, Mcl-1, between the two signal transduction pathways. Morphology studies and cell death analyses confirmed that a combination treatment of ferroptotic agent erastin (ERA) and apoptotic agent TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) synergistically enhances TRAIL-induced apoptosis in human pancreatic adenocarcinoma BxPC3 and human colorectal carcinoma HCT116 cells. We further observed that ERA upregulated the proapoptotic proteins PUMA (p53 upregulated modulator of apoptosis) and NOXA, as well as the anti-apoptotic protein Mcl-1 (myeloid cell leukemia sequence 1). These results suggest that ERA upregulates these molecules which results in maintenance of the balance between them. Interestingly, this balance was offset when BxPC3 cells and HCT116 cells were treated with ERA in combination with TRAIL. Our studies suggest that the imbalance between PUMA and NOXA and Mcl-1 during the combined treatment is responsible for ERA-enhanced TRAIL-induced apoptosis. This hypothesis was tested by employing a HCT116 Mcl-1 knock-in of phosphorylation site mutant (S121A/E125A/S159A/T163A) and investigated the synergistic interaction between the ERA and TRAIL. Along with morphology and cell death studies, immunoblotting analyses revealed that HCT116 Mcl-1 knock-in mutant cells effectively inhibited reduction of Mcl-1 and apoptosis promoted by the combination treatment. Moreover, ERA enhanced Mcl-1 inhibitor-induced apoptosis. Collectively, our studies suggest that Mcl-1 is a gatekeeper molecule between the ER stress pathway and the mitochondria-dependent apoptotic pathway.