FEBS Letters最新文献

Soluble epoxide hydrolase (sEH) is a bifunctional enzyme that has epoxide hydrolase activity and phosphatase activity. Our earlier study revealed that lysophosphatidic acids are a substrate of the phosphatase activity of sEH in vitro, but its physiological function remained unknown. Herein, we used the CRISPR/Cas9 system and i-GONAD method to generate mice that are deficient in sEH phosphatase activity. In the mouse brain, sEH was highly expressed in the olfactory bulb. Deletion of the sEH phosphatase activity resulted in decreased levels of the endocannabinoid 2-arachidonoyl glycerol (2-AG), which is a dephosphorylated form of 2-arachidonoyl-lysophosphatidic acid in the olfactory bulb. The sEH-deficient mice showed depressive-like behavior. These results indicate that sEH can regulate the production of 2-AG and brain function in vivo.

(Poly)phenols are a group of naturally occurring phytochemicals present in high amounts in plant food and beverages with various structures and activities. The impact of (poly)phenols on brain function has gained significant attention due to the growing interest in the potential benefits of these dietary bioactive molecules for cognitive health and neuroprotection. This review will therefore summarise the current knowledge related to the impact of (poly)phenols on brain health presenting evidence from both epidemiological and clinical studies. Cellular and molecular mechanisms in relation to the observed effects will also be described, including their impact on the gut microbiota through the modulation of the gut-brain axis. Although (poly)phenols have the potential to modulate the gut-brain axis regulation and influence cognitive function and decline through their interactions with gut microbiota, anti-inflammatory and antioxidant properties, further research, including randomised controlled trials and mechanistic studies, is needed to better understand the underlying mechanisms and establish causal relationships between (poly)phenol intake and brain health.

Stiffening of the brain extracellular matrix (ECM) in glioblastoma promotes tumor progression. Previously, we discovered that protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) plays a role in glioblastoma stem cell (GSC) adaptation to matrix stiffness through PERK/FLNA-dependent F-actin remodeling. Here, we examined the involvement of PERK in detecting stiffness changes via focal adhesion complex (FAC) formation. Compared to control GSCs, PERK-deficient GSCs show decreased vinculin and tensin expression, while talin and integrin-β1 remain constant. Furthermore, vimentin was also reduced while tubulin increased, and a stiffness-dependent increase of the differentiation marker GFAP expression was absent in PERK-deficient GSCs. In conclusion, our study reveals a novel role for PERK in FAC formation during matrix stiffening, which is likely linked to its regulation of F-actin remodeling.

Skin fibrosis is characterized by fibroblast activation and intradermal fat loss, resulting in excess deposition and remodeling of dermal extracellular matrix (ECM). The topography of the dominant ECM proteins, such as collagens, can indicate skin stiffness and remains understudied in evaluating fibrotic skin. Here, we adapted two different unbiased image analysis algorithms to define collagen topography and alignment in a genetically inducible and reversible Wnt activation fibrosis model. We demonstrated that Wnt-activated fibrotic skin has altered collagen fiber characteristics and a loss of collagen alignment, which were restored in the reversible model. This study highlights how unbiased algorithms can be used to analyze ECM topography, providing novel avenues to evaluate fibrotic skin onset, recovery, and treatment.

Dysregulation of human DNA polymerase delta (Polδ) subunits is associated with genome instability and pathological disorders. Genome databases suggest the expression of several spliced variants of subunits which may alter Polδ function. Here, we analyzed the protein-encoding variants of the Polδ subunit p12 and their association with cancer. p12 isoform-2 (p12*) encodes a 79 aa protein with a C-terminal tail distinct from the previously characterized p12. Like p12, p12* dimerizes and interacts with p125 and p50 subunits and is thus an integral component of Polδ. Further, we observed dysregulated p12* expression in low-grade glioma, renal, thyroid, and pancreatic carcinomas. This study identifies a previously unrecognized Polδ complex and highlights a possible regulatory role of p12 variants in cellular phenotypes.

The epidermis is a stratified epithelium that functions as the first line of defense against pathogenic invasion and acts as a barrier preventing water loss. In this study, we aimed to decipher the role of 14-3-3ε in the development of the epidermis. We report that loss of 14-3-3ε in the epidermis of juvenile and adult mice reduces cell division in the basal layer and increases the percentage of cells with multiple centrosomes, leading to a reduction in the thickness of the basal and stratified layers. We also demonstrate a decrease in the expression of differentiation markers, although no gross morphological defects in the skin or adverse effects on the survival of the mice were observed. These results suggest that loss of 14-3-3ε in the epidermis may lead to defects in proliferation and differentiation.

Non-small cell lung cancer comprises up to 85% of lung cancer cases and has a poor prognosis. At present, there are still no effective treatments for this illness. Evidence suggests that the prostaglandin [cyclooxygenase-2 (COX-2)] and leukotriene [lipoxygenase-5 (5-LOX)] pathways are involved in lung cancer carcinogenesis. Therefore, novel agents that target COX-2 and 5-LOX may have therapeutic potential. In the present study, we examined the role of asiatic acid (AA), a triterpenoid saponin, in targeting the protein kinases responsible for lung cancer proliferation and mobility. The experimental data revealed that AA inhibited the growth of lung cancer cells (> 50%) and it significantly impeded the proliferation of lung cancer cells by inhibiting COX-2, which results in downregulation of the phosphotidyl inositol-3 kinase/protein kinase B/mammalian target of rapamycin signaling pathway, leading to an induction of cytotoxic autophagy-mediated apoptosis. Mechanistically, the expression of mitogen-activated protein kinase/extracellular signal-regulated kinase, hypoxia-inducible factor-1 and vascular endothelial growth factor is downregulated by AA, thereby reducing cell mobility and invasion. It also shows negative osmotic fragility on healthy human erythrocytes. It is concluded that AA may be a viable therapeutic drug for non-small cell lung cancer treatment, which opens new opportunities for synthesizing analogues.

In this research letter, we report the development and validation of a new subset of fluorescence-based CRISPR interference (CRISPRi) tools for our scientific community. The pJL series is directly derived from the original pIRL CRISPRi vectors and conserves all the elements to perform inducible targeted gene repression. These vectors carry two distinct fluorescent markers under the constitutive promoter psmyc to simplify the selection of recombinant clones. We demonstrate the functionality of these vectors by targeting the expression of the glycopeptidolipid translocase mmpL4b and the essential genes rpoB and mmpL3. Finally, we describe an efficient single-step procedure to co-transform mycobacterial species with this integrative genetic tool alongside episomal vectors. Such tools and approaches should be useful to foster discovery in mycobacterial research.

Nanodiscs, consisting of a lipid bilayer surrounded by membrane scaffold proteins (MSPs), are extensively used to study membrane proteins (MPs) because they provide a stable lipid environment. However, the precise mechanism governing MP behavior within the nanodisc remains elusive. Here, we examined the cryo-EM structures of various MPs reconstituted in nanodiscs from EMPIAR. By analyzing the heterogeneity and interactions in the nanodiscs, we discovered that MPs display a distinct spatial preference toward the edges of the nanodisc shells. Furthermore, MPs can establish direct, amphipathic interactions with the MSPs, causing a reduction in local protein dynamics. These interactions may rearrange MSP-MSP interactions into MP-MSP interactions. Collectively, we provide structural insights into how nanodiscs contribute to MP structural behavior and dynamics. Impact statement Nanodiscs are used to study membrane proteins (MPs), but the mechanisms governing the behavior of MPs within nanodiscs remain elusive. Here, we provide structural insights into how nanodiscs contribute to the behavior of MPs, which will aid the interpretation of cryo-EM studies performed using nanodiscs.

Nanobodies (NB) are powerful tools for biotechnological and therapeutic applications. They strongly bind to their targets and are very stable. Early studies showed that NB unfolding is reversible and can be analyzed by equilibrium thermodynamics, whereas more recent studies focused on their kinetic stability in very harsh conditions that are far from storage or physiological temperatures (4-37 °C). Here, we show that the thermodynamic view of NB stability holds in a wide range of temperatures (18-100 °C). The thermodynamic stability of three different NBs did not correlate with binding affinity for their target. Alpha-Fold 2 analyses of these NBs showed structural differences in the binding site and hydrogen bond networks. We expect that our approach will be helpful to improve our capacity to enhance structure-function-stability relationships of NB.