Biomolecules最新文献

Legumes play a pivotal role in addressing global challenges of food and nutrition security by offering a sustainable source of protein and bioactive compounds. The capacity of legumes to establish symbiotic relationships with rhizobia bacteria enables biological nitrogen fixation (BNF), reducing the dependence on chemical fertilizers while enhancing soil health. However, the efficiency of this symbiosis is significantly influenced by environmental factors, such as soil acidity, salinity, temperature, moisture content, light intensity, and nutrient availability. These factors affect key processes, including rhizobia survival, nodule formation, and nitrogenase activity, ultimately determining the growth and productivity of legumes. This review summarizes current knowledge on legume-rhizobia interactions under varying abiotic conditions. It highlights the impact of salinity and acidity in limiting nodule development, soil temperature in regulating microbial community dynamics, and moisture availability in modulating metabolic and hormonal responses during drought and waterlogging. Moreover, the role of essential nutrients, including nitrogen, phosphorus, potassium, and trace elements such as iron, molybdenum, and boron, in optimizing symbiosis is critically analyzed.

Acral melanoma is a distinct subtype of cutaneous malignant melanoma that uniquely occurs on ultraviolet (UV)-shielded, glabrous skin of the palms, soles, and nail beds. While acral melanoma only accounts for 2-3% of all melanomas, it represents the most common subtype among darker-skinned, non-Caucasian individuals. Unlike other cutaneous melanomas, acral melanoma does not arise from UV radiation exposure and is accordingly associated with a relatively low tumor mutational burden. Recent advances in genomic, transcriptomic, and epigenomic sequencing have revealed genetic alterations unique to acral melanoma, including novel driver genes, high copy number variations, and complex chromosomal rearrangements. This review synthesizes the current knowledge on the clinical features, epidemiology, and treatment approaches for acral melanoma, with a focus on the genetic pathogenesis that gives rise to its unique tumor landscape. These findings highlight a need to deepen our genetic and molecular understanding to better target this challenging subtype of melanoma.

The genome of the mildly thermophilic hot spring purple sulfur bacterium, Allochromatium (Alc.) tepidum, contains a multigene pufBA family that encodes a series of α- and β-polypeptides, collectively forming a heterogeneous light-harvesting 1 (LH1) complex. The Alc. tepidum LH1, therefore, offers a unique model for studying an intermediate phenotype between phototrophic thermophilic and mesophilic bacteria, particularly regarding their LH1 Qy transition and moderately enhanced thermal stability. Of the 16 α-polypeptides in the Alc. tepidum LH1, six α1 bind Ca²⁺ to connect with β1- or β3-polypeptides in specific Ca²⁺-binding sites. Here, we use the purple bacterium Rhodospirillum rubrum strain H2 as a host to express Ca²⁺-bound and Ca²⁺-free Alc. tepidum LH1-only complexes composed of α- and β-polypeptides that either contain or lack the calcium-binding motif WxxDxI; purified preparations of each complex were then used to test how Ca²⁺ affects their thermostability and spectral features. The cryo-EM structures of both complexes were closed circular rings consisting of 14 αβ-polypeptides. The Q_y absorption maximum of Ca²⁺-bound LH1 (α1/β1 and α1/β3) was at 894 nm, while that of Ca²⁺-free (α2/β1) was at 888 nm, indicating that Ca²⁺ imparts a Q_y transition of 6 nm. Crucially for the ecological success of Alc. tepidum, Ca²⁺-bound LH1 complexes were more thermostable than Ca²⁺-free complexes, indicating that calcium plays at least two major roles in photosynthesis by Alc. tepidum-improving photocomplex stability and modifying its spectrum.

Identifying and managing pediatric sepsis is a major research focus, yet early detection and risk assessment remain challenging. In its early stages, sepsis symptoms often mimic those of mild infections or chronic conditions, complicating timely diagnosis. Although various early warning scores exist, their effectiveness is limited, particularly in prehospital settings where accurate, rapid assessment is crucial. This review examines the roles of clinical prediction tools and biomarkers in pediatric sepsis. Traditional biomarkers, like procalcitonin (PCT), have improved diagnostic accuracy but are insufficient alone, often resulting in overprescription of antibiotics or delayed treatment. Combining multiple biomarkers has shown promise for early screening, though this approach can be resource-intensive and less feasible outside hospitals. Predicting sepsis outcomes to tailor therapy remains underexplored. While serial measurements of traditional biomarkers offer some prognostic insight, their reliability is limited, with therapeutic decisions often relying on clinical judgment. Novel biomarkers, particularly those identifying early organ dysfunction, hold potential for improved prognostic accuracy, but significant barriers remain. Many are only available in hospitals, require further validation, or need specialized assays not commonly available, limiting broader clinical use. Further research is needed to establish reliable protocols and enhance the clinical applicability of these tools. Meanwhile, a multifaceted approach that combines clinical judgment with existing tools and biomarkers remains essential to optimize pediatric sepsis management, improving outcomes and minimizing risks.

Ctr1 is a membrane-spanning homotrimer that facilitates copper uptake in eukaryotic cells with high affinity. While structural details of the transmembrane domain of human Ctr1 have been elucidated using X-ray crystallography and cryo-EM, the transfer mechanisms of copper and the conformational changes that control the gating mechanism remain poorly understood. The role of the extracellular N-terminal domains is particularly unclear due to the absence of a high-resolution structure of the full-length hCtr1 protein and limited biochemical and biophysical characterization of the transporter in solution and in cell. In this study, we employed distance electron paramagnetic resonance to investigate the conformational changes of the extracellular N-terminal domain of full-length hCtr1, both in vitro and in cells, as a function of Cu(I) binding. Our results demonstrate that at specific Cu(I) concentrations, the extracellular chains move closer to the lumen to facilitate copper transfer. Additionally, while at these concentrations the intracellular part is penetrating the lumen, suggesting a ball-and-chain gating mechanism. Moreover, this phenomenon was observed for both reconstituted protein in micelles and in native cell membranes. However, the measured distance values were slightly different, suggesting that the membrane's characteristics and therefore its lipid composition also impact and even regulate the gating mechanism of hCtr1.

Small interfering RNA (siRNA) therapy in acute myeloid leukemia (AML) is a promising strategy as the siRNA molecule can specifically target proteins involved in abnormal cell proliferation. The development of a clinically applicable method for delivering siRNA molecules is imperative due to the challenges involved in effectively delivering the siRNA into cells. We investigated the delivery of siRNA to AML MOLM-13 cells with the use of two lipid-substituted polyethyleneimines (PEIs), a commercially available reagent (Prime-Fect) and a recently reported reagent with improved lipid substitution (PEI1.2k-PHPA-Lin9). The siRNAs utilized in this study were targeting the oncogenes FLT3 and KMT2A::MLLT3. Both lipopolymers gave similar-size siRNA complexes (210-220 nm) with positive ζ-potentials (+17 to +25 mV). While the binding efficiency of both lipopolymers to siRNA were similar, PEI1.2k-PHPA-Lin9 complexes were more resistant to heparin-induced dissociation. The quantitative analysis of gene silencing performed by qPCR as well as immunostaining/flow cytometry indicated significant reduction in both FLT3 expression and FLT3 protein after specific siRNA delivery. The desired inhibition of cell growth was attained with both FLT3 and KMT2A::MLLT3 siRNAs, and the combination provided more potent effects in both cell growth and colony formation assays. Induction of apoptosis was confirmed after specific siRNA treatments using the Annexin V assay. Using Luc(+) MOLM-13 cells, the growth of the xenografted cells was shown to be retarded with Prime-Fect-delivered FLT3 siRNA, unlike the siRNA delivered with PEI1.2k-PHPA-Lin9. These results demonstrate the potential of designed lipopolymers in implementing RNAi (via delivery of siRNA) for inhibition of leukemia growth and provide evidence for the feasibility of targeting different oncogenes using siRNA-mediated therapy.

Chemical leukoderma is a disorder induced by chemicals such as rhododendrol and monobenzone. These compounds possess a p-substituted phenol moiety and undergo oxidation into highly reactive and toxic o-quinone metabolites by tyrosinase. This metabolic activation plays a critical role in the development of leukoderma through the production of damage to melanocytes and immunological responses. This study aimed to develop a simple method for assessing the metabolic activation of leukoderma-inducing phenols without analyzing the metabolite. Although B16BL6 melanoma cells showed insufficient sensitivity to the cytotoxicity assay, the siRNA-mediated knockdown of the transcription factor NRF2 (NFE2L2) repressed the expression of cytoprotective factors, thereby augmenting the cytotoxicity of all six leukoderma-inducing phenols tested in a tyrosinase-dependent manner, indicating enhanced sensitivity to o-quinone metabolites. Additionally, the knockdown of the NRF2-target Slc7a11 elevated the cytotoxicity of three out of the six compounds, indicating the involvement of cystine transport in cellular protection. In contrast, the knockdown or inhibition of the NRF2-target Nqo1 had minimal effects. The same response was induced upon Nrf2 and Slc7a11 knockdown in B16-4A5 cells, albeit with low sensitivity owing to low tyrosinase expression. We conclude that the analysis of tyrosinase-dependent cytotoxicity in Nrf2-depleted B16BL6 cells may serve as a useful strategy for evaluating the metabolic activation of chemicals.

Nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of cellular homeostasis, overseeing the expression of a wide array of genes involved in cytoprotective processes such as antioxidant and proteostasis control, mitochondrial function, inflammation, and the metabolism of lipids and glucose. The accumulation of misfolded proteins triggers the release, stabilization, and nuclear translocation of NRF2, which in turn enhances the expression of critical components of both the proteasomal and lysosomal degradation pathways. This process facilitates the clearance of toxic protein aggregates, thereby actively maintaining cellular proteostasis. As we age, the efficiency of the NRF2 pathway declines due to several factors including increased activity of its repressors, impaired NRF2-mediated antioxidant and cytoprotective gene expression, and potential epigenetic changes, though the precise mechanisms remain unclear. This leads to diminished antioxidant defenses, increased oxidative damage, and exacerbated metabolic dysregulation and inflammation-key contributors to age-related diseases. Given NRF2's role in mitigating proteotoxic stress, the pharmacological modulation of NRF2 has emerged as a promising therapeutic strategy, even in aged preclinical models. By inducing NRF2, it is possible to mitigate the damaging effects of oxidative stress, metabolic dysfunction, and inflammation, thus reducing protein misfolding. The review highlights NRF2's therapeutic implications for neurodegenerative diseases and cardiovascular conditions, emphasizing its role in improving proteostasis and redox homeostasis Additionally, it summarizes current research into NRF2 as a therapeutic target, offering hope for innovative treatments to counteract the effects of aging and associated diseases.

In chronic lymphocytic leukemia (CLL), natural killer (NK) cells show a dysfunctional phenotype that correlates with disease progression. Our aim was to restore NK cell functionality in CLL through a specifically targeted IL15-stimulating activity; IL15 targeting could, in fact, potentiate the activity of NK cells and reduce off-target effects. We designed and developed a cis-acting immunocytokine composed of an anti-CD56 single-chain Fragment variable (scFv) and IL15, labeled scFvB1IL15. scFvB1IL15 was tested in vitro on peripheral blood mononuclear cells (PBMCs) obtained from both different healthy donors (HDs) and CLL patients in order to evaluate its ability to target NK cells and enhance their activation and NK-mediated directed cytotoxicity. scFvB1IL15 specifically induced strong degranulation and cytokine and chemokine production in NK cells in both HD- and CLL patient-derived PBMC samples. Furthermore, compared to IL15 alone, it was able to induce higher levels of NKG2D- and NKp30-activating receptors and restore NK-mediated direct killing in the CLL patient-derived samples. The preliminary data presented in this work suggest that IL15's targeting of NK cells via scFvB1 potentiates the effects of IL15 and that scFvB1IL15 can be a useful agent for overcoming NK functional gaps and contribute to NK-cell-based immunotherapies.

Crohn's Disease (CD) is a chronic inflammatory bowel disease affecting the gastrointestinal tract. The search continues for new markers for assessing the activity of CD. Among them, pro-inflammatory and anti-inflammatory cytokines appear promising. We performed the analysis of cytokine concentrations in blood serum using the Bio-Plex Multiplex system (Bio-Rad), and their correlations with radiological parameters were assessed by magnetic resonance enterography (MRE), and fecal calprotectin levels were measured quantitatively by ELISA and clinical evaluation according to the Crohn's Disease Activity Index (CDAI). Our study found that measuring cytokine serum concentrations can be a valuable tool in the diagnosis and treatment of CD. Positive correlations were reported between contrast enhancement on DCE-MRE and the concentrations of PDGF-BB and RANTES. Also, a positive correlation was found between the delayed-phase of DCE and IL-10 concentration, a strong negative correlation between the delayed-phase of DCE and IL-12 concentration, and a strong positive correlation between the delayed-phase of DCE and RANTES concentrations. A strong positive correlation was also observed between the thickness of the intestinal wall on T2-weighted images and RANTES concentration. Therefore, concentrations of PDGF-BB, RANTES, IL-10 and IL-12 are promising markers of CD activity. The study also demonstrated significant correlations between the severity of disease activity assessed by the CDAI and the concentrations of IL-5, IL-8 and IL-9, as well as positive correlations between the levels of fecal calprotectin and the concentrations of IL-1RA and VEGF. Therefore, the levels of IL-5, IL-8, IL-9, VEGF and IL-1RA may be useful markers in the diagnosis and clinical assessment of disease activity.