We present here the summary of two cell biology-related conferences held in Mexico in November 2024. Very broad topics were depicted, nevertheless, a focus on mechanotransduction was perceptible in the two events.
We present here the summary of two cell biology-related conferences held in Mexico in November 2024. Very broad topics were depicted, nevertheless, a focus on mechanotransduction was perceptible in the two events.
RNA plays crucial roles in cellular organization and metabolism, and modulating its activity is essential for maintaining cellular functions. RNA activity, involving both catalytic (ribozymes) and translation processes, is controlled via myriad mechanisms involving different binding partners such as proteins and smaller polar solutes. We previously reported that lipid membranes can directly interact with the artificial R3C ribozyme changing its activity, however, the effect of lipids on naturally occurring ribozymes remains unknown.
Here, we report that both catalytic activity as well as RNA integrity can be controlled by the presence of different lipid membranes. Gel-phase lipid membranes decreased the activity of hepatitis delta virus ribozyme and increased the activity of a hammerhead ribozyme. The presence of lipid liquid membrane surfaces triggered RNA degradation with greater degradation occurring in the single-stranded regions of RNA.
The interplay between RNA activity and stability in the presence of different lipid membranes introduces multiple possibilities, where different combinations of ribozyme and lipid membrane composition could produce different effects on activity.
Taken together, these observations support the hypothesis that the activity of both natural and artificial RNAs can be modulated by lipid membranes which, in turn, provides a foundation for the development of novel riboswitch-like molecules, and lipid membrane-based RNA-biosensors.
Mitosis is crucial for the faithful transmission of genetic material, and disruptions can result in chromosomal instability (CIN), a hallmark of cancer. CIN is a known driver of tumor heterogeneity and anti-cancer drug resistance, thus highlighting the need to assess CIN levels in cancer cells to design effective targeted therapy. While micronuclei are widely recognized as CIN markers, we have recently identified the toroidal nucleus, a novel ring-shaped nuclear phenotype arising as well from chromosome mis-segregation.
Here, we examined whether increasing nuclear envelope stiffness through lamin A/C overexpression could affect the formation of toroidal nuclei and micronuclei. Interestingly, lamin A/C overexpression led to an increase in toroidal nuclei while reducing micronuclei prevalence. We demonstrated that chromatin compaction and nuclear stiffness drive the formation of toroidal nuclei. Furthermore, inhibition of autophagy and lysosomal function elevated the frequency of toroidal nuclei without affecting the number of micronuclei in the whole cell population. We demonstrated that this divergence between the two CIN biomarkers is independent of defects in lamin A processing.
These findings uncover a complex interplay between nuclear architecture and levels of CIN, advancing our understanding of the mechanisms supporting genomic stability and further contributing to cancer biology.
Mitochondria, as the central hub of cellular energy metabolism and a critical regulator of signaling pathways, play indispensable roles in spermatogenesis and sperm function. In recent years, the mechanisms by which RNA-binding proteins regulate reproductive development and gametogenesis have emerged as a focal point in mitochondrial biology. Here, we review the latest progresses on the role of mitochondrial translation and its associated ribosomal regulation in sperm formation and activation. In Caenorhabditis elegans, the RNA-binding protein complex AMG-1/SLRP-1 modulates key processes of sperm development by maintaining mitochondrial homeostasis. Furthermore, we explore the distinct roles of mitochondrial translation and metabolic functions in sperm activation and motility. This review summarizes the mechanisms by which mitochondrial ribosomal regulation governs spermatogenesis and sperm function, offering a foundation for future investigations in reproductive biology.
Based on recently published parameters (Rane et al. 2023, JPCB 127, 5046–5054) for (rs)EGFP triplet state formation and decay rates and yields, we consider the power density dependence of triplet state population dynamics and its consequences for the application of green fluorescent proteins in biological single molecule fluorescence microscopy.
We find that under certain conditions, the photon budget of GFP type fluorescent proteins can be linearly dependent on power density and we propose a possible explanation for such a non-Hirschfeld photobleaching behavior. Moreover, illumination with millisecond pulses at sub-kHz rates is shown to improve photostability.
We stipulate that a judicious choice of excitation wavelength should take into account the triplet state absorption spectrum along with the singlet state absorption spectrum. Formulas are given for the estimation of the effects of such choice as function of the experimental parameters.
The linear photobleaching model as proposed by Hirschfeld 50 years ago with power-independent photon budget is not generally applicable to fluorescent proteins with millisecond-lived triplet states.
Organoids are miniature three-dimensional (3D) organ-like structures developed from primary cells that closely mimic the key histological, functional, and molecular characteristics of their parent organs. These structures self-organize through cell-cell and cell-matrix interaction in culture. In the last decade, organoids and allied 3D culture technologies have catalyzed studies involving developmental biology, disease biology, high-throughput drug screening, personalized medicine, biomarker discovery, tissue engineering, and regenerative medicine. Many organoid systems have been generated from the gastrointestinal system, for example, intestine, stomach, liver, pancreas, or colon. Gallbladder cancer (GBC) is the most common and highly aggressive form of biliary tract cancer. GBC is rare in the west but has a high incidence in South America and India. Prolonged chronic inflammation is implicated in the pathogenesis of GBC but the driving molecular pathways leading to neoplasia are not well understood. Gallbladder cholangiocyte organoids (GCO) will facilitate the understanding of the evolution of the disease and novel therapeutic strategies. In this review, we have discussed alternative methodologies and culture conditions developed to generate GCO models, applications that these models have been subjected to and the current limitations for the use of GCOs in addressing the challenges in GBC research.
The discovery of green fluorescent protein (GFP) and its derivatives has revolutionized cell biology. These fluorescent proteins (FPs) have enabled the real-time observation of protein localization and dynamics within live cells. Applications of FP vary from monitoring gene/protein expression patterns, visualizing protein-protein interactions, measuring protein stability, assessing protein mobility, and creating biosensors. The utility of FPs also extends to biochemical approaches through immunoblotting and proteomic analyses, aided by anti-FP antibodies and nanobodies. FPs are notoriously robust proteins with a tightly folded domain that confers a strong stability and a relative resistance to degradation and denaturation.
In this study, we report that various green, orange, and red FPs can be maintained in a native, fluorescent state during the entire process of protein sample extraction, incubation with sample buffer, loading, and migration on SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) with only minor adaptations of traditional protocols. This protocol results in the ability to detect and quantify in-gel fluorescence (IGF) of endogenously-expressed proteins tagged with FPs directly after migration, using standard fluorescence-imaging devices. This approach eliminates the need for antibodies and chemiluminescent reagents, as well as the time-consuming steps inherent in immunoblotting such as transfer onto a membrane and antibody incubations.
Overall, IGF detection provides clearer data with less background interference, a sensitivity comparable to or better than antibody-based detection, a better quantification, and a broader dynamic range. After fluorescence imaging, gels can still be used for other applications such as total protein staining or immunoblotting if needed. It also expands possibilities by allowing the detection of FPs for which antibodies are not available. Our study explores the feasibility, limitations, and applications of IGF for detecting endogenously expressed proteins in cell extracts, providing insights into sample preparation, imaging conditions, and sensitivity optimizations, and potential applications such as co-immunoprecipitation experiments.
Tumor hypoxia reshapes the microenvironment, driving progression, invasion, metastasis, and therapy resistance. Patient-derived tumor organoids, formed under three-dimensional conditions, preserve cellular heterogeneity and nutrient gradients, making them ideal for studying hypoxia-induced tumor responses. This study examines hypoxia-induced changes in lung tumor organoids from two patients, focusing on tumor-associated markers, stem cell markers, and migration capabilities.
Our findings demonstrate that hypoxia distinctively modulates the expression of lung cancer markers thyroid transcription factor-1, cytokeratin 7, and ΔNP63 variant. Hypoxia also induces the upregulation of stem cell-associated markers, resulting in an increased proportion of cancer stem cells. Furthermore, hypoxic lung tumor organoids exhibit unique migratory behavior upon reoxygenation, driven by epithelial-mesenchymal transition and the elevated expression of matrix metalloproteinases 7 and matrix metalloproteinases 9, indicating their enhanced invasive potential.
These findings highlight the value of lung tumor organoids as models for studying hypoxia's complex role in lung cancer. Hypoxia significantly modulates lung tumor organoids growth, stemness, and migratory behavior, providing critical insights into tumor progression and therapy resistance.
The primary objectives of this study were to characterize 3,5-dibromosalicylaldehyde (3,5-DBSA) and, investigate its antiproliferative, antimetastatic, cytotoxic, and immunoregulatory properties. NMR, Raman, UV, and FT-IR spectroscopies were used to characterize 3,5-DBSA. Potential conformations of 3,5-DBSA were evaluated using Spartan's MMFF method. Geometry optimization calculations using Gaussian software calculated conformation energy values.
Subsequently, Raman, FT-IR, UV (ethanol) and NMR (DMSO) parameters were calculated. The experimental spectrum was compared to theoretical spectroscopic data. The present investigation investigated 3,5-DBSA's anticancer properties; therefore, docking was done once the stable structure had been identified.
Identifying stable structure is crucial to molecular docking studies. In order to identify the mechanism by which 3,5-DBSA binds to PI3K as a therapeutic target, molecular docking was utilized. This work is the first to show that 3,5-DBSA is cytotoxic, anticlonogenic, antimetastatic, and immunomodulatory in glioblastoma cell line U87MG compared to healthy fibroblast L929 cells. Cytotoxicity and anti-clonogenicity studies investigated 3,5-DBSA's antiproliferative activities, whereas wound healing assays assessed cell migration. The immunomodulatory effects of 3,5-DBSA in glioblastoma were assessed by measuring Netrin-1 and IL-6 protein levels. According to our findings, 3,5-DBSA may treat glioblastoma.
This work analyzes 3,5-DBSA's conformational search, characterization, molecular docking, and structural and anticancer properties.
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