Methods in molecular biology最新文献

Oral squamous cell carcinoma (OSCC) is the most common form of head and neck cancer. The current standard for treating primary OSCC is surgical resection combined with radiotherapy and chemotherapy. Despite improved therapeutic strategies, OSCC has high rates of metastasis and mortality, with one in two patients dying of the disease. Patient-derived organoids have become promising cell culture systems for disease modeling and precision medicine. Here we describe the high-efficiency generation of organoids from OSCC patients, which can be maintained in the culture for the long term. We further provide protocols for characterizing OSCC organoids using histology and immunofluorescence staining.

While traditional assay methods face challenges in detecting specific proteins, aptamers, known for their high specificity and affinity, are emerging as a valuable biomarker detection tool. Aurora kinase A (AURKA) plays a role in cell division and influences stem cell reprogramming. In this study, an in silico approach method was conducted for a random ssDNA aptamer sequence selection and its binding with AURKA. The aptamer was designed based on AURKA's structure and nucleic acid sequence, obtained from PDB RCSB. Using RNAfold and RNA composer, we predicted the aptamer's secondary and tertiary structures. Protein-aptamer binding was analyzed via HDOCK and HADDOCK, with 2D interactions visualized in LIGPLOT+ v1.4. Autodock 4 and NAMD 2.3 tools were used to conduct docking and MD simulation studies.

The discovery of leucine-rich-containing G-protein-coupled receptor 5 (Lgr5) as an intestinal adult stem cell marker had blazed a trail in stem cell biology and laid the foundations of modern organoid technology. Up to date, several well-established intestinal organoid protocols have been reported in the literature from different sources, including adult and induced pluripotent stem cells. Here, we demonstrate a BALB/c mouse-derived intestinal organoid culture protocol, passaging, and cryopreservation procedures.

This study describes an intramolecular quenching assay to evaluate gamma-secretase (GS) enzyme activity in human dermal cells. The method utilizes a fluorogenic peptide substrate, mimicking a fragment of amyloid precursor protein (APP), in which a quencher suppresses the fluorescence of a fluorophore until enzymatic cleavage occurs, resulting in a measurable increase in fluorescence. This real-time, direct measurement of GS activity allows for precise kinetic analysis using Michaelis-Menten modeling to define Kd and Vmax. The assay is designed to quantify GS activity in human dermal fibroblasts and keratinocytes, enabling comparison between samples derived from hidradenitis suppurativa (HS) patients and healthy controls, as well as investigating the effects of subunit knockdown, such as nicastrin, on GS function. The method offers several advantages, including simplicity, cost-effectiveness, and adaptability for high-throughput screening for GS enzyme inhibitors.

Negative magnetophoresis is employed to levitate cells in a paramagnetic medium without the need for magnetic labeling, preserving their natural state and minimizing toxicity. The single-ring magnet configuration that provides an open space in the levitation chamber enhances culture accessibility and scalability, enabling the formation of millimeter-sized 3D structures through cellular self-assembly. This system provides a versatile and cost-effective approach for diverse applications, including tissue engineering and biofabrication. This protocol outlines a method for biofabrication and maintenance of 3D cellular structures using magnetic levitation with a ring magnet-based setup.

In this chapter, we present a detailed protocol for establishing a three-dimensional (3D) multicellular tumor spheroids (MCTSs) model to simulate the tumor microenvironment (ME) associated with metabolic dysfunction-associated steatotic liver disease (MASLD) for the study of hepatocellular carcinoma (HCC) and colorectal cancer (CRC) cell aggressiveness, growth, and metastasis potential. The MASLD microenvironment (MASLD-ME) is recreated by embedding hepatic stellate cells in a collagen I matrix within a Boyden chamber system. The metabolic medium mimics MASLD conditions, enriched with high glucose, fructose, insulin, and fatty acids, to simulate metabolic stresses associated with the disease.In the protocol, cancer cells are loaded in the upper compartment to analyze their migration toward the MASLD-ME, thereby facilitating studies on cancer cell invasiveness and metastatic capacity. This method offers an adaptable, reproducible model to research disease progression and investigate therapeutic interventions, contributing to preclinical research on MASLD-related liver cancer pathophysiology and potential drug responses.

Recent advances in fluorescence microscopy have now made it possible to measure the translation dynamics of individual RNA in living cells and in multiple colors. Here we describe a protocol that exploits these recent advances to simultaneously image the translation of two open reading frames encoded on a single reporter RNA yet frameshifted with respect to each other. This enables precise measurements of frameshifting dynamics and efficiency from specific frameshift stimulatory sequences, all with single-RNA precision.

Protein engineering is an established method for tailoring enzymatic reactivity. A commonly used method is directed evolution, where the mutagenesis and natural selection process is mimicked and accelerated in the laboratory. Here, we describe a reliable method for generating saturation mutagenesis libraries by Golden Gate cloning in a broad host range plasmid containing the pBBR1 replicon. The applicability is demonstrated by generating a mutant library of the iron nitrogenase gene cluster (anfHDGK) of Rhodobacter capsulatus, which is subsequently screened for the improved formation of molecular hydrogen.

Modern synthetic biology requires fast and efficient cloning strategies for the assembly of new transcription units or entire pathways. Modular Cloning (MoClo) is a standardized synthetic biology workflow, which has tremendously simplified the assembly of genetic elements for transgene expression. MoClo is based on Golden Gate Assembly and allows to combine genetic elements of a library through a hierarchical syntax-driven pipeline. Here we describe the assembly of a genetic cassette for transgene expression in the single-celled model alga Chlamydomonas reinhardtii.

Prokaryotes use CRISPR-Cas systems to interfere with viruses and other mobile genetic elements. CRISPR arrays comprise repeated DNA elements and spacer sequences that can be engineered for custom target sites. These arrays are transcribed into precursor CRISPR RNAs (pre-crRNAs) that undergo maturation steps to form individual CRISPR RNAs (crRNAs). Each crRNA contains a single spacer that identifies the target cleavage site for a large variety of Cas protein effectors. Precise manipulation of spacer sequences within CRISPR arrays is crucial for advancing the functionality of CRISPR-based technologies. Here, we describe a protocol for the design and creation of a minimal, plasmid-based CRISPR array to enable the expression of specific, synthetic crRNAs. Plasmids contain entry spacer sequences with two type IIS restriction sites and Golden Gate cloning enables the efficient exchange of these spacer sequences. Factors that influence the compatibility of the CRISPR arrays with native or recombinant Cas proteins are discussed.