High-Resolution Three-Dimensional NMR Structure Of The KRAS Proto-Oncogene Promoter Reveals Key Features Of A G-Quadruplex Involved In Transcriptional Regulation

Non-canonical base pairing within guanine-rich DNA and RNA sequences can produce G-quartets, whose stacking leads to the formation of a G-quadruplex (G4). G4s can coexist with canonical duplex DNA in the human genome and have been suggested to suppress gene transcription, and much attention has therefore focused on studying G4s in promotor regions of disease-related genes. For example, the human KRAS proto-oncogene contains a nuclease-hypersensitive element located upstream of the major transcription start site. The KRAS nuclease-hypersensitive element (NHE) region contains a G-rich element (22RT; 5′-AGGGCGGTGTGGGAATAGGGAA-3′) and encompasses a Myc-associated zinc finger-binding site that regulates KRAS transcription. The NEH region therefore has been proposed as a target for new drugs that control KRAS transcription, which requires detailed knowledge of the NHE structure. In this study, we report a high-resolution NMR structure of the G-rich element within the KRAS NHE. We found that the G-rich element forms a parallel structure with three G-quartets connected by a four-nucleotide loop and two short one-nucleotide double-chain reversal loops. In addition, a thymine bulge is found between G8 and G9. The loops of different lengths and the presence of a bulge between the G-quartets are structural elements that potentially can be targeted by small chemical ligands that would further stabilize the structure and interfere or block transcriptional regulators such as Myc-associated zinc finger from accessing their binding sites on the KRAS promoter. In conclusion, our work suggests a possible new route for the development of anticancer agents that could suppress KRAS expression

Rehabilitation of Neonatal Brachial Plexus Palsy: Integrative Literature Review

This integrative literature review has been carried out with the aim of analyzing the scientific literature aimed at identifying and describing existing rehabilitation treatments/therapies for neonatal brachial plexus palsy (NBPP). NBPP is a frequent consequence of difficult birthing, and it impairs the function of the brachial plexus in newborns. This is why knowledge on rehabilitation strategies deserves special attention. The data collection was carried out in January 2019, in the EBSCOhost and BVS (Biblioteca Virtual em Saúde) platforms, in the CINAHL Complete, MEDLINE Complete, LILACS and PubMed databases. Thirteen articles were included in this integrative literature review, based on a literature search spanning title, abstract and full text, and considering the inclusion criteria. Two main treatments/therapies for NBPP rehabilitation were identified: conservative treatment and surgical treatment. Conservative treatment includes teamwork done by physiatrists, physiotherapists and occupational therapists. These professionals use rehabilitation techniques and resources in a complementary way, such as electrostimulation, botulinum toxin injection, immobilizing splints, and constraint induced movement therapy of the non-injured limb. Professionals and family members work jointly. Surgical treatment includes primary surgeries, indicated for children who do not present any type of spontaneous rehabilitation in the first three months of life; and secondary surgeries, recommended in children who after primary surgery have some limitation of injured limb function, or in children who have had some spontaneous recovery, yet still have significant functional deficits. Treatment options for NBPP are defined by clinical evaluation/type of injury, but regardless of the type of injury, it is unanimous that conservative treatment is always started as early as possible. It should be noted that there was no evidence in the literature of other types of rehabilitation and techniques used in clinical practice, such as preventive positioning of contractures and deformities, hydrotherapy/aquatic therapy, among others, so we consider there is a need for further studies at this level in this area.info:eu-repo/semantics/publishedVersio

Superhydrophobic platforms for the combinatorial analysis of biomaterials-cells interactions using arrays of 3D scaffolds with distinct mechanical and morphological properties

High-throughput studies of cells mechanotransduction are usually performed using 2D biomaterials. However, cells-extracellular matrix interactions in the body occur in 3D environment. By using cells entrapped in hydrogels, it is not easy to isolate the mechanical effect from the chemical cues of biomaterials. We used a cytocompatible and non-expensive platform based in the patterning of wettable spots in superhydrophobic surfaces to deposit porous biomaterials in these regions. Freeze-dried alginate/chitosan scaffolds were used to create an array of mechanical properties and porosities. Adaptation of dynamic mechanic analysis equipment allowed performing on-chip single scaffold analysis. Micro-computed tomography allowed acquir- ing data for whole chips simultaneously. Results were validated using individual scaffolds and single-formulation chips. A sub-array with combined modulus/porosity properties was selected. Fibronectin (Fn) in different concentration was adsorbed in the scaffolds, and fibroblasts and osteoblast-like cells were seeded. The independent study of variables influence in cell response was performed by image-based methods. In the absence of Fn fibroblasts did not respond to mechani- cal properties in the chip range. Osteoblast-like cells showed higher cell adhesion in stiffer substrates. The adsorption of Fn was studied qualita- tively by image methods. Results related with Fn amount and scaffolds’ mechanical properties were analyzed for each cell type.</p