Non-Mammalian Models for Understanding Neurological Defects in RASopathies.

RASopathies, a group of neurodevelopmental congenital disorders stemming from mutations in the RAS/MAPK pathway, present a unique opportunity to delve into the intricacies of complex neurological disorders. Afflicting approximately one in a thousand newborns, RASopathies manifest as abnormalities across multiple organ systems, with a pronounced impact on the central and peripheral nervous system. In the pursuit of understanding RASopathies' neurobiology and establishing phenotype-genotype relationships, in vivo non-mammalian models have emerged as indispensable tools.

Cardioprotective function of sclerostin by reducing calcium deposition, proliferation, and apoptosis in human vascular smooth muscle cells.

Background: Sclerostin is an inhibitor of the Wnt/b-catenin pathway, which regulates bone formation, and can be expressed in vascular smooth muscle cells (VSMCs). Type 2 diabetes (T2D) is associated with an increased risk of cardiovascular disease (CVD) and increased serum and tissue expression of sclerostin. However, whether the role of sclerostin is detrimental or protective in the development of CVD is unknown.

Exploring the role of osteoglycin in type 2 diabetes: implications for insulin resistance and vascular pathophysiology.

Osteoglycin, a fundamental proteoglycan within the vascular extracellular matrix, is expressed in vascular smooth muscle cells (VSMCs). Type 2 diabetes (T2D) is associated with cardiovascular disease (CVD) but the role of osteoglycin in the development of CVD is controversial to date. Therefore, our aims are to determine and compare the level of osteoglycin in T2D patients with/without CVD versus control subjects both at serum and vascular tissue and to analyze in vitro role of osteoglycin in VSMCs under calcified conditions.

The therapeutic potential of neurofibromin signaling pathways and binding partners.

Neurofibromin controls many cell processes, such as growth, learning, and memory. If neurofibromin is not working properly, it can lead to health problems, including issues with the nervous, skeletal, and cardiovascular systems and cancer. This review examines neurofibromin's binding partners, signaling pathways and potential therapeutic targets.

Identification of Germinal Neurofibromin Hotspots.

Neurofibromin is engaged in many cellular processes and when the proper protein functioning is impaired, it causes neurofibromatosis type 1 (), one of the most common inherited neurological disorders. Recent advances in sequencing and screening of the gene have increased the number of detected variants. However, the correlation of these variants with the clinic remains poorly understood.

NAMPT-derived NAD+ fuels PARP1 to promote skin inflammation through parthanatos cell death.

Several studies have revealed a correlation between chronic inflammation and nicotinamide adenine dinucleotide (NAD+) metabolism, but the precise mechanism involved is unknown. Here, we report that the genetic and pharmacological inhibition of nicotinamide phosphoribosyltransferase (Nampt), the rate-limiting enzyme in the salvage pathway of NAD+ biosynthesis, reduced oxidative stress, inflammation, and keratinocyte DNA damage, hyperproliferation, and cell death in zebrafish models of chronic skin inflammation, while all these effects were reversed by NAD+ supplementation. Similarly, genetic and pharmacological inhibition of poly(ADP-ribose) (PAR) polymerase 1 (Parp1), overexpression of PAR glycohydrolase, inhibition of apoptosis-inducing factor 1, inhibition of NADPH oxidases, and reactive oxygen species (ROS) scavenging all phenocopied the effects of Nampt inhibition.

Integrated in silico MS-based phosphoproteomics and network enrichment analysis of RASopathy proteins.

Background: RASopathies are a group of syndromes showing clinical overlap caused by mutations in genes affecting the RAS-MAPK pathway. Consequent disruption on cellular signaling leads and is driven by phosphoproteome remodeling. However, we still lack a comprehensive picture of the different key players and altered downstream effectors.

Dictyostelium discoideum as a non-mammalian biomedical model.

Dictyostelium discoideum is one of eight non-mammalian model organisms recognized by the National Institute of Health for the study of human pathology. The use of this slime mould is possible owing to similarities in cell structure, behaviour and intracellular signalling with mammalian cells. Its haploid set of chromosomes completely sequenced amenable to genetic manipulation, its unique and short life cycle with unicellular and multicellular stages, and phenotypic richness encoding many human orthologues, make Dictyostelium a representative and simple model organism to unveil cellular processes in human disease.

Proteomic and Transcriptomic Profiling Identifies Early Developmentally Regulated Proteins in .

Cyclic AMP acts as a secondary messenger involving different cellular functions in eukaryotes. Here, proteomic and transcriptomic profiling has been combined to identify novel early developmentally regulated proteins in eukaryote cells. These proteomic and transcriptomic experiments were performed in Dictyostelium discoideum given the unique advantages that this organism offers as a eukaryotic model for cell motility and as a nonmammalian model of human disease.

Phosphodiesterase PdeD, dynacortin, and a Kelch repeat-containing protein are direct GSK3 substrates in Dictyostelium that contribute to chemotaxis towards cAMP.

The migration of cells according to a diffusible chemical signal in their environment is called chemotaxis, and the slime mold Dictyostelium discoideum is widely used for the study of eukaryotic chemotaxis. Dictyostelium must sense chemicals, such as cAMP, secreted during starvation to move towards the sources of the signal. Previous work demonstrated that the gskA gene encodes the Dictyostelium homologue of glycogen synthase kinase 3 (GSK3), a highly conserved serine/threonine kinase, which plays a major role in the regulation of Dictyostelium chemotaxis.

Connecting G protein signaling to chemoattractant-mediated cell polarity and cytoskeletal reorganization.

The directional movement toward extracellular chemical gradients, a process called chemotaxis, is an important property of cells. Central to eukaryotic chemotaxis is the molecular mechanism by which chemoattractant-mediated activation of G-protein coupled receptors (GPCRs) induces symmetry breaking in the activated downstream signaling pathways. Studies with mainly Dictyostelium and mammalian neutrophils as experimental systems have shown that chemotaxis is mediated by a complex network of signaling pathways.

A Gα-Stimulated RapGEF Is a Receptor-Proximal Regulator of Dictyostelium Chemotaxis.

Chemotaxis, or directional movement toward extracellular chemical gradients, is an important property of cells that is mediated through G-protein-coupled receptors (GPCRs). Although many chemotaxis pathways downstream of Gβγ have been identified, few Gα effectors are known. Gα effectors are of particular importance because they allow the cell to distinguish signals downstream of distinct chemoattractant GPCRs.

Internal sense of direction: sensing and signaling from cytoplasmic chemoreceptors.

Chemoreceptors sense environmental signals and drive chemotactic responses in Bacteria and Archaea. There are two main classes of chemoreceptors: integral inner membrane and soluble cytoplasmic proteins. The latter were identified more recently than integral membrane chemoreceptors and have been studied much less thoroughly.

Characterization of molecular interactions using isothermal titration calorimetry.

Isothermal titration calorimetry (ITC) is based on a simple titration of one ligand with another and the small heat changes caused by the molecular interaction are detected. From one ITC experiment the complete set of thermodynamic parameters of binding including association and dissociation constants as well as changes in enthalpy, entropy, and free energy can be derived. Using this technique almost any type of molecular interaction can be analyzed.

Evidence for chemoreceptors with bimodular ligand-binding regions harboring two signal-binding sites.

Chemoreceptor-based signaling is a central mechanism in bacterial signal transduction. Receptors are classified according to the size of their ligand-binding region. The well-studied cluster I proteins have a 100- to 150-residue ligand-binding region that contains a single site for chemoattractant recognition.

Bioavailability of pollutants and chemotaxis.

The exposure of bacteria to pollutants induces frequently chemoattraction or chemorepellent reactions. Recent research suggests that the capacity to degrade a toxic compound has co-evolved in some bacteria with the capacity to chemotactically react to it. There is an increasing amount of data which show that chemoattraction to biodegradable pollutants increases their bioavailability which translates into an enhancement of the biodegradation rate.

Analysis of solvent tolerance in Pseudomonas putida DOT-T1E based on its genome sequence and a collection of mutants.

Pseudomonas putida strains are prevalent in a variety of pristine and polluted environments. The genome of the solvent-tolerant P. putida strain DOT-T1E which thrives in the presence of high concentrations of monoaromatic hydrocarbons, contains a circular 6.

Responses of Pseudomonas putida to toxic aromatic carbon sources.

A number of bacteria can use toxic compounds as carbon sources and have developed complex regulatory networks to protect themselves from the toxic effects of these compounds as well as to benefit from their nutritious properties. As a model system we have studied the responses of Pseudomonas putida strains to toluene. Although this compound is highly toxic, several strains are able to use it for growth.

Bacterial chemotaxis towards aromatic hydrocarbons in Pseudomonas.

Bacterial chemotaxis is an adaptive behaviour, which requires sophisticated information-processing capabilities that cause motile bacteria to either move towards or flee from chemicals. Pseudomonas putida DOT-T1E exhibits the capability to move towards different aromatic hydrocarbons present at a wide range of concentrations. The chemotactic response is mediated by the McpT chemoreceptor encoded by the pGRT1 megaplasmid.

The pGRT1 plasmid of Pseudomonas putida DOT-T1E encodes functions relevant for survival under harsh conditions in the environment.

Pseudomonas putida DOT-T1E has the capacity to grow in the presence of high concentrations of toluene. This ability is mainly conferred by an efflux pump encoded in a self-transmissible 133 kb plasmid named pGRT1. Sequence analysis of the pGRT1 plasmid revealed several key features.

Physiologically relevant divalent cations modulate citrate recognition by the McpS chemoreceptor.

The McpS chemoreceptor of Pseudomonas putida KT2440 recognizes six different tricarboxylic acid (TCA) cycle intermediates. However, the magnitude of the chemotactic response towards these compounds differs largely, which has led to distinguish between strong attractants (malate, succinate, fumarate, oxaloacetate) and weak attractants (citrate, isocitrate). Citrate is abundantly present in plant tissues and root exudates and can serve as the only carbon source for growth.

Diversity at its best: bacterial taxis.

Bacterial taxis is one of the most investigated signal transduction mechanisms. Studies of taxis have primarily used Escherichia coli and Salmonella as model organism. However, more recent studies of other bacterial species revealed a significant diversity in the chemotaxis mechanisms which are reviewed here.

Bacterial sensor kinases: diversity in the recognition of environmental signals.

Bacteria sense and respond to a wide range of physical and chemical signals. Central to sensing and responding to these signals are two-component systems, which have a sensor histidine kinase (SK) and a response regulator (RR) as basic components. Here we review the different molecular mechanisms by which these signals are integrated and modulate the phosphorylation state of SKs.

Sensing of environmental signals: classification of chemoreceptors according to the size of their ligand binding regions.

Central to the different forms of taxis are methyl-accepting chemotaxis proteins (MCPs). The increasing number of genome sequences reveals that MCPs differ enormously in sequence, topology and genomic abundance. This work is a one-by-one bioinformatic analysis of the almost-totality of MCP genes available and a classification of motile bacteria according to their lifestyle.