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Considerable heterogeneity among training-induced effects is observed in patients with cystic fibrosis (CF). We previously showed that longitudinal changes in exercise capacity in adolescents with CF were negatively associated with Pseudomonas aeruginosa (P. aeruginosa) colonization and total immunoglobulin G (IgG) levels, independent of age, pulmonary function and bodyweight. This is the first study investigating whether chronic inflammation and infection also associate with the exercise training response in adolescents with CF. Participants performed a home-based exercise training program for 12 weeks. Pulmonary function, anthropometrics, exercise capacity, markers of inflammation and P. aeruginosa colonization status were measured at baseline. Exercise training-induced changes in pulmonary function and exercise capacity were compared between patients with a low and high inflammation-infection status. Participants with CF with high total IgG levels and P. aeruginosa colonization improved significantly less from the exercise training program, with regard to maximal oxygen consumption. These observations support the hypothesis that chronic systemic inflammation and infection leads to devastating effects on skeletal muscles, hampering skeletal muscle tissue to improve from regular physical exercise. Data further suggest that patients with CF should preferentially be encouraged to engage in regular physical exercise when inflammation and infection status is low (e.g. at a young age). [ABSTRACT FROM AUTHOR]

Abstract: The C-terminal domain of protein 4.1G was identified to interact with the cytosolic tail of the high affinity IgG receptor, FcγRI, in yeast two-hybrid screens. Proteins of the 4.1 family have previously been found to mediate receptor/cytoskeleton interactions. In the study presented here, we show an alternatively spliced 4.1G product to be associated with increased FcγRI binding in yeast two-hybrid assays, and to be selectively enriched in most immune cells at the transcript level. In addition, a detailed analysis of the 4.1G ‘docking site’ within FcγRI is provided by examining FcγRI-CY-truncated and alanine-substituted mutants. These pointed to an FcγRI membrane-proximal core motif of HxxBxxxBB (H represents hydrophobic residues, B basic residues and x represents any residue), followed by hydrophobic and (potentially) negatively charged residues to be central for interaction with protein 4.1G. [Copyright &y& Elsevier]

FcγRI requires both the intracellular domain of the α-chain and associated leukocyte Fc receptor (FcR) γ-chains for its biological function. We recently found the C terminus of periplakin to selectively interact with the cytoplasmic domain of the FcγRI α-chain. It thereby enhances the capacity of FcγRI to bind, internalize, and present antigens on MHC class II. Here, we characterized the domains involved in FcγRI-periplakin interaction using truncated and alanine-substituted FcγRI mutants and randomly mutagenized periplakin. This allowed us to design TAT peptides that selectively interfered with endogenous FcγRI-periplakin interactions. The addition of these peptides to FcγRI-expressing cells modulated FcγRI ligand binding, as assessed by erythrocyte-antibody-rosetting. These data support a dominant-negative role of C-terminal periplakin for FcγRI biological activity and implicate periplakin as a novel regulator of FcγRI in immune cells. [ABSTRACT FROM AUTHOR]

Approximately 10% of all pathological mutations are nonsense mutations which are responsible for the most severe cases of genetic diseases but for which no treatment regimens are available. The main strategy for treating nonsense mutations is by enhancing ribosomal readthrough of premature stop codons through the action of readthrough compounds, thus restoring production of full-length protein. Most preclinical studies on readthrough compounds have yielded positive results, but have been performed in reporter-based assays despite recent scientific developments that have significantly improved disease models, such as patient-derived cells in functional assays. Clinical trials have yielded disappointing results, and further interpretation of readthrough compound efficacy across clinical trials is challenging because of differences in research design, treatment length, and clinical endpoints. Characterization of factors that contribute to the translational gap between readthrough compounds in preclinical studies versus clinical trial results is necessary to make sense of nonsense mutation therapy. Approximately 10% of all pathological mutations are nonsense mutations that are responsible for several severe genetic diseases for which no treatment regimens are currently available. The most widespread strategy for treating nonsense mutations is by enhancing ribosomal readthrough of premature termination codons (PTCs) to restore the production of the full-length protein. In the past decade several compounds with readthrough potential have been identified. However, although preclinical results on these compounds are promising, clinical studies have not yielded positive outcomes. We review preclinical and clinical research related to readthrough compounds and characterize factors that contribute to the observed translational gap. [ABSTRACT FROM AUTHOR]

• Analyzing CFTR mutations in patients with cystic fibrosis (CF). • Predicting drug response for CF patients via organoid assays. • Modulating mutant CFTR activity with CF drugs in organoids. • Assessing the pros and cons of CF organoid-based assays. Cystic fibrosis (CF) is a life-shortening genetic disease caused by mutations of CFTR , the gene encoding cystic fibrosis transmembrane conductance regulator. Despite considerable progress in CF therapies, targeting specific CFTR genotypes based on small molecules has been hindered because of the substantial genetic heterogeneity of CFTR mutations in patients with CF, which is difficult to assess by animal models in vivo. There are broadly four classes (e.g., II, III, and IV) of CF genotypes that differentially respond to current CF drugs (e.g., VX-770 and VX-809). In this review, we shed light on the pharmacogenomics of diverse CFTR mutations and the emerging role of stem cell-based organoids in predicting the CF drug response. We discuss mechanisms that underlie differential CF drug responses both in organoid-based assays and in CF clinical trials, thereby facilitating the precision design of safer and more effective therapies for individual patients with CF. Stem cell-based organoid assays, enthusiastically used for genetic analysis of diverse CFTR mutations, are aiming to identify drug responders from patients with cystic fibrosis (CF) in vitro. The organoid response profiles will facilitate effective therapies for individual patients with CF. [ABSTRACT FROM AUTHOR]

Abstract: Incorporation of the unnatural amino acid l-(7-hydroxycoumarin-4-yl)ethylglycine (7-HC) is a powerful and reliable approach for the preparation of fluorescently labeled proteins. The growing popularity of this valuable amino acid prompted us to pursue an improved protocol for its synthetic preparation. The optimized procedure here described provides ready access to multi-gram quantities of 7-HC. Also reported is an extension of the utility of 7-HC in the generation of a protected building block suitable for use in solid phase peptide synthesis. The building block was successfully incorporated at various positions in a series of model peptides, including analogues of the cell penetrating HIV-Tat peptide, further illustrating the utility of this unique amino acid. [Copyright &y& Elsevier]

Cystic fibrosis (CF) is characterized by a proinflammatory pulmonary condition that may result from increased infections and altered intracellular metabolism in CFTR-deficient cells. The lipid-activated transcription factor peroxisome proliferator-activated receptor-γ (PPARγ) has well-established roles in immune cell function and inflammatory modulation and has been demonstrated to play an important role in the heightened inflammatory response in CF cells. Here, we summarize current literature describing PPARγ-dependent alterations of CF cells and discuss the potential of PPARγ ligands for treating CF. [Copyright &y& Elsevier]