Deleterious Impacts of Western diet on Jejunum Function and Health are Reversible.

The goal of this study was to determine whether the influence of high-fat high-sugar diet (Western diet) on intestinal function and health was reversible. We measured transepithelial short circuit current (Isc), across freshly isolated segments of jejunum from male C57Bl/6J mice randomly assigned to one of the following groups for the study duration: high-fat high-sugar diet for 24-weeks (HFHS), HFHS diet for 12-weeks then switched to standard chow and water for a further 12 weeks (Std), and lean controls (standard chow and water for 24-weeks). At the completion of the study, segments of jejunum were frozen for western blot determination of key proteins involved in secretory and absorptive functions, as well as senescence.

Genetic Manipulation of Caveolin-1 in a Transgenic Mouse Model of Aortic Root Aneurysm: Sex-Dependent Effects on Endothelial and Smooth Muscle Function.

Marfan syndrome (MFS) is a systemic connective tissue disorder stemming from mutations in the gene encoding Fibrillin-1 (Fbn1), a key extracellular matrix glycoprotein. This condition manifests with various clinical features, the most critical of which is the formation of aortic root aneurysms. Reduced nitric oxide (NO) production due to diminished endothelial nitric oxide synthase (eNOS) activity has been linked to MFS aortic aneurysm pathology.

Impact of TGF-β inhibition during acute exercise on Achilles tendon extracellular matrix.

The purpose of this study was to evaluate the role of TGF-β in regulating tendon extracellular matrix after acute exercise. Wistar rats exercised (n = 15) on a treadmill for four consecutive days (60 min/day) or maintained normal cage activity. After each exercise bout, the peritendinous space of each Achilles tendon was injected with a TGF-β receptor inhibitor or sham.

Postnatal Hyperplasic Effects of ActRIIB Blockade in a Severely Dystrophic Muscle.

The efficacy of two ActRIIB ligand-trapping agents (RAP-031 and RAP-435) in treating muscular dystrophy was examined by determining their morphological effects on the severely dystrophic triangularis sterni (TS) muscle of the mdx mouse, a model for Duchenne muscular dystrophy. These agents trap all endogenous ligands to the ActRIIB receptor and thereby block myostatin signaling in a highly selective manner. Short-term (1 month) and long-term (3 months) in vivo treatment of 1-month-old mdx mice increased myonuclei and fiber cross section (FCS) density but did not alter individual fiber size.

Agents Which Inhibit NF-κB Signaling Block Spontaneous Contractile Activity and Negatively Influence Survival of Developing Myotubes.

Inhibiting the NF-κB signaling pathway provides morphological and functional benefits for the mdx mouse, a model for Duchenne muscular dystrophy characterized by chronic elevations in the nuclear expression of p65, the transactivating component of the NF-κB complex. The purpose of this study was to examine p65 expression in nondystrophic and mdx myotubes using confocal immunofluorescence, and determine whether inhibitors of the NF-κB pathway alter myotube development. Primary cultures of nondystrophic and mdx myotubes had identical levels of nuclear and cytosolic p65 expression and exhibited equivalent responses to TNF-α, thus excluding the hypothesis that the lack of dystrophin is sufficient to induce increases in NF-κB signaling.

Membrane cholesterol affects stimulus-activity coupling in type 1, but not type 2, CCK receptors: use of cell lines with elevated cholesterol.

The lipid microenvironment of membrane proteins can affect their structure, function, and regulation. We recently described differential effects of acute modification of membrane cholesterol on the function of type 1 and 2 cholecystokinin (CCK) receptors. We now explore the regulatory impact of chronic cholesterol modification on these receptors using novel receptor-bearing cell lines with elevated membrane cholesterol.

Differential sensitivity of types 1 and 2 cholecystokinin receptors to membrane cholesterol.

Recent studies indicate that membrane cholesterol can associate with G protein-coupled receptors (GPCRs) and affect their function. Previously, we reported that manipulation of membrane cholesterol affects ligand binding and signal transduction of the type 1 cholecystokinin receptor (CCK1R), a Class A GPCR. We now demonstrate that the closely related type 2 cholecystokinin receptor (CCK2R) does not share this cholesterol sensitivity.

Regulation of N-formyl peptide receptor signaling and trafficking by individual carboxyl-terminal serine and threonine residues.

Adaptation, defined as the diminution of receptor signaling in the presence of continued or repeated stimulation, is critical to cellular function. G protein-coupled receptors (GPCRs) undergo multiple adaptive processes, including desensitization and internalization, through phosphorylation of cytoplasmic serine and threonine residues. However, the relative importance of individual and combined serine and threonine residues to these processes is not well understood.

Arrestin variants display differential binding characteristics for the phosphorylated N-formyl peptide receptor carboxyl terminus.

The phosphorylation-dependent binding of arrestins to cytoplasmic domains of G protein-coupled receptors (GPCRs) is thought to be a crucial step in receptor desensitization. In some GPCR systems, arrestins have also been demonstrated to be involved in receptor internalization, resensitization, and the activation of signaling cascades. The objective of the current study was to examine binding interactions of members of the arrestin family with the formyl peptide receptor (FPR), a member of the GPCR family of receptors.