Adrenomedullin suppresses interleukin-1β-induced tumor necrosis factor-α production in Swiss 3T3 cells

AbstractWe demonstrated that adrenomedullin (AM) inhibited interleukin-1β-induced tumor necrosis factor-α (TNF-α) secretion and gene transcription in Swiss 3T3 fibroblasts maximally to 23% and 18% of control, while the other peptides elevating intracellular cAMP levels elicited much weaker effects. AM rapidly reduced the gene transcript level of TNF-α, inducing a maximal effect within 1 h. The inhibitory effect of AM was restored with an AM receptor antagonist as well as a cAMP-dependent protein kinase inhibitor. These findings indicate that AM is a potent and quick suppressor of TNF-α production in Swiss 3T3 cells acting through the cAMP protein kinase A pathway. As TNF-α is a major inflammatory cytokine and stimulates AM production in fibroblasts, AM is deduced to be an autocrine or paracrine factor suppressing inflammation through the inhibition of TNF-α production

Mutations in Tyr808 reveal a potential auto-inhibitory mechanism of guanylate cyclase-B regulation

In this study, Tyr808 in GC-B (guanylate cyclase-B), a receptor of the CNP (C-type natriuretic peptide), has been shown to be a critical regulator of GC-B activity. In searching for phosphorylation sites that could account for suppression of GC-B activity by S1P (sphingosine-1-phosphate), mutations were introduced into several candidate serine/threonine and tyrosine residues. Although no novel phosphorylation sites that influenced the suppression of GC-B were identified, experiments revealed that mutations in Tyr808 markedly enhanced GC-B activity. CNP-stimulated activities of the Y808F and Y808A mutants were greater than 30-fold and 70-fold higher, respectively, than that of WT (wild-type) GC-B. The Y808E and Y808S mutants were constitutively active, expressing 270-fold higher activity without CNP stimulation than WT GC-B. Those mutations also influenced the sensitivity of GC-B to a variety of inhibitors, including S1P, Na3VO4 and PMA. Y808A, Y808E and Y808S mutations markedly weakened S1P- and Na3VO4-dependent suppression of GC-B activity, whereas Y808E and Y808S mutations rather elevated cGMP production. Tyr808 is conserved in all membrane-bound GCs and located in the niche domain showing sequence similarity to a partial fragment of the HNOBA (haem nitric oxide binding associated) domain, which is found in soluble GC and in bacterial haem-binding kinases. This finding provides new insight into the activation mechanism of GCs

Molecular Basis of Bile Acid-FXR-FGF15/19 Signaling Axis

Bile acids (BAs) are a group of amphiphilic molecules consisting of a rigid steroid core attached to a hydroxyl group with a varying number, position, and orientation, and a hydrophilic side chain. While BAs act as detergents to solubilize lipophilic nutrients in the small intestine during digestion and absorption, they also act as hormones. Farnesoid X receptor (FXR) is a nuclear receptor that forms a heterodimer with retinoid X receptor α (RXRα), is activated by BAs in the enterohepatic circulation reabsorbed via transporters in the ileum and the colon, and plays a critical role in regulating gene expression involved in cholesterol, BA, and lipid metabolism in the liver. The FXR/RXRα heterodimer also exists in the distal ileum and regulates production of fibroblast growth factor (FGF) 15/FGF19, a hormone traveling via the enterohepatic circulation that activates hepatic FGF receptor 4 (FGFR4)-β-klotho receptor complex and regulates gene expression involved in cholesterol, BA, and lipid metabolism, as well as those regulating cell proliferation. Agonists for FXR and analogs for FGF15/19 are currently recognized as a promising therapeutic target for metabolic syndrome and cholestatic diseases

Quantitative Analysis of Torso FDG-PET Scans by Using Anatomical Standardization of Normal Cases from Thorough Physical Examinations.

Understanding of standardized uptake value (SUV) of 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography (FDG-PET) depends on the background accumulations of glucose because the SUV often varies the status of patients. The purpose of this study was to develop a new method for quantitative analysis of SUV of FDG-PET scan images. The method included an anatomical standardization and a statistical comparison with normal cases by using Z-score that are often used in SPM or 3D-SSP approach for brain function analysis. Our scheme consisted of two approaches, which included the construction of a normal model and the determination of the SUV scores as Z-score index for measuring the abnormality of an FDG-PET scan image. To construct the normal torso model, all of the normal images were registered into one shape, which indicated the normal range of SUV at all voxels. The image deformation process consisted of a whole body rigid registration of shoulder to bladder region and liver registration and a non-linear registration of body surface by using the thin-plate spline technique. In order to validate usefulness of our method, we segment suspicious regions on FDG-PET images manually, and obtained the Z-scores of the regions based on the corresponding voxels that stores the mean and the standard deviations from the normal model. We collected 243 (143 males and 100 females) normal cases to construct the normal model. We also extracted 432 abnormal spots from 63 abnormal cases (73 cancer lesions) to validate the Z-scores. The Z-scores of 417 out of 432 abnormal spots were higher than 2.0, which statistically indicated the severity of the spots. In conclusions, the Z-scores obtained by our computerized scheme with anatomical standardization of torso region would be useful for visualization and detection of subtle lesions on FDG-PET scan images even when the SUV may not clearly show an abnormality

Calculated distributions of mean and SD in SUV for male and female in a coronal plane.

<p>Actual distributions are in 3D. (a) Mean distribution for male. (b) SD distribution for male. (c) Mean distribution for female. (d) SD distribution for female.</p

Standard body and registration example in a coronal plane.

<p>(a) A male standard body selected from normal database. (b) An another normal body to be deformed to the standard body shown in (a). (c) A result of physique registration. (d) A result of physique and bladder registration. (e) A result of physique, bladder, and liver registration. (f) A result of physique, organ, and surface registration.</p

Determined planes (red lines) to extract torso region.

<p>(a) Neck-Shoulder (NS) plane. (b) Arms-Chest (AC) planes (left/right). (c) Thigh-Hips (TH) plane. (d) Anterior and Posterior (A, P) planes.</p

Distribution of SUVmax vs Z-score.

<p>It is apparent that the Z-scores of the most abnormal cases are greater than 2.0.</p

Area distributions in sagittal and axial directions to determine NS and AC planes.

<p>Area distributions in sagittal and axial directions to determine NS and AC planes.</p