1183Beta-Adrenoceptor activation increases cardiac galectin-3 levels via the hippo signaling pathway

Background

Galectin-3 (Gal-3) is a clinical biomarker for risk of cardiovascular disease and a disease mediator forming a therapeutic target. However, the mechanism(s) that regulate cardiac expression of Gal-3 remains unknown. Activation of the sympatho-β-adrenergic system is a hallmark of heart disease, but the relationship of βAR activation and cardiac content of Gal-3 remains unknown.

Purpose

To determine the role of βAR activation in regulating cardiac Gal-3 level and the responsible mechanism focusing on the Hippo signalling pathway.

Methods

Wild-type and Gal-3 gene deleted (Gal3-KO) mice were used. To test the role of the Hippo pathway, we used transgenic (TG) mouse strains with cardiac overexpression of mammalian-20-like sterile kinase 1 (Mst1, mammalian orthology of Drosophila Hippo kinase) either in wild-type form (TG-Mst1) or dominative-negative kinase dead mutant form (TG-dnMst1). Effects of β-antagonist (isoprenaline, ISO) and antagonists were determined. We measured phosphorylation (Ser127) of YAP as a transcription co-regulator acting as the main signal output of the Hippo pathway.

Results

In wild-type mice, treatment with ISO led to a time- and dose-dependent increase in cardiac expression of Gal-3 (Fig. A) accompanied by elevated circulating Gal-3 levels (Fig. B). ISO treatment stimulated cardiac expression of Mst1 and YAP hyper-phosphorylation (i.e. inactivation, Fig. C), indicating activation of the Hippo signalling. These effects of ISO were inhibited by β-blockers (propranolol, Prop; carvedilol, Carv; Fig. D,E). Relative to non-TG controls, ISO-induced expression of Gal-3 was inhibited by 75% in TG-dnMst1 mice (inactivated Mst1), but exaggerated by 7-fold in TG-Mst1 mice (activated Mst1). Mst1-TG mice had a 45-fold increase in Gal-3 content, YAP hyper-phosphorylation and enhanced pro-fibrotic signaling. In Mst1-TG mice, whilst blood Gal-3 level was unchanged, treatment with ISO (6 mg, 2 days) evoked a marked increase in cardiac and blood Gal-3 levels. Using rat cardiomyoblasts, we showed that ISO-mediated Mst1 expression and YAP phosphorylation were PKA-dependent and that siRNA-mediated YAP knockdown led to Gal-3 upregulation. The role of Gal-3 in mediating ISO-induced cardiomyopathy was examined by treating wild-type and Gal3-KO mice with ISO (30 mg/kg, 7 days). ISO-treated wild-type mice had 8-fold increase in cardiac Gal-3, ventricular dysfunction, fibrosis, hypertrophy and activated inflammatory or fibrotic signalling. All these changes, except hypertrophy, were abolished by Gal3-KO.

beta-AR regulates galectin-3

Conclusion

βAR stimulation increases cardiac expression of Gal-3 through activation of the Hippo signalling pathway. This is accompanied by elevated circulating Gal-3 level. βAR antagonists inhibited βAR-Mst1 (Hippo) signalling and cardiac Gal-3 expression, actions likely contributing to the overall efficacy of β-blockers.

Acknowledgement/Funding

NHMRC of Australia; Nature Science Fund of China

Surface modification using photocrosslinkable chitosan for improving hemocompatibility

Immobilization of the anticoagulative or antithrombogenic biomolecule has been considered as one of the important methods to improve the blood compatibility of artificial biomaterials. In this study, a novel immobilization reaction scheme was utilized to incorporate O-butyrylchitosan (OBCS) onto the activated glass surface with an aim to develop an anticoagulative substrate. Activation of the glass surface was carried out by silanization and then OBCS was grafted to the silanized surface via a radiation grafting technique. The OBCS-grafted glass surfaces were characterized by electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). The blood compatibility of the OBCS-grafted glass was evaluated by platelet rich plasma (PRP) contacting experiments and protein adsorption experiments in vitro. These results have demonstrated that the surface with immobilized OBCS shows much less platelet adhesive and fibrinogen adsorption compared to the control surface. Therefore, the novel reaction scheme proposed here is very promising for future development of an anticoagulative glass substrate.

[Immunohistochemical study of the sinus mucosa during chronic maxillary sinusitis]

OBJECTIVE

To study the protective role of some immunocompetent cells and some humoral immune factors in the local mucosa during chronic sinusitis.

METHOD

Using immunohistochemical streptavidinbiotin peroxide complex (SABC) method to investigate the distribution and the numbers about the T-lymphocytes and subsets, B-cells, macrophages, NK cells, mast cells eosinophils, HLA-DR antigen and IgA, IgG, complement C3, lysozyme in the local mucosa of two type chronic sinusitis.

RESULT

The numbers of T-lymphocytes, T helper/inducer cells, B-cells and macrophages in the mucosa of chronic sinusitis type 1 was significantly more than these in the healthy control (P < 0.01). The number of T-lymphocytes, T suppressor cells, B cells, mast cells and eosinophils in the type 2 was significantly more than these in the healthy control (P < 0.01). The ratio of the helper cells to T suppressor cells significant different in the two type chronic sinusitis.

CONCLUSION

The study showed that the infiltrating of immunocompetent cells was different between the two type chronic sinusitis.

[A study of the cyclic development of poliomylitic virus in pond foul water during a two-year span]

A study on polio virus in pond foul water of town and counties in Lian Yun Gang city which had a reported case of polio. Foul water was examined by 1% NaCl-AlCl3 precipitated method quarterly during 1993-1995, to observe the cyclic development of the virus. Results showed that the isolation rate of polio virus was 57.95% with 21 strains of 18 PV I, 1 PV II and 2 PV III and 30 strains of NPEV (31.09%). In view of PV I as main epidemic strain in our country, and related strains to sabin was confirmed using RT-PCR. The above data suggested that polio virus in the pond water had been replaced by relative strains of sabin.