Mechanical stresses induce paracrine β-2 microglobulin from cardiomyocytes to activate cardiac fibroblasts through epidermal growth factor receptor

2018 ◽  
Vol 132 (16) ◽  
pp. 1855-1874 ◽  
Author(s):  
Yang Li ◽  
Xiaoyi Zhang ◽  
Lu Li ◽  
Xiang Wang ◽  
Zhidan Chen ◽  
...  

By employing a proteomic analysis on supernatant of mechanically stretched cardiomyocytes, we found that stretch induced a significantly high level of β-2 microglobulin (β2M), a non-glycosylated protein, which is related to inflammatory diseases but rarely known in cardiovascular diseases. The present data showed that serum β2M level was increased in patients with hypertension and further increased in patients with chronic heart failure (HF) as compared with control group, and the high level of serum β2M level correlated to cardiac dysfunction in these patients. In pressure overload mice model by transverse aortic constriction (TAC), β2M levels in serum and heart tissue increased progressively in a time-dependent manner. Exogenous β2M showed pro-fibrotic effects in cultured cardiac fibroblasts but few effects in cardiomyocytes. Adeno-associated virus 9 (AAV9)-mediated knockdown of β2M significantly reduced cardiac β2M level and inhibited myocardial fibrosis and cardiac dysfunction but not cardiac hypertrophy at 4 weeks after TAC. In vitro, mechanical stretch induced the rapid secretion of β2M mainly from cardiomyocytes by activation of extracellular-regulated protein kinase (ERK). Conditional medium (CM) from mechanically stretched cardiomyocytes activated cultured cardiac fibroblasts, and the effect was partly abolished by CM from β2M-knockdown cardiomyocytes. In vivo, knockdown of β2M inhibited the increase in phosphorylation of epidermal growth factor receptor (EGFR) induced by TAC. In cultured cardiac fibroblasts, inhibition of EGFR significantly attenuated the β2M-induced the activation of EGFR and pro-fibrotic responses. The present study suggests that β2M is a paracrine pro-fibrotic mediator and associated with cardiac dysfunction in response to pressure overload.

1986 ◽  
Vol 239 (3) ◽  
pp. 691-697 ◽  
Author(s):  
N Reiss ◽  
H Kanety ◽  
J Schlessinger

Several enzymes of the glycolytic pathway are phosphorylated in vitro and in vivo by retroviral transforming protein kinases. These substrates include the enzymes phosphoglycerate mutase (PGM), enolase and lactate dehydrogenase (LDH). Here we show that purified EGF (epidermal growth factor)-receptor kinase phosphorylates the enzymes PGM and enolase and also the key regulatory enzymes of the glycolytic pathway, phosphofructokinase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), in an EGF-dependent manner. Stoichiometry of phosphate incorporation into GAPDH (calculated from native Mr) is the highest, reaching approximately 1. LDH and other enzymes of the glycolytic pathway are not phosphorylated by the purified EGF-receptor kinase. These enzymes are phosphorylated under native conditions, and the Km values of EGF-receptor kinase for their phosphorylation are close to the physiological concentrations of these enzymes in the cell. EGF stimulates the reaction by 2-5-fold by increasing the Vmax. without affecting the Km of this process. Phosphorylation is rapid at 22 degrees C and at higher temperatures. However, unlike the self-phosphorylation of EGF-receptor, which occurs at 4 degrees C, the glycolytic enzymes are poorly phosphorylated at this temperature. Some enzymes, in particular enolase, increase the receptor Km for ATP in the autophosphorylation process and thus may act as competitive inhibitors of EGF-receptor self-phosphorylation. On the basis of the Km values of EGF receptor for the substrate enzymes and for ATP in the phosphorylation reaction, these enzymes may also be substrates in vivo for the EGF-receptor kinase.


2020 ◽  
Vol 6 (16) ◽  
pp. eaax4826 ◽  
Author(s):  
Hai-Lian Bi ◽  
Xiao-Li Zhang ◽  
Yun-Long Zhang ◽  
Xin Xie ◽  
Yun-Long Xia ◽  
...  

Pathological cardiac hypertrophy leads to heart failure (HF). The ubiquitin-proteasome system (UPS) plays a key role in maintaining protein homeostasis and cardiac function. However, research on the role of deubiquitinating enzymes (DUBs) in cardiac function is limited. Here, we observed that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) was significantly up-regulated in agonist-stimulated primary cardiomyocytes and in hypertrophic and failing hearts. Knockdown of UCHL1 in cardiomyocytes and mouse hearts significantly ameliorated cardiac hypertrophy induced by agonist or pressure overload. Conversely, overexpression of UCHL1 had the opposite effect in cardiomyocytes and rAAV9-UCHL1–treated mice. Mechanistically, UCHL1 bound, deubiquitinated, and stabilized epidermal growth factor receptor (EGFR) and activated its downstream mediators. Systemic administration of the UCHL1 inhibitor LDN-57444 significantly reversed cardiac hypertrophy and remodeling. These findings suggest that UCHL1 positively regulates cardiac hypertrophy by stabilizing EGFR and identify UCHL1 as a target for hypertrophic therapy.


2002 ◽  
Vol 362 (2) ◽  
pp. 499-505 ◽  
Author(s):  
Hongbing LI ◽  
Antonio VILLALOBO

Previous work from our laboratory has demonstrated that the Ca2+—calmodulin complex inhibits the intrinsic tyrosine kinase activity of the epidermal growth factor receptor (EGFR), and that the receptor can be isolated by Ca2+-dependent calmodulin-affinity chromatography [San José, Benguría, Geller and Villalobo (1992) J. Biol. Chem. 267, 15237–15245]. Moreover, we have demonstrated that the cytosolic juxtamembrane region of the human receptor (residues 645–660) binds calmodulin in a Ca2+-dependent manner when this segment forms part of a recombinant fusion protein [Martín-Nieto and Villalobo (1998) Biochemistry 37, 227–236]. However, demonstration of the direct interaction between calmodulin and the whole receptor has remained elusive. In this work, we show that calmodulin, in the presence of Ca2+, forms part of a high-molecular-mass complex built upon covalent cross-linkage of the human EGFR immunoprecipitated from two cell lines overexpressing this receptor. Although several calmodulin-binding proteins co-immunoprecipitated with the EGFR, suggesting that they interact with the receptor, we demonstrated using overlay techniques that biotinylated calmodulin binds directly to the receptor in a Ca2+-dependent manner without the mediation of any adaptor calmodulin-binding protein. Calmodulin binds to the EGFR with an apparent dissociation constant (K′d) of approx. 0.2–0.3μM. Treatment of cells with epidermal growth factor, or with inhibitors of protein kinase C and calmodulin-dependent protein kinase II, or treatment of the immunoprecipitated receptor with alkaline phosphatase, does not significantly affect the binding of biotinylated calmodulin to the receptor.


Pharmacology ◽  
2019 ◽  
Vol 104 (3-4) ◽  
pp. 113-125
Author(s):  
Kun Zhu ◽  
Kang Li ◽  
Haonan Wang ◽  
Li Kang ◽  
Chengxue Dang ◽  
...  

The breast cancer is the leading cause of death in women. Therefore, objective of the present study was to examine the antibreast cancer effect of glabridin (GBN) and to evaluate its mechanism of action. In this study, we have demonstrated that GBN causes reduction of cellular viability of human breast cancer SK-BR-3 in MTT assay. Results from Hoechst 33342 and propidium iodide staining assay suggested that GBN causes significant enhancement in the apoptosis. At the molecular level, in western blot analysis, GBN causes significant increase in c-PARP and c-caspases 3, 8, and 9 concentrations in a dose-dependent manner in breast cancer cells. The GBN further showed reduced level of p-epidermal growth factor receptor, p-AKT, p-ERK1/2, and cyclin D1 as the concentration rose in treated cells. Subsequent to this, GBN showed beneficial effect in 7,12-dimethylbenz[a]anthracene-induced breast cancer in experimental mice as confirmed by increase in body weight, reduction in tumor volume, oxidative stress, and dose-dependent restoration of all tested enzymes (phase I and II) in the treated group. GBN may, thus, play a protective role as an antibreast cancer drug for the prevention of breast cancer.


2005 ◽  
Vol 184 (1) ◽  
pp. 141-151 ◽  
Author(s):  
M C Velarde ◽  
S I Parisek ◽  
R R Eason ◽  
F A Simmen ◽  
R C M Simmen

The over-expression of epidermal growth factor receptor (EGFR) and its ligands, epidermal growth factor (EGF) and transforming growth factor-α, is a common feature of epithelial carcinomas and correlates with neoplastic progression. Secretory leukocyte protease inhibitor (SLPI), a member of the Kazal superfamily of serine anti-proteases, induces proliferation and promotes malignancy of epithelial cells and is expressed at high levels in multiple tumor types. In the present study, we have demonstrated that EGF increases SLPI expression in the human endometrial epithelial cell line Ishikawa in a dose- and time-dependent manner. We have shown that this effect of EGF occurs, in part, at the level of the SLPI promoter and involves the MAP kinase signaling pathway. We have further shown that EGF promotion of cell proliferation, but not induction of cyclin D1 gene expression, involves SLPI. Our results suggest that the regulation of SLPI expression by EGFR ligand(s) may represent a ‘feed-forward’ mechanism by which the enhanced proliferative and migratory properties of EGFR over-expressing cancer cells are sustained. Increased SLPI expression is likely an important component of altered EGFR signaling in human tumors and may have significant therapeutic implications in cancer progression.


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