Ischemic heart disease (IHD) accounts for the majority of heart disease-related deaths worldwide. Ubiquitin (UB), found in all eukaryotic cells, is a highly conserved low molecular weight (~8.5 kDa) protein. A well-known intracellular function of UB is to regulate protein turnover via the UB-proteasome system. UB is a normal constituent of plasma, and elevated levels of UB are observed in the serum of patients under a variety of pathological conditions. Recent studies provide evidence for cardioprotective potential of exogenous UB in the remodeling process of the heart in IHD, including effects on cardiac myocyte apoptosis, inflammatory response, and reorganization of the vasculature and extracellular matrix. This review summarizes functions of UB with an emphasis on the role of exogenous UB in myocardial remodeling in IHD.

Remodeling after myocardial infarction (MI) associates with left ventricular (LV) dilation, decreased cardiac function and increased mortality. The dynamic synthesis and breakdown of extracellular matrix (ECM) proteins play a significant role in myocardial remodeling post-MI. Expression of osteopontin (OPN) increases in the heart post-MI. Evidence has been provided that lack of OPN induces LV dilation which associates with decreased collagen synthesis and deposition. Inhibition of matrix metalloproteinases, key players in ECM remodeling process post-MI, increased ECM deposition (fibrosis) and improved LV function in mice lacking OPN after MI. This review summarizes — 1) signaling pathways leading to increased expression of OPN in the heart; 2) the alterations in the structure and function of the heart post-MI in mice lacking OPN; and 3) mechanisms involved in OPN-mediated ECM remodeling post-MI.

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Ataxia-telangiectasia mutated kinase (ATM) is a serine/threonine kinase. Mutations in the ATM gene cause a rare autosomal multisystemic disease known as Ataxia-telangiectasia (AT). Individuals with mutations in both copies of the ATM gene suffer from increased susceptibility to ionizing radiation, predisposition to cancer, insulin resistance, immune deficiency, and premature aging. Patients with one mutated allele make-up ~1.4 to 2% of the general population. These individuals are spared from most of the symptoms of the disease. However, they are predisposed to developing cancer or ischemic heart disease, and die 7-8 years earlier than the non-carriers. DNA double-strand breaks activate ATM, and active ATM is known to phosphorylate an extensive array of proteins involved in cell cycle arrest, DNA repair, and apoptosis. The importance of ATM in the regulation of DNA damage response signaling is fairly well-established. This review summarizes the role of ATM in the heart, specifically in cardiac remodeling following β-adrenergic receptor stimulation and myocardial infarction.

Osteopontin, also called cytokine Eta-1, is a multifunctional protein containing Arg-Gly-Asp-Ser (RODS) cell-binding sequence. It interacts with αvβ1, αvβ3 and αvβ5 integrins and CD44 receptors. OPN is suggested to play a role during inflammation via the recruitment and retention of macrophages and T-cells to inflamed sites. OPN regulates the production of inflammatory cytokines and nitric oxide in macrophages. In this review, we will discuss diverse roles of OPN related to cardiovascular diseases, including atherosclerosis, valvular stenosis, hypertrophy, myocardial infarction and heart failure.