SAR study and conformational analysis of a series of novel peptide G protein-coupled receptor kinase 2 inhibitors

The Metabolic Role of GRK2 in Insulin Resistance and Associated Conditions

Insulin resistance (IRES) is a pathophysiological condition characterized by the reduced response to insulin of several tissues, including myocardial and skeletal muscle. IRES is associated with obesity, glucose intolerance, dyslipidemia, and hypertension, evolves toward type 2 diabetes, and increases the risk of developing cardiovascular diseases. Several studies designed to explore the mechanisms involved in IRES allowed the identification of a multitude of potential molecular targets. Among the most promising, G Protein Coupled Receptor Kinase type 2 (GRK2) appears to be a suitable one given its functional implications in many cellular processes. In this review, we will discuss the metabolic role of GRK2 in those conditions that are characterized by insulin resistance (diabetes, hypertension, heart failure), and the potentiality of its inhibition as a therapeutic strategy to revert both insulin resistance and its associated phenotypes.

Pharmacological inhibition of GRK2 improves cardiac metabolism and function in experimental heart failure

Aims

The effects of GRK2 inhibition on myocardial metabolism in heart failure (HF) are unchartered. In this work, we evaluated the impact of pharmacological inhibition of GRK2 by a cyclic peptide, C7, on metabolic, biochemical, and functional phenotypes in experimental HF.

Methods and results

C7 was initially tested on adult mice ventricular myocyte from wild type and GRK2 myocardial deficient mice (GRK2‐cKO), to assess the selectivity on GRK2 inhibition. Then, chronic infusion of 2 mg/kg/day of C7 was performed in HF mice with cryogenic myocardial infarction. Cardiac function in vivo was assessed by echocardiography and cardiac catheterization. Histological, biochemical, and metabolic studies were performed on heart samples at time points. C7 induces a significant increase of contractility in wild type but not in adult ventricle myocytes from GRK2‐cKO mice, thus confirming C7 selectivity for GRK2. In HF mice, 4 weeks of treatment with C7 improved metabolic features, including mitochondrial organization and function, and restored the biochemical and contractile responses.

Conclusions

GRK2 is a critical molecule in the physiological regulation of cardiac metabolism. Its alterations in the failing heart can be pharmacologically targeted, leading to the correction of metabolic and functional abnormalities observed in HF.

Antidiabetic and Cardioprotective Effects of Pharmacological Inhibition of GRK2 in db/db Mice

Despite the availability of several therapies for the management of blood glucose in diabetic patients, most of the treatments do not show benefits on diabetic cardiomyopathy, while others even favor the progression of the disease. New pharmacological targets are needed that might help the management of diabetes and its cardiovascular complications at the same time. GRK2 appears a promising target, given its established role in insulin resistance and in systolic heart failure. Using a custom peptide inhibitor of GRK2, we assessed in vitro in L6 myoblasts the effects of GRK2 inhibition on glucose extraction and insulin signaling. Afterwards, we treated diabetic male mice (db/db) for 2 weeks. Glucose tolerance (IGTT) and insulin sensitivity (ITT) were ameliorated, as was skeletal muscle glucose uptake and insulin signaling. In the heart, at the same time, the GRK2 inhibitor ameliorated inflammatory and cytokine responses, reduced oxidative stress, and corrected patterns of fetal gene expression, typical of diabetic cardiomyopathy. GRK2 inhibition represents a promising therapeutic target for diabetes and its cardiovascular complications.

On the design of tailored liposomes for KRX29 peptide delivery

The high interest in therapeutic peptides, due to the specificity of their mechanisms of action, has stimulated the research of new delivery strategies to overcome bioavailability problems concerning the use of peptides in their naked form. In this study liposomal suitable delivery system was designed and produced.

"Freeze, Don't Move": How to Arrest a Suspect in Heart Failure - A Review on Available GRK2 Inhibitors

Cardiovascular disease and heart failure (HF) still collect the largest toll of death in western societies and all over the world. A growing number of molecular mechanisms represent possible targets for new therapeutic strategies, which can counteract the metabolic and structural changes observed in the failing heart. G protein-coupled receptor kinase 2 (GRK2) is one of such targets for which experimental and clinical evidence are established. Indeed, several strategies have been carried out in place to interface with the known GRK2 mechanisms of action in the failing heart. This review deals with results from basic and preclinical studies. It shows different strategies to inhibit GRK2 in HF in vivo (βARK-ct gene therapy, treatment with gallein, and treatment with paroxetine) and in vitro (RNA aptamer, RKIP, and peptide-based inhibitors). These strategies are based either on the inhibition of the catalytic activity of the kinase (“Freeze!”) or the prevention of its shuttling within the cell (“Don’t Move!”). Here, we review the peculiarity of each strategy with regard to the ability to interact with the multiple tasks of GRK2 and the perspective development of eventual clinical use.

G-Protein-Coupled Receptor Kinase 2 (GRK2) Inhibitors: Current Trends and Future Perspectives

G-protein-coupled receptor kinase 2 (GRK2) is a G-protein-coupled receptor kinase that is ubiquitously expressed in many tissues and regulates various intracellular mechanisms. The up- or down-regulation of GRK2 correlates with several pathological disorders. GRK2 plays an important role in the maintenance of heart structure and function; thus, this kinase is involved in many cardiovascular diseases. GRK2 up-regulation can worsen cardiac ischemia; furthermore, increased kinase levels occur during the early stages of heart failure and in hypertensive subjects. GRK2 up-regulation can lead to changes in the insulin signaling cascade, which can translate to insulin resistance. Increased GRK2 levels also correlate with the degree of cognitive impairment that is typically observed in Alzheimer's disease. This article reviews the most potent and selective GRK2 inhibitors that have been developed. We focus on their mechanism of action, inhibition profile, and structure-activity relationships to provide insight into the further development of GRK2 inhibitors as drug candidates.