Obligatory role for endothelial heparan sulphate proteoglycans and caveolae internalization in catestatin-dependent eNOS activation

The Role of Glycocalyx and Caveolae in Vascular Homeostasis and Diseases

This review highlights recent findings about the role that endothelial glycocalyx and caveolae play in vascular homeostasis. We describe the structure, synthesis, and function of glycocalyx and caveolae in vascular cells under physiological and pathophysiological conditions. Special focus will be given in glycocalyx and caveolae that are associated with impaired production of nitric oxide (NO) and generation of reactive oxygen species (ROS). Such alterations could contribute to the development of cardiovascular diseases, such as atherosclerosis, and hypertension.

Cell-Penetrating Peptides Delivering siRNAs: An Overview

Cell-Penetrating Peptides (CPP) are valuable tools capable of crossing the plasma membrane to deliver therapeutic cargo inside cells. Small interfering RNAs (siRNA) are double-stranded RNA molecules capable of silencing the expression of a specific protein triggering the RNA interference (RNAi) pathway, but they are unable to cross the plasma membrane and have a short half-life in the bloodstream. In this overview, we assessed the many different approaches used and developed in the last two decades to deliver siRNA through the plasma membrane through different CPPs sorted according to three different loading strategies: covalent conjugation, complex formation, and CPP-decorated (functionalized) nanocomplexes. Each of these strategies has pros and cons, but it appears the latter two are the most commonly reported and emerging as the most promising strategies due to their simplicity of synthesis, use, and versatility. Recent progress with siRNA delivered by CPPs seems to focus on targeted delivery to reduce side effects and amount of drugs used, and it appears to be among the most promising use for CPPs in future clinical applications.

Endothelial nitric oxide synthase activation is required for heparin receptor effects on vascular smooth muscle cells

Published studies indicate that TMEM184A is a heparin receptor that interacts with and transduces stimulation from heparin in vascular cells. Previous studies have indicated that heparin increases endothelial nitric oxide synthase (eNOS) activity in bovine endothelial cells. However, the precise mechanism remains unknown. In this study, we investigated the impact of heparin treatment and TMEM184A on eNOS's activation and the role of eNOS in heparin signaling in the cloned A7r5 rat vascular smooth muscle cell line and confirmed results in endothelial cells. We employed a combination of TMEM184A knockdown A7r5 cells along with transient eNOS knockdown and enzyme inhibitor strategies. The results indicate that heparin induces phosphorylation of eNOS. eNOS can be immunoprecipitated with TMEM184A and is internalized to the perinuclear region in a TMEM184A-dependent manner in response to heparin. We also examined how heparin treatment leads to phosphorylation of eNOS and confirmed that TMEM184A and Ca²⁺ were required to mediate heparin-elicited eNOS phosphorylation. Evidence supporting the involvement of transient receptor potential cation channel subfamily V member 4 with TMEM184A in this eNOS activation process is also presented.

Granin-derived peptides

The granin family comprises altogether 7 different proteins originating from the diffuse neuroendocrine system and elements of the central and peripheral nervous systems. The family is dominated by three uniquely acidic members, namely chromogranin A (CgA), chromogranin B (CgB) and secretogranin II (SgII). Since the late 1980s it has become evident that these proteins are proteolytically processed, intragranularly and/or extracellularly into a range of biologically active peptides; a number of them with regulatory properties of physiological and/or pathophysiological significance. The aim of this comprehensive overview is to provide an up-to-date insight into the distribution and properties of the well established granin-derived peptides and their putative roles in homeostatic regulations. Hence, focus is directed to peptides derived from the three main granins, e.g. to the chromogranin A derived vasostatins, betagranins, pancreastatin and catestatins, the chromogranin B-derived secretolytin and the secretogranin II-derived secretoneurin (SN). In addition, the distribution and properties of the chromogranin A-derived peptides prochromacin, chromofungin, WE14, parastatin, GE-25 and serpinins, the CgB-peptide PE-11 and the SgII-peptides EM66 and manserin will also be commented on. Finally, the opposing effects of the CgA-derived vasostatin-I and catestatin and the SgII-derived peptide SN on the integrity of the vasculature, myocardial contractility, angiogenesis in wound healing, inflammatory conditions and tumors will be discussed.

Potential applications of catestatin in cardiovascular diseases

Catestatin (CST) was first named in 1997 for its catecholamine-inhibitory activity. It was discovered as a potent inhibitor of catecholamine secretion and as a regulator of histamine release. Accumulating evidence shows that CST is involved with cardiovascular diseases; however, whether CST is a protective factor for these conditions and the mechanisms by which such actions may be mediated are not well understood. In this article, we review recent basic research and clinical trials in the study of CST and summarize the association of CST with cardiovascular diseases. We review data obtained from MedLine via PubMed and from our own investigations.