Effects of in vivo heregulin beta1 treatment in wild-type and ErbB gene-targeted mice depend on receptor levels and pregnancy

Insights into Structural Modifications of Valproic Acid and Their Pharmacological Profile

Valproic acid (VPA) is a well-established anticonvulsant drug discovered serendipitously and marketed for the treatment of epilepsy, migraine, bipolar disorder and neuropathic pain. Apart from this, VPA has potential therapeutic applications in other central nervous system (CNS) disorders and in various cancer types. Since the discovery of its anticonvulsant activity, substantial efforts have been made to develop structural analogues and derivatives in an attempt to increase potency and decrease adverse side effects, the most significant being teratogenicity and hepatotoxicity. Most of these compounds have shown reduced toxicity with improved potency. The simple structure of VPA offers a great advantage to its modification. This review briefly discusses the pharmacology and molecular targets of VPA. The article then elaborates on the structural modifications in VPA including amide-derivatives, acid and cyclic analogues, urea derivatives and pro-drugs, and compares their pharmacological profile with that of the parent molecule. The current challenges for the clinical use of these derivatives are also discussed. The review is expected to provide necessary knowledgebase for the further development of VPA-derived compounds.

Expression and Localization of Neuregulin-1 (Nrg1) and ErbB2/ErbB4 Receptors in Main Endocrine Organs of the Rhesus Monkey

BACKGROUND

Although Neuregulin-1 （Nrg1）and its receptors have been indicated at the mRNA level in partial human endocrine organs and its functional roles have been evaluated in vitro, their morphological distribution in higher animals are not fully studied. The present research focused on expression of Nrg1 and its main receptors ErbB2 and ErbB4 in main endocrine organs of the rhesus monkey.

MATERIALS AND METHODS

The morphological expression of Nrg1 and its receptors ErbB2 and ErbB4 as well as their potential co-localization were determined by double immunofluorescence in the pituitary, thyroid, parathyroid, pancreas and adrenal gland sample tissues. The expression level of Nrg1 on each sample was indexed by the fold of integrative fluorescence intensity (IFI) relative to that of one cortical tissue.

RESULTS

Differential expression of Nrg1 and their cognate receptors ErbB2 and ErbB4 were found selectively expressed in endocrine organs we tested, with higher expression levels detected in the adrenal gland (AG) and pancreas. Co-localization of Nrg1 with either ErbB2 or ErbB4 was detected in AG, thyroid and parathyroid gland, and Nrg1 was only co-localized with ErbB4 in the islet cells of the pancreas. In the pituitary, adjacent localization of Nrg1 positive cells with ErbB4 positive cells were observed.

CONCLUSIONS

This investigation morphologically profiles the differential expression of Nrg1 and its receptors ErbB2 and ErbB4 in the main endocrine organ structures, suggesting an autocrine or paracrine-directed Nrg1-ErbB signaling pathway in some of these structures.

Neuregulin-1/erbB-activation improves cardiac function and survival in models of ischemic, dilated, and viral cardiomyopathy

OBJECTIVES

We evaluated the therapeutic potential of a recombinant 61-residue neuregulin-1 (beta2a isoform) receptor-active peptide (rhNRG-1) in multiple animal models of heart disease.

BACKGROUND

Activation of the erbB family of receptor tyrosine kinases by rhNRG-1 could provide a treatment option for heart failure, because neuregulin-stimulated erbB2/erbB4 heterodimerization is not only critical for myocardium formation in early heart development but prevents severe dysfunction of the adult heart and premature death. Disabled erbB-signaling is also implicated in the transition from compensatory hypertrophy to failure, whereas erbB receptor-activation promotes myocardial cell growth and survival and protects against anthracycline-induced cardiomyopathy.

METHODS

rhNRG-1 was administered IV to animal models of ischemic, dilated, and viral cardiomyopathy, and cardiac function and survival were evaluated.

RESULTS

Short-term intravenous administration of rhNRG-1 to normal dogs and rats did not alter hemodynamics or cardiac contractility. In contrast, rhNRG-1 improved cardiac performance, attenuated pathological changes, and prolonged survival in rodent models of ischemic, dilated, and viral cardiomyopathy, with the survival benefits in the ischemic model being additive to those of angiotensin-converting enzyme inhibitor therapy. In addition, despite continued pacing, rhNRG-1 produced global improvements in cardiac function in a canine model of pacing-induced heart failure.

CONCLUSIONS

These beneficial effects make rhNRG-1 promising as a broad-spectrum therapeutic for the treatment of heart failure due to a variety of common cardiac diseases.

Heart-valve mesenchyme formation is dependent on hyaluronan-augmented activation of ErbB2-ErbB3 receptors

Heart septation and valve malformations constitute the most common anatomical birth defects. These structures arise from the endocardial cushions within the atrioventricular canal (AVC) through dynamic interactions between cushion cells and the extracellular matrix (termed cardiac jelly). Transformation of endothelial cells to mesenchymal cells is essential for the proper development of the AVC and subsequent septation and valve formation. Atrioventricular septal defects can result from incomplete endocardial cushion morphogenesis. We show that hyaluronan-deficient AVC explants from Has2(-/-) embryos, which normally lack mesenchyme formation, are rescued by heregulin treatment, which restores phosphorylation of ErbB2 and ErbB3. These events were blocked using a soluble ErbB3 molecule, as well as with an inhibitor of ErbB2, herstatin. We show further that ErbB3 is activated during hyaluronan treatment of Has2(-/-) explants. These data provide a link between extracellular matrix-hyaluronan and ErbB receptor activation during development of early heart-valve and septal mesenchyme.