JNK modulates FOXO3a for the expression of the mitochondrial death and mitophagy marker BNIP3 in pathological hypertrophy and in heart failure

Bcl-2 E1B 19-KDa interacting protein 3 (BNIP3) is a mitochondrial death and mitophagy marker, which is involved in inducing cardiac remodeling post myocardial infarction. In this study, we show that BNIP3 expression increases in stressed cardiomyocytes in vitro and in response to pressure overload in vivo, and that its transcription is directly related to JNK activity. BNIP3 expression gradually increased in the first weeks after pressure overload and peaked at the heart failure stage. Ultrastructurally, the mitochondrial area was inversely proportional to BNIP3 expression. Both JNK and AKT activities increased with pressure overload; however, JNK signaling dominated over AKT signaling for the activation of the transcription factor FOXO3a and for the transcription of its effector, BNIP3. 3-methyladenine attenuated JNK signaling and significantly decreased BNIP3 expression and reversed cardiac remodeling in heart failure. Ultrastructurally, the mitochondrial area was significantly increased in the 3-methyladenine group compared with placebo. Moreover, adenoviral gene delivery of dominant negative JNK in a rat model of pressure overload hypertrophy abolished the increase in BNIP3 expression in response to pressure overload. These results suggest that JNK signaling is a critical modulator of the transcription factor FOXO3a driving the expression of its effector, BNIP3, in heart failure and that JNK, through BNIP3, induces mitochondrial apoptosis and mitophagy

Central role for MCP-1/CCL2 in injury-induced inflammation revealed by in vitro, in silico, and clinical studies

The translation of in vitro findings to clinical outcomes is often elusive. Trauma/hemorrhagic shock (T/HS) results in hepatic hypoxia that drives inflammation. We hypothesize that in silico methods would help bridge in vitro hepatocyte data and clinical T/HS, in which the liver is a primary site of inflammation. Primary mouse hepatocytes were cultured under hypoxia (1% O 2) or normoxia (21% O2) for 1-72 h, and both the cell supernatants and protein lysates were assayed for 18 inflammatory mediators by Luminex™ technology. Statistical analysis and data-driven modeling were employed to characterize the main components of the cellular response. Statistical analyses, hierarchical and k-means clustering, Principal Component Analysis, and Dynamic Network Analysis suggested MCP-1/CCL2 and IL-1α as central coordinators of hepatocyte-mediated inflammation in C57BL/6 mouse hepatocytes. Hepatocytes from MCP-1-null mice had altered dynamic inflammatory networks. Circulating MCP-1 levels segregated human T/HS survivors from non-survivors. Furthermore, T/HS survivors with elevated early levels of plasma MCP-1 post-injury had longer total lengths of stay, longer intensive care unit lengths of stay, and prolonged requirement for mechanical ventilation vs. those with low plasma MCP-1. This study identifies MCP-1 as a main driver of the response of hepatocytes in vitro and as a biomarker for clinical outcomes in T/HS, and suggests an experimental and computational framework for discovery of novel clinical biomarkers in inflammatory diseases. © 2013 Ziraldo et al

Nutrient regulation of ß-cell function: what do islet cell/animal studies tell us?

Diabetes mellitus is widely recognised as one of the most serious metabolic diseases worldwide, and its incidence in Asian countries is growing at an alarming rate. Type 2 diabetes (T2DM) is closely associated with age, sedentary lifestyle and poor diet. In T2DM, ß-cell dysfunction will occur before hyperglycaemia develops. Excessive levels of glucose, lipid and various inflammatory factors interact at the level of the pancreatic islet to promote ß-cell dysfunction. Pancreatic ß-cell lines have been widely utilised since the early 1980s and have contributed a large volume of important information regarding molecular, metabolic and genetic mechanisms that regulate insulin secretion. The purpose of this review is to describe the origin and characteristics of the most commonly used ß-cell lines and their contribution to discovery of fundamental regulatory processes that control insulin production and release. Pancreatic islets obtained from rodents as well as other animals have additionally provided information on the architecture and three-dimensional design of this endocrine tissue that allows precise regulation of hormone release. Understanding the nature of failure of physiologic and metabolic processes leading to insufficient insulin release and subsequent diabetes has allowed development of novel anti-diabetic therapeutics, now in common use, worldwide.European Journal of Clinical Nutrition advance online publication, 19 April 2017; doi:10.1038/ejcn.2017.49