Tonicity-responsive enhancer binding protein (TonEBP/nuclear factor of activated T-cells 5 [NFAT5]) is a Rel homology transcription factor classically known for its osmosensitive role in regulating cellular homeostasis during states of hypo- and hypertonic stress. A recently growing body of research indicates that TonEBP is not solely regulated by tonicity, but that it can be stimulated by various tonicity-independent mechanisms in both hypertonic and isotonic tissues. Physiological and pathophysiological stimuli such as cytokines, growth factors, receptor and integrin activation, contractile agonists, ions, and reactive oxygen species have been implicated in the positive regulation of TonEBP expression and activity in diverse cell types. These new data demonstrate that tonicity-independent stimulation of TonEBP is critical for tissue-specific functions like enhanced cell survival, migration, proliferation, vascular remodeling, carcinoma invasion, and angiogenesis. Continuing research will provide a better understanding as to how these and other alternative TonEBP stimuli regulate gene expression in both health and disease.

OBJECTIVE The tonicity-responsive transcription factor, nuclear factor of activated T-cells 5 (NFAT5/TonEBP), has been well characterized in numerous cell types; however, NFAT5 function in vascular smooth muscle cells (SMCs) is unknown. Our main objective was to determine the role of NFAT5 regulation in SMCs. METHODS AND RESULTS We show that NFAT5 is regulated by hypertonicity in SMCs and is upregulated in atherosclerosis and neointimal hyperplasia. RNAi knockdown of NFAT5 inhibits basal expression of several SMC differentiation marker genes, including smooth muscle alpha actin (SMαA). Bioinformatic analysis of SMαA reveals seven putative NFAT5 binding sites in the first intron, and ChIP analysis shows NFAT5 enrichment of intronic DNA. Overexpression of NFAT5 increases SMαA promoter-intron activity, which requires an NFAT5 cis element at +1012, while dominant-negative NFAT5 decreases SMαA promoter-intron activity. Since it is unlikely that SMCs experience extreme changes in tonicity, we investigated other stimuli and uncovered two novel NFAT5-inducing factors: angiotensin II, a contractile agonist, and platelet-derived growth factor-BB (PDGF-BB), a potent mitogen in vascular injury. Angiotensin II stimulates NFAT5 translocation and activity, and NFAT5 knockdown inhibits an angiotensin II-mediated upregulation of SMαA mRNA. PDGF-BB increases NFAT5 protein and loss of NFAT5 inhibits PDGF-BB-induced SMC migration. CONCLUSIONS We have identified NFAT5 as a novel regulator of SMC phenotypic modulation and have uncovered the role of NFAT5 in angiotensin II-induced SMαA expression and PDGF-BB-stimulated SMC migration.

Objective: We have previously shown that the transcription factor, nuclear factor of activated T-cells 5 (NFAT5), regulates vascular smooth muscle cell phenotypic modulation, but the role of NFAT5 in atherosclerosis is unknown. Our main objective was to determine if NFAT5 expression in bone marrow (BM)-derived cells altered atherosclerotic development and macrophage function. Methods and Results: NFAT5+/−ApoE−/− mice were generated for in vivo atherosclerosis studies. Following high fat diet feeding, en face analysis of the thoracic aorta established that genome-wide NFAT5 haploinsufficiency reduced atherosclerotic lesion formation by 73%. BM transplant studies revealed that transplantation of NFAT5+/−ApoE−/− marrow into NFAT5+/+ApoE−/− mice resulted in a similar 86% reduction in lesion formation. In vitro functional analysis of BM-derived macrophages demonstrated that NFAT5 is required for macrophage migration, which is a key event in the propagation of atherosclerosis. Conclusion: We have identified NFAT5 in BM-derived cells as a positive regulator of atherosclerotic lesion formation and macrophage function in the vasculature.

A B S T R A C TWhen a patient experiences trauma, pre-hospital rapid sequence intubation (RSI) is often the course of action. While RSI is associated with favorable neurological outcomes among traumatic brain injury patients, it also carries the risk of increased hypotension and bradycardia. Ketamine is a fast-acting anesthetic agent used in RSI, attractive due to its ability to raise heart rate (HR) and blood pressure (BP) and thus potentially lessening the severity of RSIrelated hypotension and bradycardia. However, research in support of its use is inconclusive, with different studies reporting increases or decreases in BP and HR after ketamine administration. To study the effect of ketamine on HR and BP during RSI, we analyzed the data obtained from 1,516 patients who received trauma and nontrauma medical care including RSI from first responders and emergency personnel using two different statistical methods. We determined if there was any association between the vital signs prior to administration of ketamine and outcomes such as bradycardia and/or hypotension post-ketamine administration in patients undergoing RSI. We found that the vital signs prior to administration of ketamine (i.e. BP and HR) predict the development of bradycardia and/or hypotension in patients undergoing RSI and the relationship between baseline vital signs and the development of bradycardia and/or hypotension is moderated by the dose of ketamine. Results obtained from this study may help responders and emergency care personnel to identify the patients that are likely to benefit from ketamine as an anesthetic agent.