The amino acid response (AAR) pathway in mammalian cells is designed to detect and respond to amino acid deficiency. Limiting any essential amino acid initiates this signaling cascade, which leads to increased translation of a "master regulator," activating transcription factor (ATF) 4, and ultimately, to regulation of many steps along the pathway of DNA to RNA to protein. These regulated events include chromatin remodeling, RNA splicing, nuclear RNA export, mRNA stabilization, and translational control. Proteins that are increased in their expression as targets of the AAR pathway include membrane transporters, transcription factors from the basic region/ leucine zipper (bZIP) superfamily, growth factors, and metabolic enzymes. Significant progress has been achieved in understanding the molecular mechanisms by which amino acids control the synthesis and turnover of mRNA and protein. Beyond gaining additional knowledge of these important regulatory pathways, further characterization of how these processes contribute to the pathology of various disease states represents an interesting aspect of future research in molecular nutrition.Keywords nutrient starvation; metabolite control; protein metabolism; transcription; mRNA stability * ABBREVIATIONS: AAR, amino acid response (pathway); AARE, amino acid response element; ARE, AU-rich elements; ASNS, asparagine synthetase; Cdk, cyclin-dependent kinase; CdkI, cyclin-dependent kinase inhibitor; C/EBP, CCAAT-enhancer binding protein; ChIP, chromatin immunoprecipitation; CHOP, C/EBP homology protein/growth arrest and DNA damage 153; EMSA, electrophoresis mobility shift analysis; mTOR, mammalian target of rapamycin; NSRE, nutrient-sensing response element; UPR, unfolded protein response.

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Abdominal aortic aneurysms are often fatal due to atherosclerosis, thromboembolism, rupture, and hemorrhage, however, treatment is limited to expectant monitoring and surgical intervention. Inflammation is detected in aneurysms and in plaque with associated increased apoptosis, chemokines, cytokines, hemorrhage, and thrombosis. We compared treatment with three different myxomavirusderived anti-inflammatory proteins targeting apoptosis, thrombosis, and chemokine pathways. The effect of each protein on aortic dilatation and plaque growth was assessed after angioplasty in Apolipoprotein Enull mice. Four myxomavirus-derived proteins were studied; Serp-l a serine protease inhibitor (serpin) targeting thrombotic and thrombolytic proteases, Serp-2 a cross-class serpin inhibiting granzyme Band caspases land 8, M-T7 a broad spectrum C, CC, and CXC chemokine inhibitor, and Rl7lE, an inactive M-T7 mutant. Cell invasion, elastin breaks, plaque progression, and aortic dilatation were significantly reduced by Serp-l, Serp-2, or M-T7 protein treatment, but not by Rl7lE. PCR array analysis detected altered expression of a group of shared 40 apoptotic genes in monocytes after treatment with each active protein, but not Rl71E. Interference with inflammatory cell responses, through highly divergent inflammatory response pathways, produces similar reductions in monocyte invasion, arterial dilatation, and plaque growth potentially through modified expression of apoptotic genes.Although the risk associated with atherosclerotic cardiovascular disease is now markedly improved, the incidence ofabdominal aortic aneurysms (AAAs) is increasing (1-7). AAA is a localized dilatation of the aorta with diameter greater than 3 em (or more than 50% increase) with loss of medial elastin and associated cell death (apoptosis). There is often a marked increase in local atherosclerotic plaque and thrombosis at sites of aneurysmal dilatation. Undiagnosed AAAs affect 5% of men over 65 years of age, often causing sudden death (1-3). Nearly 2 million Americans are at risk for AAAs, with 4-8.9% prevalence worldwide, increasing as the population ages (1). Sudden rupture of the destabilized aneurysmal vessel has 50% to 80% associated mortality (1-3). While control of atherosclerotic

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