GH deficiency is known to be clinically associated with a high incidence of nonalcoholic fatty liver disease, and this can be reversed by GH administration. Here we investigated the mechanistic basis for this phenomenon using engineered male mice lacking different signaling elements of the GH receptor, hepatic stat5a/b(-/-) mice and a mouse hepatoma line. We found deficient GH-dependent signal transducer and activator of transcription (STAT)-5 signaling correlates with steatosis, and through microarray analysis, quantitative PCR, and chromatin immunoprecipitation, identified putative targets of STAT5 signaling responsible for the steatosis seen on a normal diet. These targets were verified with liver-specific stat5a/b deletion in vivo, and in vitro we show that dominant-negative (DN) STAT5 increases lipid uptake in a mouse hepatoma line. Because loss of STAT5 signaling results in elevated STAT1 and STAT3 activity and intracellular lipid accumulation, we have used DN-STAT5a/b, DN-STAT1, constitutively active (CA)-STAT3, or addition of oleate/palmitate in the hepatoma line to assign which of these apply to individual targets in STAT5 signaling deficiency. These findings and published mouse models of steatosis enable us to propose elevated cd36, pparγ, and pgc1α/β expression as primary instigators of the steatosis along with elevated fatty acid synthase, lipoprotein lipase, and very low-density lipoprotein receptor expression. Decreased fgf21 and insig2 expression may also contribute. In conclusion, despite normal plasma free fatty acids and minimal obesity, absent GH activation leads to steatosis because activated STAT5 prevents hepatic steatosis. These results raise the possibility of low-dose GH treatment for nonalcoholic fatty liver disease.

A role for myosin phosphorylation in modulating normal cardiac function has long been suspected, and we hypothesized that changing the phosphorylation status of a cardiac myosin light chain might alter cardiac function in the whole animal. To test this directly, transgenic mice were created in which three potentially phosphorylatable serines in the ventricular isoform of the regulatory myosin light chain were mutated to alanines. Lines were obtained in which replacement of the endogenous species in the ventricle with the nonphosphorylatable, transgenically encoded protein was essentially complete. The mice show a spectrum of cardiovascular changes. As previously observed in skeletal muscle, Ca 2؉ sensitivity of force development was dependent upon the phosphorylation status of the regulatory light chain. Structural abnormalities were detected by both gross histology and transmission electron microscopic analyses. Mature animals showed both atrial hypertrophy and dilatation. Echocardiographic analysis revealed that as a result of chamber enlargement, severe tricuspid valve insufficiency resulted in a detectable regurgitation jet. We conclude that regulated phosphorylation of the regulatory myosin light chains appears to play an important role in maintaining normal cardiac function over the lifetime of the animal.The roles of the regulatory myosin light chains (RLCs) 1 and the reversible post-translational modifications they undergo in striated muscle are beginning to be defined. In skeletal muscle, a serine at the amino end of the protein can be phosphorylated by a sarcoplasmic kinase (1), and it is now clear that RLCs in the different striated muscles are phosphorylated to differing degrees, leading presumably to different physiological effects. In smooth muscle, RLC phosphorylation by myosin light chain kinase (MLCK), which is activated by a Ca 2ϩ /calmodulin-dependent pathway, is responsible for initiating muscle contraction (2, 3). However, in skeletal and cardiac muscle, in which the thin, rather than thick, filament mediates control of contraction, RLC phosphorylation does not activate contraction but appears to play a modulatory role. In skinned skeletal muscle fibers, RLC phosphorylation increases sensitivity to activating Ca 2ϩ such that there is a significant leftward shift in the force-Ca 2ϩ relationship (4 -6). Increased RLC phosphorylation in skeletal muscle is also associated with potentiation of isometric twitch tension with repeated activation and inactivation of contraction (7, 8), rate of force production (9 -11), and maximum Ca 2ϩ -stimulated MgATPase activity (12). The mechanistic basis for the effects of RLC phosphorylation in striated muscle is hypothesized to be a lessening of the weak interaction of the myosin head with the myosin backbone and is probably due to a net charge change in a critical region of the protein (13). Upon phosphorylation, the myosin heads move away from the backbone to a position closer to actin, which presumably increases the rate at which myosin-actin interaction...

Using data from the 1998 Medicare Current Beneficiary Survey (MCBS), we examine changes in beneficiaries' prescription drug coverage from 1997 to 1998 and compare drug use and spending data for beneficiaries with and without drug coverage. The data show that in 1998 the aggregate prescription drug coverage rate of Medicare beneficiaries may have reached a plateau. Also, prescription drug use declined for beneficiaries without drug coverage and increased for those with drug coverage. Covered beneficiaries also paid a larger percentage of their total drug costs out of pocket in 1998 than in 1997. The result was a widening of use and spending differences between beneficiaries with and without coverage.

Crowther LM, Wang SCM, Eriksson NA, Myers SA, Murray LA, Muscat GEO. Chicken ovalbumin upstream promoter-transcription factor II regulates nuclear receptor, myogenic, and metabolic gene expression in skeletal muscle cells. Physiol Genomics 43: 213-227, 2011. First published November 30, 2010 doi:10.1152/physiolgenomics.00195.2010.-We demonstrate that chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) mRNA is more abundantly expressed (than COUP-TFI mRNA) in skeletal muscle C2C12 cells and in (type I and II) skeletal muscle tissue from C57BL/10 mice. Consequently, we have utilized the ABI TaqMan Low Density Array (TLDA) platform to analyze gene expression changes specifically attributable to ectopic COUP-TFII (relative to vector only) expression in muscle cells. Utilizing a TLDA-based platform and 5 internal controls, we analyze the entire NR superfamily, 96 critical metabolic genes, and 48 important myogenic regulatory genes on the TLDA platform utilizing 5 internal controls. The low density arrays were analyzed by rigorous statistical analysis (with Genorm normalization, Bioconductor R, and the Empirical Bayes statistic) using the (integromics) statminer software. In addition, we validated the differentially expressed pathophysiologically relevant gene (identified on the TLDA platform) glucose transporter type 4 (Glut4). We demonstrated that COUP-TFII expression increased the steady state levels of Glut4 mRNA and protein, while ectopic expression of truncated COUP-TFII lacking helix 12 (COUP-TF⌬H12) reduced Glut4 mRNA expression in C2C12 cells. Moreover, COUP-TFII expression trans-activated the Glut4 promoter (Ϫ997/ϩ3), and ChIP analysis identified selective recruitment of COUP-TFII to a region encompassing a highly conserved SP1 binding site (in mouse, rat, and human) at nt positions Ϫ131/Ϫ118. Mutation of the SpI site ablated COUP-TFII mediated trans-activation of the Glut4 promoter. In conclusion, this study demonstrates that in skeletal muscle cells, COUP-TFII regulates several nuclear hormone receptors, and critical metabolic and muscle specific genes. glucose metabolism; differentiation; TaqMan low density array; myogenesis CHICKEN OVALBUMIN UPSTREAM PROMOTER TRANSCRIPTION FACTORS (COUP-TFs) I and II are orphan members of the nuclear hormone receptor (NR) superfamily. NRs are ligand modulated transcription factors that regulate expression of genes involved in reproduction, development, cell differentiation, and metabolism (22).It is known that COUP-TFI and COUP-TFII can act as transcriptional repressors or activators, and the role of COUPTFs in metabolism has been examined in tissues such as liver and adipose tissue.In liver cells, COUP-TFII stimulates CYP7A (33, 37, 73) and CETP transcription (20), and represses apolipoprotein AI expression (38), demonstrating a role for COUP-TFII in the regulation of cholesterol homeostasis in liver. Also in HepG2 cells, COUP-TFI inhibits transactivation of the CPT-II promoter by PPAR␣/RXR␣, and is required for stimulation of phosphoenolpyruvate ca...

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