Human immunodeficiency virus type 1 (HIV-1) clade C causes >50% of all HIV infections worldwide, and an estimated 90% of all transmissions occur mucosally with R5 strains. A pathogenic R5 simian-human immunodeficiency virus (SHIV) encoding HIV clade C env is highly desirable to evaluate candidate AIDS vaccines in nonhuman primates. To this end, we generated SHIV-1157i, a molecular clone from a Zambian infant isolate that carries HIV clade C env. SHIV-1157i was adapted by serial passage in five monkeys, three of which developed peripheral CD4 ؉ T-cell depletion. After the first inoculated monkey developed AIDS at week 137 postinoculation, transfer of its infected blood to a naïve animal induced memory T-cell depletion and thrombocytopenia within 3 months in the recipient. In parallel, genomic DNA from the blood donor was amplified to generate the late proviral clone SHIV-1157ipd3. To increase the replicative capacity of SHIV1157ipd3, an extra NF-B binding site was engineered into its 3 long terminal repeat, giving rise to SHIV1157ipd3N4. This virus was exclusively R5 tropic and replicated more potently in rhesus peripheral blood mononuclear cells than SHIV-1157ipd3 in the presence of tumor necrosis factor alpha. Rhesus macaques of Indian and Chinese origin were next inoculated intrarectally with SHIV-1157ipd3N4; this virus replicated vigorously in both sets of monkeys. We conclude that SHIV-1157ipd3N4 is a highly replication-competent, mucosally transmissible R5 SHIV that represents a valuable tool to test candidate AIDS vaccines targeting HIV-1 clade C Env.

Magnetic resonance imaging has previously demonstrated its potential for indirectly mapping myelin density, either by relaxometric detection of myelin water or magnetization transfer. Here, we investigated whether myelin can be detected and possibly quantified directly. We identified the spectrum of myelin in the spinal cord in situ as well as in myelin lipids extracted via a sucrose gradient method, and investigated its spectral properties. Highresolution solution NMR spectroscopy showed the extract composition to be in agreement with myelin's known chemical make-up. The 400-MHz 1 H spectrum of the myelin extract, at 20°C (room temperature) and 37°C, consists of a narrow water resonance superimposed on a broad envelope shifted ∼3.5 ppm upfield, suggestive of long-chain methylene protons. Superimposed on this signal are narrow components resulting from functional groups matching the chemical shifts of the constituents making up myelin lipids. The spectrum could be modeled as a sum of super-Lorentzians with a T 2 * distribution covering a wide range of values (0.008-26 ms). Overall, there was a high degree of similarity between the spectral properties of extracted myelin lipids and those found in neural tissue. The normalized difference spectrum had the hallmarks of membrane proteins, not present in the myelin extract. Using 3D radially ramp-sampled proton MRI, with a combination of adiabatic inversion and echo subtraction, the feasibility of direct myelin imaging in situ is demonstrated. Last, the integrated signal from myelin suspensions is shown, both spectroscopically and by imaging, to scale with concentration, suggesting the potential for quantitative determination of myelin density. myelin in situ | myelin NMR spectrum | super-Lorentzian fitting | ultrashort echo time

Osteoblasts have recently been found to play a role in regulating glucose metabolism through secretion of osteocalcin. It is unknown, however, how this osteoblast function is regulated transcriptionally. As FoxO1 is a forkhead family transcription factor known to regulate several key aspects of glucose homeostasis, we investigated whether its expression in osteoblasts may contribute to its metabolic functions. Here we show that mice lacking Foxo1 only in osteoblasts had increased pancreatic β cell proliferation, insulin secretion, and insulin sensitivity. The ability of osteoblast-specific FoxO1 deficiency to affect metabolic homeostasis was due to increased osteocalcin expression and decreased expression of Esp, a gene that encodes a protein responsible for decreasing the bioactivity of osteocalcin. These results indicate that FoxO1 expression in osteoblasts contributes to FoxO1 control of glucose homeostasis and identify FoxO1 as a key modulator of the ability of the skeleton to function as an endocrine organ regulating glucose metabolism.

Obesity caused by feeding of a high-fat diet (HFD) is associated with an increased activation of c-Jun NH 2 -terminal kinase 1 (JNK1). Activated JNK1 is implicated in the mechanism of obesity-induced insulin resistance and the development of metabolic syndrome and type 2 diabetes. Significantly, Jnk1 ؊/؊ mice are protected against HFD-induced obesity and insulin resistance. Here we show that an ablation of the Jnk1 gene in skeletal muscle does not influence HFD-induced obesity. However, muscle-specific JNK1-deficient (M KO ) mice exhibit improved insulin sensitivity compared with control wild-type (M WT ) mice. Thus, insulin-stimulated AKT activation is suppressed in muscle, liver, and adipose tissue of HFD-fed M WT mice but is suppressed only in the liver and adipose tissue of M KO mice. These data demonstrate that JNK1 in muscle contributes to peripheral insulin resistance in response to diet-induced obesity.

The cJun N-terminal kinase 1 (JNK1) is implicated in diet-induced obesity. Indeed, germline ablation of the murine Jnk1 gene prevents diet-induced obesity. Here we demonstrate that selective deficiency of JNK1 in the murine nervous system is sufficient to suppress diet-induced obesity. The failure to increase body mass is mediated, in part, by increased energy expenditure that is associated with activation of the hypothalamicpituitary-thyroid axis. Disruption of thyroid hormone function prevents the effects of nervous system JNK1 deficiency on body mass. These data demonstrate that the hypothalamic-pituitary-thyroid axis represents an important target of metabolic signaling by JNK1.[Keywords: JNK1; obesity; insulin resistance; thyroid hormone] Supplemental material is available at http://www.genesdev.org. Human obesity represents a serious world-wide health problem. One consequence of obesity is the development of insulin resistance, hyperglycemia, and metabolic syndrome that can lead to b-cell dysfunction and type 2 diabetes (Kahn et al. 2006). It is therefore important that we gain an understanding of the physiology and pathophysiology of the development of obesity, because this knowledge represents a basis for the design of potential therapeutic interventions.The cJun N-terminal kinase 1 (JNK1) represents one signaling pathway that has been implicated in dietinduced obesity (Weston and Davis 2007). JNK1 is activated when mice are fed a high-fat diet (HFD) (Hirosumi et al. 2002). Moreover, Jnk1 À/À mice are protected against HFD-induced weight gain (Hirosumi et al. 2002). The mechanism that accounts for the effect of germline JNK1 deficiency to control body weight is unclear. Tissue-specific deficiency of JNK1 in fat, muscle, liver, and myeloid cells does not affect HFD-induced weight gain (Sabio et al. 2008(Sabio et al. , 2009(Sabio et al. , 2010. A different organ must therefore play a major role in the diet-induced regulation of body weight by JNK1. The brain represents a possible site of JNK1 function because the hypothalamus and pituitary gland are known to regulate metabolism, including feeding behavior, physical activity, and energy expenditure (Lenard and Berthoud 2008).The purpose of this study was to investigate the role of JNK1 in the brain. Our approach was to examine the effect of selective ablation of the Jnk1 gene in the mouse nervous system. We found that HFD-fed control (N WT ) mice gained substantially greater body weight than JNK1-deficient (N KO ) mice. The decreased weight gain by N KO mice was accounted for by decreased food intake, increased physical activity, and increased energy expenditure. These changes were associated with increased amounts of thyroid hormone in the blood and increased expression of thyroid hormone-responsive genes in target tissues. Importantly, pharmacological inhibition of thyroid hormone markedly attenuated N KO phenotypes. These data demonstrate that the hypothalamic-pituitary-thyroid axis is a major target of the JNK1 signaling pathway that regulates metabolis...