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Bhasin, Shalender

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Bhasin

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Shalender

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Bhasin, Shalender
Author's Publications: search.filters.isAuthorOfPublication.8fc5cef3-de80-4cf2-943f-48ab2b090a89

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    AAV-Mediated Administration of Myostatin Pro-Peptide Mutant in Adult Ldlr Null Mice Reduces Diet-Induced Hepatosteatosis and Arteriosclerosis
    (Public Library of Science, 2013) Guo, Wen; Wong, Siu; Bhasin, Shalender
    Genetic disruption of myostatin or its related signaling is known to cause strong protection against diet-induced metabolic disorders. The translational value of these prior findings, however, is dependent on whether such metabolically favorable phenotype can be reproduced when myostatin blockade begins at an adult age. Here, we reported that AAV-mediated delivery of a myostatin pro-peptide D76A mutant in adult mice attenuates the development of hepatic steatosis and arteriosclerosis, two common diet-induced metabolic diseases. A single dose of AAV-D76A in adult Ldlr null mice resulted in sustained expression of myostatin pro-peptide in the liver. Compared to vehicle-treated mice, D76A-treated mice gained similar amount of lean and fat mass when fed a high fat diet. However, D76A-treated mice displayed significantly reduced aortic lesions and liver fat, in association with a reduction in hepatic expression of lipogenic genes and improvement in liver insulin sensitivity. This suggests that muscle and fat may not be the primary targets of treatment under our experimental condition. In support to this argument, we show that myostatin directly up-regulated lipogenic genes and increased fat accumulation in cultured liver cells. We also show that both myostatin and its receptor were abundantly expressed in mouse aorta. Cultured aortic endothelial cells responded to myostatin with a reduction in eNOS phosphorylation and an increase in ICAM-1 and VCAM-1 expression. Conclusions: AAV-mediated expression of myostatin pro-peptide D76A mutant in adult Ldlr null mice sustained metabolic protection without remarkable impacts on body lean and fat mass. Further investigations are needed to determine whether direct impact of myostatin on liver and aortic endothelium may contribute to the related metabolic phenotypes.
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    Lopinavir/Ritonavir Impairs Physical Strength in Association with Reduced Igf1 Expression in Skeletal Muscle of Older Mice
    (2014) Wong, Siu; Bhasin, Shalender; Serra, Carlo; Yu, Yanan; Deng, Lynn; Guo, Wen
    Background: Late-middle age HIV patients are prone to fatigue despite effective viral control by antiretroviral therapies. Rodent models to recapitulate this phenotype are still not available. Hypothesis Drug treatment may compromise muscle strength and physical performance more in older individuals with pre-existing metabolic disorders than normal young ones. Methods: Kaletra was given to overweight male mice at late-middle age and normal young adults; both on a rodent diet containing 30% fat calorie. Body composition and grip strength were measured at baseline and after drug treatment. Rota-rod running, insulin and glucose tolerance were measured at the end of the experiment. Drug effect on metabolic activity and spontaneous movements were assessed using the metabolic cage system. Representative muscle and fat tissue were analyzed for protein and mRNA expression. Selected findings were tested using murine C2C12 myotubes. Results: Kaletra reduced grip strength in both young and older mice but impaired rotarod performance only in the old. Spontaneous movements were also reduced in Kaletra-treated old mice. Kaletra reduced IGF-1 expression in all muscle groups tested for the old and in cultured myotubes but to a less extent in the muscle of young animals. Reduced IGF-1 expression correlated with increased expression of muscle-specific atrogene MAFbx and MuRF1. Kaletra also increased abdominal fat mass markedly in the old animals and to a less extend in the young. Conclusion: Long-term Kaletra intake aggravated abdominal obesity and impaired muscle strength. This effect was worse in older animals than in normal young adults.
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    Combined administration of testosterone plus an ornithine decarboxylase inhibitor as a selective prostate-sparing anabolic therapy
    (BlackWell Publishing Ltd, 2013) Jasuja, Ravi; Costello, James C; Singh, Rajan; Gupta, Vandana; Spina, Catherine S; Toraldo, Gianluca; Jang, Hyeran; Li, Hu; Serra, Carlo; Guo, Wen; Chauhan, Pratibha; Narula, Navjot S; Guarneri, Tyler; Ergun, Ayla; Travison, Thomas; Collins, James; Bhasin, Shalender
    Because of its anabolic effects on muscle, testosterone is being explored as a function-promoting anabolic therapy for functional limitations associated with aging; however, concerns about testosterone’s adverse effects on prostate have inspired efforts to develop strategies that selectively increase muscle mass while sparing the prostate. Testosterone’s promyogenic effects are mediated through upregulation of follistatin. We show here that the administration of recombinant follistatin (rFst) increased muscle mass in mice, but had no effect on prostate mass. Consistent with the results of rFst administration, follistatin transgenic mice with constitutively elevated follistatin levels displayed greater muscle mass than controls, but had similar prostate weights. To elucidate signaling pathways regulated differentially by testosterone and rFst in prostate and muscle, we performed microarray analysis of mRNAs from prostate and levator ani of castrated male mice treated with vehicle, testosterone, or rFst. Testosterone and rFst shared the regulation of many transcripts in levator ani; however, in prostate, 593 transcripts in several growth-promoting pathways were differentially expressed after testosterone treatment, while rFst showed a negligible effect with only 9 transcripts differentially expressed. Among pathways that were differentially responsive to testosterone in prostate, we identified ornithine decarboxylase (Odc1), an enzyme in polyamine biosynthesis, as a testosterone-responsive gene that is unresponsive to rFst. Accordingly, we administered testosterone with and without α-difluoromethylornithine (DFMO), an Odc1 inhibitor, to castrated mice. DFMO selectively blocked testosterone’s effects on prostate, but did not affect testosterone’s anabolic effects on muscle. Co-administration of testosterone and Odc1 inhibitor presents a novel therapeutic strategy for prostate-sparing anabolic therapy.