Impaired Mitochondrial Fat Oxidation Induces FGF21 in Muscle

SummaryFatty acids are the primary fuel source for skeletal muscle during most of our daily activities, and impaired fatty acid oxidation (FAO) is associated with insulin resistance. We have developed a mouse model of impaired FAO by deleting carnitine palmitoyltransferase-1b specifically in skeletal muscle (Cpt1bm−/−). Cpt1bm−/− mice have increased glucose utilization and are resistant to diet-induced obesity. Here, we show that inhibition of mitochondrial FAO induces FGF21 expression specifically in skeletal muscle. The induction of FGF21 in Cpt1b-deficient muscle is dependent on AMPK and Akt1 signaling but independent of the stress signaling pathways. FGF21 appears to act in a paracrine manner to increase glucose uptake under low insulin conditions, but it does not contribute to the resistance to diet-induced obesity

E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture

Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance(IR), are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular glucose uptake via a Ras-mediated activation of phosphatidyl inositol 3-kinase(PI3K), and improves hyperglycemia in mice, despite a high-fat diet and without reducing adiposity. Ex-vivo studies suggest that Ad36 improves hyperglycemia in mice by increasing glucose uptake by adipose tissue and skeletal muscle, and by reducing hepatic glucose output. It is impractical to use Ad36 for therapeutic action. Instead, we investigated if the E4orf1 protein of Ad36, mediates its anti-hyperglycemic action. Such a candidate protein may offer an attractive template for therapeutic development. Experiment-1 determined that Ad36 ‘requires’ E4orf1 protein to up-regulate cellular glucose uptake. Ad36 significantly increased glucose uptake in 3T3-L1 preadipocytes, which was abrogated by knocking down E4orf1 with siRNA. Experiment-2 identified E4orf1 as ‘sufficient’ to up-regulate glucose uptake. 3T3-L1 cells that inducibly express E4orf1, increased glucose uptake in an induction-dependent manner, compared to null vector control cells. E4orf1 up-regulated PI3K pathway and increased abundance of Ras–the obligatory molecule in Ad36-induced glucose uptake. Experiment-3: Signaling studies of cells transiently transfected with E4orf1 or a null vector, revealed that E4orf1 may activate Ras/PI3K pathway by binding to Drosophila discs-large(Dlg1) protein. E4orf1 activated total Ras and, particularly the H-Ras isoform. By mutating the PDZ domain binding motif(PBM) of E4orf1, Experiment-4 showed that E4orf1 requires its PBM to increase Ras activation or glucose uptake. Experiment-5: In-vitro, a transient transfection by E4orf1 significantly increased glucose uptake in preadipocytes, adipocytes, or myoblasts, and reduced glucose output by hepatocytes. Thus, the highly attractive anti-hyperglycemic effect of Ad36 is mirrored by E4orf1 protein, which may offer a novel ligand to develop anti-hyperglycemic drugs

Horizontal gene transfer in Histophilus somni and its role in the evolution of pathogenic strain 2336, as determined by comparative genomic analyses

<p>Abstract</p> <p>Background</p> <p>Pneumonia and myocarditis are the most commonly reported diseases due to <it>Histophilus somni</it>, an opportunistic pathogen of the reproductive and respiratory tracts of cattle. Thus far only a few genes involved in metabolic and virulence functions have been identified and characterized in <it>H. somni </it>using traditional methods. Analyses of the genome sequences of several <it>Pasteurellaceae </it>species have provided insights into their biology and evolution. In view of the economic and ecological importance of <it>H. somni</it>, the genome sequence of pneumonia strain 2336 has been determined and compared to that of commensal strain 129Pt and other members of the <it>Pasteurellaceae</it>.</p> <p>Results</p> <p>The chromosome of strain 2336 (2,263,857 bp) contained 1,980 protein coding genes, whereas the chromosome of strain 129Pt (2,007,700 bp) contained only 1,792 protein coding genes. Although the chromosomes of the two strains differ in size, their average GC content, gene density (total number of genes predicted on the chromosome), and percentage of sequence (number of genes) that encodes proteins were similar. The chromosomes of these strains also contained a number of discrete prophage regions and genomic islands. One of the genomic islands in strain 2336 contained genes putatively involved in copper, zinc, and tetracycline resistance. Using the genome sequence data and comparative analyses with other members of the <it>Pasteurellaceae</it>, several <it>H. somni </it>genes that may encode proteins involved in virulence (<it>e.g</it>., filamentous haemaggutinins, adhesins, and polysaccharide biosynthesis/modification enzymes) were identified. The two strains contained a total of 17 ORFs that encode putative glycosyltransferases and some of these ORFs had characteristic simple sequence repeats within them. Most of the genes/loci common to both the strains were located in different regions of the two chromosomes and occurred in opposite orientations, indicating genome rearrangement since their divergence from a common ancestor.</p> <p>Conclusions</p> <p>Since the genome of strain 129Pt was ~256,000 bp smaller than that of strain 2336, these genomes provide yet another paradigm for studying evolutionary gene loss and/or gain in regard to virulence repertoire and pathogenic ability. Analyses of the complete genome sequences revealed that bacteriophage- and transposon-mediated horizontal gene transfer had occurred at several loci in the chromosomes of strains 2336 and 129Pt. It appears that these mobile genetic elements have played a major role in creating genomic diversity and phenotypic variability among the two <it>H. somni </it>strains.</p

An Observational Study of the Association between Adenovirus 36 Antibody Status and Weight Loss among Youth

Objective: Although the human adenovirus 36 (Ad-36) is associated with obesity and relative hypolipidemia, its role in pediatric weight loss treatment response is uncertain. Therefore, the primary study objective was to determine whether Ad-36 antibody (AB) status was associated with response to a pediatric weight loss program. The secondary objective was to assess the association between Ad-36 AB status and baseline lipid values. Methods: Participants included 73 youth aged 10-17 years in a residential camp-based weight loss program. The study examined differences in baseline lipid values between Ad-36 AB+ and AB- youth as well as differences in response to treatment, including indices of body size and fitness. Results: At baseline, results showed that Ad-36 AB+ youth evidenced significantly lower levels of total cholesterol and triglycerides than Ad-36 AB- youth (all p Conclusion: Ad-36 AB status showed a weak association with treatment response, but was associated with a better lipid profile. Ad-36 AB status should be assessed in studies of pediatric obesity treatment and prevention

Examination of carnitine palmitoyltransferase 1 abundance in white adipose tissue: implications in obesity research

Carnitine palmitoyltransferase 1 (CPT1) is essential for the transport of long-chain fatty acids into the mitochondria for oxidation. Recently, it was reported that decreased CPT1b mRNA in adipose tissue was a contributing factor for obesity in rats. We therefore closely examined the expression level of in adipose tissue from mice, rats, and humans. is the predominate isoform in adipose tissue from all three species. Rat white adipose tissue has a moderate amount of mRNA, but it is very minor compared with expression in muscle. Total CPT1 activity in adipose tissue is also minor relative to other tissues. Both and mRNA were increased in gonadal fat but not inguinal fat by diet-induced obesity in mice. We also measured and expression in subcutaneous adipose tissue from human subjects with a wide range of body mass indexes (BMIs). Interestingly, expression positively correlated with BMI ( = 0.46), but there was no correlation with ( = 0.04). Our findings indicate that white adipose tissue fatty acid oxidation capacity is minor compared with that of metabolically active tissues. Furthermore, given the already low abundance of in white adipose tissue, it is unlikely that decreases in its expression can quantitatively decrease whole body energy expenditure enough to contribute to an obese phenotype

Efficacy of low-level laser therapy for body contouring and spot fat reduction

BACKGROUND: Low-level laser therapy (LLLT) is commonly used in medical applications, but scientific studies of its efficacy and the mechanism by which it causes loss of fat from fat cells for body contouring are lacking. This study examined the effectiveness and mechanism by which 635–680 nm LLLT acts as a non-invasive body contouring intervention method. METHODS: Forty healthy men and women ages 18–65 years with a BMI \u3c30 kg/m2 were randomized 1:1 to laser or control treatment. Subject\u27s waistlines were treated 30 min twice a week for 4 weeks. Standardized waist circumference measurements and photographs were taken before and after treatments 1, 3, and 8. Subjects were asked not to change their diet or exercise habits. In vitro assays were conducted to determine cell lysis, glycerol, and triglyceride release. RESULTS: Data were analyzed for those with body weight fluctuations within 1.5 kg during 4 weeks of the study. Each treatment gave a 0.4–0.5 cm loss in waist girth.Cumulative girth loss after 4 weeks was −2.15 cm (−0.78 ± 2.82 vs. 1.35 ± 2.64 cm for the control group,p \u3c 0.05). A blinded evaluation of standardized pictures showed statistically significant cosmetic improvement after 4 weeks of laser treatment. In vitro studies suggested that laser treatment increases fat loss from adipocytes by release of triglycerides, without inducing lipolysis or cell lysis. CONCLUSIONS: LLLT achieved safe and significant girth loss sustained over repeated treatments and cumulative over 4 weeks of eight treatments. The girth loss from the waist gave clinically and statistically significant cosmetic improvement

Examination of carnitine palmitoyltransferase 1 abundance in white adipose tissue: implications in obesity research

Carnitine palmitoyltransferase 1 (CPT1) is essential for the transport of long-chain fatty acids into the mitochondria for oxidation. Recently, it was reported that decreased CPT1b mRNA in adipose tissue was a contributing factor for obesity in rats. We therefore closely examined the expression level of in adipose tissue from mice, rats, and humans. is the predominate isoform in adipose tissue from all three species. Rat white adipose tissue has a moderate amount of mRNA, but it is very minor compared with expression in muscle. Total CPT1 activity in adipose tissue is also minor relative to other tissues. Both and mRNA were increased in gonadal fat but not inguinal fat by diet-induced obesity in mice. We also measured and expression in subcutaneous adipose tissue from human subjects with a wide range of body mass indexes (BMIs). Interestingly, expression positively correlated with BMI ( = 0.46), but there was no correlation with ( = 0.04). Our findings indicate that white adipose tissue fatty acid oxidation capacity is minor compared with that of metabolically active tissues. Furthermore, given the already low abundance of in white adipose tissue, it is unlikely that decreases in its expression can quantitatively decrease whole body energy expenditure enough to contribute to an obese phenotype

CRISPR/Cas9-engineered Drosophila knock-in models to study VCP diseases

Mutations in Valosin Containing Protein (VCP) are associated with several degenerative diseases, including multisystem proteinopathy (MSP-1) and amyotrophic lateral sclerosis. However, patients with VCP mutations vary widely in their pathology and clinical penetrance, making it difficult to devise effective treatment strategies. A deeper understanding of how each mutation affects VCP function could enhance the prediction of clinical outcomes and design of personalized treatment options. The power of a genetically tractable model organism coupled with well-established in vivo assays and a relatively short life cycle make Drosophila an attractive system to study VCP disease pathogenesis. Using CRISPR/Cas9, we have generated individual Drosophila knock-in mutants that include nine hereditary VCP disease mutations. Our models display many hallmarks of VCP-mediated degeneration, including progressive decline in mobility, protein aggregate accumulation and defects in lysosomal and mitochondrial function. We also made some novel and unexpected findings, including nuclear morphology defects and sex-specific phenotypic differences in several mutants. Taken together, the Drosophila VCP disease models generated in this study will be useful for studying the etiology of individual VCP patient mutations and testing potential genetic and/or pharmacological therapies