Ceramides contribute to the lipotoxicity that underlies diabetes, hepatic steatosis, and heart disease. By genetically engineering mice, we deleted the enzyme dihydroceramide desaturase 1 (DES1), which normally inserts a conserved double bond into the backbone of ceramides and other predominant sphingolipids. Ablation of DES1 from whole animals or tissue-specific deletion in the liver and/or adipose tissue resolved hepatic steatosis and insulin resistance in mice caused by leptin deficiency or obesogenic diets. Mechanistic studies revealed ceramide actions that promoted lipid uptake and storage and impaired glucose utilization, none of which could be recapitulated by (dihydro)ceramides that lacked the critical double bond. These studies suggest that inhibition of DES1 may provide a means of treating hepatic steatosis and metabolic disorders.

No abstract

Targeted modification of the pig genome can be challenging. Recent applications of the CRISPR/Cas9 system hold promise for improving the efficacy of genome editing. When a designed CRISPR/Cas9 system targeting CD163 or CD1D was introduced into somatic cells, it was highly efficient in inducing mutations. When these mutated cells were used with somatic cell nuclear transfer, offspring with these modifications were created. When the CRISPR/Cas9 system was delivered into in vitro produced presumptive porcine zygotes, the system was effective in creating mutations in eGFP, CD163, and CD1D (100% targeting efficiency in blastocyst stage embryos); however, it also presented some embryo toxicity. We could also induce deletions in CD163 or CD1D by introducing two types of CRISPRs with Cas9. The system could also disrupt two genes, CD163 and eGFP, simultaneously when two CRISPRs targeting two genes with Cas9 were delivered into zygotes. Direct injection of CRISPR/Cas9 targeting CD163 or CD1D into zygotes resulted in piglets that have mutations on both alleles with only one CD1D pig having a mosaic genotype. We show here that the CRISPR/Cas9 system can be used by two methods. The system can be used to modify somatic cells followed by somatic cell nuclear transfer. System components can also be used in in vitro produced zygotes to generate pigs with specific genetic modifications.

Identification of individual major genes affecting quantitative traits in livestock species has been limited to date. By using a candidate gene approach and a divergent breed cross involving the Chinese Meishan pig, we have shown that a specific allele of the estrogen receptor (ER) locus is associated with increased litter size. Female pigs from synthetic lines with a 50% Meishan background that were homozygous for this beneficial allele produced 2.3 more pigs in first parities and 1.5 more pigs averaged over all parities than females from the same synthetic lines and homozygous for the undesirable allele. This beneficial ER allele was also found in pigs with Large White breed ancestory. Analysis of females with Large White breed background showed an advantage for females homozygous for the beneficial allele as compared to females homozygous for the other allele of more than 1 total pig born. Analyses of growth performance test records detected no significant unfavorable associations of the beneficial allele with growth and developmental traits. Mapping of the ER gene demonstrated that the closest known genes or markers were 3 centimorgans from ER. To our knowledge, one of these, superoxide dismutase gene (SOD2), was mapped for the first time in the pig. Analysis of ER and these linked markers indicated that ER is the best predictor of litter size differences. Introgression of the beneficial allele into commercial pig breeding lines, in which the allele was not present, and marker-assisted selection for the beneficial allele in lines with Meishan and Large White background have begun.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide ( 1 ). Dyslipidemia has been shown to be one of the most potent risk factors for coronary heart disease (CHD) ( 2, 3 ). Dyslipidemia is characterized by elevated plasma cholesterol, especially low density lipoprotein cholesterol (LDL-c) levels. Management of dyslipidemia is considered throughout the primary and secondary prevention of CHD ( 4 ). For the past 20 years, the statin (3-hydroxy-3-methylglutaryl CoA reductase inhibitors) class of cholesterol-lowering drugs has been used for the treatment of hypercholesterolemia, either alone or in combination with other classes of lipid-lowering drugs Abstract In an attempt to understand the applicability of various animal models to dyslipidemia in humans and to identify improved preclinical models for target discovery and validation for dyslipidemia, we measured comprehensive plasma lipid profi les in 24 models. These included fi ve mouse strains, six other nonprimate species, and four nonhuman primate (NHP) species, and both healthy animals and animals with metabolic disorders. Dyslipidemic humans were assessed by the same measures. Plasma lipoprotein profi les, eight major plasma lipid fractions, and FA compositions within these lipid fractions were compared both qualitatively and quantitatively across the species. Given the importance of statins in decreasing plasma low-density lipoprotein cholesterol for treatment of dyslipidemia in humans, the responses of these measures to simvastatin treatment were also assessed for each species and compared with dyslipidemic humans. NHPs, followed by dog, were the models that demonstrated closest overall match to dyslipidemic humans. For the subset of the dyslipidemic population with high plasma triglyceride levels, the data also pointed to hamster and db/db mouse as representative models for practical use in target validation. Most traditional models, including rabbit, Zucker diabetic fatty rat, and the majority of mouse models, did not demonstrate overall similarity to dyslipidemic humans in this study . -