Mice homozygous for the Tnftm1Gkl targeted mutation are viable and fertile. Development of both lymph nodes and Peyer's patches is normal, and homozygous mutant mice show no apparent phenotypic abnormalities. Homozygous mice completely lack splenic primary B cell follicles and cannot form organized follicular dendritic cell networks and germinal centers. TNF-deficient mice treated to induce skin carcinogenesis develop significantly less benign and malignant tumors than treated wildtype mice. Nonobese homozygous mutant mice show modest decreases in body weight, epididymal fat depot weight, and percent body fat (statistically significant in males at 28 weeks of age). Further characterization indicates that 28 week old male mutant mice display lower insulin, triglyceride, and leptin levels compared to wildtype controls. Characterization of TNF deficient homozygotes injected with gold-thioglucose (GTG) to induce hyperphagic obesity indicates that the presence of TNF does not affect the degree of obesity. However, fasting plasma glucose and insulin levels, and the insulin response to an oral glucose load were significantly decreased in obese TNF deficient mice compared to obese wildtype controls. These results indicate TNF plays a role in lipid and glucose metabolism but is not sufficient to completely eliminate hyperglycemia and hyperinsulinemia in this induced obesity model.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
