Allograft inflammatory factor-1-like is not essential for age dependent weight gain or HFD-induced obesity and glucose insensitivity

The allograft inflammatory factor (AIF) gene family consists of two identified paralogs – AIF1 and AIF1-like (AIF1L). The encoded proteins, AIF1 and AIF1L, are 80% similar in sequence and show conserved tertiary structure. While studies in human populations suggest links between AIF1 and metabolic diseases such as obesity and diabetes, such associations with AIF1L have not been reported. Drawing parallels based on structural similarity, we postulated that AIF1L might contribute to metabolic disorders, and studied it using mouse models. Here we report that AIF1L is expressed in major adipose depots and kidney but was not detectable in liver or skeletal muscle; in notable contrast to AIF1, AIF1L was also not found in spleen. Studies of AIF1L deficient mice showed no obvious postnatal developmental phenotype. In response to high fat diet (HFD) feeding for 6 or 18 weeks, WT and AIF1L deficient mice gained weight similarly, showed no differences in fat or lean mass accumulation, and displayed no changes in energy expenditure or systemic glucose handling. These findings indicate that AIF1L is not essential for the development of obesity or impaired glucose handling due to HFD, and advance understanding of this little-studied gene and its place in the AIF gene family.