Alopecia in Harlequin Mutant Mice Is Associated with Reduced AIF Protein Levels and Expression of Retroviral Elements

In the study from December 26, 2020, researchers explored the role of apoptosis-inducing factor (AIF) in hair growth by examining Harlequin (Hq) mutant mice, which developed abnormalities in their hair during hair follicle morphogenesis. These abnormalities were linked to a decrease in the expression of genes responsible for hair structure, despite normal levels of key transcriptional regulators for hair follicle development. Mice with a specific Aifm1 mutation exhibited minor hair defects, even with significantly reduced AIF levels. Additionally, the study identified the overexpression of an integrated ecotropic provirus in the Aifm1Hq allele, which, when expressed in wild-type keratinocyte cell lines, led to the down-regulation of hair follicle-specific genes without affecting other keratin genes. The findings suggest that the lack of hair in Hq mutant mice is due to a severe AIF deficiency and potentially influenced by the expression of retroviral elements that may affect the transcription of structural hair proteins.