The Transcriptional Regulator Prdm1 Is Essential for the Early Development of the Sensory Whisker Follicle and Is Linked to the Beta-Catenin First Dermal Signal

The study investigates the role of the transcriptional regulator Prdm1 in the early development of sensory whisker follicles in mice. It was found that Prdm1 is expressed at the initial stages of whisker development and is crucial for the expression of several key genes (Bmp2, Shh, Bmp4, Krt17, Edar, and Gli1) involved in follicle formation. The conditional knockout of Prdm1 in mice does not affect the β-catenin-driven first dermal signal but leads to the loss of whisker follicles, while pelage hair development remains unaffected. Prdm1-expressing cells serve as a signaling center and a multipotent progenitor for various lineages in the adult whisker. The absence of macro vibrissae due to Prdm1 knockout results in altered nerve wiring in the mystacial pads and reorganization of the barrel cortex. The study also identifies that Lef1 acts upstream of Prdm1 and notes a primate-specific deletion of a Lef1 enhancer, which may have played a role in the evolutionary loss of vibrissae in primates.