Activation of the Notch Pathway in the Hair Cortex Leads to Aberrant Differentiation of the Adjacent Hair-Shaft Layers

The study investigated the role of the Notch pathway in hair follicle cell differentiation by using transgenic mice with overexpressed Notch1 in the hair cortex. These mice exhibited curly whiskers and wavy hair, indicating phenotypic changes. The activation of Notch signaling in the cortex led to abnormal differentiation in the medulla and cuticle, which did not express activated Notch, suggesting that these effects were due to cell-cell interactions within the hair follicle. The study concluded that Notch may play a role in directing follicular cell differentiation or helping cells interpret signals from the dermal papilla.