Sarah Steiner, Graduate Student (Coulombe Laboratory), Department of Cell and Developmental Biology , Department of Dermatology (Gudjonsson Laboratory), University of Michigan Medical School
The skin on the palms of our hands and the soles of our feet is different from that of most of the rest of the body. This skin (or epidermis) is hairless and has a wrinkled surface that helps us grasp objects. It is also particularly thick and tough, to protect these regions from the high mechanical stresses that impact this tissue on a day-to-day basis. One of the proteins that contributes to this mechanical toughness is keratin 9, an intermediate filament protein that forms a strong filamentous network to strengthen the skin. In this section of human plantar (or sole) skin, cells expressing keratin 9 are red; green marks expression of a related protein, keratin 16, while cell nuclei appear blue. The heart-shaped region represents a protrusion of the dermis (the tissue underneath the skin) up into the epidermis. Because keratin 9 is expressed exclusively in the palms and soles, mutations in this protein result in an inherited disease known as epidermolytic palmoplantar keratoderma, a condition with thickening and scaling of these regions.