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Review
. 2022 Feb;142(2):282-284.
doi: 10.1016/j.jid.2021.06.016. Epub 2021 Aug 6.

Understanding and Harnessing Epithelial‒Mesenchymal Interactions in the Development of Palmoplantar Identity

Jerry Tsai  1 , Mary Rostom  1 , Luis A Garza  2
Affiliations
Review

Understanding and Harnessing Epithelial‒Mesenchymal Interactions in the Development of Palmoplantar Identity

Jerry Tsai et al. J Invest Dermatol. 2022 Feb.

Abstract

Palmoplantar skin has several unique characteristics such as increased thickness, high resilience, hypopigmentation, and lack of hair follicles. The establishment of palmoplantar identity occurs through keratinocyte‒fibroblast interactions, with keratin 9 expression and Wnt signaling playing key roles. Understanding how palmoplantar features develop may help efforts to reproduce them at both palmoplantar and nonpalmoplantar body sites.

Trial registration: ClinicalTrials.gov NCT03947450.

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Conflict of interest statement

Conflicts of interest: The authors have no conflicts of interest to declare.

Figures

Figure 1.
Figure 1.. Signaling molecules and pathways likely involved in the development of palmoplantar characteristics.
Expression of keratin 9 (KRT9) is a marker for palmoplantar keratinocyte differentiation, but there is uncertainty on whether KRT9 expression results from activation or inhibition of canonical Wnt signaling. Additional molecules including Dickkopf (DKK) proteins, R-spondin (RSPO) proteins, double-stranded RNA (dsRNA), inactive rhomboid protein 2 (iRHOM2), and epidermal growth factor (EGF) have been implicated in regulation of Wnt signaling or KRT9 expression, warranting further study on the interaction of different signaling pathways in the context of palmoplantar biology.
See this image and copyright information in PMC

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