338 Targeted molecular mimicry to prevent infection: Using the airway epithelium as a model

Abstract

Desmogleins (Dsgs) are cadherin family members present in desmosomes and essential for epidermal integrity. Dsgs associate with lipid raft membrane microdomains, but the physiological significance of this association is not clear. Here, we report that the Dsg transmembrane domain (TMD) is the primary determinant of lipid raft association. Further, we identify a novel mutation in the DSG1 TMD (G562R) that causes severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome. Cell based experiments revealed that the Dsg1 TMD mutant is defective in both lipid raft and desmosome association. Interestingly, molecular modeling indicates that this mutation shortens the length of the Dsg1 TMD. In addition, cryo-electron tomography of normal epithelial tissue indicates that the lipid bilayer within the desmosome is w10% thicker than adjacent regions of the plasma membrane, suggesting that hydrophobic matching of the Dsg TMD to lipid bilayer thickness contributes to the formation of a specialized membrane domain. This observation represents the first demonstration of a thicker lipid bilayer in a plasma membrane domain known to be enriched in lipid raft proteins, thereby confirming predictions about raft domains based on model membranes. Together, these findings demonstrate that differences in lipid bilayer thickness and features of cadherin TMDs drive the organization of adhesion molecules within the keratinocyte plasma membrane. Further, these findings suggest that the desmosome is a mesoscale lipid raft-like membrane domain and that mutations in Dsgs that alter raft targeting cause epidermal disease. 335Development of a new three-dimensional reconstructed human epidermis model silenced for key circadian rhythm genes to study their roles on epidermal homeostasis and 3 Biospectrum, Gyeonggi-do, Korea (the Democratic People's Republic of) Many physiological functions are under the control of a central biological clock regulated by the circadian rhythm, which follows the successive night and day cycles. At a molecular level the circadian clock consists of an auto-regulatory gene expression feedback loop driven by oscillating expression of a family of transcription factors called clock genes (Clock, Bmal, Per, Cry). The skin is the first barrier of the body against environmental aggressions such as UVs, pollution, but is also submitted to internal cellular stresses that varies a lot depending on the time of the day, therefore it is consistent that skin functions and mechanisms are monitored by circadian clock.The behavior of epidermal keratinocytes has been shown to follow a circadian rhythm, nevertheless the link between circadian rhythmicity alteration and skin integrity is largely unexplored. Besides, some recent evidences, in mice, have linked circadian rhythm abnormalities (Bmal1 KO) and skin aging. Unfortunately, the role of period genes and skin physiology and in particular skin aging was not investigated. For this purpose, we performed keratinocytes knocked down for PER2, PER3 or both expressions using sm...