DPM1 loss impairs cell cohesion and epidermal differentiation. (a and b) Dispase-based dissociation assays to semiquantitatively assess cell–cell adhesion in HaCaT keratinocytes (N = 4). One-way ANOVA, Dunn’s multiple comparison test. Higher fragment numbers represent lower adhesive strength. (c and d) Dispase-based dissociation assays of primary human keratinocytes (N = 5). Unpaired Student’s t test. (e) Schematic of epidermis (top) and of 3D-RHE model design from primary human keratinocytes (bottom). (f) H&E staining and immunostainings for CK10/Filaggrin, DPM1, and Ki67 of control (sgNT1) and DPM1 KD (sgDPM1) 3D-RHEs 12 days after airlift. Insets (zoomed 2× of original image) and arrows denote interfollicular gaps in different layers of epidermal equivalents of sgDPM1. White dashed line indicates insert membrane. Scale bar: 50 µm distance on H&E images and 10 µm on immunostaining images. (g–i) Quantification of epidermal thickness parameters from four independent biological replicates, from two different donors. Each dot represents one biological replicate. Unpaired Student’s t test. (j) Analysis showing Ki67-positive nuclei normalized to total number of nuclei (N = 3). Unpaired Student’s t test. (k) Violin plot showing quantification of intercellular spaces within the epidermis in sgNT1 and sgDPM1 3D-RHE. The cutoff for defining intercellular spaces was set to be >50 µm² to exclude shrinking artifacts. A minimum of 20 individual fields of view were used for analysis from three independent biological replicates. Unpaired Student’s t test.