Triphasic epithelia formed by a 3.0-µm-pored membrane

(a) Schematic diagram of experiments using normal human epidermal keratinocytes cultured on a microporous membrane and exposed to air for 14 days to produce 3D epidermis. (b) Hematoxylin and eosin (HE) staining and vimentin (Vim: brown) labeling of 3D tissue derived from each microporous membrane (Mem). Scale bar: 50 μm. (c) HE staining of 3D tissue formed by a 3.0-µm-pored membrane. Scale bar: 50 μm. (d) E-cadherin (E-cad)/N-cadherin (N-cad) (upper images), Slug (middle images), and Vim (lower images) staining of 3D tissue formed by a 0.4-µm- (left) or 3.0-µm-pored (right) membrane. Scale bar: 50 μm (low-magnified images) and 20 μm (high-magnified image). (e) Vim staining of 3D tissue formed by a 3.0-µm-pored membrane. Scale bar: 20 μm. (f) Quantitative RT-PCR (qRT-PCR) of CDH1 and CDH2. (g) qRT-PCR of FN1, VIM, SNAI1, and SNAI2. Data were analyzed with two-tailed Mann–Whitney U tests. * p < 0.05; *** p < 0.001; **** p < 0.0001. (h) Schematic diagram of the triphasic epithelia.

Reciprocating movement of keratinocytes on a 3.0-µm-pored membrane

(a) Schematic diagram of LifeAct-KCs cultured on a microporous membrane. Observation at the level of cell exit from the micropores. (b) Time-lapse images of LifeAct-KCs at the level of cell exit from 3.0-µm micropores. Representative images are shown at 30-minute time intervals. Time stamp shows hour:minute. Arrows indicate the cells that exit from the pores and expand under the membrane. Arrowheads indicate the cells that show reciprocating movement. Scale bar: 20 µm. (c) Schematic diagram of LifeAct-KCs cultured on a microporous membrane. Observation at the level of cell entry into the micropores. (d) Time-lapse images of LifeAct-KCs at the level of cell entry into 3.0-µm micropores. Representative images are shown at 5-minute intervals. Time stamp shows hour:minute. Arrowheads indicate the cells that show reciprocating movement. Scale bar: 20 µm. (e, f) Time-lapse images and schematic diagrams of LifeAct-KCs at the level of cell entry into 3.0-µm (e) or 8.0-µm (f) micropores. Representative images are shown at 2-minute intervals. Time stamp shows hour:minute. Scale bar: 10 µm. (g–i) Quantification of reciprocal movement of LifeAct-KCs on 3.0-µm or 8.0-µm micropores. (g) LifeAct signals (white) are shown as a spectrogram, where the X-axis represents each pore, and the Y-axis represents time. (h) Graphs comparing the number of pores presenting the LifeAct signals within 3.0-µm or 8.0-µm micropores per time. The left panel shows oscillation time as the X-axis and the number of pores as the Y-axis. The right panel shows unidirectional movement of the cells (no oscillation within 30 minutes) within each micropore. (i, j) E-cad and Vim labeling of LifeAct-KCs at the level of cells above (i) or within (j) 3.0-µm or 8.0-µm micropores. Autofluorescence of micropores is shown in blue (j). Scale bar: 10 µm.

Chemical treatment on KC entry into and exit from 3.0-µm micropores

(a,b) Quantification of LifeAct-KCs present within 3.0-µm micropores 6 hours after cell seeding. Cells were treated with TGF-β ligand (a) or TGF-β receptor inhibitors, SB431542, and SB525334 (b). (c, d) Quantification of LifeAct-KCs present below 3.0-µm micropores 24 hours after cell seeding. Cells were treated with TGF-β ligand (c) or TGF-b receptor inhibitors (d). (e, f) Quantification of LifeAct-KCs present within 3.0-µm micropores 6 hours after cell seeding. Cells were treated with cytochalasin D (e) or blebbistatin (f). (g, h) Quantification of LifeAct-KCs present below 3.0-µm micropores 24 hours after cell seeding. Cells were treated with cytochalasin D (g) or blebbistatin (h). Two-tailed Mann–Whitney U tests (a, c, e–h) and Kruskal–Wallis tests followed by Dunn’s multiple comparison test (b, d) were performed. * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.

Regulatory role of Piezo1 and KRT6 on KC entry to and exit from 3.0- µm micropores

(a,b) Quantification of ruthenium red–treated LifeAct-KCs present within 3.0 µm micropores at 6 hours (a) and the cells present below 3.0-µm micropores 24 hours after cell seeding (b). (c, d) Quantification of Piezo1 KO LifeAct-KCs present within 3.0 µm micropores at 6 hours (c) and the cells present below 3.0-µm micropores 24 hours after cell seeding (d). (e, f) Quantification of Yoda1-treated LifeAct-KCs present within 3.0-µm micropores at 6 hours (e) and the cells present below 3.0-µm micropores 24 hours after cell seeding (f). (g) Schematic diagram of bulk RNA-seq comparing HaCaT KCs cultured on a 0.4-µm- or 3.0-µm-pored membrane. The magenta dashed rectangles indicate the cells compared in the bulk RNA-seq. (h) Heatmap of differentially expressed genes identified by the bulk RNA-seq. (i) Gene ontology biological process terms enriched in upregulated and downregulated genes. (j) Heatmap of differentially expressed keratin genes in HaCaT KCs cultured on a 0.4-µm- or 3.0 µm-pored membrane. (k) Keratin 6 (KRT6) labeling of normal human epidermal KCs cultured on a 0.4-µm- or 3.0-µm-pored membrane for 14 days. Scale bar: 20 µm. (l, m) Quantification of pan-KRT6 KO LifeAct-KCs present within 3.0-µm micropores at 6 hours (l) and the cells present below 3.0-µm micropores 24 hours after cell seeding (m). Two-tailed Mann–Whitney U tests (a–f) and Kruskal–Wallis tests followed by Dunn’s multiple comparison test (l, m) were performed. * p < 0.05; ** p < 0.01; **** p < 0.0001.

Primers used in qRT-PCR