1. The “Caveolae Brake Hypothesis” and the Epidermal Barrier
Truus Roelandt, Christina Giddelo, Carol Heughebaert, Geertrui Denecker, Melanie Hupe, Debra Crumrine, Andy Kusuma, Marek Haftek, Diane Roseeuw, Wim Declercq, Kenneth R. Feingold, Peter M. Elias, Jean-Pierre Hachem 
Journal of Investigative Dermatology 
Volume 129, Issue 4, Pages (April 2009)
DOI: /jid
Copyright © 2009 The Society for Investigative Dermatology, Inc Terms and Conditions

2. Figure 1
Epidermal barrier status regulates apical plasma membrane dynamics in hairless mice. Quantitative EM was used to assess changes in apical plasma membrane (APM) dynamics and the LB secretion density before (baseline) and following tape stripping-induced acute barrier abrogation (3hours). APM dynamics were assessed as the number (#) of invaginations at the stratum granulosum–(SG) stratum corneum (SC) interface as well as the length (L) and the diameter (D) of each APM invagination (a: scheme). Barrier abrogation provokes a decrease in the (b) no. of APM invaginations which become (d) larger and (e) wider in size, associated with a significant increase in (c) LB density secretion. Results are shown as mean±SEM; n≥4 for each group.
Journal of Investigative Dermatology  , DOI: ( /jid )
Copyright © 2009 The Society for Investigative Dermatology, Inc Terms and Conditions

3. Figure 2
Electron microscopy illustrating apical plasma membrane dynamics following barrier abrogation. Under basal conditions, before tape stripping (TS), apical plasma membrane (APM) invaginations (white arrows), corresponding to the lamellar bodies secretion (S) area, exhibit alternating large and small protrusions within the cytoplasm of the uppermost stratum granulosum (SG) cell. At 3hours following TS-induced barrier abrogation, APM invaginations decrease in number and consist dominantly of large protrusion. Magnification bar: 1μm.
Journal of Investigative Dermatology  , DOI: ( /jid )
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4. Figure 3
Apical plasma membrane dynamics are MβCD sensitive. Permeability barrier recovery was assessed at 3hours after tape stripping (TS)-induced barrier abrogation in hairless mice treated with either MβCD (1mgml−1 in propylene glycol:ethanol; 7:3 vol/vol) or vehicle (propylene glycol:ethanol) alone immediately after tape stripping. MβCD delayed barrier recovery (a) in hairless mice which paralleled a significant decrease in both the number (#) of apical plasma membrane (APM) invaginations at the (b) stratum granulosum– (SG) stratum corneum (SC) interface and (c) LB secretion density assessed by quantitative EM (illustrated in Figure 4). In addition, MβCD application produced a marked defect in APM dynamics by stretching the length (L) without affecting the diameter of the (d, e) APM invaginations. Results are shown as mean±SEM; n≥4 for each group.
Journal of Investigative Dermatology  , DOI: ( /jid )
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5. Figure 4
Electron microscopy micrographs illustrating the effects of MβCD on apical plasma membrane. Compared to vehicle treatment, application of MβCD following tape stripping (TS)-induced barrier abrogation provokes a flattening and a decrease in the number of apical plasma membrane (APM) invaginations at the SG/SC secretion area. Magnification bar: 1μm.
Journal of Investigative Dermatology  , DOI: ( /jid )
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6. Figure 5
Caveolin-1 regulates apical plasma membrane dynamics. Permeability barrier recovery was assessed in caveolin-1 (cav-1) knockout (cav-1−/-) and wild-type littermates (cav-1+/+) at 3hours after tape stripping-induced barrier abrogation. Absence of cav-1 in cav-1−/- animals accelerated (a) barrier recovery kinetics compared to the wild-type animals. APM dynamics were assessed by quantitative EM in both cav-1−/- and cav-1+/+ littermates 3hours after tape stripping. Although the no. of invaginations was identical between cav-1−/- and cav-1+/+ mice at the (b) stratum granulosum– (SG) stratum corneum (SC) interface, absence of cav-1 produced the formation of large APM invaginations (significant increase in both the length (L) and the diameter (D); (d, e) leading to a significant increase in (c) LB density secretion in cav-1−/- animals. Results are shown as mean±SEM; n≥4 for each group.
Journal of Investigative Dermatology  , DOI: ( /jid )
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7. Figure 6
Electron microscopy illustrating the consequences of Cav-1 absence on apical plasma membrane morphology. Giant areas of lamellar bodies secretion content (delineated by white dots) at the SG/SC interface are observed in cav-1−/- mice compared to wild-type littermates (cav-1+/+) 3hours following barrier abrogation. Magnification bar: 1μm.
Journal of Investigative Dermatology  , DOI: ( /jid )
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8. Figure 7
Caveolin-1 traffic regulates lipid raft formation. Lipid raft (LR) formation was assessed in situ by either the cholera toxin B assay (a–c) or filipin staining (b). Although tape stripping (TS)-induced barrier abrogation provokes a decrease in LR formation (a, b), LR persist in cav-1−/- mice compared to (d) cav-1+/+ littermates. Acute barrier abrogation in hairless mice provokes phosphorylated (P)-cav-1 translocation (but not the non-P form: cav-1) from the cytoplasmic to the LR domains following tape stripping. Application of monensin (M), which inhibits LB secretion, prevents P-cav-1 traffic following tape stripping. Western immunoblotting for β-actin shows equal sample loading for the cytoplasmic fraction. Scale bar: 10μm.
Journal of Investigative Dermatology  , DOI: ( /jid )
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9. Figure 8
Caveolin-1 insertion into the APM signals terminal differentiation. Terminal differentiation was assessed in cav-1−/- and cav-1+/+ littermates ±monensin application using (a) TUNEL staining and (c, d) caspase 14 (casp 14) western immunoblotting/immunohistochemistry. Absence of cav-1 in knockout animals or application of monensin (for both cav-1−/- and cav-1+/+) delays the tape stripping (TS)-induced wave of cornification (decrease in both (a) TUNEL-positive cells and (c, d) caspase 14 activation). Likewise, (b) PCNA-positive cells are significantly increased in cav-1−/- animals (before and following tape stripping) and/or after the application of monensin in both cav-1−/- and cav-1+/+. Results are shown as mean±SEM. Western immunoblotting for β-actin shows equal loading; n≥4 for each group.
Journal of Investigative Dermatology  , DOI: ( /jid )
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10. Figure 9
Persistence of LR formation in Cav-1−/- mice sensitizes murine epidermis to hyperplasia. Epidermal hyperplasia was experimentally induced in cav-1−/- and cav-1+/+ mice by twice daily tape stripping (TS) of the SC for 4 consecutive days. Epidermal thickness is significantly increased in cav-1−/- animals compared to cav-1+/+ littermates (illustrated in b and assessed in c) in parallel with persistence of (a) LR formation. Consistently, a significant decrease in (e) TUNEL positive cells and (f) caspase 14 (casp 14) activation and an increase in (d) PCNA-positive cells is observed in cav-1−/- vs cav-1+/+ littermates. Results are shown as mean±SEM; n≥4 for each group. Magnification bar: 10μm.
Journal of Investigative Dermatology  , DOI: ( /jid )
Copyright © 2009 The Society for Investigative Dermatology, Inc Terms and Conditions