Table 1.
Localization, regulation and physiological roles of human/rodent skin aquaporins.
| AQP | Permeability | Skin Layer, Cell Type and Subcellular Location | Agents/Conditions Regulating the Expression/Trafficking of the AQP | Suggested Roles in the Skin |
|---|---|---|---|---|
| AQP1 | Water, hydrogen peroxide | Keratinocytes (ED) | Undefined | Creation of hydraulic pressure for cell migration |
| Melanocytes (ED; SB) | Hypertonic stress ↑ (?) | Growth of melanocyte dendrites (?); melanosome transfer to keratinocytes (?) | ||
| Fibroblast (D) | Hypertonic stress ↑ | Cellular response to hypertonic stress (?) | ||
| Vascular endothelial cells (D, HD) | Undefined | Water exchange blood-dermis (skin hydration) | ||
| AQP3 | Water, glycerol, urea, hydrogen peroxide, ammonia |
Keratinocytes (ED; SB: PM and IC; SS: PM and IC; SG: PM) | HDAC3 ↓; p73 ↑; PPARγ ↑; LXR, RAR, RXR ↑; VD3 ↓; * high levels of extracellular Ca2+ ↓↑; osmotic stress (translocation to PM↑); circadian rhythm |
Keratinocyte early differentiation **; keratinocyte proliferation and migration during wound healing; skin hydration (circadian rhythm); maintenance of epidermal water permeability barrier |
| Dermal-resident T cells (PM) | Hapten-induced skin contact | Chemokine-dependent T cell migration in skin hypersensitivity to haptens | ||
| AQP5 | Water, hydrogen peroxide | Sweat glands: secretory cells (APM, BPM); excretory duct cells (APM) | Muscarinic agonists | Sweat secretion |
| AQP7 | Water, glycerol | Langherans cells (ED); Dermal dendritic cells (D) | Undefined | Cell migration, antigen uptake, immune surveillance |
| AQP9 | Water, glycerol, hydrogen peroxide, ammonia | Keratinocytes (ED; upper SG) | VD3 ↑ | Keratinocyte late differentiation; transcellular route for glycerol and urea movement (?) |
| AQP10 | Water, glycerol | Keratinocytes (ED; SC) | Undefined | Barrier function |
BPM, basolateral plasma membrane; D, dermis; ED, epidermis; HD, hypodermis; SB, stratum basale; SG, stratum granulosum; SS, stratum spinosum; SC, stratum corneum; PM, plasma membrane; APM, apical plasma membrane; IC, intracellular; VD3, 1,25-dihydroxyvitamin D3. *, decrease of non-glycosylated AQP3 and increase of glycosylated AQP3. **, controversial results in the literature. ↑, increase in AQP3 mRNA/protein expression or protein translocation to PM. ↓, decrease in AQP3 mRNA/protein expression.