Osmolyte transporter expression is reduced in photoaged human skin: implications for skin hydration in aging

April Foster, Cecile El Chami, Catherine O'Neill, Rachel Watson

Research output: Contribution to journalArticlepeer-review


Aging is characterized by the deterioration of tissue structure and function. In skin, environmental factors, e.g. ultraviolet radiation (UVR), can accelerate the effects of aging such as decline in barrier function and subsequent loss of hydration. Water homeostasis is vital for all cellular functions and it is known that organic osmolyte transport is critical to this process. Therefore, we hypothesized that as we age, these tightly controlled physiological mechanisms
become disrupted, possibly due to loss of transporter expression. We investigated this in vivo, using human skin samples from photoprotected and photoexposed sites of young and aged volunteers. We show a reduction in keratinocyte cell size with age and a downregulation of osmolyte transporters SMIT and TAUT with both chronic and acute UVR exposure. Single cell live imaging demonstrated that aged keratinocytes lack efficient cell volume recovery
mechanisms possessed by young keratinocytes following physiological stress. However, addition of exogenous taurine significantly rescued cell volume; this was corroborated by a reduction in TAUT mRNA and protein in aged, as compared to young, keratinocytes. Collectively, these novel data demonstrate that human epidermal keratinocytes possess osmolyte-mediated cell volume regulatory mechanisms, which may be compromised in ageing. Therefore, this suggests that organic osmolytes - especially taurine - play a critical role
in cutaneous age-related xerosis and highlights a fundamental mechanism, vital to our understanding of the pathophysiology of skin aging.
Original languageEnglish
JournalAging cell
Publication statusPublished - 26 Jan 2020


  • ageing
  • accelerated aging
  • human


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