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Ulrich Warskulat, Stefanie Brookmann, Andrea Reinen, Dieter Hussinger

Ultraviolet B radiation induces cell shrinkage and increases osmolyte transporter mRNA expression and osmolyte uptake in HaCaT keratinocytes

Keywords: betaine, cell volume, keratinocytes, myo-inositol, osmolytes, taurine, ultraviolet radiation

We have previously shown that compatible organic osmolytes, such as betaine, myoinositol and taurine, are part of the stress response of normal human keratinocytes (NHKs) to ultraviolet B (UVB) radiation. In this regard, we now tested human HaCaT keratinocytes as a surrogate cell line for NHK. HaCaT cells osmo-dependently express mRNA specific for transport proteins for betaine (BGT-1), myo-inositol (SMIT) and taurine (TAUT). Compared to normoosmotic (305 mosmol/l) controls, which strongly constitutively expressed BGT-1 mRNA, strong induction of SMIT and TAUT mRNA as well as low induction of BGT-1 mRNA expression was observed between 3 and 9 hours after hyperosmotic exposure (405 mosmol/l). This expression correlated with an increased osmolyte uptake. Conversely, hypoosmotic (205 mosmol/l) stimulation led to a significant efflux of osmolytes. Exposure to ultraviolet B (290-315 nm) radiation induced cell shrinkage which was followed by an upregulation of osmolyte transporter mRNA levels and osmolyte uptake.

These results demonstrate that human HaCaT keratinocytes possess an osmolyte strategy including UVB induced cell shrinkage and following increased osmolyte uptake. However, several differences in osmolyte transporter expression and uptake were noted between NHK and HaCaT cells, indicating that the use of HaCaT cells as a surrogate cell line for NHK has limitations.

Biological Chemistry, Walter de Gruyter

Print ISSN: 1431-6730
Volume: 2007
Pages: -

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