title: Ultraviolet B radiation induces cell shrinkage and increases osmolyte transporter mRNA expression and osmolyte uptake in HaCaT keratinocytes.
abstract: We have previously shown that compatible organic osmolytes, such as betaine, myo-inositol and taurine, are part of the stress response of normal human keratinocytes (NHKs) to ultraviolet B (UVB) radiation. In this regard, we 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 h 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 UVB (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.
authors.affiliation: Department of Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany. warskulat@med.uni-duesseldorf.de
authors.forename: Ulrich
authors.initials: U
authors.lastname: Warskulat
authors.forename: Stefanie
authors.initials: S
authors.lastname: Brookmann
authors.forename: Andrea
authors.initials: A
authors.lastname: Reinen
authors.forename: Dieter
authors.initials: D
authors.lastname: Häussinger
mesh_terms: D001622:Betaine / Q000378:metabolism; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D048429:Cell Size / Q000528:radiation effects*; D050485:GABA Plasma Membrane Transport Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007294:Inositol / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000235:genetics; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D027981:Symporters / Q000096:biosynthesis / Q000235:genetics; D013654:Taurine / Q000378:metabolism; D014466:Ultraviolet Rays; D014867:Water / Q000378:metabolism; D000099247:Taurine Transporters
chemical_list: D001622:Betaine; D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; D006360:Heat-Shock Proteins; D007294:Inositol; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D027981:Symporters; D013654:Taurine; D014867:Water; D000099247:Taurine Transporters; C072207:betaine plasma membrane transport proteins; C073884:SLC5A3 protein, human