title: Protein phosphatase-1 is involved in the maintenance of normal homeostasis and in UVA irradiation-induced pathological alterations in HaCaT cells and in mouse skin.
abstract: The number of ultraviolet (UV) radiation-induced skin diseases such as melanomas is on the rise. The altered behavior of keratinocytes is often coupled with signaling events in which Ser/Thr specific protein kinases and phosphatases regulate various cellular functions. In the present study the role of protein phosphatase-1 (PP1) was investigated in the response of human keratinocyte (HaCaT) cells and mouse skin to UV radiation. PP1 catalytic subunit (PP1c) isoforms, PP1cα/γ and PP1cδ, are all localized to the cytoskeleton and cytosol of keratinocytes, but PP1cδ was found to be dominant over PP1α/γ in the nucleus. PP1c-silencing in HaCaT cells decreased the phosphatase activity and suppressed the viability of the cells. Exposure to a 10 J/cm(2) UVA dose induced HaCaT cell death and resulted in a 30% decrease of phosphatase activity. PP1c-silencing and UVA irradiation altered the gene expression profile of HaCaT cells and suggested that the expression of 19 genes was regulated by the combined treatments with many of these genes being involved in malignant transformation. Microarray analysis detected altered expression levels of genes coding for melanoma-associated proteins such as keratin 1/10, calcium binding protein S100A8 and histone 1b. Treatment of Balb/c mice with the PP1-specific inhibitor tautomycin (TM) exhibited increased levels of keratin 1/10 and S100A8, and a decreased level of histone 1b proteins following UVA irradiation. Moreover, TM treatment increased pigmentation of the skin which was even more apparent when TM was followed by UVA irradiation. Our data identify PP1 as a regulator of the normal homeostasis of keratinocytes and the UV-response.
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Dedinszki
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Adrienn
authors.initials: A
authors.lastname: Sipos
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kiss
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Róbert
authors.initials: R
authors.lastname: Bátori
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Kónya
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary; MTA-DE Cell Biology and Signaling Research Group, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Virág
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary; MTA-DE Cell Biology and Signaling Research Group, University of Debrecen, Debrecen H-4032, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Erdődi
authors.affiliation: Department of Medical Chemistry, University of Debrecen, Debrecen H-4032, Hungary. Electronic address: lontay@med.unideb.hu.
authors.forename: Beáta
authors.initials: B
authors.lastname: Lontay
mesh_terms: D000818:Animals; D020134:Catalytic Domain; D002460:Cell Line; D020868:Gene Silencing; D006706:Homeostasis; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D054645:Protein Phosphatase 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011859:Radiography; D012867:Skin / Q000000981:diagnostic imaging* / Q000201:enzymology / Q000473:pathology; D014466:Ultraviolet Rays
chemical_list: D054645:Protein Phosphatase 1
keywords: Gene expression; Histone 1b; Keratin 1/10; Keratinocyte; Protein phosphatase-1; UV irradiation