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- Björntorp, Elisabeth, et al.
(författare)
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The helix-loop-helix transcription factor Id1 is highly expressed in psoriatic involved skin.
- 2003
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Ingår i: Acta dermato-venereologica. - : Medical Journals Sweden AB. - 0001-5555. ; 83:6, s. 403-9
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Tidskriftsartikel (refereegranskat)abstract
- The helix-loop-helix transcription factor Id1 (inhibitor of differentiation/inhibitor of DNA binding) functions as an inhibitor of differentiation. We have examined Id1 gene expression in cultured keratinocytes in punch biopsies from psoriatic involved and uninvolved skin, and in skin specimens from normal individuals. Id1 mRNA expression was measured with an RNase protection assay and with Northern blot. Id1 immunoreactivity was determined in skin biopsies by immunofluorescence using a polyclonal antibody directed against the Id1 protein. In cultured keratinocytes, the expression of Id1 mRNA was strongest in small cells with high proliferative potential, whereas in large cells, which are terminally differentiated, the expression was low. Expression of the Id1 mRNA in psoriatic involved skin (n = 9) was significantly elevated compared to uninvolved skin from the same patient (n = 5) and to skin from normal controls (n = 9). Id1 immunoreactivity was intranuclear throughout all the layers in psoriatic involved epidermis, except in the stratum corneum, while no immunoreactivity was detected in uninvolved epidermis. In normal controls, cytoplasmatic Id1 immunoreactivity was detected in the basal layer in epidermis obtained from newborns, while no immunoreactivity was detected in epidermis obtained from the adults in the control group. We conclude that Id1 is expressed in cells with high proliferative potential, and is downregulated in cells that undergo terminal differentiation. Along with the overexpression of the Id1 gene in psoriatic involved skin, these observations suggest that Id1 is involved in the process of differentiation of keratinocytes seen in normal skin and that the Id1 pathway is activated in psoriasis.
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| 2. |
- Björntorp Mark, Elisabeth, 1964, et al.
(författare)
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Expression of genes involved in the regulation of p16 in psoriatic involved skin
- 2006
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Ingår i: Arch Dermatol Res. - : Springer Science and Business Media LLC. - 0340-3696. ; 297:10, s. 459-67
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that the up-regulation of the tumour suppressor p16 gene and induction of senescence protect the phenotype of psoriatic involved skin from malignant transformation. On the other hand, Id1, which is inversely correlated with p16 has been shown to be up-regulated in psoriatic involved skin. To test the hypothesis that there may be an altered regulation of p16 in psoriatic involved skin, we have measured genes involved in the Igf-1 receptor signalling through the Ras/MAPK cascade. Igf-1R, IGFBP3, hRas, Ets2, JunB, Egr-1, Id1, MIDA1 and p16 gene expressions were measured using quantitative real-time PCR in total RNA isolated from punch biopsies from psoriatic involved (n = 9) and uninvolved skin (n = 9) and from cutaneous squamous cell cancer (SCC) involved (n = 8) and uninvolved skin (n = 8). The IGFBP3, hRas, JunB, Egr-1, Id1 and MIDA1 genes were up-regulated in psoriatic involved skin compared with uninvolved skin. The p16, JunB and MIDA1 genes were up-regulated in SCC involved skin compared with uninvolved skin. Our results indicate that there may be a balance between the proliferation and induction of senescence in psoriasis. This balance may vary and the psoriatic involved skin represented in this study appears to be in a proliferative state rather than senescence. Furthermore, we suggest that the noted up-regulation of JunB, which has been shown to up-regulate p16, in combination with the previously reported elevation of p16 expression in psoriatic involved skin, may indicate activation of a pathway by which JunB may protect the psoriatic plaque by inducing p16 in an event of malignant stress.
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| 3. |
- Björntorp Mark, Elisabeth, 1964
(författare)
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Keratinocyte differentiation. Involvement of the growth hormon (GH)/insulinlike growth factor1 (IGFI) axis and IGF1 post receptor signaling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- At cellular level, little is known about the genes that regulate keratinocyte differentiation andproliferation. Psoriasis is regarded as a T-cell mediated inflammatory disease with hyperproliferativekeratinocytes. The aim of this thesis was to investigate whether the growth hormone(GH)/insulin like growth factor-1 (IGF-1) axis and IGF-1 post receptor signaling were affected inthe differentiation process of normal keratinocytes and the abnormalities seen in psoriasis. Weexplored the extracellular parameters of the GH/IGF-1 axis and one downstream target of IGF-1receptor signaling, the helix-loop-helix (HLH) protein Id1.In paper I, serum concentrations of IGF-1, IGF-binding protein-3, GH-binding protein and GHurine concentration were measured by immunoassays. GH receptor (GHR) gene expression insuction-blister roofs was measured using an RNase protection assay (RPA) or quantitative reversetranscriptase/polymerase chain reaction (RT-PCR). Our data demonstrated that normal epidermisexpressed GHRs. However, no significant difference between psoriatic patients and normal controlswas detected concerning the parameters studied.In paper II, Id1 gene expression in cultured keratinocytes and punch biopsies from normaland psoriatic involved and uninvolved skin was measured by RPA or Northern blot. Id1immunoreactivity was determined by immunofluorescence or Western blot. We found elevatedId1 expression in cells with high proliferative potential, which was downregulated in terminal differentiatedcells. Furthermore, the expression of Id1 in psoriatic involved skin was significantlyelevated compared with uninvolved skin and normal controls. The results indicated that Id1 maybe involved in the process of keratinocyte differentiation seen in normal skin and that the Id1pathway is activated in psoriatic involved skin. Furthermore, the results suggested that Id1 is likelyto have a specific dimerization partner in the skin. In paper III, we therefore searched for additionalunknown members of the HLH family by using the bioinformatics tools provided by the NCBI forhomology searches. This resulted in the cloning of a fourth member of the human achaete-scutecomplex family of genes, Hash4, which was mainly expressed in fetal skin. The function of Hash4remains to be clarified.The objectives of paper IV were to test the hypothesis that an altered regulation of the tumorsuppressor gene p16 in psoriasis was involved in a relative resistance of psoriatic plaque to transformationinto squamous cell cancer. To address this question, expression of genes involved in theIGF-1 receptor signaling through the Ras-Raf-MEK-ERK cascade were measured using real-timePCR, since candidates in this pathway are associated with the regulation of both Id1 and p16. Theresult showed that several genes in this pathway including JunB, which is an inducer of p16, wereupregulated in psoriatic involved skin. The results indicated activation of a pathway that mayprotect the keratinocytes by inducing p16 in an event of malignant stress.The results of this thesis indicate perturbation of genes involved in IGF-1 receptor signaling inpsoriatic involved skin. However, they do not support a major role for the systemic parameters of theGH/IGF-1 axis. Furthermore, the results indicate that Id1 is involved in the process of keratinocytedifferentiation seen in normal skin.
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