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Transcriptional regulation induced by cAMP elevation in mouse Schwann cells.

Schmid D, Zeis T, Schaeren-Wiemers N - ASN Neuro (2014)

Bottom Line: One of the strongest differentially regulated gene transcripts was the transcription factor Olig1 (oligodendrocyte transcription factor 1), whose mRNA expression levels were reduced in treated Schwann cells.Olig1 protein was localized in myelinating and nonmyelinating Schwann cells within the sciatic nerve as well as in primary Schwann cells, proposing it as a novel transcription factor of the Schwann cell lineage.Data analysis further revealed that a number of differentially expressed genes in forskolin-treated Schwann cells were associated with the ECM (extracellular matrix), underlining its importance during Schwann cell differentiation in vitro.

View Article: PubMed Central - PubMed

Affiliation: *Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland.

ABSTRACT
In peripheral nerves, Schwann cell development is regulated by a variety of signals. Some of the aspects of Schwann cell differentiation can be reproduced in vitro in response to forskolin, an adenylyl cyclase activator elevating intracellular cAMP levels. Herein, the effect of forskolin treatment was investigated by a comprehensive genome-wide expression study on primary mouse Schwann cell cultures. Additional to myelin-related genes, many so far unconsidered genes were ascertained to be modulated by forskolin. One of the strongest differentially regulated gene transcripts was the transcription factor Olig1 (oligodendrocyte transcription factor 1), whose mRNA expression levels were reduced in treated Schwann cells. Olig1 protein was localized in myelinating and nonmyelinating Schwann cells within the sciatic nerve as well as in primary Schwann cells, proposing it as a novel transcription factor of the Schwann cell lineage. Data analysis further revealed that a number of differentially expressed genes in forskolin-treated Schwann cells were associated with the ECM (extracellular matrix), underlining its importance during Schwann cell differentiation in vitro. Comparison of samples derived from postnatal sciatic nerves and from both treated and untreated Schwann cell cultures showed considerable differences in gene expression between in vivo and in vitro, allowing us to separate Schwann cell autonomous from tissue-related changes. The whole data set of the cell culture microarray study is provided to offer an interactive search tool for genes of interest.

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Effect of forskolin treatment on mRNA expression levels of known                            components of the ECM in Schwann cells                        (A) Data analysis of the microarray was performed by a two-way ANOVA, and                            unadjusted P-values <0.01 were accounted as                            significant. Forskolin had a regulatory effect on the majority of                            investigated ECM-associated genes. n.s.: not significant. (B) Schematic                            illustration of components of the ECM and the basal lamina in Schwann                            cells. The effect of forskolin on gene expression of selected genes                            associated with the ECM and the basal lamina (red line) was shown by                            blue (reduced), red (increased) or green (unaltered) arrows.
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Figure 4: Effect of forskolin treatment on mRNA expression levels of known components of the ECM in Schwann cells (A) Data analysis of the microarray was performed by a two-way ANOVA, and unadjusted P-values <0.01 were accounted as significant. Forskolin had a regulatory effect on the majority of investigated ECM-associated genes. n.s.: not significant. (B) Schematic illustration of components of the ECM and the basal lamina in Schwann cells. The effect of forskolin on gene expression of selected genes associated with the ECM and the basal lamina (red line) was shown by blue (reduced), red (increased) or green (unaltered) arrows.

Mentions: To determine the effect of elevated cAMP levels by forskolin on transcriptional regulation of components of the ECM and the basal lamina, a list of selected genes associated with the ECM was compiled and schematic illustrated (Figure 4). Most of the investigated components of the basal lamina showed differentially expressed mRNA expression levels upon forskolin treatment of cultured Schwann cells. One of the strongest reductions could be detected for α-dystrobrevin (Dtna), a member of the DGC (dystrophin–glycoprotein complex). Furthermore, the transcription of syntrophin acidic 1 (Snta1), also a component of this complex, was significantly reduced upon forskolin treatment, although expression levels of the other syntrophin isoforms were not changed. The DGC is linked to the basal lamina by interaction with agrin (Agrn), whose mRNA expression levels were also reduced in treated Schwann cells, or with laminin. A reduced expression was identified for laminin γ2 (Lamc2), whereas increased expression levels were detected for laminin α1, α2 (Lama1, Lama2) and laminin γ1 (Lamc1) upon treatment. Investigation of the laminin receptor integrin manifested that forskolin treatment reduced the transcription of integrins such as the integrin α1, α2, α5, β1 and β5 (Itga1, Itga2, Itga5, Itgb1 and Itgb5) in primary mouse Schwann cells. In contrast, forskolin treatment induced the transcription of integrin β4 and β8 (Itgb4 and Itgb8), in agreement with a study reporting elevated integrin β4 expression during development and upon forskolin treatment in rat Schwann cells (Feltri et al., 1994). Collagen fibers are another major component of the ECM. Elevation of cAMP levels by forskolin resulted in induced transcription of collagen type II α1 (Col2a1), in line with a previous report on rat Schwann cells (D’Antonio et al., 2006), and collagen type IV α2 (Col4a2). Forskolin treatment led to reduced transcription of collagen type IV α5 (Col4a5), collagen type V α2 (Col5a2) and of collagen type VI α3 (Col6a3). Additional analysis of basal lamina components revealed significantly increased mRNA expression levels of nidogen1 (entactin, Nid1), nidogen2 (entactin 2, Nid2) and of the proteoglycan perlecan (Hspg2).


Transcriptional regulation induced by cAMP elevation in mouse Schwann cells.

Schmid D, Zeis T, Schaeren-Wiemers N - ASN Neuro (2014)

Effect of forskolin treatment on mRNA expression levels of known                            components of the ECM in Schwann cells                        (A) Data analysis of the microarray was performed by a two-way ANOVA, and                            unadjusted P-values <0.01 were accounted as                            significant. Forskolin had a regulatory effect on the majority of                            investigated ECM-associated genes. n.s.: not significant. (B) Schematic                            illustration of components of the ECM and the basal lamina in Schwann                            cells. The effect of forskolin on gene expression of selected genes                            associated with the ECM and the basal lamina (red line) was shown by                            blue (reduced), red (increased) or green (unaltered) arrows.
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Figure 4: Effect of forskolin treatment on mRNA expression levels of known components of the ECM in Schwann cells (A) Data analysis of the microarray was performed by a two-way ANOVA, and unadjusted P-values <0.01 were accounted as significant. Forskolin had a regulatory effect on the majority of investigated ECM-associated genes. n.s.: not significant. (B) Schematic illustration of components of the ECM and the basal lamina in Schwann cells. The effect of forskolin on gene expression of selected genes associated with the ECM and the basal lamina (red line) was shown by blue (reduced), red (increased) or green (unaltered) arrows.
Mentions: To determine the effect of elevated cAMP levels by forskolin on transcriptional regulation of components of the ECM and the basal lamina, a list of selected genes associated with the ECM was compiled and schematic illustrated (Figure 4). Most of the investigated components of the basal lamina showed differentially expressed mRNA expression levels upon forskolin treatment of cultured Schwann cells. One of the strongest reductions could be detected for α-dystrobrevin (Dtna), a member of the DGC (dystrophin–glycoprotein complex). Furthermore, the transcription of syntrophin acidic 1 (Snta1), also a component of this complex, was significantly reduced upon forskolin treatment, although expression levels of the other syntrophin isoforms were not changed. The DGC is linked to the basal lamina by interaction with agrin (Agrn), whose mRNA expression levels were also reduced in treated Schwann cells, or with laminin. A reduced expression was identified for laminin γ2 (Lamc2), whereas increased expression levels were detected for laminin α1, α2 (Lama1, Lama2) and laminin γ1 (Lamc1) upon treatment. Investigation of the laminin receptor integrin manifested that forskolin treatment reduced the transcription of integrins such as the integrin α1, α2, α5, β1 and β5 (Itga1, Itga2, Itga5, Itgb1 and Itgb5) in primary mouse Schwann cells. In contrast, forskolin treatment induced the transcription of integrin β4 and β8 (Itgb4 and Itgb8), in agreement with a study reporting elevated integrin β4 expression during development and upon forskolin treatment in rat Schwann cells (Feltri et al., 1994). Collagen fibers are another major component of the ECM. Elevation of cAMP levels by forskolin resulted in induced transcription of collagen type II α1 (Col2a1), in line with a previous report on rat Schwann cells (D’Antonio et al., 2006), and collagen type IV α2 (Col4a2). Forskolin treatment led to reduced transcription of collagen type IV α5 (Col4a5), collagen type V α2 (Col5a2) and of collagen type VI α3 (Col6a3). Additional analysis of basal lamina components revealed significantly increased mRNA expression levels of nidogen1 (entactin, Nid1), nidogen2 (entactin 2, Nid2) and of the proteoglycan perlecan (Hspg2).

Bottom Line: One of the strongest differentially regulated gene transcripts was the transcription factor Olig1 (oligodendrocyte transcription factor 1), whose mRNA expression levels were reduced in treated Schwann cells.Olig1 protein was localized in myelinating and nonmyelinating Schwann cells within the sciatic nerve as well as in primary Schwann cells, proposing it as a novel transcription factor of the Schwann cell lineage.Data analysis further revealed that a number of differentially expressed genes in forskolin-treated Schwann cells were associated with the ECM (extracellular matrix), underlining its importance during Schwann cell differentiation in vitro.

View Article: PubMed Central - PubMed

Affiliation: *Neurobiology, Department of Biomedicine, University Hospital Basel, University of Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland.

ABSTRACT
In peripheral nerves, Schwann cell development is regulated by a variety of signals. Some of the aspects of Schwann cell differentiation can be reproduced in vitro in response to forskolin, an adenylyl cyclase activator elevating intracellular cAMP levels. Herein, the effect of forskolin treatment was investigated by a comprehensive genome-wide expression study on primary mouse Schwann cell cultures. Additional to myelin-related genes, many so far unconsidered genes were ascertained to be modulated by forskolin. One of the strongest differentially regulated gene transcripts was the transcription factor Olig1 (oligodendrocyte transcription factor 1), whose mRNA expression levels were reduced in treated Schwann cells. Olig1 protein was localized in myelinating and nonmyelinating Schwann cells within the sciatic nerve as well as in primary Schwann cells, proposing it as a novel transcription factor of the Schwann cell lineage. Data analysis further revealed that a number of differentially expressed genes in forskolin-treated Schwann cells were associated with the ECM (extracellular matrix), underlining its importance during Schwann cell differentiation in vitro. Comparison of samples derived from postnatal sciatic nerves and from both treated and untreated Schwann cell cultures showed considerable differences in gene expression between in vivo and in vitro, allowing us to separate Schwann cell autonomous from tissue-related changes. The whole data set of the cell culture microarray study is provided to offer an interactive search tool for genes of interest.

Show MeSH