Limits...
TGF-beta induces the expression of SAP30L, a novel nuclear protein.

Lindfors K, Viiri KM, Niittynen M, Heinonen TY, Mäki M, Kainulainen H - BMC Genomics (2003)

Bottom Line: Differential display analysis resulted in the identification of a novel TGF-beta upregulated mRNA species, the Sin3-associated protein 30-like, SAP30L.The mRNA is expressed in several human tissues and codes for a nuclear protein of 183 amino acids 70% identical with Sin3 associated protein 30 (SAP30).The predicted nuclear localization signal of SAP30L is sufficient for nuclear transport of the protein although mutating it does not completely remove SAP30L from the nuclei.

View Article: PubMed Central - HTML - PubMed

Affiliation: Paediatric Research Centre, Tampere University Hospital, Tampere, Finland. katri.lindfors@uta.fi

ABSTRACT

Background: We have previously set up an in vitro mesenchymal-epithelial cell co-culture model which mimics the intestinal crypt villus axis biology in terms of epithelial cell differentiation. In this model the fibroblast-induced epithelial cell differentiation from secretory crypt cells to absorptive enterocytes is mediated via transforming growth factor-beta (TGF-beta), the major inhibitory regulator of epithelial cell proliferation known to induce differentiation in intestinal epithelial cells. The aim of this study was to identify novel genes whose products would play a role in this TGF-beta-induced differentiation.

Results: Differential display analysis resulted in the identification of a novel TGF-beta upregulated mRNA species, the Sin3-associated protein 30-like, SAP30L. The mRNA is expressed in several human tissues and codes for a nuclear protein of 183 amino acids 70% identical with Sin3 associated protein 30 (SAP30). The predicted nuclear localization signal of SAP30L is sufficient for nuclear transport of the protein although mutating it does not completely remove SAP30L from the nuclei. In the nuclei SAP30L concentrates in small bodies which were shown by immunohistochemistry to colocalize with PML bodies only partially.

Conclusions: By reason of its nuclear localization and close homology to SAP30 we believe that SAP30L might have a role in recruiting the Sin3-histone deacetylase complex to specific corepressor complexes in response to TGF-beta, leading to the silencing of proliferation-driving genes in the differentiating intestinal epithelial cells.

Show MeSH

Related in: MedlinePlus

Transfection of the different EGFP fusion constructs to IMR-90 fibroblasts. A) The wild-type SAP30L concentrates in small dense bodies in the nuclei. B) The nuclear localization of the fusion protein with only the NLS of SAP30L provides evidence for the functionality of the nuclear localization signal. C) Mutating the NLS disrupts the nuclear localization of the protein to some extent. D) Anti-PML-antibody staining (red) of wild-type SAP30L-transfected cells shows that the nuclear concentrates are other than PML bodies.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC319701&req=5

Figure 5: Transfection of the different EGFP fusion constructs to IMR-90 fibroblasts. A) The wild-type SAP30L concentrates in small dense bodies in the nuclei. B) The nuclear localization of the fusion protein with only the NLS of SAP30L provides evidence for the functionality of the nuclear localization signal. C) Mutating the NLS disrupts the nuclear localization of the protein to some extent. D) Anti-PML-antibody staining (red) of wild-type SAP30L-transfected cells shows that the nuclear concentrates are other than PML bodies.

Mentions: In transient transfection experiments on IMR-90 fibroblasts we were able to show that the wild-type SAP30L-EGFP fusion protein is indeed nuclear and concentrates in small dense bodies (Figure 5a). The transfection of the EGFP fusion protein, which had only the putative nuclear localization and six flanking amino acids on either side (pEGFP-NLS), also resulted in the nuclear localization of the protein (Figure 5b), thus providing evidence for the functionality of the signal. Mutation in the nuclear localization signal (NLS) (KRKRK → KSNRK) disturbed this nuclear localization to some extent, causing the protein to be visible also in the cytosol although it did not completely inhibit the protein's nuclear transport (Figure 5c). Immunocytochemical staining of these transfected cells with anti-promyelotocytic leukaemia (PML) antibody showed these nuclear structures to be other than PML bodies (Figure 5d).


TGF-beta induces the expression of SAP30L, a novel nuclear protein.

Lindfors K, Viiri KM, Niittynen M, Heinonen TY, Mäki M, Kainulainen H - BMC Genomics (2003)

Transfection of the different EGFP fusion constructs to IMR-90 fibroblasts. A) The wild-type SAP30L concentrates in small dense bodies in the nuclei. B) The nuclear localization of the fusion protein with only the NLS of SAP30L provides evidence for the functionality of the nuclear localization signal. C) Mutating the NLS disrupts the nuclear localization of the protein to some extent. D) Anti-PML-antibody staining (red) of wild-type SAP30L-transfected cells shows that the nuclear concentrates are other than PML bodies.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC319701&req=5

Figure 5: Transfection of the different EGFP fusion constructs to IMR-90 fibroblasts. A) The wild-type SAP30L concentrates in small dense bodies in the nuclei. B) The nuclear localization of the fusion protein with only the NLS of SAP30L provides evidence for the functionality of the nuclear localization signal. C) Mutating the NLS disrupts the nuclear localization of the protein to some extent. D) Anti-PML-antibody staining (red) of wild-type SAP30L-transfected cells shows that the nuclear concentrates are other than PML bodies.
Mentions: In transient transfection experiments on IMR-90 fibroblasts we were able to show that the wild-type SAP30L-EGFP fusion protein is indeed nuclear and concentrates in small dense bodies (Figure 5a). The transfection of the EGFP fusion protein, which had only the putative nuclear localization and six flanking amino acids on either side (pEGFP-NLS), also resulted in the nuclear localization of the protein (Figure 5b), thus providing evidence for the functionality of the signal. Mutation in the nuclear localization signal (NLS) (KRKRK → KSNRK) disturbed this nuclear localization to some extent, causing the protein to be visible also in the cytosol although it did not completely inhibit the protein's nuclear transport (Figure 5c). Immunocytochemical staining of these transfected cells with anti-promyelotocytic leukaemia (PML) antibody showed these nuclear structures to be other than PML bodies (Figure 5d).

Bottom Line: Differential display analysis resulted in the identification of a novel TGF-beta upregulated mRNA species, the Sin3-associated protein 30-like, SAP30L.The mRNA is expressed in several human tissues and codes for a nuclear protein of 183 amino acids 70% identical with Sin3 associated protein 30 (SAP30).The predicted nuclear localization signal of SAP30L is sufficient for nuclear transport of the protein although mutating it does not completely remove SAP30L from the nuclei.

View Article: PubMed Central - HTML - PubMed

Affiliation: Paediatric Research Centre, Tampere University Hospital, Tampere, Finland. katri.lindfors@uta.fi

ABSTRACT

Background: We have previously set up an in vitro mesenchymal-epithelial cell co-culture model which mimics the intestinal crypt villus axis biology in terms of epithelial cell differentiation. In this model the fibroblast-induced epithelial cell differentiation from secretory crypt cells to absorptive enterocytes is mediated via transforming growth factor-beta (TGF-beta), the major inhibitory regulator of epithelial cell proliferation known to induce differentiation in intestinal epithelial cells. The aim of this study was to identify novel genes whose products would play a role in this TGF-beta-induced differentiation.

Results: Differential display analysis resulted in the identification of a novel TGF-beta upregulated mRNA species, the Sin3-associated protein 30-like, SAP30L. The mRNA is expressed in several human tissues and codes for a nuclear protein of 183 amino acids 70% identical with Sin3 associated protein 30 (SAP30). The predicted nuclear localization signal of SAP30L is sufficient for nuclear transport of the protein although mutating it does not completely remove SAP30L from the nuclei. In the nuclei SAP30L concentrates in small bodies which were shown by immunohistochemistry to colocalize with PML bodies only partially.

Conclusions: By reason of its nuclear localization and close homology to SAP30 we believe that SAP30L might have a role in recruiting the Sin3-histone deacetylase complex to specific corepressor complexes in response to TGF-beta, leading to the silencing of proliferation-driving genes in the differentiating intestinal epithelial cells.

Show MeSH
Related in: MedlinePlus