title: Mammary epithelial-mesenchymal interaction regulates fibronectin alternative splicing via phosphatidylinositol 3-kinase.
abstract: The way alternative splicing is regulated within tissues is not understood. A relevant model of this process is provided by fibronectin, an important extracellular matrix protein that plays a key role in cell adhesion and migration and contains three alternatively spliced regions known as EDI, EDII, and IIICS. We used a cell culture system to simulate mammary epithelial-stromal communication, a process that is crucial for patterning and function of the mammary gland, and studied the effects of extracellular signals on the regulation of fibronectin pre-mRNA alternative splicing. We found that soluble factors from a mammary mesenchymal cell-conditioned medium, as well as the growth factors HGF/SF (hepatocyte growth factor/scatter factor), KGF (keratinocyte growth factor), and aFGF (acidic fibroblast growth factor), stimulate EDI and IIICS but not EDII inclusion into fibronectin mRNA in the mammary epithelial cell line SCp2, favoring fibronectin isoforms associated with proliferation, migration, and tissue remodeling. We explored the signaling pathways involved in this regulation and found that the mammary mesenchymal cell-conditioned medium and HGF/SF act through a phosphatidylinositol 3-kinase-dependent cascade to alter fibronectin alternative splicing. This splicing regulation is independent from promoter structure and de novo protein synthesis but does require two exonic elements within EDI. These results shed light on how extracellular stimuli are converted into changes in splicing patterns.
authors.affiliation: Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II (C1428EHA) Buenos Aires, Argentina.
authors.forename: Matías
authors.initials: M
authors.lastname: Blaustein
authors.forename: Federico
authors.initials: F
authors.lastname: Pelisch
authors.forename: Omar A
authors.initials: OA
authors.lastname: Coso
authors.forename: Mina J
authors.initials: MJ
authors.lastname: Bissell
authors.forename: Alberto R
authors.initials: AR
authors.lastname: Kornblihtt
authors.forename: Anabella
authors.initials: A
authors.lastname: Srebrow
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects / Q000235:genetics*; D000818:Animals; D018920:Coculture Techniques; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D005091:Exons; D005260:Female; D005353:Fibronectins / Q000235:genetics*; D006133:Growth Substances / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000166:cytology*; D008648:Mesoderm / Q000166:cytology / Q000502:physiology*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D005353:Fibronectins; D006133:Growth Substances; D011994:Recombinant Proteins; D019869:Phosphatidylinositol 3-Kinases