title: Transforming Growth Factor Beta 1 Modulates the Functional Expression of the Neurokinin-1 Receptor in Human Keratocytes.
abstract: Transforming growth factor beta 1 (TGF-β1) is a cytokine involved in a variety of processes, such as differentiation of fibroblasts into myofibroblasts. TGF-β1 has also been shown to delay the internalization of the neurokinin-1 receptor (NK-1 R) after its activation by its ligand, the neuropeptide substance P (SP). NK-1 R comprises two naturally occurring variants, a full-length and a truncated form, triggering different cellular responses. SP has been shown to affect important events in the cornea - such as stimulating epithelial cell proliferation - processes that are involved in corneal wound healing and thus in maintaining the transparency of the corneal stroma. An impaired signaling through NK-1 R could thus impact the visual quality. We hypothesize that TGF-β1 modulates the expression pattern of NK-1 R in human corneal stroma cells, keratocytes. The purpose of this study was to test that hypothesis.
  
  
  
  Cultures of primary keratocytes were set up with cells derived from healthy human corneas, obtained from donated transplantation graft leftovers, and characterized by immunocytochemistry and Western blot. Immunocytochemistry for TGF-β receptors and NK-1 R was performed. Gene expression was assessed with real-time polymerase chain reaction (qPCR).
  
  
  
  Expression of TGF-β receptors was confirmed in keratocytes in vitro. Treating the cells with TGF-β1 significantly reduced the gene expression of NK-1 R. Furthermore, immunocytochemistry for NK-1 R demonstrated that it is specifically the expression of the full-length isotype of the receptor that is reduced after treatment with TGF-β1, which was also confirmed with qPCR using a specific probe for the full-length receptor.
  
  
  
  TGF-β1 down-regulates the gene expression of the full-length variant of NK-1 R in human keratocytes, which might impact its signaling pathway and thus explain the known delay in internalization after activation by SP seen with TGF-β1 treatment.
authors.affiliation: a Department of Integrative Medical Biology , Umeå University , Umeå , Sweden.
authors.forename: Sandrine Le
authors.initials: SL
authors.lastname: Roux
authors.affiliation: a Department of Integrative Medical Biology , Umeå University , Umeå , Sweden.
authors.forename: Gabor
authors.initials: G
authors.lastname: Borbely
authors.affiliation: a Department of Integrative Medical Biology , Umeå University , Umeå , Sweden.|b Department of Clinical Sciences, Ophthalmology , Umeå University , Umeå , Sweden.
authors.forename: Marta
authors.initials: M
authors.lastname: Słoniecka
authors.affiliation: a Department of Integrative Medical Biology , Umeå University , Umeå , Sweden.
authors.forename: Ludvig J
authors.initials: LJ
authors.lastname: Backman
authors.affiliation: a Department of Integrative Medical Biology , Umeå University , Umeå , Sweden.|b Department of Clinical Sciences, Ophthalmology , Umeå University , Umeå , Sweden.
authors.forename: Patrik
authors.initials: P
authors.lastname: Danielson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D060527:Corneal Keratocytes / Q000166:cytology / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012313:RNA / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018040:Receptors, Neurokinin-1; D053773:Transforming Growth Factor beta1; D012313:RNA
keywords: Cornea; cytokines; neuropeptides; stroma; substance P