title: Differential regulation of cell functions by CSD peptide subdomains.
abstract: BACKGROUND
  In fibrotic lung diseases, expression of caveolin-1 is decreased in fibroblasts and monocytes. The effects of this deficiency are reversed by treating cells or animals with the caveolin-1 scaffolding domain peptide (CSD, amino acids 82-101 of caveolin-1) which compensates for the lack of caveolin-1. Here we compare the function of CSD subdomains (Cav-A, Cav-B, Cav-C, Cav-AB, and Cav-BC) and mutated versions of CSD (F92A and T90A/T91A/F92A).
  
  
  METHODS
  Migration toward the chemokine CXCL12 and the associated expression of F-actin, CXCR4, and pSmad 2/3 were studied in monocytes from healthy donors and SSc patients. Fibrocyte differentiation was studied using PBMC from healthy donors and SSc patients. Collagen I secretion and signaling were studied in fibroblasts derived from the lung tissue of healthy subjects and SSc patients.
  
  
  RESULTS
  Cav-BC and CSD at concentrations as low as 0.01 μM inhibited the hypermigration of SSc monocytes and TGFβ-activated Normal monocytes and the differentiation into fibrocytes of SSc and Normal monocytes. While CSD also inhibited the migration of poorly migrating Normal monocytes, Cav-A (and other subdomains to a lesser extent) promoted the migration of Normal monocytes while inhibiting the hypermigration of TGFβ-activated Normal monocytes. The effects of versions of CSD on migration may be mediated in part via their effects on CXCR4, F-actin, and pSmad 2/3 expression. Cav-BC was as effective as CSD in inhibiting fibroblast collagen I and ASMA expression and MEK/ERK signaling. Cav-C and Cav-AB also inhibited collagen I expression, but in many cases did not affect ASMA or MEK/ERK. Cav-A increased collagen I expression in scleroderma lung fibroblasts. Full effects on fibroblasts of versions of CSD required 5 μM peptide.
  
  
  CONCLUSIONS
  Cav-BC retains most of the anti-fibrotic functions of CSD; Cav-A exhibits certain pro-fibrotic functions. Results obtained with subdomains and mutated versions of CSD further suggest that the critical functional residues in CSD depend on the cell type and readout being studied. Monocytes may be more sensitive to versions of CSD than fibroblasts and endothelial cells because the baseline level of caveolin-1 in monocytes is much lower than in these other cell types.
authors.affiliation: Department of Medicine/Division of Rheumatology and Immunology, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29425, USA. tourkine@musc.edu.
authors.forename: Charles
authors.initials: C
authors.lastname: Reese
authors.forename: Shanice
authors.initials: S
authors.lastname: Dyer
authors.forename: Beth
authors.initials: B
authors.lastname: Perry
authors.forename: Michael
authors.initials: M
authors.lastname: Bonner
authors.forename: James
authors.initials: J
authors.lastname: Oates
authors.forename: Ann
authors.initials: A
authors.lastname: Hofbauer
authors.forename: William
authors.initials: W
authors.lastname: Sessa
authors.forename: Pascal
authors.initials: P
authors.lastname: Bernatchez
authors.forename: Richard P
authors.initials: RP
authors.lastname: Visconti
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Corey M
authors.initials: CM
authors.lastname: Hatfield
authors.forename: Richard M
authors.initials: RM
authors.lastname: Silver
authors.forename: Stanley
authors.initials: S
authors.lastname: Hoffman
authors.forename: Elena
authors.initials: E
authors.lastname: Tourkina
mesh_terms: D000199:Actins / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D051242:Caveolin 1 / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D045170:Matrix Attachment Regions; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D017434:Protein Structure, Tertiary; D019718:Receptors, CXCR4 / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000378:metabolism* / Q000473:pathology; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D055815:Young Adult
chemical_list: D000199:Actins; C527276:CXCR4 protein, human; D051242:Caveolin 1; D019718:Receptors, CXCR4; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein