Fibroblast growth factor-2 (FGF-2) is expressed as high molecular weight (> 20 kDa, Hi-FGF-2), or low molecular weight, (18 kDa, Lo-FGF-2) isoforms with distinct functions in the heart and other tissues. Studies to-date have focused on Lo-FGF-2, while the biology of Hi-FGF-2 is less well understood. This work investigated potential autocrine and paracrine effects of rat and human Hi-FGF-2 on cardiac myocytes and non-myocytes (myofibroblasts).
Using rat ventricular myofibroblast cultures stimulated with angiotensin II (Ang II), in the absence or presence of YVAD, a peptide inhibitor of caspase-1, it was shown that caspase-1 activity was required for the Ang II-stimulated Hi-FGF-2 secretion. Secreted rat Hi-FGF-2 was shown to be biologically active and capable of stimulating neonatal as well as adult cardiomyocyte hypertrophy in vitro. The effect of extracellular-acting Hi- versus Lo-FGF-2 on the secretome profile of rat cardiac myofibroblasts was compared. Conditioned media collected after stimulation with rat Hi- or Lo-FGF-2 were analyzed by mass spectroscopy (LC-MS/MS). Secretome profiles suggested that Hi-FGF-2 was more potent than Lo-FGF-2 in upregulating several matricellular and fibrosis-associated proteins, most prominently periostin, follistatin-like protein 1, plasminogen activator inhibitor-1, and tenascin.
Human heart (atrial) tissue, pericardial fluid, and human heart-derived myofibroblasts were shown to accumulate predominantly Hi-FGF-2. Ang II up-regulated Hi-FGF-2 in human cells, via activation of: type 1 or type 2 Ang II receptors (AT-1R, AT-2R); the ERK pathway; and matrix metalloprotease-2. Neutralizing antibodies specific for Hi-FGF-2 (neu-AbHi-FGF-2) reduced expression of proteins associated with fibroblast-to-myofibroblast conversion and fibrosis. Blocking the autocrine action of Hi-FGF-2 on human cells with neu-AbHi-FGF-2 resulted in down-regulation of periostin, as well as α-smooth muscle actin, pro-collagen, embryonic smooth muscle myosin, and extra domain A fibronectin, consistent with a reversal from activated myofibroblast to fibroblast phenotype. Stimulation of human myofibroblasts with human Hi-FGF-2 was significantly more potent than Lo-FGF-2 in upregulating pro-interleukin-1β and plasminogen activator inhibitor-1, considered to be pro-inflammatory proteins.
It is concluded that exported, extracellular-acting Hi-FGF-2 has pro-fibrotic, pro-inflammatory, and pro-hypertrophic properties, contributes to the ‘activated fibroblast’ phenotype, and represents a therapeutic target for prevention of maladaptive cardiac remodeling in humans.
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/23867 |
| Date | 14 May 2014 |
| Creators | Santiago, Jon-Jon |
| Contributors | Kardami, Elissavet (Physiology), Dixon, Ian (Physiology) Zahradka, Peter (Physiology) Netticadan, Thomas (Physiology) Wigle, Jeff (Biochemistry & Medical Genetics) Anand-Srivastava, Madhu (University of Montreal) |
| Publisher | Oxford Journals, Open Access Scholarly Publishers Association |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
Page generated in 0.0018 seconds