Context-specific Effects of Fibulin-5 (DANCE/EVEC) on Cell Proliferation, Motility, and Invasion

Abstract

The Fibulin gene family comprises five distinct genes that encode more than eight protein products via alternative splicing. Fibulins are widely expressed secretory proteins found in the blood and in the basement membranes and stroma of most tissues, where they self-associate (e.g. Fibulins 1 and 2) (1, 2) and/or interact with a variety of extracellular matrix components, including fibronectin, laminin, nidogen, aggrecan, versican, endostatin, and elastin (3-5). Thus, Fibulins likely participate in the assembly and stabilization of extracellular matrix structures; they also have been implicated in regulating organogenesis, vasculogenesis, fibrogenesis, and tumorigenesis (6 -8). Although the molecular mechanisms underlying the various biological activities of Fibulins remain to be elucidated, recent work suggests that Fibulins may interact directly with cell surface receptors, raising the possibility that these secretory proteins also function in mediating cell-cell and cell-matrix communication.The newest member of the Fibulin family is Fibulin-5 (FBLN-5; also known as EVEC (9) or DANCE (10)), 1 a 448-amino acid glycoprotein with interesting structural features; it contains an integrin-binding RGD motif, six calcium-binding epidermal growth factor-like repeats, a Pro-rich insert in the first calcium-binding epidermal growth factor-like repeat, and a globular C-terminal domain (9, 10). Functionally, FBLN-5 binds ␣ v ␤ 3 , ␣ v ␤ 5 , and ␣ 9 ␤ 1 integrins (4) and mediates endothelial cell adhesion via its RGD motif (10). In response to mechanical injury, FBLN-5 expression is induced dramatically in vascular endothelial and smooth muscle cells (9, 10), suggesting that FBLN-5 regulates vasculogenesis and endothelial cell function. Inactivation of the FBLN-5 gene in mice produces profound elastinopathy in the skin, lung, and vasculature (4, 5), demonstrating its importance in scaffolding cells to elastic fibers.Despite these recent advances, many questions regarding the role of FBLN-5 in mammalian biology remain to be answered, particularly (i) what are the signaling systems/molecules that regulate (ii) what are the effects of FBLN-5 on cell proliferation, migration, and invasion, and (iii) what are the signaling systems/molecules stimulated by FBLN-5. Through the use of expression proteomics, we show here that FBLN-5 is a novel TGF-␤-inducible protein that

Fibulins 3 and 5 Antagonize Tumor Angiogenesis In vivo

“…The resulting PCR fragment was ligated into pcDNA3.1/Myc-His B vector (Invitrogen, Carlsbad, CA) at HindIII (NH 2 terminus) and EcoRI (COOH terminus) restriction sites, which appended Myc and (His) 6 tags to the COOH terminus of FBLN-3. Afterward, the tagged FBLN-3 cDNA was PCR amplified using oligonucleotides containing BglII (NH 2 terminus) and XhoI (COOH terminus) restriction sites and ligated into identical sites in pMSCV-IRES-GFP (7). All FBLN-3 cDNA constructs were sequenced on an Applied Biosystems 377A DNA sequencing machine.…”

“…A key component of physiologic tissue development and repair is angiogenesis (3), which when left unchecked can promote the pathogenicity of diabetic retinopathy, arthritis, macular degeneration, endometriosis, inflammation, and cancer (4)(5)(6). We independently identified FBLN-5 as a novel gene target of the tumor suppressor, transforming growth factor-h, and showed that (a) FBLN-5 regulates normal and cancer cell proliferation, migration, and invasion in a cell-and context-specific manner (7,8); (b) tumorigenesis down-regulates FBLN-5 expression in metastatic human tumors (7); and (c) FBLN-5 antagonizes vascular endothelial growth factor (VEGF) signaling in and angiogenic sprouting by endothelial cells in vitro (8). Thus, FBLN-5 may suppress tumor formation and progression in part by antagonizing angiogenesis.…”

Altered vascular remodeling in fibulin-5-deficient mice reveals a role of fibulin-5 in smooth muscle cell proliferation and migration

“…Previous studies (38) showed fbln-5 increased cell proliferation of HT1080 fibrosarcoma cells synergistically with TGB-␤1, and enhanced fibronectin-induced HT1080 migration and invasion). Fbln-5 has also been shown to bind integrins (␣V␤3, ␣V␤5, and ␣9␤1) in vitro and to mediate cell attachment in an RGD motif-dependent manner in endothelial cells (10,39).…”

Genomic profiling identifies alterations in TGFβ signaling through loss of TGFβ receptor expression in human renal cell carcinogenesis and progression

“…Fibulin-5 is a recently discovered TGFb-regulated gene, which has tumor suppressor activity. Fibulin-5 is an ECM protein that is believed to signal through interaction with integrins (Schiemann et al, 2002). CTGF is a secreted protein involved in angiogenesis, skeletogenesis, and wound healing.…”