fibulin-1; FIBL-1 (FBLN1)

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Function

incorporated into fibronectin-containing matrix fibers
may play a role in cell adhesion & migration along protein fibers within the extracellular matrix
may have role in developmental processes & in supramolecular organization of extracellular matrix architecture, especially basement membranes
role in cellular transformation & tumor invasion
- appears to be a tumor suppressor
may play a role in haemostasis & thrombosis owing to its ability to bind fibrinogen & incorporate into clots.
possible role in modulating neurotrophic activities of APP, particularly soluble APP
homomultimerizes & interacts with various extracellular matrix components such as FN1, LAMA1, LAMA2, NID, ACAN, CSPG2 & type 4 collagen
interacts also APP, NOV, FGB & HPV type 16, HPV type 18, HPV type 31 & BPV type 1 E6 proteins
interacts with FBLN7 (putative)

named isoforms=4; A,B,C,D

isoform A & isoform B are only expressed in placenta
isoform C & isoform D are expressed in a variety of tissues & cultured cells
widely expressed during embryonic development
prominent in the matrix of the leptomeninges, in basement membranes of the neuroepithelium & the perineurium of peripheral nerves
in embryos of gestational week 4, staining was observed in the early mesenchymal bone anlagen
in gestational week 4 6.5 & 8, all perichondrial structures showed expression
- chondrocytes themselves showed no staining
in gestational week 10, expression is prominent in the interterritorial matrix surrounding the hypertrophic chondrocytes
induced expression increased by estrogen in ovarian cancer cells

chromosomal translocation t(12;22)(p11.2;q13.3) involving FBLN1 with RASSF8 is found in a complex type of synpolydactyly associated with metacarpal & metatarsal synostoses
- the t(12;22)(p11.2;q13.3) translocation may result in haploinsufficiency of the isoform D splice variant, which could lead to the observed limb malformation
elevated expression & altered processing of FBLN1 protein is associated with breast cancer