Cloning and characterization of the human osteopontin gene and its promoter

Abstract

We isolated the human osteopontin (hOP) gene and the 5' upstream region, and analysed its exon-intron structure and potential regulatory sequences of the promoter region in comparison with those of the mouse and porcine gene. The coding sequence is split into 7 exons which are similar to those of the mouse gene, although the hOP gene is longer than the mouse gene. The difference in length is mainly due to variations in intron 3, which is approximately 2.7-fold longer than that of the mouse OP gene. The 5' upstream region of the hOP, which is highly conserved up to nucleotide -250, contains a number of potential cis regulatory consensus sequences. A series of sequentially 5'-deleted chimeric clones was tested for the ability to stimulate chloramphenicol acetyltransferase (CAT). Initial CAT analysis demonstrated that nucleotides at positions -474 to -270, -124 to -80, and -55 to -39 contained cis-acting enhancing sequences in a human monocyte cell line, SCC-3, although the -124 to -80 region was much more active than other regions. Deletion of the sequences between -474 and -270 localized this cis region to the sequence at positions -439 to -410, whereas the deletion between -124 to -80 localized the regions to -124 to -115, and -94 to -80. Gel-shift analysis using as probes synthesized double-stranded DNA corresponding to the 10 and 15 bp region at positions -124 to -115 and -94 to -80 respectively revealed that each probe formed a major band complexed with nuclear proteins prepared from SCC-3 cells.

Osteopontin Induces Ubiquitin-Dependent Degradation of STAT1 in RAW264.7 Murine Macrophages

“…Constitutive expression of OPN exists in several cell types but induced expression is detected in T lymphocytes, epidermal cells, bone cells, macrophages, and tumor cells in remodeling processes such as inflammation, ischemia-reperfusion, bone resorption, and tumor progression (33,37,38). A variety of stimuli, including PMA, 1,25-dihydroxyvitamin D, basic fibroblast growth factor, TNF-␣, IL-1, IFN-␥, and LPS, appears to up-regulate OPN expression (33,37,38,42). OPN has multiple molecular functions that mediate cell adhesion, chemotaxis, macrophage-directed IL-10 suppression, stress-dependent angiogenesis, prevention of apoptosis, and anchorage-independent growth of tumor cells (33,37,38,42).…”

“…A variety of stimuli, including PMA, 1,25-dihydroxyvitamin D, basic fibroblast growth factor, TNF-␣, IL-1, IFN-␥, and LPS, appears to up-regulate OPN expression (33,37,38,42). OPN has multiple molecular functions that mediate cell adhesion, chemotaxis, macrophage-directed IL-10 suppression, stress-dependent angiogenesis, prevention of apoptosis, and anchorage-independent growth of tumor cells (33,37,38,42). With regard to our findings, we define OPN to be a unique and as yet, poorly characterized, transactivator of STAT1 degradation by the Ub-proteasome system in LPS treated macrophages.…”

Pre- and post-translational regulation of osteopontin in cancer

“…Full length OPN pre-mRNA consists of 7 exons (Rodrigues et al 2007) while OPN-b lacks exon 5 and OPN-c lacks exon 4 (Hijiya et al 1994;Kiefer et al 1989;Saitoh et al 1995;Young et al 1990) (Fig. 1).…”

Elevation of osteopontin levels in brain tumor cells reduces burden and promotes survival through the inhibition of cell dispersal

“…It is constitutively secreted in diverse tissues and inducible in T-lymphocytes, epidermal cells, bone, macrophages and tumor cells of various origins [11,16,23,36]. Multiple cellular functions are influenced by OPN including apoptosis, cellular proliferation, angiogenesis and cell migration within a pro-survival paradigm leading to the hypothesis that OPN expression represents a generalized cellular response to stress [13,21].…”