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Secreted PhosphoProtein 24 kDa (SPP24)
 A Bone Matrix Protein

Secreted Phosphoprotein 24 kD (Spp24) and Spp14 Affect TGF-β Induced Bone Formation Differently

Transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMPs) have opposing but complementary functions in directing bone growth, repair, and turnover. Both are found in the bone matrix. Proteins that bind to and affect the activity of these growth factors will determine the relative abundance of the growth factors and, therefore, regulate bone formation. Secreted phosphoprotein 24 kD (Spp24) is a bone matrix protein that has been demonstrated to bind to and affect the activity of BMPs. The arginine-rich carboxy terminus of Spp24 is proteolytically processed to produce three other predictable truncation products (Spp18.1, Spp16.0, and Spp14.5). In this work, we report that kinetic data obtained by surface plasmon resonance demonstrate that Spp24 and the three C-terminal truncation products all bind to TGF-β1 and TGF-β2 with a similar but somewhat less affinity than they bind BMP-2; that, as in the case of BMP-2, the full-length (FL) form of Spp24 binds TGF-β with greater affinity than do the truncation products; that FL-Spp24 inhibits TGF-β2 induced bone formation in vivo, but Spp14.5 does not; and that co-administration of FL-Spp24 or Spp14.5 with TGF-β2 in vivo is associated with a reduction in the amount of cartilage, relative to new bone, present at the site of injection. This finding is consistent with the observation that low-dose TGF-β administration in vivo is associated with greater bone formation than high-dose TGF-β administration, and suggests that one function of Spp24 and its truncation products is to down-regulate local TGF-β activity or availability during bone growth and development. The similarities and differences of the interactions between Spp24 proteins and TGF-β compared to the interaction of the Spp24 proteins and BMPs have significant implications with respect to the regulation of bone metabolism and with respect to engineering therapeuticproteins for skeletal disorders.
Tian H., et al. PLoS One. 2013 Aug 26;8(8):e72645. doi: 10.1371/journal.pone.0072645.

Effects of the bone morphogenetic protein binding protein spp24 (secreted phosphoprotein 24 kD) on the growth of human lung cancer cells

Bone morphogenetic proteins (BMPs) and transforming growth factor-beta (TGF-β) contribute to the growth of some skeletal metastases through autocrine stimulation. Secreted phosphoprotein 24 kDa (spp24) has been shown to bind to both BMP-2 and TGF-β and to markedly inhibit the osteogenic properties of rhBMP-2. We hypothesized that the addition of spp24 would sequester autocrine growth factors (especially BMP-2) and reduce tumor growth in a system (A549 human non-small cell lung cancer cell line) where autocrine stimulation by BMP-2 is known to be important. A549 cells were injected into two sites (subcutaneous and intraosseus) in SCID mice with and without the co-injection of BMP-2 and spp24. Tumor growth after 8 weeks was assessed through gross examination, radiological imaging, and histological analysis. Spp24 attenuated the tumor growth enhancing effects of rhBMP-2 and reduced the tumor growth when added to tumor cells that were not treated with BMP-2. We conclude that spp24 can reduce A549 cell tumor growth in both soft tissue and intraosseus environments. We hypothesize that the mechanism for this inhibition is interruption of autocrine stimulation through the sequestration of BMP-2. Spp24 can be developed into a therapeutic agent that can be employed in clinical situations where the inhibitions of BMPs and related proteins is advantageous.
Lee KB., et al. J Orthop Res. 2011 Nov;29(11):1712-8.

Secreted Phosphoprotein 24 KDa (SPP24) (Human) Recombinant
Code No.: 00240-01-100
Size: 100 ug
Price: $290.00 USD
Protein ID:Q13103
Gene ID: 6694
MW: 24 KD
Tag: His Tag on N-Terminus
Expressed: E. Coli
Purity: 95%
Data Sheet: PDF
  Anti Secreted Phosphoprotein 24 KDa (SPP24) (Human) IgG
Code No.: A00240-01-100
Size: 100ug
Price: $350.00 USD
Host: rabbit
Antigen: human SPP24 Rec.
Target Protein ID:Q13103
Traget Gene ID: 6694
Target MW: 24 KD
Antibody Type: Polyclonal IgG
Purification: Protein A affinity
Application: E., IHC
Data Sheet: PDF
Code No.
Price ($)
Secreted Phosphoprotein 24 KDa (SPP24) (Human), Rec.
50 ug
Secreted Phosphoprotein 24 KDa (SPP24) (Human), Rec.
100 ug
Secreted Phosphoprotein 24 KDa (SPP24) (Human), Rec.
1000 ug
Anti Secreted Phosphoprotein 24 KDa (SPP24) (Human) IgG A00240-01-100 100 ug 350.00