Dentin Phosphoprotein Binds Annexin 2 and Is Involved in Calcium Transport in Rat Kidney Ureteric Bud Cells

Alvares, Keith; Stern, Paula H.; Veis, Arthur

doi:10.1074/jbc.m112.389627

Cited by 7 publications

(6 citation statements)

References 48 publications

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“…DSPP is an evolutionary younger member of the acidic secretory calcium-binding phosphoprotein gene family (7). The two major DSPP cleaved functional units, DSP and DPP, are highly acidic, with human DPP presenting a very low isoelectric point of 2.84 and high calcium affinity (7,8). It is therefore conceivable that DSPP serves as a buffer protein in ER calcium homeostasis with a similar functional role to other calcium-dependent proteins: Calnexin, calreticulin and GRP78 (64).…”

Section: Discussionmentioning

confidence: 99%

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The tumorigenic role of DSPP and its potential regulation of the unfolded protein response and ER stress in oral cancer cells

et al. 2018

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Dentin sialophosphoprotein (DSPP) is upregulated in various human cancers, including head and neck squamous cell carcinoma. Cancer cells are commonly found under constant endoplasmic reticulum (ER) stress and exhibit increased levels of misfolded proteins, due to gene mutations and a stressful microenvironment. The present study examined the effects of DSPP silencing on the regulation of ER stress and the unfolded protein response (UPR) in oral cancer cells. A recently established stable DSPP short hairpin (sh)RNA-silenced OSC2 oral cancer cell line was used. The mRNA expression levels of ER stress-associated proteins, including 78 kDa glucose-regulated protein (GRP78), sarcoplasmic/endoplasmic reticulum calcium ATPase 2b (SERCA2b), inositol 1,4,5-trisphosphate receptor (IP3r), protein kinase R-like endoplasmic reticulum kinase (PERK), serine/threonine-protein kinase/endoribonuclease IRE1 (IRE1), activating transcription factor 6 (ATF6) and matrix metalloproteinase 20 (MMP20), were assessed by reverse transcription-quantitative polymerase chain reaction. The expression levels of apoptosis-related [B‑cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax) and cytochrome c] and cell proliferation-related [proliferating cell nuclear antigen (PCNA)] proteins were analyzed by western blotting. Cell viability, apoptosis and migration were monitored by MTT assay, Annexin V-fluorescein isothiocyanate flow cytometry and wound-healing assay, respectively. In transiently transfected puromycin‑free OSC2 cells, DSPP silencing markedly downregulated the mRNA expression levels of major ER stress regulators, including GRP78, SERCA2b, PERK, IRE1 and ATF6, as well as MMP20. DSPP silencing also resulted in decreased cell viability and migration, and enhanced apoptosis. Furthermore, PCNA and Bcl2 levels were decreased, whereas Bax and cytochrome c protein levels were increased in DSPP-silenced OSC2 cells. Sustained puromycin treatment partially counteracted the effects of DSPP silencing on the mRNA expression levels of ER stress-related proteins and MMP20, and on the migratory capacity of OSC2 cells. However, following puromycin treatment of DSPP-silenced cells, cell viability was further reduced and apoptosis was enhanced. In conclusion, these data provide evidence to suggest that DSPP may be involved in ER stress mechanisms in oral squamous cell carcinoma, since its downregulation in OSC2 cells led to significant alterations in the levels of major ER stress-associated proteins, and subsequent collapse of the UPR system.

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Section: Discussionmentioning

confidence: 99%

“…DSP occupies the N-terminal domain and presents a Cys205 (the only cysteine in DSPP) domain (6,7). C-terminal DPP possesses 165 Asp-Ser-Ser sequence motifs, has a low isoelectric point of 2.84 and exhibits high calcium affinity (7,8). The short DGP fragment is sandwiched between the N-terminal DSP and the C-terminal DPP.…”

Section: Introductionmentioning

confidence: 99%

The tumorigenic role of DSPP and its potential regulation of the unfolded protein response and ER stress in oral cancer cells

et al. 2018

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“…Delay in the maturation of the nephrons was reflected by overall smaller size of the metanephros and less polarized epithelial layers in the nephrons (50). More recently we have shown that in the rat ureteric bud cell line, DPP is localized on the cell membrane where it is associated with annexin 2 (51). When these cells were treated with anti-DPP antibodies the influx of calcium into the cells was reduced by 40%, implying that in non-mineralizing tissues, DPP may play a role in calcium transport (51).…”

Section: Introductionmentioning

confidence: 99%

The role of acidic phosphoproteins in biomineralization

Alvares

2014

Connective Tissue Research

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Biomineralization is the process by which living organisms deposit mineral in the extracellular matrix. In nature, almost 50% of biominerals are calcium-bearing minerals. In addition to calcium, we also find biominerals formed from silica and magnetite. Calcium containing biominerals could be either calcium phosphate as in apatite found in vertebrates or calcium carbonate as in calcite and aragonite found in many invertebrates. Since all biomineralization is matrix mediated, an understanding of the nature of the proteins involved is essential in elucidating its mechanism. This review will discuss some of the proteins involved in the process of biomineralization involving calcium. Two proteins, dentin matrix protein 1 and dentin phosphoprotein (Phosphophoryn) will serve as models for the vertebrate system, and two others - P16 and phosphodontin will serve as models for the invertebrate system.

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“…The Dspp gene is known to be primarily expressed in odontoblasts and, to a lesser extent, in osteoblasts [7] , [8] . Dspp is also expressed in other tissues such as the salivary glands, lungs, and kidneys [9] – [11] . Functional analyses in genetically altered mouse models mainly elucidated the function of DSPP as an inducer of mineralization in the extracellular matrix [12] – [14] .…”

Section: Introductionmentioning

confidence: 99%

Adhesive and Migratory Effects of Phosphophoryn Are Modulated by Flanking Peptides of the Integrin Binding Motif

et al. 2014

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Phosphophoryn (PP) is generated from the proteolytic cleavage of dentin sialophosphoprotein (DSPP). Gene duplications in the ancestor dentin matrix protein-1 (DMP-1) genomic sequence created the DSPP gene in toothed animals. PP and DMP-1 are phosphorylated extracellular matrix proteins that belong to the family of small integrin-binding ligand N-linked glycoproteins (SIBLINGs). Many SIBLING members have been shown to evoke various cell responses through the integrin-binding Arg-Gly-Asp (RGD) domain; however, the RGD-dependent function of PP is not yet fully understood. We demonstrated that recombinant PP did not exhibit any obvious cell adhesion ability, whereas the simultaneously purified recombinant DMP-1 did. A cell adhesion inhibitory analysis was performed by pre-incubating human osteosarcoma MG63 cells with various PP peptides before seeding onto vitronectin. The results obtained revealed that the incorporation of more than one amino acid on both sides of the PP-RGD domain was unable to inhibit the adhesion of MG63 cells onto vitronectin. Furthermore, the inhibitory activity of a peptide containing the PP-RGD domain with an open carboxyl-terminal side (H-463SDESDTNSESANESGSRGDA482-OH) was more potent than that of a peptide containing the RGD domain with an open amino-terminal side (H-478SRGDASYTSDESSDDDNDSDSH499-OH). This phenomenon was supported by the potent cell adhesion and migration abilities of the recombinant truncated PP, which terminated with Ala482. Furthermore, various point mutations in Ala482 and/or Ser483 converted recombinant PP into cell-adhesive proteins. Therefore, we concluded that the Ala482-Ser483 flanking sequence, which was detected in primates and mice, was the key peptide bond that allowed the PP-RGD domain to be sequestered. The differential abilities of PP and DMP-1 to act on integrin imply that DSPP was duplicated from DMP-1 to serve as a crucial extracellular protein for tooth development rather than as an integrin-mediated signaling molecule.

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Dentin Phosphoprotein Binds Annexin 2 and Is Involved in Calcium Transport in Rat Kidney Ureteric Bud Cells

Cited by 7 publications

References 48 publications

The tumorigenic role of DSPP and its potential regulation of the unfolded protein response and ER stress in oral cancer cells

The tumorigenic role of DSPP and its potential regulation of the unfolded protein response and ER stress in oral cancer cells

The role of acidic phosphoproteins in biomineralization

Adhesive and Migratory Effects of Phosphophoryn Are Modulated by Flanking Peptides of the Integrin Binding Motif

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