Studies of the DMP1 57-kDa functional domain both in vivo and in vitro

Yongbo Lu, Chunlin Qin, Yixia Xie, Lynda Bonewald, Jian Q. Feng

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Dmp1-null mice and patients with mutations in dentin matrix protein 1 (DMP1) resulting in autosomal recessive hypophosphatemic rickets display similar skeletal defects. As mutations were observed in the last 18 amino acids of DMP1 in 1 subset of patients and as fragments of intact DMP1, a 37-kDa N-terminal and a 57-kDa C-terminal fragment, have been purified from bone and dentin, we hypothesized that the cleaved 57-kDa C-terminal fragment is the essential functional domain of DMP1. To test this hypothesis, different forms of recombinant DMP1 were expressed in 293EBNA, CHO and 2T3 cells. The results showed that DMP1 was processed into a 37-kDa N-terminal and a 57-kDa C-terminal fragment in vitro in all cell lines examined. DMP1 processing in CHO cells was blocked by a furin protease inhibitor, decanoyl-Arg-Val-Lys-Arg-chloromethyl ketone, in a dose-dependent manner. Coexpression of PHEX, a potential upstream protease, had no apparent effect on DMP1 cleavage in 293EBNA cells, suggesting that PHEX may not be required for DMP1 processing. To test the in vivo role of the C-terminal fragment, transgenic mice overexpressing full-length DMP1 or the 57-kDa fragment controlled by the 3.6-kb Col1 promoter were generated. Overexpression of these transgenes had no effect on the wild-type skeleton, but on the Dmp1-null background showed expression in the osteoblast layer and throughout the bone matrix leading to the rescue of the null bone phenotype. This suggests that the 57-kDa C-terminal fragment may be able to recapitulate the function of intact DMP1 in vivo.

Original languageEnglish (US)
Pages (from-to)175-185
Number of pages11
JournalCells Tissues Organs
Volume189
Issue number1-4
DOIs
StatePublished - Dec 2008
Externally publishedYes

Fingerprint

Dentin
Proteins
CHO Cells
In Vitro Techniques
Hypophosphatemic Rickets
Furin
Bone and Bones
Mutation
Bone Matrix
Protease Inhibitors
Osteoblasts
Transgenes
Skeleton
Transgenic Mice
Peptide Hydrolases
Phenotype
Amino Acids
Cell Line

Keywords

  • DMP1
  • Furin-like proprotein convertase
  • PHEX
  • Transgenic mice

ASJC Scopus subject areas

  • Anatomy
  • Histology

Cite this

Studies of the DMP1 57-kDa functional domain both in vivo and in vitro. / Lu, Yongbo; Qin, Chunlin; Xie, Yixia; Bonewald, Lynda; Feng, Jian Q.

In: Cells Tissues Organs, Vol. 189, No. 1-4, 12.2008, p. 175-185.

Research output: Contribution to journalArticle

Lu, Yongbo ; Qin, Chunlin ; Xie, Yixia ; Bonewald, Lynda ; Feng, Jian Q. / Studies of the DMP1 57-kDa functional domain both in vivo and in vitro. In: Cells Tissues Organs. 2008 ; Vol. 189, No. 1-4. pp. 175-185.
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