PMID- 11499870
OWN - NLM
STAT- MEDLINE
DCOM- 20020130
LR  - 20131121
IS  - 0884-0431 (Print)
IS  - 0884-0431 (Linking)
VI  - 16
IP  - 8
DP  - 2001 Aug
TI  - Characterization of tissue transglutaminase in human osteoblast-like cells.
PG  - 1477-85
AB  - Tissue transglutaminase (tTG) is a calcium-dependent and guanosine 
      5'-triphosphate (GTP) binding enzyme, which catalyzes the post-translational 
      modification of proteins by forming intermolecular epsilon(gamma-glutamyl)lysine 
      cross-links. In this study, human osteoblasts (HOBs) isolated from femoral head 
      trabecular bone and two osteosarcoma cell lines (HOS and MG-63) were studied for 
      their expression and localization of tTG. Quantitative evaluation of 
      transglutaminase (TG) activity determined using the [1,4 14C]-putrescine 
      incorporation assay showed that the enzyme was active in all cell types. However, 
      there was a significantly higher activity in the cell homogenates of MG-63 cells 
      as compared with HOB and HOS cells (p < 0.001). There was no significant 
      difference between the activity of the enzyme in HOB and HOS cells. All three 
      cell types also have a small amount of active TG on their surface as determined 
      by the incorporation of biotinylated cadaverine into fibronectin. Cell 
      surface-related tTG was further shown by preincubation of cells with tTG 
      antibody, which led to inhibition of cell attachment. Western blot analysis 
      clearly indicated that the active TG was tTG and immunocytochemistry showed it be 
      situated in the cytosol of the cells. In situ extracellular enzyme activity also 
      was shown by the cell-mediated incorporation of fluorescein cadaverine into 
      extracellular matrix (ECM) proteins. These results clearly showed that MG-63 
      cells have high extracellular activity, which colocalized with the ECM protein 
      fibronectin and could be inhibited by the competitive primary amine substrate 
      putrescine. The contribution of tTG to cell surface/matrix interactions and to 
      the stabilization of the ECM of osteoblast cells therefore could by an important 
      factor in the cascade of events leading to bone differentiation and 
      mineralization.
FAU - Heath, D J
AU  - Heath DJ
AD  - School of Biomedical Sciences, Queen's Medical Center, University of Nottingham, 
      United Kingdom.
FAU - Downes, S
AU  - Downes S
FAU - Verderio, E
AU  - Verderio E
FAU - Griffin, M
AU  - Griffin M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Bone Miner Res
JT  - Journal of bone and mineral research : the official journal of the American 
      Society for Bone and Mineral Research
JID - 8610640
RN  - 0 (Fibronectins)
RN  - 0 (Fluoresceins)
RN  - EC 2.3.2.13 (Transglutaminases)
RN  - L90BEN6OLL (Cadaverine)
SB  - IM
MH  - Blotting, Western
MH  - Cadaverine/metabolism
MH  - Cell Adhesion/physiology
MH  - Cell Membrane/enzymology
MH  - Cells, Cultured
MH  - Extracellular Space/metabolism
MH  - Femur Head
MH  - Fibronectins/metabolism
MH  - Fluoresceins/metabolism
MH  - Humans
MH  - Osteoblasts/cytology/*enzymology
MH  - Osteosarcoma
MH  - Transglutaminases/*metabolism
MH  - Tumor Cells, Cultured
EDAT- 2001/08/14 10:00
MHDA- 2002/01/31 10:01
CRDT- 2001/08/14 10:00
PHST- 2001/08/14 10:00 [pubmed]
PHST- 2002/01/31 10:01 [medline]
PHST- 2001/08/14 10:00 [entrez]
AID - 10.1359/jbmr.2001.16.8.1477 [doi]
PST - ppublish
SO  - J Bone Miner Res. 2001 Aug;16(8):1477-85. doi: 10.1359/jbmr.2001.16.8.1477.