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Cellular Factor XIIIA Transglutaminase Localizes in Caveolae and Regulates Caveolin-1 Phosphorylation,

Shuai Wang1, Mari T Kaartinen2,1

  • 1Division of Biomedical Sciences, Faculty of Dentistry, McGill University, Montreal, QC, Canada. (SW, MTK)

The Journal of Histochemistry and Cytochemistry : Official Journal of the Histochemistry Society
|August 2, 2015
PubMed

Insights

Intracellular Factor XIII-A (FXIII-A) localizes to osteoblast caveolae, influencing cell signaling pathways. This enzyme

Area of Science:

  • Biochemistry
  • Cell Biology
  • Osteoblast Biology

Background:

  • Transglutaminases (TGs) are enzymes catalyzing protein crosslinking.
  • Extracellular Factor XIII-A (FXIII-A) influences osteoblast matrix deposition.
  • The role of intracellular FXIII-A in osteoblasts remains largely uncharacterized.

Purpose of the Study:

  • To investigate the intracellular localization of FXIII-A in MC3T3-E1 osteoblasts.
  • To explore the functional role of intracellular FXIII-A in osteoblast signaling pathways.

Main Methods:

  • Immunofluorescence microscopy and TIRF microscopy for FXIII-A and caveolin-1 co-localization.
  • Methyl-β-cyclodextrin treatment to disrupt caveolae.
  • Sucrose density gradient ultracentrifugation and western blotting for caveolae-enriched fractions.
  • Monodansylcadaverine incorporation assay for transglutaminase activity.
  • Treatment with TG inhibitor NC9 to assess FXIII-A displacement and downstream signaling.

Main Results:

  • FXIII-A co-localizes with caveolin-1 in osteoblast caveolae.
  • Caveolae disruption agents and TG inhibitor NC9 alter FXIII-A localization.
  • No detectable transglutaminase activity was found within isolated caveolae.
  • NC9-induced FXIII-A displacement from caveolae activates c-Src signaling, leading to caveolin-1 and Akt phosphorylation.

Conclusions:

  • Intracellular FXIII-A is localized to osteoblast caveolae.
  • FXIII-A within caveolae plays a regulatory role in c-Src signaling pathways.
  • This finding provides new insights into the non-enzymatic functions of FXIII-A in osteoblasts.
Keywords:
Factor XIII-A transglutaminasec-Src kinasecaveolaecaveolin-1osteoblast differentiation

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