Transglutaminase participates in the incorporation of latent TGF beta intothe extracellular matrix of aging articular chondrocytes

Citation
M. Le et al., Transglutaminase participates in the incorporation of latent TGF beta intothe extracellular matrix of aging articular chondrocytes, CONNECT TIS, 42(4), 2001, pp. 245
Citations number
26
Categorie Soggetti
da verificare
Journal title
CONNECTIVE TISSUE RESEARCH
ISSN journal
03008207 → ACNP
Volume
42
Issue
4
Year of publication
2001
Database
ISI
SICI code
0300-8207(2001)42:4<245:TPITIO>2.0.ZU;2-F
Abstract
TGF beta1 is a multifunctional peptide growth factor that promotes processe s associated with age-related degenerative diseases in articular cartilage. Large quantities of TGF beta1 are stored in cartilage extracellular matrix (ECM) in a latent form (LTGF beta1), and yet little is known about the fac tors that participate in the incorporation of LTGF beta1 into the highly sp ecialized cartilage ECM. We previously demonstrated high levels of the prot ein cross-linking enzyme transglutaminase (TGase) in aging articular chondr ocytes and showed that this enzyme participated in LTGF beta1 activation. T his work explores the hypothesis that extracellular TGase participates in L TGF beta1 incorporation into ECM in aging chondrocytes. We studied the effe cts of TGase inhibitors on TGF beta1 levels in ECM of old and young porcine articular chondrocytes. TGase inhibitors decreased the quantity of LTGF be ta1 in the ECM in old but not in young chondrocytes to 60-70% of control va lues (p < .05). Fibronectin, an extracellular TGase competitive substrate, also decreased LTGF beta1 levels in ECM (p < .01). Levels of activated TGF beta1 also decreased in the presence of TGase inhibitors, as did levels of latent TGF beta binding protein I in the cell layer. Extracellular TGase ac tivity was present in old but not young chondrocyte cultures. These finding s support a role for extracellular TGase in the incorporation of LTGF beta1 in the ECM of aging chondrocytes.