Changes in the Expression of Extracellular Matrix (ECM) and Matrix Metalloproteinases (MMP) of Proliferating Rat Parotid Acinar Cells

Abstract

Tissue morphogenesis, development, and maintenance of function are mediated by signals generated through the composition of the extracellular matrix. The regulation of the composition of matrix is determined by enzymes specific for their degradation, the matrix metalloproteinases. Chronic injections of the beta-adrenergic receptor agonist, isoproterenol, result in a non-neoplastic hypertrophy and hyperplasia of the rat parotid gland. The activity of matrix metalloproteinases, as measured by gelatin zymography and enzymatic digestion of Azocoll substrates by gland lysates, decreased significantly (P < 0.05) following 24 hrs of agonist treatment, and slowly recovered to control values by 6 days of treatment. Daily administration of the broad-spectrum matrix metalloproteinase inhibitor Galardin for 3 days in combination with isoproterenol resulted in enhanced gland hypertrophy compared with that produced by isoproterenol alone. Given alone, Galardin also caused hypertrophy. The relative abundance of mRNA for the extracellular matrix molecules, collagens I and III and fibronectin, declined rapidly following the initiation of beta-agonist treatment in vivo, while laminin B1 and B2 mRNA levels increased initially before declining below control levels. These changes in patterns of mRNA levels also were observed in the concentrations of glandular protein when Western dot blot analysis of collagens I and III and laminin, respectively, was used. The importance of laminin, in vivo, was demonstrated by coinjection of anti-laminin antibody along with isoproterenol, which resulted in the inhibition of beta-agonist-induced parotid gland hypertrophy and hyperplasia. These data suggest that modulation of the ECM is associated with isoproterenol-induced salivary gland hypertrophy and hyperplasia. It is likely that this modulation of the ECM takes place through transcriptional regulation of some ECM genes and regulation of matrix-degrading enzyme activity.

Immunoexpression of extracellular matrix proteins in human salivary gland development

“…Extracellular matrix (ECM) proteins have been studied during salivary gland development by using rats and mice, using gland rudiments in organ culture and by molecular biology techniques that permit RNA quantification (1–13). However, the distribution of these proteins during human salivary gland development has not previously been described.…”

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“…The cellular responses within the LV are integrated by the extracellular matrix stimuli that bind to surface receptors. As such, the ECM coordinates the healing response to MI [3], [4], [5], [6], [7], [8].…”

Neuropathic pain: role of inflammation, immune response, and ion channel activity in central injury mechanisms

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