Expression of mRNAs encoding for α and β integrin subunits, MMPs, and TIMPs in stretched human periodontal ligament and gingival fibroblasts

The biological mechanisms of tooth movement result from the cellular responses of connective tissues to exogenous mechanical forces. Among these responses, the degradation of the extracellular matrix takes place, but the identification of the molecular basis as well as the components implicated in this degradation are poorly understood. To contribute to this identification, we subjected human fibroblasts obtained from the periodontal ligament (PDLs) and from the gingiva (HGFs) to a continuous stretch to quantify the mRNAs encoding for various metalloproteinases (MMPs), their tissue inhibitors (TIMPs), and or and beta integrin subunits. Both cell lines reacted by inducing the expression of the mRNAs encoding for MMP-1, MMP-2, TIMP-1, and TIMP-2, while other mRNAs did not vary (MT1-MMP, TIMP-3) or were not expressed (MMP-9). PDLs expressed selectively the mRNAs encoding for alpha 4 and alpha v, with no difference measurable under stretching, while the mRNAs encoding for alpha 6 and beta 1 were increased and the one encoding for alpha 5 was decreased. HGFs increased the mRNAs encoding for alpha 2, alpha 6, beta 1, and beta 3 and decreased the one encoding for alpha 3. Analysis of our data indicated that stretched HGFs and PDLs induced the same pattern of mRNAs encoding for MMPs and TIMPs but differed for those encoding various integrin subunits, known to act as protein receptors in mechanotransduction.