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

The biological mechanisms of tooth movement result from the cellular respon ses of connective tissues to exogenous mechanical forces. Among these respo nses, the degradation of the extracellular matrix takes place, but the iden tification of the molecular basis as well as the components implicated in t his degradation are poorly understood. To contribute to this identification , we subjected human fibroblasts obtained from the periodontal ligament (PD Ls) and from the gingiva (HGFs) to a continuous stretch to quantify the mRN As encoding for various metalloproteinases (MMPs), their tissue inhibitors (TIMPs), and or and beta integrin subunits. Both cell lines reacted by indu cing the expression of the mRNAs encoding for MMP-1, MMP-2, TIMP-1, and TIM P-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 alp ha v, with no difference measurable under stretching, while the mRNAs encod ing 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 mRN As encoding for MMPs and TIMPs but differed for those encoding various inte grin subunits, known to act as protein receptors in mechanotransduction.