Differential display PCR identified another potential gene that is specifically induced by rapid intermittent stretching of skin. Two different methods of stretching were used, linear load cycling with a skin hook (Gibson’s technique) and hemispherical load cycling with an inflated subcutaneous silicone balloon (Rapid Intraoperative Tissue Expansion or RITE). Unstretched flaps served as postoperative controls. Among four differential gene fragments examined, one was specifically induced 6 h after RITE application. Gene expression was confirmed by Northern blot hybridization. The cDNA fragment was extended and the resultant sequence analyzed to reveal induction of truncated long interspersed nucleotide element 1 (LINE-1 or L1). Northern hybridization using rat insulin 1 and mouse myotubularin cDNA probes verified up-regulation. Truncated L1 elements are located inside introns of many genes, and insulin 1 and myotubularin are two known to regulate angiogenesis and cell growth. This is the first report demonstrating that insulin 1 like L1 and myotubularin are responsive to RITE and not to rapid linear stretch using the Gibson’s technique. Our findings suggest enhancement of long-term flap viability by induction of yet another beneficial RITE-responsive gene that promotes wound healing. They provide a lead into the screening of other RITE-responsive genes that contain L1 in their introns.
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