MMP-9 is expressed during wound healing in Japanese flounder skin

Fish, like mammals, have several stages of wound healing, including inflammation, reepithelialization, proliferation, organization, and differentiation. However, little is known about the molecular mechanisms of fish skin wound healing. In the present study, 23 polymerase chain reaction (PCR) bands were identified which appeared to be specifically expressed during wound healing by a simple differential display (DD) method. Sequences of cDNAs from these 14 bands were highly homologous to known genes. However, reverse transcriptase PCR (RT-PCR) analyses of these 14 bands revealed that only one of them, the gene for matrix metalloproteinase 9 (MMP-9), was significantly expressed in wounded skin, and that the others were probably false positives. MMPs are known to have gelatinolytic activity, and film in situ zymography detected strong gelatinolytic activity in the surface and dermis of wounded skin of flounder.