Are Matrix Metalloproteinases (MMPs) Present in Skeletal Muscle of the Spiny Dogfish Shark, Squalus acanthias?

The MMPs are proteolytic enzymes whose functions are associated with tumor angiogenesis, metastasis, and with the physiological remodeling of the female reproductive tract. During the 22-month gestation period of the spiny dogfish shark, the ovaries and uteri undergo dramatic tissue remodeling to accommodate the growth of follicles and fetuses, respectively. These changes correlate to morphological and biochemical endpoints obtained following autopsy. With declining populations of sharks as a growing concern and the difficulty in obtaining blood samples from large pelagic sharks, we seek to develop non-lethal approaches to assess shark reproductive status. Because MMPs are involved in tissue remodeling of the reproductive tract, and because of the relative ease in obtaining muscle samples, our goal was to determine if MMPs are found in shark skeletal muscle. Muscle samples were collected from spiny dogfish of 4 gestational stages: A (n=6), B (n=6), C (n=5) and D (n=9). Gelatin zymography was performed to assess gelatinase (MMP) activity. Visual observations of zymograms revealed low expression of gelatin-degrading enzymes in dogfish skeletal muscle. Although we have not yet established a relationship between muscle MMPs and reproductive status, we showed that dogfish shark muscle tissue expressed MMPs