Matrix metalloproteinase activities of turkey (Meleagris gallopavo) bile

Isolation and characterization of chicken bile matrix metalloproteinase

Avian bile is rich in matrix metalloproteinases (MMP), the enzymes that cleave extracellular matrix proteins such as collagens and proteoglycans. Changes in bile MMP expression have been correlated with hepatic and gall bladder pathologies, but the significance of their expression in normal, healthy bile is not understood. We hypothesized that the MMP in bile may aid the digestion of native collagens that are resistant to conventional gastric proteases. Hence, the objective of this study was to characterize the bile MMP and check its regulation in association with dietary factors. We used substrate zymography, azocoll protease assay, and gelatin affinity chromatography to identify and purify the MMP from chicken bile. Using zymography and SDS PAGE, 5 bands at 70, 64, 58, 50, and 42 kDa were detected. The bands corresponding to 64, 50, and 42 kDa were identified as MMP2 using trypsin in-gel digestion and matrix-assisted laser desorption time-of-flight mass spectrometry and peptide mass fingerprinting. Chickens fed diets containing gelatin supplements showed higher levels of MMP expression in the bile by both azocoll assay and zymography. We conclude that the bile MMP may be associated with the digestion of collagens and other extracellular matrix proteins in avian diets.

First-time report of metalloproteinases in fish bile and their potential as bioindicators regarding environmental contamination

Gallbladder bile from 2 fish species, mullet (Mugil liza) and tilapias (Tilapia rendalli), contain substantial matrix metalloproteinases (MMPs). Extensive purification studies were conducted in order to obtain workable samples for SDS-PAGE and zymography analysis. Proteinase activities were assayed by gelatin substrate zymography. Several protein bands were observed, corresponding to molecular weights of 200, 136, 43, 36, 34, 29, 23 and 14 kDa in mullet bile and 179, 97, 79, 61, 54, 45, 36, 33 and 21 kDa in tilapia bile. Specific inhibitor studies were conducted, in which MMPS were inhibited by EDTA and 1,10 phenanthroline, but not by serine and cysteine protease inhibitors, such as phenylmethylsulfonyl fluoride (PMSF) and transepoxysuccinyl-l-leucylamido-l-guanidino butane (E-64), confirming the proteinase identities as MMPs. Differences in proteinase expression were observed in fish from a contaminated and reference site. Some studies regarding MMPs in different fish tissues exist, however this is the first study conducted in fish bile, and their involvement in detoxification processes and organism protection against the effects of aquatic contaminants may be a possibility.

Fish metalloproteins as biomarkers of environmental contamination

Fish are well-recognized bioindicators of environmental contamination. Several recent proteomic studies have demonstrated the validity and value of using fish in the search and discovery of new biomarkers. Certain analytical tools, such as comparative protein expression analyses, both in field and lab exposure studies, have been used to improve the understanding of the potential for chemical pollutants to cause harmful effects. The metallomic approach is in its early stages of development, but has already shown great potential for use in ecological and environmental monitoring contexts. Besides discovering new metalloproteins that may be used as biomarkers for environmental contamination, metallomics can be used to more comprehensively elucidate existing biomarkers, which may enhance their effectiveness. Unfortunately, metallomic profiling for fish has not been explored, because only a few fish metalloproteins have thus far been discovered and studied. Of those that have, some have shown ecological importance, and are now successfully used as biomarkers of environmental contamination. These biomarkers have been shown to respond to several types of environmental contamination, such as cyanotoxins, metals, and sewage effluents, although many do not yet possess any known function. Examples of successes include MMPs, superoxide dismutases, selenoproteins, and iron-bound proteins. Unfortunately, none of these have, as yet, been extensively studied. As data are developed for them, valuable new information on their roles in fish physiology and in inducing environmental effects should become available.