Hyaluronan catabolism

A scheme for hyaluronan catabolism is presented below (Figure 21.1). 

FIGURE 21.1 Scheme for Hyaluronan Catabolism. (Reprinted by the courtesy of the European Journal of Cell Biology, Elsevier Press.)... 

Formby, B. and Stem, R., Lactate-sensitive response elements in genes involved in hyaluronan catabolism, Biochem. Biophys. Res. Commun., 305, 203, 2003. 

Keywords Glycosaminoglycans, hyaluronan biosynthesis, hyaluronan catabolism, hyaluronan oxidative degradation, inflammation, inflammatory mediators, regenerative medicine... 

Hyaluronan is very metabolically active, with a half-life of 3 to 5 min in the circulation,less than one day in skin, and even in an inert a tissue as cartilage, the HA turns over with a half-life of 1 to 3 weeks.66,67,184 This catabolic activity is primarily the result of hyaluronidases, endoglycolytic enzymes with a specificity in most cases for the ft 1 1 glycosidic bond. 

Noble, P.W., Hyaluronan and its catabolic products in tissue injury and repair. Matrix Biol., 21, 25,... 

Tammi, R. et al., Hyaluronan enters keratinocytes by a novel endocytic route for catabolism, J. Biol. Chem., 276, 35111,2001. 

Laurent, U.B., Dahl, L.B., and Reed, R.K., Catabolism of hyaluronan in rabbit skin takes place locally, in lymph nodes and liver, Exp. Physiol., 76, 695, 1991. 

The hyaluronan content of skin has been estimated to be between 0.03% and 0.09%, and dermatan sulfate represents 30 to 40% of dermal proteoglycans. The GAG content is reported to decrease with respect to the amount of protein with increased age, and a recent report suggests that there is a decrease in the proportion of versican and an increase in decorin with increased age, which is associated with the appearance of a small PG that may be a catabolic fragment of decorin. 

Hyaluronic acid is found abundantly in the body and has an extraordinarily high rate of turnover. There are 15 g of hyaluronan in the 70-kg individual, of which 5 g are cycled daily through the catabolic pathways, mostly as the result of the hyaluronidases [97]. Hyaluronan deposition and turnover is even more abundant and more rapid in malignant tissues [116],... 

PHYSIOLOGIC OXIDATIVE CATABOLISM OF HYALURONAN PARTICIPATION OF BIOGENIC TRANSITION METALIONS... 

Tammi, R., K. Rilla, J.-P. Pienimaki, D.K. MacCallum, M. Hogg, M. Luukkonen, V.C. Hascall, and M. Tammi. 2001. Hyaluronan enters keratinocytes by a novel endocytic route for catabolism. Journal of Biological Chemistry 276(37) 35111-35122. 

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