FACTOR XIIIA AS A NERVE-ASSOCIATED TRANSGLUTAMINASE

Recent findings have led to changes in the traditional concept of nerv e recovery, including the realization that injured nerves, like any ot her injured tissue, need the assistance of blood-derived cells and fac tors in order to heal. We show that factor XIIIa (FXIIIa, the potentia lly active a(2)-subunit of factor XIII), an enzyme that participates i n blood coagulation by stabilizing the fibrin clot, is also active in the nervous system where it may play a key role in the healing of inju red tissue. We demonstrate that the plasma, macrophages and nerves of fish contain a 55 kDa form of transglutaminase that cross-reacts immun ologically with the a-subunit of FXIII in mammals (80 kDa). The fish e nzyme in the plasma, unlike its mammalian counterpart, is active, poin ting to a difference in control of the coagulation pathway in the two species. Analysis of FXIIIa expression in mammalian neural tissues and their response to injury revealed high levels of the enzyme in media conditioned by peripheral nerves as compared with medium conditioned b y nerves of the central nervous system. Furthermore, similarity was ob served in the postinjury behavior of FXIIIa in regenerating nerve tiss ues (peripheral nervous system of mammals and the central nervous syst em of fish). We suggest that the postinjury level of factor XIIIa in t he nervous system may be related to the tissue's regenerative capacity , and that FXIIIa may therefore be a link underlying a possible associ ation between the processes of blood coagulation and nerve healing.