Involvement of annexin I and annexin II in hepatocyte proliferation: Can annexins I and II be markers for proliferative hepatocytes?



Annexin is the name of a new family of Ca2+-dependent membrane-binding proteins. Eleven types of its related proteins have been reported to date. Among those, annexin I and annexin II have been reported to possess many biological functions in vitro. Its actual role in vivo, however, is yet unknown. The involvement of annexin I and annexin II in the proliferation processes of hepatocytes was examined in the following aspects: (a) hepatocyte proliferation after carbon tetrachloride—induced liver damage, (b) hepatocyte regeneration after partial hepatectomy and (c) postnatal development of hepatocytes. These results showed collectively that annexin I and annexin II were increased in proliferative (or regenerative) hepatocytes, suggesting that both proteins play a certain role in the proliferation event. Furthermore, annexin I—and annexin II—positive hepatocytes always show a wider distribution than that of proliferating cell nuclear antigen or cytokeratin 7—positive hepatocytes, indicating that annexin I and annexin II may be useful markers for detecting not only actively proliferating hepatocytes but also hepatocytes in preproliferative and postproliferative stages. (Hepatology 1994;20:425–435.)