Ca. Abbott et al., INCREASED SERUM LEVELS OF DIPEPTIDYL PEPTIDASE-IV (CD26) IN RATS UNDERGOING LIVER-REGENERATION, HEPATOLOGY RESEARCH, 4(3), 1995, pp. 165-174
Dipeptidyl Peptidase IV (DPP IV; CD26) is a cell surface ectopeptidase
that has been shown to alter the binding of hepatocytes to the extrac
ellular matrix (ECM), play a role in lymphocyte proliferation and alte
r the biological activity of several proteins. During hepatic regenera
tion, there is obvious alteration in the interaction between hepatocyt
es and the ECM during a rapid phase of hepatic growth. In addition, th
ere is an upregulation of many hepatic and non-hepatic molecules. Our
aim was to determine whether the expression of DPP IV in liver regener
ation is consistent with a role in either binding of hepatocytes to EC
M or modification of growth factors. To achieve this we have measured
serum DPP IV levels and compared the expression of DPP IV at the prote
in and mRNA levels in regenerating and sham-operated liver and kidney
tissue, This study reports elevated serum DPP IV levels during hepatic
regeneration. Serum DPP IV enzyme activity and antigen levels were in
creased up to 10-fold at 48 h after partial hepatectomy, This followed
the same time course as the increase in hepatic DNA replication. Ther
e was no significant increase in the serum levels of another bile cana
licular enzyme, leucine aminopeptidase. Analysis of hepatic and renal
tissue during regeneration showed no detectable increases in DPP IV en
zyme or mRNA. The lack of a detectable increase in enzyme and mRNA lev
els in the kidney or liver suggests other sources for serum DPP IV or
increased release of soluble DPP IV from the liver. The increase in se
rum may be part of a response to control the biological activity of mo
lecules that appear in the blood during the regenerative process.