J Korean Med Sci.  1999 Dec;14(6):635-642. 10.3346/jkms.1999.14.6.635.

Changes in expression of cell cycle regulators and their hepatic lobular distribution in partial hepatectomy-induced regenerating rat liver

• Jeong JS
• Lee JH
• Kim HI
• Park JI

• KMID: 646039
• DOI: http://doi.org/10.3346/jkms.1999.14.6.635

Abstract

Partial hepatectomy (PH) endorses quiescent hepatocytes to reenter the cell cycle. The regenerating liver returns to its preresection weight after 7 days, following one or two cell division and maintains nearly its original volume after then. We focused on the inhibition of further hepatocyte proliferation, hypothesizing possible involvement of cell cycle upregulators and inhibitors. We studied protein levels in expression of cyclins, cyclin dependent kinases (CDKs) and CDK inhibitors (CKIs), and their in situ hepatic lobular distributions in partial hepatectomized rat liver. Cyclin E was expressed in the same levels in normal liver and after PH. Expression of cyclin A, not detected in normal liver, increased in following times after PH and reached a maximum at 7 day. CDK2 and 4 showed increased expression toward terminal period. Contradictory findings of cyclin A and these CDKs might play an important role in the inhibition of further cell division, although still unclear. Constitutively expressed CDK6 decreased after 1 day. p18 showed peak expression within 1 day, and p16, p21, p27 and p57 were stronger at terminal periods. During the expected period of their activity, intranuclear translocations were observed in cyclin E, p18 and p16. There was no evidence of regional distribution in hepatic lobular architecture, instead, diffuse in situ expression, corroborating synchronous event, was found.

Keyword

Hepatectomy; Liver regeneration; Cyclins; Cyclin-dependent kinases; Enzyme inhibitors

MeSH Terms

Animal
Cell Cycle/physiology*
Cyclin-Dependent Kinases/metabolism
Cyclin-Dependent Kinases/antagonists & inhibitors
Cyclins/metabolism*
Cyclins/immunology
Flow Cytometry
Hepatectomy
Immunoblotting
Immunohistochemistry
Interphase/physiology
Liver/metabolism*
Liver Regeneration/physiology*
Male
Rats
Rats, Sprague-Dawley
S Phase/physiology