PI3K/Akt activation is critical for early hepatic regeneration after partial hepatectomy

Hepatic resection is associated with rapid proliferation and regeneration of the remnant liver. Phosphatidylinositol 3-kinase (PI3K), composed of a p85Ą regulatory and a p110Ą catalytic subunit, participates in multiple cellular processes, including cell growth and survival; however, the role of PI3K in liver regeneration has not been clearly delineated. In these studies, I used the potent PI3K inhibitor, wortmannin, and small-interfering RNA (siRNA) targeting the p85Ą and p110Ą subunits to determine if total or selective PI3K inhibition would abrogate the proliferative response of the liver following resection. After partial hepatectomy in mice, there is an increase in PI3K activity; total PI3K blockade with wortmannin, and selective inhibition of p85Ą or p110Ą with siRNA resulted in a significant decrease in hepatocyte proliferation, especially at the earliest timepoints (ie, 48h and 72h). Fewer macrophages and Kupffer cells were present in the regenerating liver of mice treated with wortmannin or siRNA to p85Ą or p110Ą, as reflected by a paucity of F4/80+ cells present by immunohistochemistry (IHC). Additionally, PI3K inhibition led to an aberrant hepatocyte architecture characterized by vacuolization, lipid deposition, and glycogen accumulation. My data demonstrate that PI3K/Akt pathway activation plays a critical role in the early regenerative response of the liver after resection; inhibition of this pathway markedly abrogates the normal hepatic regenerative response, perhaps by inhibiting macrophage infiltration and cytokine elaboration and thus hepatocyte priming for replication.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Grantor

The University of Texas Medical Branch

Year dc:date.issued

2008

Author dc:creator

• Lindsey Nicole Jackson

Advisor dc:contributor.advisor

• B. Mark Evers, M.D.

Committee members dc:contributor.committeemember

• Sundararajah Thevananther, Ph.D.
• Kathleen O'Connor, Ph.D.
• Frank C. Schmalstieg, M.D., Ph.D.
• Cornelis Elferink, Ph.D.

• wortmannin
• phosphatidylinositol 3-kinase
• p85-alpha
• p110-alpha
• liver regeneration

Statement dc:rights

• Copyright © is held by the author. Presentation of this material on the TDL web site by The University of Texas Medical Branch at Galveston was made possible under a limited license grant from the author who has retained all copyrights in the works.

Language dc:language.iso

eng

Dc Identifier Other

etd-12182008-133713

OAI identifier oai:identifier

oai:utmb-ir.tdl.org:2152.3/297