studies

542A AASLD ABSTRACTS HEPATOLOGY, October, 2015
injected with Tamoxiphen (1mg/ml) and injected i.p everyday
for 5 days. Controls were injected with corn oil alone.This
treatment deleted exon 16 that contains a critical ATP-binding
site in the intracellular tyrosine kinase (TK) domain, essential for
the activation of c-met. PhosphoEGFR was inhibited by using
Canertinib, an irreversible pan-pEGFR inhibitor that was administered
i.p at 80 mg/kg. Mice were injected a day before PHx
and then everyday for 14 days. Appropriate vehicle controls
were also used. In mice treated with Tyrosine kinase inhibitors,
pEGFR levels were significantly reduced compared to vehicle
treated controls. Analysis of proliferation indices indicated significant
drop in KI67 positive staining in treated mice compared
to controls Conclusion: Combined elimination of both MET and
EGFR signaling resulted in sustained inhibition of liver regeneration
up to 14 days.The PI3K-AKT-mTOR and the RAS-MEK-
ERK pathways associated with cellular proliferation were down
regulated in MET-EGFR inhibited mice.A significant reduction
in Ki67 labeling was also evident, as was a reduction in liver to
body weight ratio, suggesting a liver regeneration deficit.The
increase in hepatocyte size in Met and EGFR suppressed livers
may represent a compensatory effect to increase liver weight
in the absence of hepatocyte proliferation.Suppression of MET-
EGFR caused profound alterations in expression of many cell
cycle associated genes. microRNA`s and LncRNA`s.
Disclosures:
George K. Michalopoulos - Consulting: Vital Therapies
The following authors have nothing to disclose: Shirish Paranjpe, William C.
Bowen, Meagan Haynes, Anne Orr, Wendy M. Mars, Jianhua Luo
671
Hyperammonemia impairs skeletal muscle protein synthesis
via a myostatin dependent mechanism
Srinivasan Dasarathy 1 , Gangarao Davuluri 2 , Samjhana Thapaliya
2 , Avinash Kumar 2 , Gabriella A. Ten Have 3 , Dharmvir
Singh 2 , Stephen L. Welle 4 , Marielle Engelen 3 , Sathyamangla
V. Naga Prasad 5 , Nicolaas E. Deutz 3 ; 1 Department Of Gastroenterology
and Hepatology, Cleveland Clinic, Cleveland, OH;
2 Pathobiology, Cleveland Clinic, Cleveland, OH; 3 Department of
Health and Kinesiology, Texas A&M University, College Station,
TX; 4 Medicine, University of Rochester Medical Center, Rochester,
NY; 5 Molecular Cardiology, Cleveland Clinic, Cleveland, OH
Hyperammonemia is a consistent abnormality in cirrhosis and
contributes to sarcopenia or skeletal muscle loss. We have
previously shown that myostatin expression is increased in
the hyperammonemic portacaval anastomosis (PCA) rat and
in C2C12 myotubes in vitro. To demonstrate that hyperammonemia
induced skeletal muscle loss is mediated via an
increased expression of myostatin in vivo, we induced hyperammonemia
in post developmental myostatin-/- and myostatin+/+
mice and the metabolic and molecular signaling
responses regulating protein synthesis (mTOR1 targets p70s6k,
ribosomal s6 protein, 4EBP1) in the gastrocnemius muscle were
studied. The post developmental myostatin knockout mice were
generated by floxing the 3rd exon of myostatin gene (codes
for entire active protein), a transgene encoding tamoxifen-activated
Cre recombinase. At 4 months of age, mice were fed
tamoxifen for 2 weeks to deplete myostatin. Hyperammonemia
was induced by daily intraperitoneal injection of ammonium
acetate for 4 weeks. Muscle protein synthesis was quantified
by administration of a pulse of L-ring-D5 phenylalanine
(D5Phe) and protein incorporation of labeled D5-Phe quantified
using LC-MS/MS. Plasma (60.1±22.2 vs 378.0±71.2
μmol/l; p