title: Distinct mechanism of small-for-size fatty liver graft injury--Wnt4 signaling activates hepatic stellate cells.
abstract: In this study, we aimed to investigate the significance of hepatic stellate cells (HSCs) activation in small-for-size fatty liver graft injury and to explore the underlying molecular mechanism in a rat liver transplantation model. A rat orthotopic liver transplantation model using fatty grafts (40% of fatty changes) and cirrhotic recipients was applied. Intragraft gene expression profiles, ultrastructure features and HSCs activation were compared among the rats received different types of grafts (whole vs. small-for-size, normal vs. fatty). The distinct molecular signature of small-for-size fatty graft injury was identified by cDNA microarray screening and confirmed by RT-PCR detection. In vitro functional studies were further conducted to investigate the direct effect of specific molecular signature on HSCs activation. HSCs activation was predominantly present in small-for-size fatty grafts during the first 2 weeks after transplantation, and was strongly correlated with progressive hepatic sinusoidal damage and significant upregulation of intragraft Wnt4 signaling pathway. In vitro suppression of Wnt4 expression could inhibit HSC activation directly. In conclusion, upregulation of Wnt4 signaling led to direct HSC activation and subsequently induced small-for-size fatty liver grafts injury. Discovery of this distinct mechanism may lay the foundation for prophylactic treatment for marginal graft injury in living donor liver transplantation.
authors.affiliation: Department of Surgery and Centre for Cancer Research, LKS Faculty of Medicine, the University of Hong Kong, Hong Kong. kwanman@hkucc.hku.hk
authors.forename: Q
authors.initials: Q
authors.lastname: Cheng
authors.forename: K T
authors.initials: KT
authors.lastname: Ng
authors.forename: S T
authors.initials: ST
authors.lastname: Fan
authors.forename: Z X
authors.initials: ZX
authors.lastname: Lim
authors.forename: D Y
authors.initials: DY
authors.lastname: Guo
authors.forename: X B
authors.initials: XB
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: R T P
authors.initials: RT
authors.lastname: Poon
authors.forename: C M
authors.initials: CM
authors.lastname: Lo
authors.forename: K
authors.initials: K
authors.lastname: Man
mesh_terms: D000818:Animals; D005234:Fatty Liver / Q000473:pathology; D020869:Gene Expression Profiling; D055166:Hepatic Stellate Cells; D016031:Liver Transplantation / Q000502:physiology; D019520:Living Donors; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D019651:Plastic Surgery Procedures; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics*; D015854:Up-Regulation; D051153:Wnt Proteins; D060528:Wnt4 Protein
chemical_list: D051153:Wnt Proteins; D060528:Wnt4 Protein; C555583:Wnt4 protein, rat