Proteomic Analysis of Ischemia-Reperfusion Injury upon Human Liver Transplantation Reveals the Protective Role of IQGAP1

Abstract

Ischemia-reperfusion injury (IRI) represents a major determinant of liver transplantation. IRI-induced graft dysfunction is related to biliary damage, partly due to a loss of bile canaliculi (BC) integrity associated with a dramatic remodeling of actin cytoskeleton. However, the molecular mechanisms associated with these events remain poorly characterized. Using liver biopsies collected during the early phases of organ procurement (ischemia) and transplantation (reperfusion), we characterized the global patterns of expression and phosphorylation of cytoskeletonrelated proteins during hepatic IRI. This targeted functional proteomic approach, which combined protein expression pattern profiling and phosphoprotein enrichment followed by mass spectrometry analysis, allowed us to identify IQGAP1, a Cdc42/Rac1 effector, as a potential regulator of actin cytoskeleton remodeling and maintenance of BC integrity. Cell fractionation and immunohistochemistry revealed that IQGAP1 expression and localization were affected upon IRI and related to actin reorganization. Furthermore using an IRI model in human hepatoma cells, we demonstrated that IQGAP1 silencing decreased the basal level of actin polymerization at BC periphery, reflecting a defect in BC structure coincident with reduced cellular resistance to IRI. In summary, this study uncovered new mechanistic insights into the global regulation of IRI-induced cytoskeleton remodeling and led to the identification of IQGAP1 as a regulator of BC structure.

Involvement of IQGAP3, a regulator of Ras/ERK‐related cascade, in hepatocyte proliferation in mouse liver regeneration and development

“…The expression of IQGAP1/ 2 was detected in Kupffer and sinusoidal endothelial cells, respectively. These findings were partly inconsistent with the previous statements that IQGAP1 and/or IQGAP2 were expressed in hepatocytes (Emadali et al, 2006;Schmidt et al, 2008). However, further studies on these points are required in future to conclusively determine the specific signals in hepatocytes, since for rather weak signals in tissue, several points are needed to be critically examined with respect to conditions for immunostaining.…”

“…The expression of IQGAP3 was highly induced in the liver regeneration process due to partial hepatectomy and CCl 4 injury and was also induced in the liver development process, suggesting that the novel IQGAP3/Ras/ERK-related signaling was involved in vivo in hepatocyte proliferation. On the other hand, IQGAP1/2 with binding affinity to Rac and Cdc42 showed distinct localization in Kupffer and sinusoidal endothelial cells, respectively (Li et al, 2000;Sugimoto, 2001;Noritake et al, 2005;Emadali et al, 2006;Schmidt et al, 2008). The findings were discussed with special reference to the Ras-mediated critical role of IQGAP3 in hepatocyte proliferation and to the Rac-and Cdc42-mediated roles of IQGAP1/2/3 in Kupffer and sinusoidal endothelial cells and hepatocytes, respectively, in tissue remodeling due to liver regeneration and embryonic liver development.…”

Oxidative Inactivation of Key Mitochondrial Proteins Leads to Dysfunction and Injury in Hepatic Ischemia Reperfusion

“…Recent reports show that a few proteins are altered in humans undergoing liver transplantation. 25,44,45 In addition, some other proteins were also altered in rabbit hearts following I/R injury. 24,46 However, these studies were conducted using whole cell homogenate without subcellular fractionation and functional characterization of those proteins altered during I/R injury.…”

The MAP Kinase Phosphatase-1 MKP-1/DUSP1 Is a Regulator of Human Liver Response to Transplantation

“…• C in the presence of antimycin A for 1 h, which is used as a model for ATP depletion during the ischemic phase (9). Following this treatment, the medium was replaced by DMEM + 10% FBS at 37…”

“…Three biopsies, 0.5 cm, were surgically removed in the course of eight liver transplantation procedures performed within the McGill University Health Centre with approval of the institution's ethics committee (ERB 05-003) as previously described (8)(9)(10) (Figure 1A). Briefly (12).…”