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Thrombospondin-1 is a novel negative regulator of liver regeneration after partial hepatectomy through transforming growth factor-beta1 activation in mice.

ABSTRACT: The matricellular protein, thrombospondin-1 (TSP-1), is prominently expressed during tissue repair. TSP-1 binds to matrix components, proteases, cytokines, and growth factors and activates intracellular signals through its multiple domains. TSP-1 converts latent transforming growth factor-beta1 (TGF-?1) complexes into their biologically active form. TGF-? plays significant roles in cell-cycle regulation, modulation of differentiation, and induction of apoptosis. Although TGF-?1 is a major inhibitor of proliferation in cultured hepatocytes, the functional requirement of TGF-?1 during liver regeneration remains to be defined in vivo. We generated a TSP-1-deficient mouse model of a partial hepatectomy (PH) and explored TSP-1 induction, progression of liver regeneration, and TGF-?-mediated signaling during the repair process after hepatectomy. We show here that TSP-1-mediated TGF-?1 activation plays an important role in suppressing hepatocyte proliferation. TSP-1 expression was induced in endothelial cells (ECs) as an immediate early gene in response to PH. TSP-1 deficiency resulted in significantly reduced TGF-?/Smad signaling and accelerated hepatocyte proliferation through down-regulation of p21 protein expression. TSP-1 induced in ECs by reactive oxygen species (ROS) modulated TGF-?/Smad signaling and proliferation in hepatocytes in vitro, suggesting that the immediately and transiently produced ROS in the regenerating liver were the responsible factor for TSP-1 induction.We have identified TSP-1 as an inhibitory element in regulating liver regeneration by TGF-?1 activation. Our work defines TSP-1 as a novel immediate early gene that could be a potential therapeutic target to accelerate liver regeneration.

SUBMITTER: Hayashi H

PROVIDER: S-EPMC3295913 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Thrombospondin-1 is a novel negative regulator of liver regeneration after partial hepatectomy through transforming growth factor-beta1 activation in mice.

Hayashi Hiromitsu H Sakai Keiko K Baba Hideo H Sakai Takao T

Hepatology (Baltimore, Md.) 20120318 5

<h4>Unlabelled</h4>The matricellular protein, thrombospondin-1 (TSP-1), is prominently expressed during tissue repair. TSP-1 binds to matrix components, proteases, cytokines, and growth factors and activates intracellular signals through its multiple domains. TSP-1 converts latent transforming growth factor-beta1 (TGF-β1) complexes into their biologically active form. TGF-β plays significant roles in cell-cycle regulation, modulation of differentiation, and induction of apoptosis. Although TGF-β ...[more]

PMID: 22105716

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Project description:BackgroundA strategy for accelerating liver regeneration after hepatectomy would offer great benefits in preventing postoperative liver failure and improving surgical outcomes. Transforming growth factor (TGF) β is a potent inhibitor of hepatocyte proliferation. Recently, thrombospondin (TSP) 1 has been identified as a negative regulator of liver regeneration by activation of local TGF-β signals. This study aimed to clarify whether the LSKL (leucine-serine-lysine-leucine) peptide, which inhibits TSP-1-mediated TGF-β activation, promotes liver regeneration after hepatectomy in mice.MethodsMice were operated on with a 70 per cent hepatectomy or sham procedure. Operated mice received either LSKL peptide or normal saline intraperitoneally at abdominal closure and 6 h after hepatectomy. Perioperative plasma TSP-1 levels were measured by enzyme-linked immunosorbent assay in patients undergoing hepatectomy.ResultsAdministration of LSKL peptide attenuated Smad2 phosphorylation at 6 h. S-phase entry of hepatocytes was accelerated at 24 and 48 h by LSKL peptide, which resulted in faster recovery of the residual liver and bodyweight. Haematoxylin and eosin tissue staining and blood biochemical examinations revealed no significant adverse effects following the two LSKL peptide administrations. In the clinical setting, plasma TSP-1 levels were lowest on the first day after hepatectomy. However, plasma TSP-1 levels at this stage were significantly higher in patients with subsequent liver dysfunction compared with levels in those without liver dysfunction following hepatectomy.ConclusionOnly two doses of LSKL peptide during the early period after hepatectomy can promote liver regeneration. The transient inhibition of TSP-1/TGF-β signal activation using LSKL peptide soon after hepatectomy may be a promising strategy to promote subsequent liver regeneration. Surgical relevance Although the mechanisms of liver regeneration after hepatectomy have been explored intensively in vivo, no therapeutic tools are thus far available to accelerate liver regeneration after hepatectomy in the clinical setting. Recently, the matricellular protein thrombospondin (TSP) 1, a major activator of latent transforming growth factor (TGF) β1, has been identified as a negative regulator of liver regeneration after hepatectomy. In this study, the inhibition of TSP-1-mediated TGF-β signal activation by LSKL (leucine-serine-lysine-leucine) peptide in the early period after hepatectomy accelerated liver regeneration without any adverse effects. In addition, continuous high plasma TSP-1 levels after hepatectomy were associated with liver damage in humans. The transient inhibition of TSP-1/TGF-β signal activation using LSKL peptide in the early period after hepatectomy could be a novel therapeutic strategy to accelerate liver regeneration after hepatectomy.

Dataset Information

Thrombospondin-1 is a novel negative regulator of liver regeneration after partial hepatectomy through transforming growth factor-beta1 activation in mice.

Publications

Thrombospondin-1 is a novel negative regulator of liver regeneration after partial hepatectomy through transforming growth factor-beta1 activation in mice.

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