Syncoilin is an intermediate filament protein in activated hepatic stellate cells.

Hepatic stellate cells (HSCs) play an important role in several (patho)physiologic conditions in the liver. In response to chronic injury, HSCs are activated and change from quiescent to myofibroblast-like cells with contractile properties. This shift in phenotype is accompanied by a change in expression of intermediate filament (IF) proteins. HSCs express a broad, but variable spectrum of IF proteins. In muscle, syncoilin was identified as an alpha-dystrobrevin binding protein with sequence homology to IF proteins. We investigated the expression of syncoilin in mouse and human HSCs. Syncoilin expression in isolated and cultured HSCs was studied by qPCR, Western blotting, and fluorescence immunocytochemistry. Syncoilin expression was also evaluated in other primary liver cell types and in in vivo-activated HSCs as well as total liver samples from fibrotic mice and cirrhotic patients. Syncoilin mRNA was present in human and mouse HSCs and was highly expressed in in vitro- and in vivo-activated HSCs. Syncoilin protein was strongly upregulated during in vitro activation of HSCs and undetectable in hepatocytes and liver sinusoidal endothelial cells. Syncoilin mRNA levels were elevated in both CCl4- and common bile duct ligation-treated mice. Syncoilin immunocytochemistry revealed filamentous staining in activated mouse HSCs that partially colocalized with α-smooth muscle actin, ß-actin, desmin, and α-tubulin. We show that in the liver, syncoilin is predominantly expressed by activated HSCs and displays very low-expression levels in other liver cell types, making it a good marker of activated HSCs. During in vitro activation of mouse HSCs, syncoilin is able to form filamentous structures or at least to closely interact with existing cellular filaments.

Hepatic stellate cells express synemin, a protein bridging intermediate filaments to focal adhesions.

BACKGROUND AND AIMS: In the liver, stellate cells play several important (patho)physiological roles. They express a broad but variable spectrum of intermediate filament (IF) proteins. The aim of this study was to investigate the expression and functions of the intermediate filament protein synemin in hepatic stellate cells (HSCs). METHODS: In isolated and cultured rat HSCs, synemin expression was examined by quantitative reverse transcriptase polymerase chain reaction, western blotting, and immunocytochemistry. Protein-protein interaction between synemin and possible binding partners was investigated by co-immunoprecipitation and confocal microscopy. RESULTS: Expression of synemin was significantly downregulated with increased culture time. In 1-day cultured HSCs, synemin associated with other IF proteins (GFAP, desmin, and vimentin), and with the focal adhesion proteins vinculin and talin, but not with alpha-actinin or paxillin. Synemin IF and focal adhesion proteins co-localised in long slender processes, but not in the lamellipodia. In human and rat liver tissue, the presence of synemin was investigated by immunohistochemistry. In normal rat and human livers, synemin immunoreactivity was found in HSCs, smooth muscle cells of hepatic arterioles, and nerve bundles in portal tracts, but not in portal fibroblasts. In CCl4-intoxicated rat livers and in human cirrhotic livers, immunoreactivity for synemin in the parenchymal tissue was decreased. Thus synemin was expressed in quiescent HSCs but not in portal fibroblasts; and synemin expression decreased with HSC activation in vivo during chronic liver damage and with HSC activation in culture. CONCLUSIONS: Synemin forms heteropolymeric filaments with type-III IF proteins and acts as a bridging protein between IFs and a specific type of focal adhesions.

Reduction of peritoneal trauma by using nonsurgical gauze leads to less implantation metastasis of spilled tumor cells.

OBJECTIVES: To evaluate whether infliction of peritoneal trauma would promote tumor cell adherence to damaged peritoneal surfaces; to investigate whether peritoneal damage could promote tumor growth of extraperitoneal tumors; and to evaluate whether the amount of trauma correlated with the degree of tumor cell adherence and local and distant tumor growth. BACKGROUND DATA: After potentially curative resection of colorectal carcinoma, the most common site for recurrence is locoregional. We previously demonstrated that surgical trauma induces a cascade of events leading to adhesion formation. The same mechanisms may be responsible for improved tumor cell adherence and growth facilitation in early local recurrence. METHODS: A reproducible rat model was used in which peritoneal damage was inflicted by standardized rubbing of the peritoneum with surgical gauzes of different texture. In the first experiment, tumor cell adherence and growth at traumatized and nontraumatized peritoneal sites were assessed semiquantitatively 3 weeks after perioperative intra-abdominal injection of CC-531 tumor cells. In the second experiment, the effect of peritoneal trauma on ectopic tumor growth was investigated (CC-531 implanted under the renal capsule). In the final experiment, we evaluated how soon after peritoneal traumatization tumor cell adhesion and growth-promoting factors were active and whether they could be passively transferred to naïve nontraumatized abdominal cavities. RESULTS: A significant correlation between the amount of peritoneal trauma and the degree of tumor take at damaged peritoneal surfaces was found (p < or = 0.018). Tumor take at remote peritoneal sites not directly traumatized was also significantly higher after severe trauma than after moderate trauma of the peritoneum (p < or = 0.005). In addition, a significant correlation between the degree of peritoneal trauma and the growth of ectopic tumors under the renal capsule was observed (p < or = 0.009). The final experiment demonstrated that within a few hours after infliction of peritoneal trauma, tumor growth-promoting effects could be passively transferred to naïve recipients. CONCLUSIONS: Surgical trauma is an important factor in the promotion of local recurrence. The enhancing effect of trauma is not restricted to the inflicted site but rather has a generalized character. Avoidance of unnecessary surgical trauma by using gentle techniques and materials is therefore indicated.