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Cholestasis induces reversible accumulation of periplakin in mouse liver.

Ito S, Satoh J, Matsubara T, Shah YM, Ahn SH, Anderson CR, Shan W, Peters JM, Gonzalez FJ - BMC Gastroenterol (2013)

Bottom Line: PPL serves as a structural component of the cornified envelope in the skin and interacts with various types of proteins in cultured cells; its level decreases dramatically during tumorigenic progression in human epithelial tissues.In addition, similar accumulation of PPL at cellular boundaries was found in epithelial cells around renal tubules upon ureteral obstruction.Further examination of the roles for PPL may lead to the discovery of a novel mechanism for cellular protection by cytolinkers that is applicable to many tissues and in many contexts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biofrontier Platform, Graduate School of Medicine, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. ito.shinji.3v@kyoto-u.ac.jp

ABSTRACT

Background: Periplakin (PPL) is a rod-shaped cytolinker protein thought to connect cellular adhesion junctional complexes to cytoskeletal filaments. PPL serves as a structural component of the cornified envelope in the skin and interacts with various types of proteins in cultured cells; its level decreases dramatically during tumorigenic progression in human epithelial tissues. Despite these intriguing observations, the physiological roles of PPL, especially in non-cutaneous tissues, are still largely unknown. Because we observed a marked fluctuation of PPL expression in mouse liver in association with the bile acid receptor farnesoid X receptor (FXR) and cholestasis, we sought to characterize the role of PPL in the liver and determine its contributions to the etiology and pathogenesis of cholestasis.

Methods: Time- and context-dependent expression of PPL in various mouse models of hepatic and renal disorders were examined by immunohistochemistry, western blotting, and quantitative real-time polymerase chain reactions.

Results: The hepatic expression of PPL was significantly decreased in Fxr-/- mice. In contrast, the expression was dramatically increased during cholestasis, with massive PPL accumulation observed at the boundaries of hepatocytes in wild-type mice. Interestingly, the hepatic accumulation of PPL resulting from cholestasis was reversible. In addition, similar accumulation of PPL at cellular boundaries was found in epithelial cells around renal tubules upon ureteral obstruction.

Conclusions: PPL may be involved in the temporal accommodation to fluid stasis in different tissues. Further examination of the roles for PPL may lead to the discovery of a novel mechanism for cellular protection by cytolinkers that is applicable to many tissues and in many contexts.

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Related in: MedlinePlus

The hepatic accumulation of PPL was highly associated with cholestasis. (A) Representative images for the hepatic accumulation of PPL under different types of hepatitis mediated by the indicated triggers. Protein abundance of PPL measured by western blotting is also shown at the bottom. Equal amounts of protein from 5 mice were combined in each group for western blotting. The immunoblot for GAPDH was used as the loading control. Scale bar: 100 μm. (B) Hepatic PPL expression in vehicle- or ANIT-treated mice examined by immunohistochemical and western blotting analyses. Protein abundances of K19 and ZO-1 examined by western blotting are also shown. Four or 5 mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (C) Hepatic PPL expression levels in bile duct-ligated (BDL, for indicated durations) or sham-operated mice examined by immunohistochemical and western blotting analyses. Immunoblots for K19 and ZO-1 are also shown. Five mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (D) Time course of the induction of hepatic Ppl mRNA expression in wild-type mice after bile duct ligation. Five to 10 mice per group were examined. mRNA expression levels are normalized to Gapdh and are expressed as mean ± SD. The average value in the liver of untreated mice was set to 1.0. ***: P < 0.001 by one-way ANOVA with Dunnett’s test (vs. untreated). (E) Time course of the hepatic PPL accumulation in bile duct-ligated mice examined by western blotting analysis. Three mice per group were examined. The immunoblot for GAPDH was used as the loading control. (F) Representative images for the time course of the hepatic PPL accumulation in bile duct-ligated mice examined by immunohistochemical analysis. Scale bar: 100 μm.
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Figure 6: The hepatic accumulation of PPL was highly associated with cholestasis. (A) Representative images for the hepatic accumulation of PPL under different types of hepatitis mediated by the indicated triggers. Protein abundance of PPL measured by western blotting is also shown at the bottom. Equal amounts of protein from 5 mice were combined in each group for western blotting. The immunoblot for GAPDH was used as the loading control. Scale bar: 100 μm. (B) Hepatic PPL expression in vehicle- or ANIT-treated mice examined by immunohistochemical and western blotting analyses. Protein abundances of K19 and ZO-1 examined by western blotting are also shown. Four or 5 mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (C) Hepatic PPL expression levels in bile duct-ligated (BDL, for indicated durations) or sham-operated mice examined by immunohistochemical and western blotting analyses. Immunoblots for K19 and ZO-1 are also shown. Five mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (D) Time course of the induction of hepatic Ppl mRNA expression in wild-type mice after bile duct ligation. Five to 10 mice per group were examined. mRNA expression levels are normalized to Gapdh and are expressed as mean ± SD. The average value in the liver of untreated mice was set to 1.0. ***: P < 0.001 by one-way ANOVA with Dunnett’s test (vs. untreated). (E) Time course of the hepatic PPL accumulation in bile duct-ligated mice examined by western blotting analysis. Three mice per group were examined. The immunoblot for GAPDH was used as the loading control. (F) Representative images for the time course of the hepatic PPL accumulation in bile duct-ligated mice examined by immunohistochemical analysis. Scale bar: 100 μm.

Mentions: One of the most distinctive physiological alterations following CA feeding is hepatocellular injury [31,32]. To evaluate the effects of hepatocellular injury on PPL expression, we broadly examined PPL expression in damaged liver of selected mouse models. First, we examined non-cholestatic models mimicked by a non-bile acid detergent, SDS; a plant lectin, ConA; and an organic solvent, CCl4. These models represent detergent-induced (SDS), hyperactive T lymphocyte-mediated (ConA), and reactive oxygen species-mediated (CCl4) injuries [33,34]. Although slight differences were observed depending on the doses and durations applied, all of these treatments caused similar effects on PPL expression, with incremental changes in mRNA; however, robust protein accumulation was not detected (Table 1 and Figure 6A). Second, the expression of PPL was examined in models with chronic damages from hepatic fibrosis or steatosis. CCl4 is a potent inducer of hepatic fibrosis when administered chronically [34]. After 4 weeks of CCl4 intoxication, severe hepatic fibrosis accompanied by a substantial elevation in serum ALT and AST levels was induced. However, a marked increase in Ppl mRNA or robust accumulation of PPL protein was not observed (Table 1 and Figure 6A). Next, leptin-deficient genetically obese (ob/ob) mice were used as a model for steatosis. While a slight increase in Ppl mRNA expression was observed, robust accumulation of PPL protein was not detected in this model (Table 1 and Figure 6A). Lastly, expression of PPL in cholestatic mouse models was investigated using ANIT and BDL; these approaches induce 2 distinct types of cholestasis, cholangiocellular injury-derived (intrahepatic) and obstructive (extrahepatic) cholestasis, respectively [35,36]. Severe cholestasis was induced by both treatments, as confirmed by serum T-BA and T-Bil levels (Table 1). Both the increase in Ppl mRNA expression and the accumulation of the PPL protein at cellular boundaries were quite apparent in these models (Table 1 and Figure 6A, B, and C). Notably, the accumulation of PPL following BDL was observed as early as 2 days post-ligation, suggesting a role for PPL in early response to cholestasis (Figure 6D, E, and F). In addition, while bile duct ligation significantly increased the amount of K19, ANIT did not affect K19 expression, similar to dietary CA (Figures 6B, C, and 3F).


Cholestasis induces reversible accumulation of periplakin in mouse liver.

Ito S, Satoh J, Matsubara T, Shah YM, Ahn SH, Anderson CR, Shan W, Peters JM, Gonzalez FJ - BMC Gastroenterol (2013)

The hepatic accumulation of PPL was highly associated with cholestasis. (A) Representative images for the hepatic accumulation of PPL under different types of hepatitis mediated by the indicated triggers. Protein abundance of PPL measured by western blotting is also shown at the bottom. Equal amounts of protein from 5 mice were combined in each group for western blotting. The immunoblot for GAPDH was used as the loading control. Scale bar: 100 μm. (B) Hepatic PPL expression in vehicle- or ANIT-treated mice examined by immunohistochemical and western blotting analyses. Protein abundances of K19 and ZO-1 examined by western blotting are also shown. Four or 5 mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (C) Hepatic PPL expression levels in bile duct-ligated (BDL, for indicated durations) or sham-operated mice examined by immunohistochemical and western blotting analyses. Immunoblots for K19 and ZO-1 are also shown. Five mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (D) Time course of the induction of hepatic Ppl mRNA expression in wild-type mice after bile duct ligation. Five to 10 mice per group were examined. mRNA expression levels are normalized to Gapdh and are expressed as mean ± SD. The average value in the liver of untreated mice was set to 1.0. ***: P < 0.001 by one-way ANOVA with Dunnett’s test (vs. untreated). (E) Time course of the hepatic PPL accumulation in bile duct-ligated mice examined by western blotting analysis. Three mice per group were examined. The immunoblot for GAPDH was used as the loading control. (F) Representative images for the time course of the hepatic PPL accumulation in bile duct-ligated mice examined by immunohistochemical analysis. Scale bar: 100 μm.
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Figure 6: The hepatic accumulation of PPL was highly associated with cholestasis. (A) Representative images for the hepatic accumulation of PPL under different types of hepatitis mediated by the indicated triggers. Protein abundance of PPL measured by western blotting is also shown at the bottom. Equal amounts of protein from 5 mice were combined in each group for western blotting. The immunoblot for GAPDH was used as the loading control. Scale bar: 100 μm. (B) Hepatic PPL expression in vehicle- or ANIT-treated mice examined by immunohistochemical and western blotting analyses. Protein abundances of K19 and ZO-1 examined by western blotting are also shown. Four or 5 mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (C) Hepatic PPL expression levels in bile duct-ligated (BDL, for indicated durations) or sham-operated mice examined by immunohistochemical and western blotting analyses. Immunoblots for K19 and ZO-1 are also shown. Five mice per group were examined. The immunoblots for GAPDH were used as the loading controls. Scale bar: 100 μm. (D) Time course of the induction of hepatic Ppl mRNA expression in wild-type mice after bile duct ligation. Five to 10 mice per group were examined. mRNA expression levels are normalized to Gapdh and are expressed as mean ± SD. The average value in the liver of untreated mice was set to 1.0. ***: P < 0.001 by one-way ANOVA with Dunnett’s test (vs. untreated). (E) Time course of the hepatic PPL accumulation in bile duct-ligated mice examined by western blotting analysis. Three mice per group were examined. The immunoblot for GAPDH was used as the loading control. (F) Representative images for the time course of the hepatic PPL accumulation in bile duct-ligated mice examined by immunohistochemical analysis. Scale bar: 100 μm.
Mentions: One of the most distinctive physiological alterations following CA feeding is hepatocellular injury [31,32]. To evaluate the effects of hepatocellular injury on PPL expression, we broadly examined PPL expression in damaged liver of selected mouse models. First, we examined non-cholestatic models mimicked by a non-bile acid detergent, SDS; a plant lectin, ConA; and an organic solvent, CCl4. These models represent detergent-induced (SDS), hyperactive T lymphocyte-mediated (ConA), and reactive oxygen species-mediated (CCl4) injuries [33,34]. Although slight differences were observed depending on the doses and durations applied, all of these treatments caused similar effects on PPL expression, with incremental changes in mRNA; however, robust protein accumulation was not detected (Table 1 and Figure 6A). Second, the expression of PPL was examined in models with chronic damages from hepatic fibrosis or steatosis. CCl4 is a potent inducer of hepatic fibrosis when administered chronically [34]. After 4 weeks of CCl4 intoxication, severe hepatic fibrosis accompanied by a substantial elevation in serum ALT and AST levels was induced. However, a marked increase in Ppl mRNA or robust accumulation of PPL protein was not observed (Table 1 and Figure 6A). Next, leptin-deficient genetically obese (ob/ob) mice were used as a model for steatosis. While a slight increase in Ppl mRNA expression was observed, robust accumulation of PPL protein was not detected in this model (Table 1 and Figure 6A). Lastly, expression of PPL in cholestatic mouse models was investigated using ANIT and BDL; these approaches induce 2 distinct types of cholestasis, cholangiocellular injury-derived (intrahepatic) and obstructive (extrahepatic) cholestasis, respectively [35,36]. Severe cholestasis was induced by both treatments, as confirmed by serum T-BA and T-Bil levels (Table 1). Both the increase in Ppl mRNA expression and the accumulation of the PPL protein at cellular boundaries were quite apparent in these models (Table 1 and Figure 6A, B, and C). Notably, the accumulation of PPL following BDL was observed as early as 2 days post-ligation, suggesting a role for PPL in early response to cholestasis (Figure 6D, E, and F). In addition, while bile duct ligation significantly increased the amount of K19, ANIT did not affect K19 expression, similar to dietary CA (Figures 6B, C, and 3F).

Bottom Line: PPL serves as a structural component of the cornified envelope in the skin and interacts with various types of proteins in cultured cells; its level decreases dramatically during tumorigenic progression in human epithelial tissues.In addition, similar accumulation of PPL at cellular boundaries was found in epithelial cells around renal tubules upon ureteral obstruction.Further examination of the roles for PPL may lead to the discovery of a novel mechanism for cellular protection by cytolinkers that is applicable to many tissues and in many contexts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biofrontier Platform, Graduate School of Medicine, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. ito.shinji.3v@kyoto-u.ac.jp

ABSTRACT

Background: Periplakin (PPL) is a rod-shaped cytolinker protein thought to connect cellular adhesion junctional complexes to cytoskeletal filaments. PPL serves as a structural component of the cornified envelope in the skin and interacts with various types of proteins in cultured cells; its level decreases dramatically during tumorigenic progression in human epithelial tissues. Despite these intriguing observations, the physiological roles of PPL, especially in non-cutaneous tissues, are still largely unknown. Because we observed a marked fluctuation of PPL expression in mouse liver in association with the bile acid receptor farnesoid X receptor (FXR) and cholestasis, we sought to characterize the role of PPL in the liver and determine its contributions to the etiology and pathogenesis of cholestasis.

Methods: Time- and context-dependent expression of PPL in various mouse models of hepatic and renal disorders were examined by immunohistochemistry, western blotting, and quantitative real-time polymerase chain reactions.

Results: The hepatic expression of PPL was significantly decreased in Fxr-/- mice. In contrast, the expression was dramatically increased during cholestasis, with massive PPL accumulation observed at the boundaries of hepatocytes in wild-type mice. Interestingly, the hepatic accumulation of PPL resulting from cholestasis was reversible. In addition, similar accumulation of PPL at cellular boundaries was found in epithelial cells around renal tubules upon ureteral obstruction.

Conclusions: PPL may be involved in the temporal accommodation to fluid stasis in different tissues. Further examination of the roles for PPL may lead to the discovery of a novel mechanism for cellular protection by cytolinkers that is applicable to many tissues and in many contexts.

Show MeSH
Related in: MedlinePlus