Nuclear serine protease activity contributes to bile acid-induced apoptosis in hepatocytes

P. Kwo, Tushar C Patel, S. F. Bronk, Gregory James Gores

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98 Citations (Scopus)

Abstract

Glycodeoxycholate (GDC) induces apoptosis in hepatocytes by a mechanism associated with DNA cleavage by endonucleases. In many models of apoptosis, proteolysis is required prior to DNA cleavage. Our aims were to determine if enhanced proteolysis is a mechanism causing GDC-mediated apoptosis. In cultured rat hepatocytes exposed to 50 μM GDC for 4 h, nonlysosomal proteolysis increased by 65% compared with controls. The serine protease inhibitor Na-p-tosyl-L-lysine chloromethyl ketone (TLCK; 100 μM) reduced cell death from apoptosis by 75% after 4 h of treatment with GDC. TLCK also inhibited DNA fragmentation. There was a twofold increase in nuclear serinelike protease activity during GDC-induced apoptosis accompanied by a 2.5-fold reduction in nonnuclear serine protease activity, suggesting translocation of the protease from the cytosol to the nucleus. Zn2+, an inhibitor of apoptosis, also inhibited nonlysosomal proteolysis and nuclear serinelike protease activity. These novel data suggest that nonlysosomal serinelike protease activity contributes to hepatocyte apoptosis. These data may be important in understanding apoptosis in other cell types and in providing insight into the mechanisms of liver injury during cholestasis.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume268
Issue number4 31-4
StatePublished - 1995

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Serine Proteases
bile acids
serine proteinases
Glycodeoxycholic Acid
Bile Acids and Salts
hepatocytes
Hepatocytes
apoptosis
Apoptosis
proteolysis
Proteolysis
Tosyllysine Chloromethyl Ketone
Peptide Hydrolases
proteinases
DNA Cleavage
cholestasis
Serine Proteinase Inhibitors
Deoxyribonuclease I
Cholestasis
DNA fragmentation

Keywords

  • acridine orange
  • bile salts
  • cholestasis
  • deoxyribonucleic acid fragmentation
  • endonucleases
  • nuclear proteases
  • protease inhibitors
  • serine proteases
  • zinc

ASJC Scopus subject areas

  • Physiology
  • Gastroenterology
  • Agricultural and Biological Sciences(all)

Cite this

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title = "Nuclear serine protease activity contributes to bile acid-induced apoptosis in hepatocytes",
abstract = "Glycodeoxycholate (GDC) induces apoptosis in hepatocytes by a mechanism associated with DNA cleavage by endonucleases. In many models of apoptosis, proteolysis is required prior to DNA cleavage. Our aims were to determine if enhanced proteolysis is a mechanism causing GDC-mediated apoptosis. In cultured rat hepatocytes exposed to 50 μM GDC for 4 h, nonlysosomal proteolysis increased by 65{\%} compared with controls. The serine protease inhibitor Na-p-tosyl-L-lysine chloromethyl ketone (TLCK; 100 μM) reduced cell death from apoptosis by 75{\%} after 4 h of treatment with GDC. TLCK also inhibited DNA fragmentation. There was a twofold increase in nuclear serinelike protease activity during GDC-induced apoptosis accompanied by a 2.5-fold reduction in nonnuclear serine protease activity, suggesting translocation of the protease from the cytosol to the nucleus. Zn2+, an inhibitor of apoptosis, also inhibited nonlysosomal proteolysis and nuclear serinelike protease activity. These novel data suggest that nonlysosomal serinelike protease activity contributes to hepatocyte apoptosis. These data may be important in understanding apoptosis in other cell types and in providing insight into the mechanisms of liver injury during cholestasis.",
keywords = "acridine orange, bile salts, cholestasis, deoxyribonucleic acid fragmentation, endonucleases, nuclear proteases, protease inhibitors, serine proteases, zinc",
author = "P. Kwo and Patel, {Tushar C} and Bronk, {S. F.} and Gores, {Gregory James}",
year = "1995",
language = "English (US)",
volume = "268",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
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T1 - Nuclear serine protease activity contributes to bile acid-induced apoptosis in hepatocytes

AU - Kwo, P.

AU - Patel, Tushar C

AU - Bronk, S. F.

AU - Gores, Gregory James

PY - 1995

Y1 - 1995

N2 - Glycodeoxycholate (GDC) induces apoptosis in hepatocytes by a mechanism associated with DNA cleavage by endonucleases. In many models of apoptosis, proteolysis is required prior to DNA cleavage. Our aims were to determine if enhanced proteolysis is a mechanism causing GDC-mediated apoptosis. In cultured rat hepatocytes exposed to 50 μM GDC for 4 h, nonlysosomal proteolysis increased by 65% compared with controls. The serine protease inhibitor Na-p-tosyl-L-lysine chloromethyl ketone (TLCK; 100 μM) reduced cell death from apoptosis by 75% after 4 h of treatment with GDC. TLCK also inhibited DNA fragmentation. There was a twofold increase in nuclear serinelike protease activity during GDC-induced apoptosis accompanied by a 2.5-fold reduction in nonnuclear serine protease activity, suggesting translocation of the protease from the cytosol to the nucleus. Zn2+, an inhibitor of apoptosis, also inhibited nonlysosomal proteolysis and nuclear serinelike protease activity. These novel data suggest that nonlysosomal serinelike protease activity contributes to hepatocyte apoptosis. These data may be important in understanding apoptosis in other cell types and in providing insight into the mechanisms of liver injury during cholestasis.

AB - Glycodeoxycholate (GDC) induces apoptosis in hepatocytes by a mechanism associated with DNA cleavage by endonucleases. In many models of apoptosis, proteolysis is required prior to DNA cleavage. Our aims were to determine if enhanced proteolysis is a mechanism causing GDC-mediated apoptosis. In cultured rat hepatocytes exposed to 50 μM GDC for 4 h, nonlysosomal proteolysis increased by 65% compared with controls. The serine protease inhibitor Na-p-tosyl-L-lysine chloromethyl ketone (TLCK; 100 μM) reduced cell death from apoptosis by 75% after 4 h of treatment with GDC. TLCK also inhibited DNA fragmentation. There was a twofold increase in nuclear serinelike protease activity during GDC-induced apoptosis accompanied by a 2.5-fold reduction in nonnuclear serine protease activity, suggesting translocation of the protease from the cytosol to the nucleus. Zn2+, an inhibitor of apoptosis, also inhibited nonlysosomal proteolysis and nuclear serinelike protease activity. These novel data suggest that nonlysosomal serinelike protease activity contributes to hepatocyte apoptosis. These data may be important in understanding apoptosis in other cell types and in providing insight into the mechanisms of liver injury during cholestasis.

KW - acridine orange

KW - bile salts

KW - cholestasis

KW - deoxyribonucleic acid fragmentation

KW - endonucleases

KW - nuclear proteases

KW - protease inhibitors

KW - serine proteases

KW - zinc

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