Dataset Information

A trigger model of apoptosis induced by tumor necrosis factor signaling.

ABSTRACT: BACKGROUND: The ability of living cells to respond appropriately to apoptosis signals is crucial for the proper development and homeostasis of multicellular organisms. For example, viable cells must be stable enough to appropriately respond to apoptosis signaling so that an irreversible death program is only induced when apoptosis signaling reaches a certain threshold. Previous studies have introduced bistability models in which signaling by caspase-3 activity represents a key regulator of cell fate in response to apoptosis stimuli. RESULTS: In this study, apoptosis induced by tumor necrosis factor (TNF) signaling is investigated, and a mathematical model without the requirement for bistability is proposed. In this model, rapid degradation of the active forms of caspases -8 and -3 are included, and TNF-signaling is found to induce a pulse of caspase-3 activation and trigger an irreversible death program. This result agrees with experimental observations. The ability of a cell to respond to, or resist, apoptosis stimuli is also discussed. Furthermore, the activation efficiencies of caspases -8 and -3 that are essential to a cell's response to extracellular apoptosis stimuli are defined. Based on the simulations performed, it is observed that activation efficiencies must be sufficiently sensitive to appropriately compromise a cell's resistance and effectiveness in response to apoptosis stimuli. CONCLUSIONS: Our results suggest that bistability may not be a necessary condition for the induction of apoptosis by TNF signaling. Rather, a sharp increase in caspase-3 activity might be sufficient to trigger the induction of an irreversible death program. Accordingly, regulation of caspase activity and degradation of active caspases is essential for a cell's response to apoptosis stimuli.

SUBMITTER: Gu C

PROVIDER: S-EPMC3121113 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A trigger model of apoptosis induced by tumor necrosis factor signaling.

Gu Chang C Zhang Junjie J Chen Yingyu Y Lei Jinzhi J

BMC systems biology 20110620

<h4>Background</h4>The ability of living cells to respond appropriately to apoptosis signals is crucial for the proper development and homeostasis of multicellular organisms. For example, viable cells must be stable enough to appropriately respond to apoptosis signaling so that an irreversible death program is only induced when apoptosis signaling reaches a certain threshold. Previous studies have introduced bistability models in which signaling by caspase-3 activity represents a key regulator o ...[more]

PMID: 21689472

Similar Datasets

Project description:BackgroundThe mechanisms triggering nonalcoholic steatohepatitis (NASH) remain poorly defined.ResultsKupffer cells are the first responding cells to hepatocyte injuries, leading to TNF? production, chemokine induction, and monocyte recruitment. The silencing of TNF? in myeloid cells reduces NASH progression.ConclusionIncrease of TNF?-producing Kupffer cells is crucial for triggering NASH via monocyte recruitment.SignificanceMyeloid cells-targeted silencing of TNF? might be a tenable therapeutic approach. Nonalcoholic steatohepatitis (NASH), characterized by lipid deposits within hepatocytes (steatosis), is associated with hepatic injury and inflammation and leads to the development of fibrosis, cirrhosis, and hepatocarcinoma. However, the pathogenic mechanism of NASH is not well understood. To determine the role of distinct innate myeloid subsets in the development of NASH, we examined the contribution of liver resident macrophages (i.e. Kupffer cells) and blood-derived monocytes in triggering liver inflammation and hepatic damage. Employing a murine model of NASH, we discovered a previously unappreciated role for TNF? and Kupffer cells in the initiation and progression of NASH. Sequential depletion of Kupffer cells reduced the incidence of liver injury, steatosis, and proinflammatory monocyte infiltration. Furthermore, our data show a differential contribution of Kupffer cells and blood monocytes during the development of NASH; Kupffer cells increased their production of TNF?, followed by infiltration of CD11b(int)Ly6C(hi) monocytes, 2 and 10 days, respectively, after starting the methionine/choline-deficient (MCD) diet. Importantly, targeted knockdown of TNF? expression in myeloid cells decreased the incidence of NASH development by decreasing steatosis, liver damage, monocyte infiltration, and the production of inflammatory chemokines. Our findings suggest that the increase of TNF?-producing Kupffer cells in the liver is crucial for the early phase of NASH development by promoting blood monocyte infiltration through the production of IP-10 and MCP-1.

Dataset Information

A trigger model of apoptosis induced by tumor necrosis factor signaling.

Publications

A trigger model of apoptosis induced by tumor necrosis factor signaling.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets