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CD95 (Fas/Apo-1)-induced apoptosis results in loss of glucose transporter function
M V Berridge1, A S Tan, K D McCoy
1Malaghan Institute of Medical Research, Wellington School of Medicine, Wellington, New Zealand.
Abstract:
Treatment of activated human T cells with CD95 (Fas/Apo-1) ligand or Abs against CD95 results in apoptotic cell death. Although cellular responses to CD95 ligation have been described in some detail, the early molecular events that result in T cell death are only now beginning to be elucidated. Using Jurkat cells as a model of activated human T cells, we have investigated the effects of CD95 ligation on glucose transport and on glucose transporter function. We show that within minutes of CD95 activation, the ability to transport glucose across the plasma membrane is compromised and that transient exposure to Abs against CD95 for as little as 3 min results in reduced glucose transport and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) responses measured at 16 h. The effects of CD95 ligation on glucose transport are shown to be associated with loss of affinity of glucose transporters for glucose without altered maximum velocity and without changes in the cell surface expression of Glut 1, the predominant glucose transporter isotype on Jurkat cells. These results support a model of CD95 induced cell death that, at least in its early stages, does not depend on signaling to the nucleus or on macromolecular synthesis. Acute regulation of glucose transport is proposed to be an early effector mechanism in CD95-induced apoptotic cell death.
Insights
CD95 ligation rapidly impairs glucose transport in T cells, preceding cell death. This early effect on glucose transporters occurs without nuclear signaling or new protein synthesis, suggesting a novel mechanism in apoptosis.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- CD95 (Fas/Apo-1) ligand binding triggers apoptosis in activated human T cells.
- Early molecular events leading to CD95-induced T cell death are not fully understood.
Purpose of the Study:
- Investigate the impact of CD95 ligation on glucose transport and transporter function in activated T cells.
- Elucidate the role of glucose transport regulation in early stages of CD95-mediated apoptosis.
Main Methods:
- Utilized Jurkat cells as a model for activated human T cells.
- Assessed glucose transport and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) responses following CD95 activation.
- Analyzed glucose transporter (Glut 1) affinity and cell surface expression.
Main Results:
- CD95 ligation rapidly reduced glucose transport capacity within minutes.
- Short exposure to anti-CD95 antibodies (3 min) led to decreased glucose transport and MTT responses at 16 hours.
- CD95 ligation decreased glucose transporter affinity for glucose without altering maximum velocity or Glut 1 surface expression.
Conclusions:
- Acute regulation of glucose transport is an early effector mechanism in CD95-induced T cell death.
- Early stages of CD95-mediated apoptosis may not require nuclear signaling or macromolecular synthesis.
- CD95 ligation affects glucose transporter function, impacting cellular metabolism during apoptosis induction.