Integrin β3-mediated Src activation regulates apoptosis in IEC-6 cells via Akt and STAT3

Sujoy Bhattacharya, Ramesh M. Ray, Leonard R. Johnson

Research output: Contribution to journalArticle

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Abstract

Intestinal epithelial (IEC-6) cells are resistant to apoptosis following the inhibition of ODC (ornithine decarboxylase) and subsequent polyamine depletion. The depletion of polyamines rapidly activates NF-κB (nuclear factor κB) and STAT3 (signal transducer and activator of transcription 3), which is responsible for the observed decrease in apoptosis. Since both NF-κB and STAT3 signalling pathways can be activated by Src kinase, we examined its role in the antiapoptotic response. Inhibition of ODC by DFMO (α-difluoromethylornithine) increased the activity of Src and ERK1/2 (extracellular-signal-regulated kinase 1/2) within 30 min, which was prevented by exogenous polyamines added to the DFMO-containing medium. Conversely, epidermal growth factor-mediated Src and ERK1/2 activation was not prevented by the addition of polyamines. Inhibition of Src with PP2 {4-amino-5-(4- chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine} and a DN-Src (dominant-negative Src) construct prevented the activation of Akt, JAK (Janus kinase) and STAT3. Spontaneous apoptosis was increased in DN-Src-expressing cells and the protective effect of polyamine depletion was lost. Polyamine depletion by DFMO increased integrin β3 Tyr785 phosphorylation. Cells plated on fibronectin had significantly higher β3 phosphorylation and Src activation compared with plastic. Exogenous polyamines added to the fibronectin matrix prevented Src activation. Arg-Gly-Asp-Ser inhibited β3, Src and Akt phosphorylation and sensitized polyamine-depleted cells to tumour necrosis factor α/cycloheximide-mediated apoptosis. Fibronectin activated Src and subsequently protected cells from apoptosis. Together, these results suggest that the inhibition of ODC rapidly removes a small pool of available polyamines triggering the activation of β3 integrin, which in turn activates Src. The subsequent Akt and JAK activation is accompanied by translocation of NF-κB and STAT3 to the nucleus and the synthesis of antiapoptotic proteins.

Original languageEnglish (US)
Pages (from-to)437-447
Number of pages11
JournalBiochemical Journal
Volume397
Issue number3
DOIs
StatePublished - Aug 1 2006

Fingerprint

STAT3 Transcription Factor
Polyamines
Integrins
Chemical activation
Apoptosis
Eflornithine
Phosphorylation
Ornithine Decarboxylase
Fibronectins
Janus Kinases
Mitogen-Activated Protein Kinase 3
Mitogen-Activated Protein Kinase 1
arginyl-glycyl-aspartyl-serine
src-Family Kinases
Cycloheximide
Epidermal Growth Factor
Plastics
Tumor Necrosis Factor-alpha

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Integrin β3-mediated Src activation regulates apoptosis in IEC-6 cells via Akt and STAT3. / Bhattacharya, Sujoy; Ray, Ramesh M.; Johnson, Leonard R.

In: Biochemical Journal, Vol. 397, No. 3, 01.08.2006, p. 437-447.

Research output: Contribution to journalArticle

Bhattacharya, Sujoy ; Ray, Ramesh M. ; Johnson, Leonard R. / Integrin β3-mediated Src activation regulates apoptosis in IEC-6 cells via Akt and STAT3. In: Biochemical Journal. 2006 ; Vol. 397, No. 3. pp. 437-447.
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