Related Experiment Videos
beta1 integrin antagonism on adherent, differentiated human neuroblastoma cells triggers an apoptotic signaling
1Department of Immunology, The Scripps Research Institute, La Jolla, CA 90237, USA.
Abstract:
Integrin receptors mediate several functions including prevention of matrix detachment-induced apoptosis (anoikis) of several adherent cell types. We report here that antagonists of beta1 integrins trigger an apoptotic signaling pathway in adherent differentiated LAN-5 human neuroblastoma cells, a cell line which represents a model system for the study of human neurons. The pathway is characterized by cytochrome c release into the cytoplasm, and activation of caspase-9 and caspase-3, 4-6h after treatment; cleavage products of caspase-8 and caspase-2 were not detectable in the cells. Coordinate inactivation of cell survival pathways, including cleavage of focal adhesion kinase, decreased expression of protein kinase B, and reduced phosphorylation of the pro-apoptotic protein, Bad, also characterized the signaling pathway. These events occurred in adherent cells; DNA fragmentation and detachment followed as late events 18-24h after addition of beta1 integrin antagonists. zDEVD-fmk, an irreversible inhibitor of caspase-3-like enzymes, and cytochalasin D, an actin depolymerizing agent, blocked caspase-3 cleavage and delayed cell death. In contrast to these results, undifferentiated, adherent and dividing LAN-5 cells did not die in response to beta1 integrin antagonists. These studies identify a distinct apoptotic pathway which is triggered by antagonists of beta1 integrins on differentiated adherent neuronal cells.
Insights
Beta1 integrin antagonists trigger apoptosis in differentiated neuronal cells by activating caspases and inhibiting survival pathways. This distinct cell death pathway highlights beta1 integrins
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Integrin receptors are crucial for cell adhesion and survival, preventing anoikis (detachment-induced apoptosis).
- LAN-5 human neuroblastoma cells serve as a model for studying neuronal apoptosis.
Purpose of the Study:
- To investigate the role of beta1 integrins in apoptosis of differentiated neuronal cells.
- To elucidate the signaling pathway triggered by beta1 integrin antagonists.
Main Methods:
- Treatment of differentiated and undifferentiated LAN-5 cells with beta1 integrin antagonists.
- Analysis of apoptotic markers including cytochrome c release, caspase activation (caspase-3, -9, -8, -2), and DNA fragmentation.
- Assessment of cell survival pathways involving focal adhesion kinase, protein kinase B, and Bad phosphorylation.
- Inhibition studies using zDEVD-fmk (caspase-3 inhibitor) and cytochalasin D (actin depolymerizing agent).
Main Results:
- Beta1 integrin antagonists induced apoptosis in differentiated LAN-5 cells, characterized by cytochrome c release and caspase-9/-3 activation.
- Cell survival pathways were inactivated, evidenced by focal adhesion kinase cleavage and reduced protein kinase B/Bad phosphorylation.
- DNA fragmentation and cell detachment were late events.
- Undifferentiated LAN-5 cells did not undergo apoptosis in response to beta1 integrin antagonists.
- Caspase inhibition and actin depolymerization delayed cell death.
Conclusions:
- Beta1 integrin antagonists trigger a distinct apoptotic pathway in differentiated adherent neuronal cells.
- This pathway involves caspase activation and inactivation of pro-survival signaling.
- The response is specific to differentiated neuronal cells, suggesting a role for cell differentiation status.