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Protection against fatal Sindbis virus encephalitis by beclin, a novel Bcl-2-interacting protein
X H Liang1, L K Kleeman, H H Jiang
1Departments of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Abstract:
bcl-2, the prototypic cellular antiapoptotic gene, decreases Sindbis virus replication and Sindbis virus-induced apoptosis in mouse brains, resulting in protection against lethal encephalitis. To investigate potential mechanisms by which Bcl-2 protects against central nervous system Sindbis virus infection, we performed a yeast two-hybrid screen to identify Bcl-2-interacting gene products in an adult mouse brain library. We identified a novel 60-kDa coiled-coil protein, Beclin, which we confirmed interacts with Bcl-2 in mammalian cells, using fluorescence resonance energy transfer microscopy. To examine the role of Beclin in Sindbis virus pathogenesis, we constructed recombinant Sindbis virus chimeras that express full-length human Beclin (SIN/beclin), Beclin lacking the putative Bcl-2-binding domain (SIN/beclinDeltaBcl-2BD), or Beclin containing a premature stop codon near the 5' terminus (SIN/beclinstop). The survival of mice infected with SIN/beclin was significantly higher (71%) than the survival of mice infected with SIN/beclinDeltaBcl-2BD (9%) or SIN/beclinstop (7%) (P < 0.001). The brains of mice infected with SIN/beclin had fewer Sindbis virus RNA-positive cells, fewer apoptotic cells, and lower viral titers than the brains of mice infected with SIN/beclinDeltaBcl-2BD or SIN/beclinstop. These findings demonstrate that Beclin is a novel Bcl-2-interacting cellular protein that may play a role in antiviral host defense.
Insights
The anti-apoptotic gene Bcl-2 protects against lethal encephalitis by reducing Sindbis virus replication. A novel protein, Beclin, interacts with Bcl-2 and enhances host defense against viral infection.
Area of Science:
- Neurovirology
- Molecular Biology
- Immunology
Background:
- The anti-apoptotic gene bcl-2 confers protection against lethal Sindbis virus encephalitis in mice.
- Understanding the molecular mechanisms of Bcl-2-mediated protection is crucial for developing antiviral strategies.
Purpose of the Study:
- To identify Bcl-2-interacting proteins in the central nervous system involved in Sindbis virus infection.
- To elucidate the role of the identified protein, Beclin, in Sindbis virus pathogenesis and antiviral defense.
Main Methods:
- Yeast two-hybrid screening of an adult mouse brain library to identify Bcl-2 interacting partners.
- Confirmation of Bcl-2 and Beclin interaction using fluorescence resonance energy transfer (FRET) microscopy.
- Construction and infection of mice with recombinant Sindbis viruses expressing different forms of Beclin.
Main Results:
- A novel 60-kDa coiled-coil protein, Beclin, was identified as a Bcl-2 interacting partner.
- Mice infected with Sindbis virus expressing full-length Beclin (SIN/beclin) showed significantly higher survival rates (71%) compared to controls.
- SIN/beclin infected brains exhibited reduced viral RNA, apoptosis, and viral titers, indicating Beclin's role in antiviral defense.
Conclusions:
- Beclin is a novel Bcl-2-interacting protein with a potential role in antiviral host defense.
- Beclin expression enhances protection against Sindbis virus infection in the central nervous system.
- Targeting Beclin-Bcl-2 interactions may offer therapeutic avenues for viral encephalitis.