Stories about: Hao Wu

When antibiotics fail: A potential new angle on severe bacterial infection and sepsis

bacterial infection sepsisBacterial infections that don’t respond to antibiotics are of rising concern. And so is sepsis — the immune system’s last-ditch, failed attack on infection that ends up being lethal itself. Sepsis is the largest killer of newborns and children worldwide and, in the U.S. alone, kills a quarter of a million people each year. Like antibiotic-resistant infections, it has no good treatment.

Reporting this week in Nature, scientists in Boston Children’s Hospital’s Program in Cellular and Molecular Medicine (PCMM) describe new potential avenues for controlling both sepsis and the runaway bacterial infections that provoke it.

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Science seen: A “wheel of death” for bacteria

inflammasome innate immunity

The innate immune system acts like a border patrol for the body, picking up bacteria and other invading pathogens using molecular sensors. One key player is the inflammasome, a multi-protein complex depicted here through cryo-electron microscopy (cryo-EM). Using structural biology tools like cryo-EM and X-ray crystallography, the Wu lab in Boston Children’s Hospital’s Program in Cellular and Molecular Medicine show how protein components come together in inflammasomes to form a “wheel of death” against bacterial infection.

Once they detect an invader, inflammasomes send out signals that trigger infected cells to die using an inflammatory death pathway called pyroptosis. They also call for backup from the adaptive immune system, in the form of inflammation. (Image: Wu laboratory/Liman Zhang)

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Putting structure around the genetic basis of some immune diseases

The saying in the design world is that form follows function. But in biology, and protein biology in particular, it would be more correct to say that form begets function. Shape and structure are the foundation for most protein-based interactions in cells, and are why basic functions like receptor binding, antibody neutralization and gene transcription work.

Two enzymes in the immune system’s B cells, called RAG1 and RAG2, are a perfect example. Together, they form a complex that splices antibody-producing genes together in unique combinations through a process called V(D)J recombination. They do a similar job in T cells to build antigen-binding T-cell receptors (TCRs). In either case, the enzymes are essential to a robust immune response.

In a recent Cell paper, a team led by Hao Wu, PhD, of the Program in Cellular and Molecular Medicine (PCMM) at Boston Children’s Hospital and Maofu Liao, PhD, at Harvard Medical School used electronic microscopy to reveal how RAG1 and 2 interact at a structural level, both with each other and with DNA. The structural biology images they’ve created show plainly what mutations in the genes for these proteins do to cause disease.

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