In Nature this week, researchers at Rockefeller University in New York say intravenous gammaglobulin suppresses inflammation through a novel TH2 pathway. The researchers generated humanized DC-SIGN mice to demonstrate that the anti-inflammatory activity of immunoglobulin can be recreated by the transfer of bone-marrow-derived sFc-treated hDC-SIGN+ macrophages or dendritic cells into naive recipients. This results in the production of IL-33, which then induces expansion of IL-4-producing basophils that promote increased expression of the inhibitory Fc receptor FcγRIIB on effector macrophages. "Systemic administration of the TH2 cytokines IL-33 or IL-4 upregulates FcγRIIB on macrophages, and suppresses serum-induced arthritis. Consistent with these results, transfer of IL-33-treated basophils suppressed induced arthritic inflammation," the authors write. "This novel DC-SIGN–TH2 pathway initiated by an endogenous ligand, sFc, provides an intrinsic mechanism for maintaining immune homeostasis."
Also in Nature this week, researchers at Harvard Medical School use integrative genomics to identify MCU as an essential component of the mitochondrial calcium uniporter. Using genome phylogenetic profiling, genome-wide RNA co-expression analysis and organelle-wide protein coexpression analysis, the team predicted proteins functionally related to MICU1, which previous studies have shown serves as a putative regulator of the uniporter, and all three methods pointed to the transmembrane protein CCDC109A — what the researchers dubbed the "mitochondrial calcium uniporter," or MCU. "MCU forms oligomers in the mitochondrial inner membrane, physically interacts with MICU1, and resides within a large molecular weight complex," the authors write. "Silencing MCU in cultured cells or in vivo in mouse liver severely abrogates mitochondrial Ca2+ uptake, whereas mitochondrial respiration and membrane potential remain fully intact."
Nature presents an outlook on biofuels this week, with articles on various biofuel projects, benefits to the economy, and the political climate surrounding biofuels. In one article, Neil Savage writes about the use of algae as a biofuel — last year, the US Department of Energy gave $44 million to create a research consortium to advance algal biofuel technology, and industry is also ramping up its efforts to make a viable biofuel out of algae. Aircraft maker Boeing has helped establish the Algal Biomass Organization to promote the use of algal jet fuel, Savage adds. "Genetic engineering could create algae that produce more oil and are more efficient at converting solar energy to biomass. Engineers are working on improved designs for growth systems, such as structures that stack algae in layers for better sunlight exposure, and harvesting systems that could use microwaves or sound waves to extract the oil," he says.
And finally in Nature this week, researchers in California and Morocco present findings from a study of the structural basis of steroid hormone perception by the receptor kinase BRI1. The team reports the structure of the Arabidopsis thaliana BRI1 ligand-binding domain, and finds a superhelix of 25 twisted leucine-rich repeats, "an architecture that is strikingly different from the assembly of LRRs in animal Toll-like receptors." The authors say that steroid binding to BRI1 generates a docking platform for a co-receptor that is required for receptor activation.