Rational Selection of Syngeneic Preclinical Tumor Models for Immunotherapeutic Drug Discovery.

Murine syngeneic tumor models are critical to novel immuno-based therapy development, but the molecular and immunologic features of these models are still not clearly defined. The translational relevance of differences between the models is not fully understood, impeding appropriate preclinical model selection for target validation, and ultimately hindering drug development. Across a panel of commonly used murine syngeneic tumor models, we showed variable responsiveness to immunotherapies.

Structural basis of the C1q/C1s interaction and its central role in assembly of the C1 complex of complement activation.

Complement component C1, the complex that initiates the classical pathway of complement activation, is a 790-kDa assembly formed from the target-recognition subcomponent C1q and the modular proteases C1r and C1s. The proteases are elongated tetramers that become more compact when they bind to the collagen-like domains of C1q. Here, we describe a series of structures that reveal how the subcomponents associate to form C1.

Regulation of T lymphopoiesis by Notch1 and Lunatic fringe-mediated competition for intrathymic niches.

Notch1 activation regulates T lineage commitment and early T cell development. Fringe glycosyltransferases alter the sensitivity of Notch receptors to Delta-like versus Jagged Notch ligands, but their functions in T lymphopoiesis have not been defined. Here we show that developmental stage-specific expression of the glycosyltransferase lunatic fringe (Lfng) is required for coordination of the access of T cell progenitors to intrathymic niches that support Notch1-dependent phases of T cell development.

Fine-tuning Notch1 activation by endocytosis and glycosylation.

Recent studies have shown that disruption of Notch1 signaling in lymphocyte progenitors (LP) inhibits T cell development and promotes B cell development in the thymus. Conversely, inappropriate activation of Notch1 in LP inhibits B cell development and causes ectopic T cell development in the bone marrow. These observations imply that Notch1 activation must be spatially regulated to ensure that LP generate B cells in the bone marrow and T cells in the thymus.

Superoxide activates mitochondrial uncoupling proteins.

Uncoupling protein 1 (UCP1) diverts energy from ATP synthesis to thermogenesis in the mitochondria of brown adipose tissue by catalysing a regulated leak of protons across the inner membrane. The functions of its homologues, UCP2 and UCP3, in other tissues are debated. UCP2 and UCP3 are present at much lower abundance than UCP1, and the uncoupling with which they are associated is not significantly thermogenic.

Artifactual uncoupling by uncoupling protein 3 in yeast mitochondria at the concentrations found in mouse and rat skeletal-muscle mitochondria.

Western blots detected uncoupling protein 3 (UCP3) in skeletal-muscle mitochondria from wild-type but not UCP3 knock-out mice. Calibration with purified recombinant UCP3 showed that mouse and rat skeletal muscle contained 0.14 microg of UCP3/mg of mitochondrial protein.

The basal proton conductance of skeletal muscle mitochondria from transgenic mice overexpressing or lacking uncoupling protein-3.

The ability of native uncoupling protein-3 (UCP3) to uncouple mitochondrial oxidative phosphorylation is controversial. We measured the expression level of UCP3 and the proton conductance of skeletal muscle mitochondria isolated from transgenic mice overexpressing human UCP3 (UCP3-tg) and from UCP3 knockout (UCP3-KO) mice. The concentration of UCP3 in UCP3-tg mitochondria was approximately 3 microg/mg protein, approximately 20-fold higher than the wild type value.