The Global COVID-19 Observatory and Resource Center for Childhood Cancer: A response for the pediatric oncology community by SIOP and St. Jude Global

The COVID-19 pandemic quickly led to an abundance of publications and recommendations, despite a paucity of information on how COVID-19 affects children with cancer. This created a dire need for a trusted resource with curated information and a space for the pediatric oncology community to share experiences. The Global COVID-19 Observatory and Resource Center for Childhood Cancer was developed, launched, and maintained by the International Society of Pediatric Oncology and St. Jude Children's Research Hospital. The three components (Resource Library, Global Registry, and Collaboration Space) complement each other, establishing a mechanism to generate and transfer knowledge rapidly throughout the community

Electrostatic Effects in the Folding of the SH3 Domain of the c-Src Tyrosine Kinase: pH-Dependence in 3D-Domain Swapping and Amyloid Formation

The SH3 domain of the c-Src tyrosine kinase (c-Src-SH3) aggregates to form intertwined dimers and amyloid fibrils at mild acid pHs. In this work, we show that a single mutation of residue Gln128 of this SH3 domain has a significant effect on: (i) its thermal stability; and (ii) its propensity to form amyloid fibrils. The Gln128Glu mutant forms amyloid fibrils at neutral pH but not at mild acid pH, while Gln128Lys and Gln128Arg mutants do not form these aggregates under any of the conditions assayed. We have also solved the crystallographic structures of the wild-type (WT) and Gln128Glu, Gln128Lys and Gln128Arg mutants from crystals obtained at different pHs. At pH 5.0, crystals belong to the hexagonal space group P6522 and the asymmetric unit is formed by one chain of the protomer of the c-Src-SH3 domain in an open conformation. At pH 7.0, crystals belong to the orthorhombic space group P212121, with two molecules at the asymmetric unit showing the characteristic fold of the SH3 domain. Analysis of these crystallographic structures shows that the residue at position 128 is connected to Glu106 at the diverging β-turn through a cluster of water molecules. Changes in this hydrogen-bond network lead to the displacement of the c-Src-SH3 distal loop, resulting also in conformational changes of Leu100 that might be related to the binding of proline rich motifs. Our findings show that electrostatic interactions and solvation of residues close to the folding nucleation site of the c-Src-SH3 domain might play an important role during the folding reaction and the amyloid fibril formation.This research was funded by the Spanish Ministry of Science and Innovation and Ministry of Economy and Competitiveness and FEDER (EU): BIO2009-13261-C02-01/02 (ACA); BIO2012-39922-C02-01/02 (ACA); CTQ2013-4493 (JLN) and CSD2008-00005 (JLN); Andalusian Regional Government (Spain) and FEDER (EU): P09-CVI-5063 (ACA); and Valentian Regional Government (Spain) and FEDER (EU): Prometeo 2013/018 (JLN). Data collection was supported by European Synchrotron Radiation Facility (ESRF), Grenoble, France: BAG proposals MX-1406 (ACA) and MX-1541 (ACA); and ALBA (Barcelona, Spain) proposals 2012010072 (ACA) and 2012100378 (ACA)

The nuclear receptor LXRα controls the functional specialization of splenic macrophages

Macrophages are professional phagocytic cells that orchestrate innate immune responses and display remarkable phenotypic diversity at different anatomical locations. However, the mechanisms that control the heterogeneity of tissue macrophages are not well characterized. Here, we report that the nuclear receptor LXRα is essential for the differentiation of macrophages in the marginal zone (MZ) of the spleen. LXR deficient mice are defective in the generation of MZ and metallophilic macrophages, resulting in abnormal responses to blood-borne antigens. Myeloid specific expression of LXRα or adoptive transfer of wild-type monocytes rescues the MZ microenvironment in LXRα deficient mice. These results demonstrate that LXRα signaling in myeloid cells is crucial for the generation of splenic MZ macrophages and reveal an unprecedented role for a nuclear receptor in the generation of specialized macrophage subsets