GPC3-Unc5 receptor complex structure and role in cell migration.

Neural migration is a critical step during brain development that requires the interactions of cell-surface guidance receptors. Cancer cells often hijack these mechanisms to disseminate. Here, we reveal crystal structures of Uncoordinated-5 receptor D (Unc5D) in complex with morphogen receptor glypican-3 (GPC3), forming an octameric glycoprotein complex. In the complex, four Unc5D molecules pack into an antiparallel bundle, flanked by four GPC3 molecules. Central glycan-glycan interactions are formed by N-linked glycans emanating from GPC3 (N241 in human) and C-mannosylated tryptophans of the Unc5D thrombospondin-like domains. MD simulations, mass spectrometry and structure-based mutants validate the crystallographic data. Anti-GPC3 nanobodies enhance or weaken Unc5-GPC3 binding and, together with mutant proteins, show that Unc5/GPC3 guide migrating pyramidal neurons in the mouse cortex, and cancer cells in an embryonic xenograft neuroblastoma model. The results demonstrate a conserved structural mechanism of cell guidance, where finely balanced Unc5-GPC3 interactions regulate cell migration.

Characteristics of peripheral blood differential counts in hospitalized patients with COVID-19.

BACKGROUND: A lot remains unknown about the features and laboratory findings that may predict worse outcomes in patients with coronavirus disease 2019 (COVID-19). The aim of this study was to evaluate the difference in complete blood count parameters and differential counts in patients hospitalized with COVID-19 who survived compared to those who died. DESIGN: We performed a single-center retrospective study including 242 patients with confirmed COVID-19. We described the characteristics of the complete blood count parameters in these patients. Mann-Whitney U test was used to compare hematologic parameters of patients who died and those who survived; multivariate logistic regression was used to look for associations with mortality. RESULTS: Patients with COVID-19 who died had significantly lower median absolute monocyte count (AMC) (0.4 vs 0.5, P = .039) and median platelet count (169 vs 213, P = .009) compared to those who survived. Patients who died had a significantly higher neutrophil-to-lymphocyte ratio (6.4 vs 4.5, P = .001). The NLR was positively associated with death (OR = 1.038; 95% CI, 1.003-1.074, P = .031), while AMC was inversely associated with death (OR = 0.200; 95% CI, 0.052-0.761, P = .018). CONCLUSION: Among patients with COVID-19, a lower AMC and higher NLR are associated with higher mortality.

Structural Characterization of the Extracellular Domain of CASPR2 and Insights into Its Association with the Novel Ligand Contactin1.

Contactin-associated protein-like 2 (CNTNAP2) encodes for CASPR2, a multidomain single transmembrane protein belonging to the neurexin superfamily that has been implicated in a broad range of human phenotypes including autism and language impairment. Using a combination of biophysical techniques, including small angle x-ray scattering, single particle electron microscopy, analytical ultracentrifugation, and bio-layer interferometry, we present novel structural and functional data that relate the architecture of the extracellular domain of CASPR2 to a previously unknown ligand, Contactin1 (CNTN1). Structurally, CASPR2 is highly glycosylated and has an overall compact architecture. Functionally, we show that CASPR2 associates with micromolar affinity with CNTN1 but, under the same conditions, it does not interact with any of the other members of the contactin family. Moreover, by using dissociated hippocampal neurons we show that microbeads loaded with CASPR2, but not with a deletion mutant, co-localize with transfected CNTN1, suggesting that CNTN1 is an endogenous ligand for CASPR2. These data provide novel insights into the structure and function of CASPR2, suggesting a complex role of CASPR2 in the nervous system.