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Broadly-neutralizing antibodies (bNAbs) against HIV-1 Env can protect from infection. We characterize Ab1303 and Ab1573, heterologously-neutralizing CD4-binding site (CD4bs) antibodies, isolated from sequentially-immunized macaques. Ab1303/Ab1573 binding is observed only when Env trimers are not constrained in the closed, prefusion conformation. Fab-Env cryo-EM structures show that both antibodies recognize the CD4bs on Env trimer with an 'occluded-open' conformation between closed, as targeted by bNAbs, and fully-open, as recognized by CD4. The occluded-open Env trimer conformation includes outwardly-rotated gp120 subunits, but unlike CD4-bound Envs, does not exhibit V1V2 displacement, 4-stranded gp120 bridging sheet, or co-receptor binding site exposure. Inter-protomer distances within trimers measured by double electron-electron resonance spectroscopy suggest an equilibrium between occluded-open and closed Env conformations, consistent with Ab1303/Ab1573 binding stabilizing an existing conformation. Studies of Ab1303/Ab1573 demonstrate that CD4bs neutralizing antibodies that bind open Env trimers can be raised by immunization, thereby informing immunogen design and antibody therapeutic efforts.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmia syndrome caused by gene mutations that render RYR2 Ca release channels hyperactive, provoking spontaneous Ca release and delayed afterdepolarizations (DADs). What remains unknown is the cellular source of ventricular arrhythmia triggered by DADs: Purkinje cells in the conduction system or ventricular cardiomyocytes in the working myocardium. To answer this question, we used a genetic approach in mice to knock out cardiac calsequestrin either in Purkinje cells or in ventricular cardiomyocytes. Total loss of calsequestrin in the heart causes a severe CPVT phenotype in mice and humans. We found that loss of calsequestrin only in ventricular myocytes produced a full-blown CPVT mice. Subendocardial chemical ablation or restoration of calsequestrin expression in subendocardial cardiomyocytes neighboring Purkinje cells was sufficient to protect against catecholamine-induced arrhythmias. In silico modeling demonstrated that DADs in ventricular myocardium can trigger full generated at the Purkinje-myocardial junction via a heretofore unrecognized tissue mechanism, whereby DADs in the ventricular myocardium trigger full action potentials in adjacent Purkinje cells.

This analysis contrasts traditional not-for-profit academic with new corporate practices of reproductive medicine and offers an assessment of risks to quality of patient care with investors entering the for-profit reproductive medicine market. Large corporate enterprises may have a global impact on access to care while at the same time is putting at risk the training of the next generation of reproductive medicine specialists.

The Arp2/3 complex inhibitor Arpin controls cell migration by interrupting a feedback loop involving Rac-WAVE-Arp2/3 complex Here, the authors use structural, biochemical, and cellular studies to reveal Arpin's mechanism of inhibition. Positive feedback loops involving signaling and actin assembly factors mediate the formation and remodeling of branched actin networks in processes ranging from cell and organelle motility to mechanosensation. The Arp2/3 complex inhibitor Arpin controls the directional persistence of cell migration by interrupting a feedback loop involving Rac-WAVE-Arp2/3 complex, but Arpin's mechanism of inhibition is unknown. Here, we describe the cryo-EM structure of Arpin bound to Arp2/3 complex at 3.24-angstrom resolution. Unexpectedly, Arpin binds Arp2/3 complex similarly to WASP-family nucleation-promoting factors (NPFs) that activate the complex. However, whereas NPFs bind to two sites on Arp2/3 complex, on Arp2-ArpC1 and Arp3, Arpin only binds to the site on Arp3. Like NPFs, Arpin has a C-helix that binds at the barbed end of Arp3. Mutagenesis studies in vitro and in cells reveal how sequence differences within the C-helix define the molecular basis for inhibition by Arpin vs. activation by NPFs.

Background CARD9 deficiency is an autosomal recessive primary immunodeficiency underlying increased susceptibility to fungal infection primarily presenting as invasive CNS Candida and/or cutaneous/invasive dermatophyte infections. More recently, a rare heterozygous dominant negative CARD9 variant c.1434 + 1G> C was reported to be protective from inflammatory bowel disease. Objective We studied two siblings carrying homozygous CARD9 variants (c.1434 + 1G> C) and born to heterozygous asymptomatic parents. One sibling was asymptomatic and the other presented with candida esophagitis, upper respiratory infections, hypogammaglobulinemia, and low class-switched memory B cells. Methods and Results The CARD9 c.1434 + 1G > C variant generated two mutant transcripts confirmed by mRNA and protein expression: an out-of-frame c.1358-1434 deletion/ similar to 55 kDa protein (CARD9 Delta ex.11) and an in-frame c.1417-1434 deletion/ similar to 61 kDa protein (CARD9 Delta 18 nt.). Neither transcript was able to form a complete/functional CBM complex, which includes TRIM62. Based on the index patient's CVID-like phenotype, CARD9 expression was tested and detected in lymphocytes and monocytes from humans and mice. The functional impact of different CARD9 mutations and gene dosage conditions was evaluated in heterozygous and homozygous c.1434 +1 G> C members of the index family, and in WT (two WT alleles), haploinsufficiency (one WT, one null allele), and null (two null alleles) individuals. CARD9 gene dosage impacted lymphocyte and monocyte functions including cytokine generation, MAPK activation, T-helper commitment, transcription, plasmablast differentiation, and immunoglobulin production in a differential manner. Conclusions CARD9 exon 11 integrity is critical to CBM complex function. CARD9 is expressed and affects particular T and B cell functions in a gene dosage-dependent manner, which in turn may contribute to the phenotype of CARD9 deficiency.

Metal catalysis, a common approach in conventional organic synthesis, poses a challenge in DEL chemistry due to the vulnerability of DNA fragments and the requirement of aqueous media. Here, we describe a facile one-pot palladium-catalyzed reaction for the formation of C(sp(2))-C(sp(3)) and C(sp(3))-S bonds in the presence of DNA encoding. Using 3, 4-dimethoxybenzenesulfonohydrazide (L8) as a bridging reactant, our studies showed that DNA-conjugated benzaldehyde (HP-ArCHO-1), serving as a common precursor, reacted with derivatives of iodine, bromine, trifluoromethanesulfonate, and disulfides in metal-catalyzed one-pot chemical transformation to afford on-DNA diarylmethanes and thioethers. Notably, all reactions displayed wide substrate scopes and moderate to excellent yields under mild reaction conditions. These chemical reactions greatly expand the chemical space of DNA-compatible reactions and the molecular scaffold diversity of DNA-encoded libraries.

Author summaryAlthough genetic diversity in the olfactory receptor repertoire contributes to variation in odor perception, we have few explicit predictions relating variation in a specific OR to perception. Here, we performed genome-wide scans on odor-perception phenotypes for ten odors in 1000 Han Chinese and validated results for six of these odors in an ethnically diverse population (n = 364). We identified novel receptors for musk and human body odor that have implications for how structurally different molecules can have similar odors. Summarizing all the published genetic variation that associates with odor perception, we found that individuals with ancestral versions of the receptors tend to rate the corresponding odor as more intense, supporting the hypothesis that the primate olfactory gene repertoire has degenerated over time. This study of olfactory genetic and perceptual variation will improve our understanding of how the olfactory system encodes odor properties. The olfactory system combines input from multiple receptor types to represent odor information, but there are few explicit examples relating olfactory receptor (OR) activity patterns to odor perception. To uncover these relationships, we performed genome-wide scans on odor-perception phenotypes for ten odors in 1000 Han Chinese and validated results for six of these odors in an ethnically diverse population (n = 364). In both populations, consistent with previous studies, we replicated three previously reported associations (beta-ionone/OR5A1, androstenone/OR7D4, cis-3-hexen-1-ol/OR2J3 LD-band), but not for odors containing aldehydes, suggesting that olfactory phenotype/genotype studies are robust across populations. Two novel associations between an OR and odor perception contribute to our understanding of olfactory coding. First, we found a SNP in OR51B2 that associated with trans-3-methyl-2-hexenoic acid, a key component of human underarm odor. Second, we found two linked SNPs associated with the musk Galaxolide in a novel musk receptor, OR4D6, which is also the first human OR shown to drive specific anosmia to a musk compound. We noticed that SNPs detected for odor intensity were enriched with amino acid substitutions, implying functional changes of odor receptors. Furthermore, we also found that the derived alleles of the SNPs tend to be associated with reduced odor intensity, supporting the hypothesis that the primate olfactory gene repertoire has degenerated over time. This study provides information about coding for human body odor, and gives us insight into broader mechanisms of olfactory coding, such as how differential OR activation can converge on a similar percept.

Background Hepatocellular carcinoma (HCC) patient-derived xenograft (PDX) models hold potential to advance knowledge in HCC biology to help improve systemic therapies. Beside hepatitis B virus-associated tumors, HCC is poorly established in PDX. Methods PDX formation from fresh HCC biopsies were obtained and implanted intrahepatically or in subrenal capsule (SRC). Mouse liver injury was induced in immunodeficient Fah(-/-) mice through cycling off nitisinone after HCC biopsy implantation, versus continuous nitisinone as non-liver injury controls. Mice with macroscopically detectable PDX showed rising human alpha1-antitrypsin (hAAT) serum levels, and conversely, no PDX was observed in mice with undetectable hAAT. Results Using rising hAAT as a marker for PDX formation, 20 PDX were established out of 45 HCC biopsy specimens (44%) reflecting the four major HCC etiologies most commonly identified at Memorial SloanKettering similar to many other institutions in the United States. PDX was established only in severely immunodeficient mice lacking lymphocytes and NK cells. Implantation under the renal capsule improved PDX formation two-fold compared to intrahepatic implantation. Two out of 18 biopsies required murine liver injury to establish PDX, one associated with hepatitis C virus and one with alcoholic liver disease. PDX tumors were histologically comparable to biopsy specimens and 75% of PDX lines could be passaged. Conclusions Using cycling off nitisinone-induced liver injury, HCC biopsies implanted under the renal capsule of severely immunodeficient mice formed PDX with 57% efficiency as determined by rising hAAT levels. These findings facilitate a more efficient make-up of PDX for research into subset-specific HCC.