The rockefeller university

Monoclonal antibodies (mAbs) have provided valuable information regarding the structure and function of platelet aIIb(33. Protein disulfide isomerase (PDI) has been implicated in aIIb(33 activation and binds to thrombin-activated aIIb(33. Using human platelets as the immunogen, we identified a new mAb (R21D10) that inhibits the binding of PDI to platelets activated with thrombin receptor-activating peptide (T6). R21D10 also partially inhibited T6-induced fibrinogen and PAC-1 binding to platelets, as well as T6- and adenosine 5'-diphosphate-induced platelet aggregation. Mutual competition experiments showed that R21D10 does not inhibit the binding of mAbs 10E5 (anti-aIIb cap domain) or 7E3 (anti-(33 (3-I domain), and immunoblot studies indicated that R21D10 binds to (33. The dissociation of aIIb(33 by EDTA had a minimal effect on R21D10 binding. Cryogenic electron microscopy of the aIIb(33-R21D10 Fab complex revealed that R21D10 binds to the (33 integrin-epidermal growth factor 1 (I-EGF1) domain and traps an intermediate conformation of aIIb(33 with semiextended leg domains. The binding of R21D10 produces a major structural change in the (33 I-EGF2 domain associated with a new interaction between the (33 I-EGF2 and aIIb thigh domains, which may prevent the swing-out motion of the (33 hybrid domain required for high-affinity ligand binding and protect aIIb(33 from EDTA-induced dissociation. R21D10 partially reversed the ligand binding priming effect of eptifibatide, suggesting that it could convert the swung-out conformation into a semiextended conformation. We concluded that R21D10 inhibits ligand binding to aIIb(33 via a unique allosteric mechanism, which may or may not be related to its inhibition of PDI binding.

According to Mendel's second law, chromosomes segregate randomly in meiosis. Non-random segregation is primarily known for cases of selfish meiotic drive in females, in which particular alleles bias their own transmission into the oocyte. Here we report a rare example of unselfish meiotic drive for crossover inheritance in the clonal raider ant, Ooceraea biroi, in which both alleles are co-inherited at all loci across the entire genome. This species produces diploid offspring parthenogenetically via fusion of two haploid nuclei from the same meiosis. This process should cause rapid genotypic degeneration due to loss of heterozygosity, which results if crossover recombination is followed by random (Mendelian) segregation of chromosomes. However, by comparing whole genomes of mothers and daughters, we show that loss of heterozygosity is exceedingly rare, raising the possibility that crossovers are infrequent or absent in O. biroi meiosis. Using a combination of cytology and whole-genome sequencing, we show that crossover recombination is, in fact, common but that loss of heterozygosity is avoided because crossover products are faithfully co-inherited. This results from a programmed violation of Mendel's law of segregation, such that crossover products segregate together rather than randomly. This discovery highlights an extreme example of cellular 'memory' of crossovers, which could be a common yet cryptic feature of chromosomal segregation. This study reports non-random segregation of chromosomes during meiosis in the clonal raider ant, Ooceraea biroi, but no loss of heterozygosity because crossover products are faithfully co-inherited.

Alterations leading to unconstrained protein kinase A signaling, regardless of the presence or absence of PRKACA fusions, drive the phenotypes of fibrolamellar hepatocellular carcinoma, reshaping understanding of the pathogenesis of this rare liver cancer. Fibrolamellar hepatocellular carcinoma (FLC) is a rare liver cancer that is driven by the fusion of DNAJB1 and PRKACA, the catalytic subunit of protein kinase A (PKA). PKA activity is controlled through regulatory proteins that both inhibit catalytic activity and control localization, and an excess of regulatory subunits ensures PRKACA activity is inhibited. Here, we found an increase in the ratio of catalytic to regulatory units in FLC patient tumors driven by DNAJB1::PRKACA using mass spectrometry, biochemistry, and immunofluorescence, with increased nuclear localization of the kinase. Overexpression of DNAJB1::PRKACA, ATP1B1::PRKACA, or PRKACA, but not catalytically inactive kinase, caused similar transcriptomic changes in primary human hepatocytes, recapitulating the changes observed in FLC. Consistently, tumors in patients missing a regulatory subunit or harboring an ATP1B1::PRKACA fusion were indistinguishable from FLC based on the histopathological, transcriptomic, and drug-response profiles. Together, these findings indicate that the DNAJB1 domain of DNAJB1::PRKACA is not required for FLC. Instead, changes in PKA activity and localization determine the FLC phenotype.Significance: Alterations leading to unconstrained protein kinase A signaling, regardless of the presence or absence of PRKACA fusions, drive the phenotypes of fibrolamellar hepatocellular carcinoma, reshaping understanding of the pathogenesis of this rare liver cancer.

Neurotransmitters play a crucial role in regulating communication between neurons within the brain and central nervous system. Thus, imaging neurotransmitters has become a high priority in neuroscience. This minireview focuses on recent advancements in the development of fluorescent small-molecule fluorescent probes for neurotransmitter imaging and applications of these probes in neuroscience. Innovative approaches for probe design are highlighted as well as attributes which are necessary for practical utility, with a view to inspiring new probe development capable of visualizing neurotransmitters. This minireview focuses on recent progress in the field of small-molecule fluorescent probes designed for imaging neurotransmitters. We delve into the methodologies employed in creating these probes, specifically targeting a variety of neurotransmitters. Additionally, we emphasize the essential properties necessary for practical applications. image

Elevated pernio incidence was observed during the COVID-19 pandemic. This prospective study enrolled subjects with pandemic-associated pernio in Wisconsin and Switzerland. Because pernio is a cutaneous manifestation of the interferonopathies, and type I interferon (IFN-I) immunity is critical to COVID-19 recovery, we tested the hypothesis that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)mediated IFN-I signaling might underlie some pernio cases. Tissue-level IFN-I activity and plasmacytoid dendritic cell infiltrates were demonstrated in 100% of the Wisconsin cases. Across both cohorts, sparse SARS-CoV-2 RNA was captured in 25% (6/22) of biopsies, all with high inflammation. Affected patients lacked adaptive immunity to SARS-CoV-2. A hamster model of intranasal SARS-CoV-2 infection was used as a proof-of-principle experiment: RNA was detected in lungs and toes with IFN-I activity at both the sites, while replicating virus was found only in the lung. These data support a viral trigger for some pernio cases, where sustained local IFN-I activity can be triggered in the absence of seroconversion.

Acquired resistance to PARP inhibitors (PARPi) remains a treatment challenge for BRCA1/2-mutant breast cancer that drastically shortens patient survival. Although several resistance mechanisms have been identified, none have been successfully targeted in the clinic. Using new PARPi-resistance models of Brca1- and Bard1-mutant breast cancer generated in-vivo, we identified FLT1 (VEGFR1) as a driver of resistance. Unlike the known role of VEGF signaling in angiogenesis, we demonstrate a novel, non-canonical role for FLT1 signaling that protects cancer cells from PARPi in-vivo through a combination of cell-intrinsic and cell-extrinsic pathways. We demonstrate that FLT1 blockade suppresses AKT activation, increases tumor infiltration of CD8+ T cells, and causes dramatic regression of PARPi-resistant breast tumors in a T-cell-dependent manner. Moreover, PARPi-resistant tumor cells can be readily re-sensitized to PARPi by targeting Flt1 either genetically (Flt1-suppression) or pharmacologically (axitinib). Importantly, a retrospective series of breast cancer patients treated with PARPi demonstrated shorter progression-free survival in cases with FLT1 activation at pre-treatment. Our study therefore identifies FLT1 as a potential therapeutic target in PARPi-resistant, BRCA1/2-mutant breast cancer. PARP inhibitor (PARPi) resistance is a major treatment challenge that dramatically shortens patient survival. Using new mouse models of PARPi response and recurrence, we identified FLT1 as a potential biomarker and therapeutic target for reversing PARPi resistance in BRCA-mutant breast cancer.New mouse models were developed that recapitulate the PARPi response and recurrence observed in patients.A novel PARPi-adaptive resistance mechanism driven by the PGF-FLT1-AKT pathway was identified.FLT1 signaling protected the cells from PARPi-induced death by activating AKT pro-survival pathways and by dampening the cytotoxic immune response.Blocking FLT1 signaling, either genetically or pharmacologically using axitinib, re-sensitized PARPi-resistant tumors to PARPi treatment in mice.High FLT1 activation in tumor cells at pre-treatment significantly correlated with shorter progression-free survival on PARPi in patients with breast cancer. PARP inhibitor (PARPi) resistance is a major treatment challenge that dramatically shortens patient survival. Using new mouse models of PARPi response and recurrence, we identified FLT1 as a potential biomarker and therapeutic target for reversing PARPi resistance in BRCA-mutant breast cancer.

The small molecule epiberberine (EPI) is a natural alkaloid with versatile bioactivities against several diseases including cancer and bacterial infection. EPI can induce the formation of a unique binding pocket at the 5 ' side of a human telomeric G-quadruplex (HTG) sequence with four telomeric repeats (Q4), resulting in a nanomolar binding affinity (K D approximately 26 nM) with significant fluorescence enhancement upon binding. It is important to understand (1) how EPI binding affects HTG structural stability and (2) how enhanced EPI binding may be achieved through the engineering of the DNA binding pocket. In this work, the EPI-binding-induced HTG structure stabilization effect was probed by a peptide nucleic acid (PNA) invasion assay in combination with a series of biophysical techniques. We show that the PNA invasion-based method may be useful for the characterization of compounds binding to DNA (and RNA) structures under physiological conditions without the need to vary the solution temperature or buffer components, which are typically needed for structural stability characterization. Importantly, the combination of theoretical modeling and experimental quantification allows us to successfully engineer Q4 derivative Q4-ds-A by a simple extension of a duplex structure to Q4 at the 5 ' end. Q4-ds-A is an excellent EPI binder with a K D of 8 nM, with the binding enhancement achieved through the preformation of a binding pocket and a reduced dissociation rate. The tight binding of Q4 and Q4-ds-A with EPI allows us to develop a novel magnetic bead-based affinity purification system to effectively extract EPI from Rhizoma coptidis (Huang Lian) extracts.

Many archetypal and emerging classes of small-molecule therapeutics form covalent protein adducts. In vivo, both the resulting conjugates and their off-target side-conjugates have the potential to elicit antibodies, with implications for allergy and drug sequestration. Although beta-lactam antibiotics are a drug class long associated with these immunological phenomena, the molecular underpinnings of off-target drug-protein conjugation and consequent drug-specific immune responses remain incomplete. Here, using the classical beta-lactam penicillin G (PenG), we probe the B and T cell determinants of drug-specific IgG responses to such conjugates in mice. Deep B cell clonotyping reveals a dominant murine clonal antibody class encompassing phylogenetically-related IGHV1, IGHV5 and IGHV10 subgroup gene segments. Protein NMR and x-ray structural analyses reveal that these drive structurally convergent binding modes in adduct-specific antibody clones. Their common primary recognition mechanisms of the penicillin side-chain moiety (phenylacetamide in PenG)-regardless of CDRH3 length-limits cross-reactivity against other beta-lactam antibiotics. This immunogenetics-guided discovery of the limited binding solutions available to antibodies against side products of an archetypal covalent inhibitor now suggests future potential strategies for the 'germline-guided reverse engineering' of such drugs away from unwanted immune responses. Penicillin and other beta-lactam drugs form protein adducts that can facilitate allergic and other drug-directed responses. Here, Deimel et al. describe the pharmacokinetic, immunologic and structural determinants of anti-penicillin antibodies.