Atomistic Mechanism of Lipid Membrane Binding for Blood Coagulation Factor VIII with Molecular Dynamics Simulations on a Microsecond Time Scale.

During the blood coagulation cascade, coagulation factor VIII (FVIII) is activated by thrombin to form activated factor VIII (FVIIIa). FVIIIa associates with platelet surfaces at the site of vascular damage to form an intrinsic tenase complex with activated factor IX. A working model for FVIII membrane binding involves the association of positively charged FVIII residues with negatively charged lipid headgroups and the burial of hydrophobic residues into the membrane interior.

Biophysical characterization of blood coagulation factor VIII binding to lipid nanodiscs that mimic activated platelet surfaces.

Background: Following proteolytic activation, activated blood coagulation factor (F)VIII (FVIIIa) binds to activated platelet membranes, forming the intrinsic tenase complex with activated FIX (FIXa). Previous studies have identified the C1 and C2 domains as the membrane binding domains of FVIII through conserved arginine residues. A membrane binding model for the FVIII C domains proposes that surface-exposed hydrophobic and positively charged residues at each C domain interact with the membrane, yet a comprehensive thermodynamic and structural description of this interaction is lacking.

Blunting specific T-dependent antibody responses with engineered "decoy" B cells.

Antibody inhibitors pose an ongoing challenge to the treatment of subjects with inherited protein deficiency disorders, limiting the efficacy of both protein replacement therapy and corrective gene therapy. Beyond their central role as producers of serum antibody, B cells also exhibit many unique properties that could be exploited in cell therapy applications, notably including antigen-specific recognition and the linked capacity for antigen presentation. Here we employed CRISPR-Cas9 to demonstrate that ex vivo antigen-primed Blimp1-knockout "decoy" B cells, incapable of differentiation into plasma cells, participated in and downregulated host antigen-specific humoral responses after adoptive transfer.

Structure of coagulation factor VIII bound to a patient-derived anti-C1 domain antibody inhibitor.

The development of pathogenic antibody inhibitors against coagulation factor VIII (FVIII) occurs in ∼30% of patients with congenital hemophilia A receiving FVIII replacement therapy, as well as in all cases of acquired hemophilia A. KM33 is an anti-C1 domain antibody inhibitor previously isolated from a patient with severe hemophilia A. In addition to potently blocking FVIII binding to von Willebrand factor and phospholipid surfaces, KM33 disrupts FVIII binding to lipoprotein receptor-related protein 1 (LRP1), which drives FVIII hepatic clearance and antigen presentation in dendritic cells.

Stable binding to phosphatidylserine-containing membranes requires conserved arginine residues in tandem C domains of blood coagulation factor VIII.

At sites of vascular damage, factor VIII (fVIII) is proteolytically activated by thrombin and binds to activated platelet surfaces with activated factor IX (fIXa) to form the intrinsic "tenase" complex. Previous structural and mutational studies of fVIII have identified the C1 and C2 domains in binding to negatively charged membrane surfaces through β-hairpin loops with solvent-exposed hydrophobic residues and a ring of positively charged basic residues. Several hemophilia A-associated mutations within the C domains are suggested to disrupt lipid binding, preventing formation of the intrinsic tenase complex.

Occipitocervical instrumentation in the pediatric population using a custom loop construct: initial results and long-term follow-up experience.

Object: Rigid occipitocervical instrumentation for craniovertebral instability is gaining widespread acceptance for use in pediatric patients; however, most of the instrumentation has been modified from adult-sized hardware. The Wasatch loop system (formerly the Avery-Brockmeyer-Thiokol loop system) is a rigid occipitocervical fixation device designed specifically for use in children. It affixes to the occiput and incorporates either C1-2 transarticular screws or C-2 pars screws.

The AT-hook-containing proteins SOB3/AHL29 and ESC/AHL27 are negative modulators of hypocotyl growth in Arabidopsis.

SOB3, which encodes a plant-specific AT-hook motif containing protein, was identified from an activation-tagging screen for suppressors of the long-hypocotyl phenotype of a weak phyB allele, phyB-4. sob3-D (suppressor of phyB-4#3 dominant) overexpressing seedlings have shorter hypocotyls, and as adults develop larger flowers and leaves, and are delayed in senescence compared with wild-type plants. At the nucleotide level, SOB3 is closely related to ESCAROLA (ESC), which was identified in an independent activation-tagging screen.