Biology subjects

Disharoon, D.

Publications and source records attributed to Disharoon, D..

4 recordsLinked to original sources

bioRxiv2025

Characterizing venom resistance in Monodelphis domestica yields new insights into mammalian blood physiology

Interactions between predators and prey are often characterized by strong selection pressures that shape extreme physiological adaptations. Venom resistance in large-bodied South American opossums (Clade Didelphini) is a striking example, as these marsupials prey on venomous snakes and exhibit remarkable resistance to their venom. While resistance is well documented in Didelphini, relatively little is known about venom resistance in the smaller, more diverse members of Didelphidae, which inhabit the same regions and encounter the same predators. Here, we investigate venom resistance in the small-bodied opossum, Monodelphis domestica, through multi-level physiological assays, examining responses to purified venom components and whole venom from sympatric and allopatric vipers. Our results show M. domestica resists venom-induced disruptions to blood coagulation, retains platelet function in the presence of platelet-disrupting venoms, and inhibits snake venom metalloproteinases. Unexpectedly, we find that M. domestica von Willebrand Factor (VWF) requires increased shear force to elongate, a previously unknown aspect of opossum blood physiology that may contribute to venom resistance and may have relevance to human coagulopathies. These findings expand the extent of venom resistance beyond large-bodied Didelphini, suggesting it is a widespread trait in South American marsupials and providing new insights into venom-mammal coevolution. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/634112v2_ufig1.gif" ALT="Figure 1"> View larger version (67K): org.highwire.dtl.DTLVardef@1efb74forg.highwire.dtl.DTLVardef@ebcb82org.highwire.dtl.DTLVardef@7ddef2org.highwire.dtl.DTLVardef@1b81569_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2024

Mice with Reduced PAR4 Reactivity show Decreased Venous Thrombosis and Platelet Procoagulant Activity

BackgroundHypercoagulation and thrombin generation are major risk factors for venous thrombosis. Sustained thrombin signaling through PAR4 promotes platelet activation, phosphatidylserine exposure, and subsequent thrombin generation. A single-nucleotide polymorphism in PAR4 (rs2227376) changes proline to leucine extracellular loop 3 (P310L), which decreases PAR4 reactivity and is associated with a lower risk for venous thromboembolism (VTE) in a GWAS meta-analysis. ObjectiveThe goal of this study is to determine the mechanism for the association of rs2227376 with reduced risk for VTE in using mice with a homologous mutation (PAR4-P322L). MethodsVenous thrombosis was examined using our recently generated PAR4-P322L mice in the inferior vena cava stasis and stenosis models. Coagulation and clot stability was measured using rotational thromboelastometry (ROTEM). Thrombin generating potential was measured in platelet-rich plasma. Phosphatidylserine surface expression and platelet-neutrophil aggregates were analyzed using flow cytometry. ResultsPAR4P/L and PAR4L/L had reduced incidence and size of venous clots at 48 hours. PAR4P/L and PAR4L/L platelets had progressively decreased phosphatidylserine in response to thrombin and convulxin, which led to decreased thrombin generation and decreased PAR4-mediated platelet-neutrophil aggregation. ConclusionsThe leucine allele in extracellular loop 3, PAR4-322L leads to fewer procoagulant platelets and decreased endogenous thrombin potential. This decreased ability to generate thrombin offers a mechanism for PAR4s role in VTE highlighting a key role for PAR4 signaling.

physiology↗

bioRxiv2023

Magnetically Powered Microwheel Thrombolysis of Occlusive Thrombi in Zebrafish

Tissue plasminogen activator (tPA) is the only FDA approved treatment for ischemic stroke but carries significant risks, including major hemorrhage. Additional options are needed, especially in small vessel thrombi which account for [~]25% of ischemic strokes. We have previously shown that tPA-functionalized colloidal microparticles can be assembled into microwheels ({micro}wheels) and manipulated under the control of applied magnetic fields to enable rapid thrombolysis of fibrin gels in microfluidic models of thrombosis. Providing a living microfluidic analog, transparent zebrafish larvae have a highly conserved coagulation cascade that enables studies of hemostasis and thrombosis in the context of intact vasculature, clotting factors, and blood cells. Here we show that tPA-functionalized {micro}wheels can perform rapid and targeted recanalization in vivo. This effect requires both tPA and {micro}wheels, as minimal to no recanalization is achieved with tPA alone, {micro}wheels alone, or tPA-functionalized microparticles in the absence of a magnetic field. We evaluated tPA-{micro}wheels in CRISPR-generated plasminogen (plg) heterozygous and homozygous mutants and confirmed that tPA-{micro}wheels are dose-dependent on plasminogen for lysis. We have found that magnetically powered {micro}wheels as a targeted tPA delivery system are dramatically more efficient at plasmin-mediated thrombolysis than systemic delivery in vivo. Further development of this system in fish and mammalian models could enable a less invasive strategy for alleviating ischemia that is safer than directed thrombectomy or systemic infusion of tPA.

bioengineering↗

bioRxiv2021

Breaking the fibrinolytic speed limit with microwheel co-delivery of tissue plasminogen activator and plasminogen

Fibrinolysis is the enzymatic degradation of fibrin, the biopolymer that gives blood clots their mechanical integrity. To reestablish blood flow in vessels occluded by clots, tissue plasminogen activator (tPA) can be used; however, its efficacy is limited by transport to and into a clot and by the depletion of its substrate, plasminogen. To overcome these rate limitations, we design a platform to co-deliver tPA and plasminogen based on microwheels (wheels), wheel-like assemblies of superparamagnetic colloidal beads that roll along surfaces at high speeds and carry therapeutic payloads in applied magnetic fields. By experimentally measuring fibrinolysis of plasma clots at varying concentrations of tPA and plasminogen, the biochemical speed limit was first determined. These data, in conjunction with measurements of wheel translation, activity of immobilized tPA on beads, and plasminogen release kinetics from magnetic mesoporous silica nanoparticles (mMSN), were used in a mathematical model to identify the optimal tPA:plasminogen ratio and guide the coupling of plasminogen-loaded mMSN to tPA functionalized superparamagnetic beads. Once coupled, particle-bead assemblies form into a co-delivery vehicle that rolls to plasma clot interfaces and lyses them at rates comparable to the biochemical speed limit. With the addition of mechanical action provided by rotating wheels to penetrate clots, this barrier was exceeded by rates 40-fold higher lysis by 50 nM tPA. This co-delivery of an immobilized enzyme and its substrate via a microbot capable of mechanical work has the potential to target and rapidly lyse clots that are inaccessible by mechanical thrombectomy devices or recalcitrant to systemic tPA delivery.

bioengineering↗