Functional characterization of recombinant snake venom rhodocytin: rhodocytin mutant blocks CLEC-2/podoplanin-dependent platelet aggregation and lung metastasis

Essentials We generated recombinant rhodocytin that could aggregate platelets via CLEC-2. Recombinant wild-type rhodocytin formed heterooctamer with four α- and β-subunits. Asp 4 in α-subunit of rhodocytin was required for binding to CLEC-2. Inhibitory mutant of rhodocytin blocked podoplanin-dependent hematogenous metastasis.

SUMMARY

Background Rhodocytin, a disulfide-linked heterodimeric C-type lectin from Calloselasma rhodostoma consisting of α-subunits and β-subunits, induces platelet aggregation through C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a physiological binding partner of podoplanin (PDPN), which is expressed on some tumor cell types, and is involved in tumor cell-induced platelet aggregation and tumor metastasis. Thus, modified rhodocytin may be a possible source of anti-CLEC-2 drugs for both antiplatelet and antimetastasis therapy. However, its molecular function has not been well characterized, because of the lack of recombinant rhodocytin that induces platelet aggregation. Objective To produce recombinant rhodocytin, in order to verify its function with mutagenesis, and to develop an anti-CLEC-2 drug based on the findings. Methods We used Chinese hamster ovary cells to express recombinant rhodocytin (wild-type [WT] and mutant), which was analyzed for induction/inhibition of platelet aggregation with light transmission aggregometry, the formation of multimers with blue native PAGE, and binding to CLEC-2 with flow cytometry. Finally, we investigated whether mutant rhodocytin could suppress PDPN-induced metastasis in an experimental lung metastasis mouse model. Results Functional WT] rhodocytin (αWTβWT) was obtained by coexpression of both subunits. Asp4 in α-subunits of rhodocytin was required for CLEC-2 binding. αWTβWT formed a heterooctamer similarly to native rhodocytin. Moreover, an inhibitory mutant of rhodocytin (αWTβK53A/R56A), forming a heterotetramer, bound to CLEC-2 without inducing platelet aggregation, and blocked CLEC-2-PDPN interaction-dependent platelet aggregation and experimental lung metastasis. Conclusion These findings provide molecular characterization information on rhodocytin, and suggest that mutant rhodocytin could be used as a therapeutic agent to target CLEC-2.

Identification and initial characterization of novel neural immediate early genes possibly differentially contributing to foraging-related learning and memory processes in the honeybee

Despite possessing a limited number of neurones compared to vertebrates, honeybees show remarkable learning and memory performance, an example being 'dance communication'. In this phenomenon, foraging honeybees learn the location of a newly discovered food source and transmit the information to nestmates by symbolic abdomen vibrating behaviour, leading to navigation of nestmates to the new food source. As an initial step toward understanding the detailed molecular mechanisms underlying the sophisticated learning and memory performance of the honeybee, we focused on the neural immediate early genes (IEGs), which are specific genes quickly transcribed after neural activity without de novo protein synthesis. Although these have been reported to play an essential role in learning and memory processes in vertebrates, far fewer studies have been performed in insects in this regard. From RNA-sequencing analysis and subsequent assays, we identified three genes, Src homology 3 (SH3) domain binding kinase, family with sequence similarity 46 and GB47136, as novel neural IEGs in the honeybee. Foragers and/or orientating bees, which fly around their hives to memorize the positional information, showed induced expression of these IEGs in the mushroom body, a higher-order centre essential for learning and memory, indicating a possible role for the novel IEGs in foraging-related learning and memory processes in the honeybee.

A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Quantum-disordered state of magnetic and electric dipoles in an organic Mott system

Strongly enhanced quantum fluctuations often lead to a rich variety of quantum-disordered states. Developing approaches to enhance quantum fluctuations may open paths to realize even more fascinating quantum states. Here, we demonstrate that a coupling of localized spins with the zero-point motion of hydrogen atoms, that is, proton fluctuations in a hydrogen-bonded organic Mott insulator provides a different class of quantum spin liquids (QSLs). We find that divergent dielectric behavior associated with the approach to hydrogen-bond order is suppressed by the quantum proton fluctuations, resulting in a quantum paraelectric (QPE) state. Furthermore, our thermal-transport measurements reveal that a QSL state with gapless spin excitations rapidly emerges upon entering the QPE state. These findings indicate that the quantum proton fluctuations give rise to a QSL—a quantum-disordered state of magnetic and electric dipoles—through the coupling between the electron and proton degrees of freedom.

The organic material κ-H₃(Cat-EDT-TTF)₂ has been suggested to exhibit a quantum spin liquid phase in which quantum fluctuations prevent the formation of magnetic order. Here, the authors show that this may be a result of fluctuations of hydrogen atoms, rather than more conventional geometric frustration.

Internal Fixation of Only the Distal End in a Bipolar Segmental Clavicle Fracture: A Case Report

Bipolar segmental clavicle fractures are simultaneous clavicle fractures of both proximal and distal ends. Few case reports describing these fractures have been published, and the management of these injuries have remained controversial. Non-operative treatment is likely to result in poor shoulder function due to the instability of the fracture in patients with high physical demands. In contrast, surgical treatment with fixation of both proximal and distal ends of the clavicle possibly may cause life-threatening complications. We present a 74-year old female farmer who had injured her left shoulder and was diagnosed with a bipolar segmental clavicle fracture. Taking the fracture mechanism into consideration, we surgically treated only the distal end of the clavicle fracture with a locking plate. The proximal end of the clavicle fracture was treated without surgical intervention. Both fracture sites achieved bony union after four months and she returned to her activities as a farmer. Quick DASH score was 5.0 with excellent results at three years after operation.

Crystallization and vitrification of electrons in a glass-forming charge liquid

Charge ordering (CO) is a phenomenon in which electrons in solids crystallize into a periodic pattern of charge-rich and charge-poor sites owing to strong electron correlations. This usually results in long-range order. In geometrically frustrated systems, however, a glassy electronic state without long-range CO has been observed. We found that a charge-ordered organic material with an isosceles triangular lattice shows charge dynamics associated with crystallization and vitrification of electrons, which can be understood in the context of an energy landscape arising from the degeneracy of various CO patterns. The dynamics suggest that the same nucleation and growth processes that characterize conventional glass-forming liquids guide the crystallization of electrons. These similarities may provide insight into our understanding of the liquid-glass transition.