Structural Biology of LRRK2 and its Interaction with Microtubules

Mutations in leucine rich repeat kinase 2 (LRRK2) are a major cause of familial Parkinson's disease (PD) and a risk factor for its sporadic form. LRRK2 hyperactivity has also been reported in sporadic PD, making LRRK2 an appealing target for PD small-molecule therapeutics. At a cellular level, increasing evidence suggests that LRRK2 regulates membrane trafficking. Under some conditions LRRK2 also associates with microtubules, the cellular tracks used by dynein and kinesin motors to move membranes. At a structural level, however, relatively little was known about LRRK2. An important step toward bridging this gap took place last year with the publication of structures of LRRK2's cytosolic and microtubule-bound forms. Here, we review the main findings from these studies and discuss what we see as the major challenges going forward with a focus on areas that will require structural information. We also introduce the structural techniques—cryo-electron microscopy and cryo-electron tomography—that were instrumental to solving the structures of LRRK2. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society     

Isolation and expansion of thymus-derived regulatory T cells for use in pediatric heart transplant patients

Regulatory T-cells (Tregs) are a subset of T cells generated in the thymus with intrinsic immunosuppressive properties. Phase I clinical trials have shown safety and feasibility of Treg infusion to promote immune tolerance and new studies are ongoing to evaluate their efficacy. During heart transplantation, thymic tissue is routinely discarded providing an attractive source of Tregs. In this study, we developed a GMP-compatible protocol for expanding sorted thymus-derived CD3⁺CD4⁺CD25⁺CD127^– (Tregs) as well as CD3⁺CD4⁺CD25⁺CD127^–CD45RA⁺ (RA⁺Tregs) cells. We aimed to understand whether thymic RA⁺Tregs can be isolated and expanded offering an advantage in terms of stability as it has been previously shown for circulating adult CD45RA⁺ Tregs. We show that both Tregs and RA⁺Tregs could be expanded in large numbers and the presence of rapamycin is essential to inhibit the growth of IFN-γ producing cells. High levels of FOXP3, CTLA4, and CD25 expression, demethylation of the FOXP3 promoter, and high suppressive ability were found with no differences between Tregs and RA⁺Tregs. After freezing and thawing, all Treg preparations maintained their suppressive ability, stability, as well as CD25 and FOXP3 expression. The number of thymic Tregs that could be isolated with our protocol, their fold expansion, and functional characteristics allow the clinical application of this cell population to promote tolerance in pediatric heart transplant patients.     

Improving bonding to eroded dentin by using collagen cross-linking agents: 2 years of water storage

Clinical Oral Investigations - The aim of this study was to investigate the effects of collagen cross-linking agents on nanomechanical and bonding properties of eroded dentin (ED), 24 h...     

Clathrin-mediated endocytosis is required for compensatory regulation of GLR-1 glutamate receptors after activity blockade

Chronic changes in neural activity trigger a variety of compensatory homeostatic mechanisms by which neurons maintain a normal level of synaptic input. Here we show that chronic activity blockade triggers a compensatory change in the abundance of GLR-1, a Caenorhabditis elegans glutamate receptor. In mutants lacking a voltage-dependent calcium channel (unc-2) or a vesicular glutamate transporter (VGLUT; eat-4), the abundance of GLR-1 in the ventral nerve cord was increased. Similarly, the amplitude of glutamate-evoked currents in ventral cord interneurons was increased in eat-4 VGLUT mutants compared with wild-type controls. The effects of eat-4 VGLUT mutations on GLR-1 abundance in the ventral cord were eliminated in double mutants lacking both the clathrin adaptin protein unc-11 AP180 and eat-4 VGLUT. In contrast, mutations that decreased ubiquitination of GLR-1 did not prevent increased ventral cord abundance of GLR-1 in eat-4 VGLUT mutants. Taken together, our results suggest that GLR-1 is regulated in a homeostatic manner and that this effect depends on clathrin-mediated endocytosis but does not require ubiquitination of GLR-1.     

Assessment of Platelet REACtivity After Transcatheter Aortic Valve Replacement: The REAC-TAVI Trial

Objectives

The REAC-TAVI (Assessment of platelet REACtivity after Transcatheter Aortic Valve Implantation) trial enrolled patients with aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) pre-treated with aspirin + clopidogrel, aimed to compare the efficacy of clopidogrel and ticagrelor in suppressing high platelet reactivity (HPR) after TAVI.