Tau’s Three-Repeat Domain and EFhd2 Co-incubation Leads to Increased Thioflavin Signal

Aggregation of the protein tau is a pathological hallmark of Alzheimer’s disease (AD) and related disorders. However, the molecular mechanisms that lead to tau protein aggregation are still unclear. Previously, we showed that EFhd2 protein is associated with pathological aggregated forms of tau in AD brain. Further, immuno-gold analyses of purified tau aggregates showed that EFhd2 co-localized with filamentous tau structures. We demonstrated that EFhd2’s coiled-coil domain is required for its association with tau proteins. However, it is unknown the role that EFhd2 plays in tau aggregation. Here, we show that incubation of K19-tau with substoichiometric amount of EFhd2 promote the formation of amyloid structures in vitro. The result suggests that EFhd2 may play a role in the biogenesis of aggregated tau

Identification and functional analysis of novel phosphorylation sites in the RNA surveillance protein Upf1.

One third of inherited genetic diseases are caused by mRNAs harboring premature termination codons as a result of nonsense mutations. These aberrant mRNAs are degraded by the Nonsense-Mediated mRNA Decay (NMD) pathway. A central component of the NMD pathway is Upf1, an RNA-dependent ATPase and helicase. Upf1 is a known phosphorylated protein, but only portions of this large protein have been examined for phosphorylation sites and the functional relevance of its phosphorylation has not been elucidated in Saccharomyces cerevisiae. Using tandem mass spectrometry analyses, we report the identification of 11 putative phosphorylated sites in S. cerevisiae Upf1. Five of these phosphorylated residues are located within the ATPase and helicase domains and are conserved in higher eukaryotes, suggesting a biological significance for their phosphorylation. Indeed, functional analysis demonstrated that a small carboxy-terminal motif harboring at least three phosphorylated amino acids is important for three Upf1 functions: ATPase activity, NMD activity and the ability to promote translation termination efficiency. We provide evidence that two tyrosines within this phospho-motif (Y-738 and Y-742) act redundantly to promote ATP hydrolysis, NMD efficiency and translation termination fidelity

Engaging diverse populations in aging research during the COVID-19 pandemic: Lessons learned from four National Institutes of Health funded-Centers

BackgroundThe COVID-19 pandemic’s impact on our personal and professional lives required a rapid adaptation to the evolving health crisis and accumulating social stresses. Established measures to reduce the spread of infection and potential death had a direct effect on ongoing research that involved older adults and underrepresented racial/ethnic groups. Although important to preserve public health, these measures risk further isolation of vulnerable research participant populations and threatened established community partnerships. To address the social and research challenges evolving from the COVID-19 pandemic, four National Institutes of Health funded-Centers that engage with community members to enhance research and advance the science of aging came together to learn from each other’s efforts, approaches, and communication with community partners.MethodsMonthly meetings served as a venue to discuss the challenges of engagement with research participants and support community partners during the pandemic. The developed learning community also contributed to recognize and address research staff stress and isolation. We describe how these conversations led our Centers to address unprecedented challenges and sustain community engagement within diverse populations, especially Black/African Americans, Latinos, Middle Eastern/Arab Americans and the oldest-old.ResultsThe exchange of information resulted in maintaining long standing community relationships and partnerships in the face of the uncertainties generated by the pandemic. The strategies included adapting education programs to reduce risk of infection, recognizing symptoms, promoting vaccination and understanding of the effect of COVID-19 to the brain. Different strategies were used to address the effects of isolation and maintain community engagement. Although new research participant enrollment was a challenge, telephone and virtual visits allowed research participants to remain active in research. Community members participation in virtual learning events was variable, ranging from a dozen to hundreds of participants. Invitations to organize panels about newly developed topics indicated the need for information from trusted sources.ConclusionIn sum, the COVID-19 pandemic re - directed all four Centers’ commitment to community service led to developing strategies for social support, which will potentially contribute to transforming public perceptions about research and researchers

The Rho-Family GTPase Rac1 Regulates Integrin Localization in Drosophila Immunosurveillance Cells

BACKGROUND: When the parasitoid wasp Leptopilina boulardi lays an egg in a Drosophila larva, phagocytic cells called plasmatocytes and specialized cells known as lamellocytes encapsulate the egg. The Drosophila β-integrin Myospheroid (Mys) is necessary for lamellocytes to adhere to the cellular capsule surrounding L. boulardi eggs. Integrins are heterodimeric adhesion receptors consisting of α and β subunits, and similar to other plasma membrane receptors undergo ligand-dependent endocytosis. In mammalian cells it is known that integrin binding to the extracellular matrix induces the activation of Rac GTPases, and we have previously shown that Rac1 and Rac2 are necessary for a proper encapsulation response in Drosophila larvae. We wanted to test the possibility that Myospheroid and Rac GTPases interact during the Drosophila anti-parasitoid immune response. RESULTS: In the current study we demonstrate that Rac1 is required for the proper localization of Myospheroid to the cell periphery of haemocytes after parasitization. Interestingly, the mislocalization of Myospheroid in Rac1 mutants is rescued by hyperthermia, involving the heat shock protein Hsp83. From these results we conclude that Rac1 and Hsp83 are required for the proper localization of Mys after parasitization. SIGNIFICANCE: We show for the first time that the small GTPase Rac1 is required for Mysopheroid localization. Interestingly, the necessity of Rac1 in Mys localization was negated by hyperthermia. This presents a problem, in Drosophila we quite often raise larvae at 29°C when using the GAL4/UAS misexpression system. If hyperthermia rescues receptor endosomal recycling defects, raising larvae in hyperthermic conditions may mask potentially interesting phenotypes

Synchronous diversification of Sulawesi’s iconic artiodactyls driven by recent geological events

The high degree of endemism on Sulawesi has previously been suggested to have vicariant origins, dating back 40 Myr ago. Recent studies, however, suggest that much of Sulawesi’s fauna assembled over the last 15 Myr. Here, we test the hypothesis that more recent uplift of previously submerged portions of land on Sulawesi promoted diversification, and that much of its faunal assemblage is much younger than the island itself. To do so, we combined palaeogeographical reconstructions with genetic and morphometric data sets derived from Sulawesi’s three largest mammals: the Babirusa, Anoa, and Sulawesi warty pig. Our results indicate that although these species most likely colonized the area that is now Sulawesi at different times (14 Myr ago to 2-3 Myr ago), they experienced an almost synchronous expansion from the central part of the island. Geological reconstructions indicate that this area was above sea level for most of the last 4 Myr, unlike most parts of the island. We conclude that emergence of land on Sulawesi (~1–2 Myr) may have allowed species to expand synchronously. Altogether, our results indicate that the establishment of the highly endemic faunal assemblage on Sulawesi was driven by geological events over the last few million years

Genome-wide association study identifies susceptibility loci for B-cell childhood acute lymphoblastic leukemia.

Genome-wide association studies (GWAS) have advanced our understanding of susceptibility to B-cell precursor acute lymphoblastic leukemia (BCP-ALL); however, much of the heritable risk remains unidentified. Here, we perform a GWAS and conduct a meta-analysis with two existing GWAS, totaling 2442 cases and 14,609 controls. We identify risk loci for BCP-ALL at 8q24.21 (rs28665337, P = 3.86 × 10-9, odds ratio (OR) = 1.34) and for ETV6-RUNX1 fusion-positive BCP-ALL at 2q22.3 (rs17481869, P = 3.20 × 10-8, OR = 2.14). Our findings provide further insights into genetic susceptibility to ALL and its biology

The genomic landscape of balanced cytogenetic abnormalities associated with human congenital anomalies

Despite the clinical significance of balanced chromosomal abnormalities (BCAs), their characterization has largely been restricted to cytogenetic resolution. We explored the landscape of BCAs at nucleotide resolution in 273 subjects with a spectrum of congenital anomalies. Whole-genome sequencing revised 93% of karyotypes and demonstrated complexity that was cryptic to karyotyping in 21% of BCAs, highlighting the limitations of conventional cytogenetic approaches. At least 33.9% of BCAs resulted in gene disruption that likely contributed to the developmental phenotype, 5.2% were associated with pathogenic genomic imbalances, and 7.3% disrupted topologically associated domains (TADs) encompassing known syndromic loci. Remarkably, BCA breakpoints in eight subjects altered a single TAD encompassing MEF2C, a known driver of 5q14.3 microdeletion syndrome, resulting in decreased MEF2C expression. We propose that sequence-level resolution dramatically improves prediction of clinical outcomes for balanced rearrangements and provides insight into new pathogenic mechanisms, such as altered regulation due to changes in chromosome topology

Molecular dynamics pre-simulations for nanoscale computational fluid dynamics

We present a procedure for using molecular dynamics (MD) simulations to provide essential fluid and interface properties for subsequent use in computational fluid dynamics (CFD) calculations of nanoscale fluid flows. The MD pre-simulations enable us to obtain an equation of state, constitutive relations, and boundary conditions for any given fluid/solid combination, in a form that can be conveniently implemented within an otherwise conventional Navier–Stokes solver. Our results demonstrate that these enhanced CFD simulations are then capable of providing good flow field results in a range of complex geometries at the nanoscale. Comparison for validation is with full-scale MD simulations here, but the computational cost of the enhanced CFD is negligible in comparison with the MD. Importantly, accurate predictions can be obtained in geometries that are more complex than the planar MD pre-simulation geometry that provides the nanoscale fluid properties. The robustness of the enhanced CFD is tested by application to water flow along a (15,15) carbon nanotube, and it is found that useful flow information can be obtained