Functional and Biochemical Characterization of Hepatitis C Virus (HCV) Particles Produced in a Humanized Liver Mouse Model

Lipoprotein components are crucial factors for hepatitis C virus (HCV) assembly and entry. As hepatoma cells producing cell culture-derived HCV (HCVcc) particles are impaired in some aspects of lipoprotein metabolism, it is of upmost interest to biochemically and functionally characterize the in vivo produced viral particles, particularly regarding how lipoprotein components modulate HCV entry by lipid transfer receptors such as scavenger receptor BI (SR-BI). Sera from HCVcc-infected liver humanized FRG mice were separated by density gradients. Viral subpopulations, termed HCVfrg particles, were characterized for their physical properties, apolipoprotein association, and infectivity. We demonstrate that, in contrast to the widely spread distribution of apolipoproteins across the different HCVcc subpopulations, the most infectious HCVfrg particles are highly enriched in apoE, suggesting that such apolipoprotein enrichment plays a role for entry of in vivo derived infectious particles likely via usage of apolipoprotein receptors. Consistent with this salient feature, we further reveal previously undefined functionalities of SR-BI in promoting entry of in vivo produced HCV. First, unlike HCVcc, SR-BI is a particularly limiting factor for entry of HCVfrg subpopulations of very low density. Second, HCVfrg entry involves SR-BI lipid transfer activity but not its capacity to bind to the viral glycoprotein E2. In conclusion, we demonstrate that composition and biophysical properties of the different subpopulations of in vivo produced HCVfrg particles modulate their levels of infectivity and receptor usage, hereby featuring divergences with in vitro produced HCVcc particles and highlighting the powerfulness of this in vivo model for the functional study of the interplay between HCV and liver components

Comparative roadmaps of reprogramming and oncogenic transformation identify Bcl11b and Atoh8 as broad regulators of cellular plasticity

Coordinated changes of cellular plasticity and identity are critical for pluripotent reprogramming and oncogenic transformation. However, the sequences of events that orchestrate these intermingled modifications have never been comparatively dissected. Here, we deconvolute the cellular trajectories of reprogramming (via Oct4/Sox2/Klf4/c-Myc) and transformation (via Ras/c-Myc) at the single-cell resolution and reveal how the two processes intersect before they bifurcate. This approach led us to identify the transcription factor Bcl11b as a broad-range regulator of cell fate changes, as well as a pertinent marker to capture early cellular intermediates that emerge simultaneously during reprogramming and transformation. Multiomics characterization of these intermediates unveiled a c-Myc/Atoh8/Sfrp1 regulatory axis that constrains reprogramming, transformation and transdifferentiation. Mechanistically, we found that Atoh8 restrains cellular plasticity, independent of cellular identity, by binding a specific enhancer network. This study provides insights into the partitioned control of cellular plasticity and identity for both regenerative and cancer biology.A. Huyghe ... J.M Polo ... et al

HTLV-1 propels thymic human T cell development in “human immune system” Rag2-/- IL-2R γc-/- Mice

Alteration of early haematopoietic development is thought to be responsible for the onset of immature leukemias and lymphomas. We have previously demonstrated that TaxHTLV-1 interferes with ß-selection, an important checkpoint of early thymopoiesis, indicating that human T-cell leukemia virus type 1 (HTLV-1) infection has the potential to perturb thymic human αβ T-cell development. To verify that inference and to clarify the impact of HTLV-1 infection on human T-cell development, we investigated the in vivo effects of HTLV-1 infection in a “Human Immune System” (HIS) Rag2-/-γc-/- mouse model. These mice were infected with HTLV-1, at a time when the three main subpopulations of human thymocytes have been detected. In all but two inoculated mice, the HTLV-1 provirus was found integrated in thymocytes; the proviral load increased with the length of the infection period. In the HTLV-1-infected mice we observed alterations in human T-cell development, the extent of which correlated with the proviral load. Thus, in the thymus of HTLV-1-infected HIS Rag2-/-γc-/- mice, mature single-positive (SP) CD4+ and CD8+ cells were most numerous, at the expense of immature and double-positive (DP) thymocytes. These SP cells also accumulated in the spleen. Human lymphocytes from thymus and spleen were activated, as shown by the expression of CD25: this activation was correlated with the presence of tax mRNA and with increased expression of NF-kB dependent genes such as bfl-1, an anti-apoptotic gene, in thymocytes. Finally, hepato-splenomegaly, lymphadenopathy and lymphoma/thymoma, in which Tax was detected, were observed in HTLV-1-infected mice, several months after HTLV-1 infection. These results demonstrate the potential of the HIS Rag2-/-γc-/- animal model to elucidate the initial steps of the leukemogenic process induced by HTLV-1

Assessment of the current and emerging criteria for the histopathological classification of lung neuroendocrine tumours in the lungNENomics project

Background: Six thoracic pathologists reviewed 259 lung neuroendocrine tumours (LNETs) from the lungNENomics project, with 171 of them having associated survival data. This cohort presents a unique opportunity to assess the strengths and limitations of current World Health Organization (WHO) classification criteria and to evaluate the utility of emerging markers. Patients and methods: Patients were diagnosed based on the 2021 WHO criteria, with atypical carcinoids (ACs) defined by the presence of focal necrosis and/or 2-10 mitoses per 2 mm2. We investigated two markers of tumour proliferation: the Ki-67 index and phospho-histone H3 (PHH3) protein expression, quantified by pathologists and automatically via deep learning. Additionally, an unsupervised deep learning algorithm was trained to uncover previously unnoticed morphological features with diagnostic value. Results: The accuracy in distinguishing typical from ACs is hampered by interobserver variability in mitotic counting and the limitations of morphological criteria in identifying aggressive cases. Our study reveals that different Ki-67 cut-offs can categorise LNETs similarly to current WHO criteria. Counting mitoses in PHH3+ areas does not improve diagnosis, while providing a similar prognostic value to the current criteria. With the advantage of being time efficient, automated assessment of these markers leads to similar conclusions. Lastly, state-of-the-art deep learning modelling does not uncover undisclosed morphological features with diagnostic value. Conclusions: This study suggests that the mitotic criteria can be complemented by manual or automated assessment of Ki-67 or PHH3 protein expression, but these markers do not significantly improve the prognostic value of the current classification, as the AC group remains highly unspecific for aggressive cases. Therefore, we may have exhausted the potential of morphological features in classifying and prognosticating LNETs. Our study suggests that it might be time to shift the research focus towards investigating molecular markers that could contribute to a more clinically relevant morpho-molecular classification.</p

Career transitions: an empirical examination of second career of military retirees

We examined the prospects of successful career transition from the defense forces and into the dynamic and turbulent civilian career, focusing on possible antecedents for success in the second career. Based on a sample of 202 high level retirees from military and civilian defense organizations in Israel, our results indicate that preparations for retirement, social capital, perception of organizational politics in the new working place and work-family conflict are related to the dependent variables and affect the retiree’s success in their second career. In addition, organizational commitment was found to serve as a mediator in these relationships. Implications for theory of career development and change, as well as practical implications and recommendations for future studies, are discussed

Complete photonic bandgaps in 12-fold symmetric quasicrystals

Photonic crystals are attracting current interest for a variety of reasons, such as their ability to inhibit the spontaneous emission of light. This and related properties arise from the formation of photonic bandgaps, whereby multiple scattering of photons by lattices of periodically varying refractive indices acts to prevent the propagation of electromagnetic waves having certain wavelengths. One route to forming photonic crystals is to etch two-dimensional periodic lattices of vertical air holes into dielectric slab waveguides. Such structures can show complete photonic bandgaps, but only for large-diameter air holes in materials of high refractive index (such as gallium arsenide, n = 3.69), which unfortunately leads to significantly reduced optical transmission when combined with optical fibres of low refractive index. It has been suggested that quasicrystalline (rather than periodic) lattices can also possess photonic bandgaps. Here we demonstrate this concept experimentally and show that it enables complete photonic bandgaps—non-directional and for any polarization—to be realized with small air holes in silicon nitride (n = 2.02), and even glass (n = 1.45). These properties make photonic quasicrystals promising for application in a range of optical devices

First evidence for vanillin in the old world: its use as mortuary offering in Middle Bronze Canaan

Four small ceramic juglets that had been used as containers for offerings in an elite Middle Bronze Age III (ca. 1650–1550 BCE) masonry tomb uncovered at Tel Megiddo in the Jezreel Valley, Israel were tested using organic residue analysis. Notably, residues of vanillin, 4-hydroxybenzaldehyde, and acetonvanillone were identified in three of the four juglets examined. These are the major fragrance and flavour components of natural vanilla extract. To date, it has been commonly accepted that vanilla was domesticated in the New World and subsequently spread to other parts of the globe. Our research first ruled out all possibility of sample contamination and then conducted a post-organic residue analysis investigation of various species within the plant kingdom from which these principle compounds could have been exploited. The results shed new light on the first known exploitation of vanilla in an Old World context, including local uses, the significance and employment in mortuary practices, and possible implications for understanding trade networks in the ancient Near East during the second millennium BCE

Inactivation of the UNC5C Netrin-1 receptor is associated with tumor progression in colorectal malignancies.

BACKGROUND & AIMS: The UNC5H netrin-1 receptors (UNC5H1-3 also called UNC5A-C) belong to the functional dependence receptors family, which share the ability to induce apoptosis in the absence of their ligands. Such a trait has been hypothesized to confer a tumor-suppressor activity. Indeed, cells harboring these receptors are thought to be dependent on ligand availability for their survival, thereby inhibiting uncontrolled tumor cell proliferation. We investigate here whether UNC5C acts as a tumor suppressor in colorectal malignancies. METHODS: The level of UNC5C was analyzed in a panel of 86 primary sporadic colorectal carcinomas. Loss of heterozygosity in the UNC5C locus and epigenetic alterations in the UNC5C promoter were also analyzed. Intestinal tumor progression was monitored in mice bearing both UNC5C and APC1638N mutations, and apoptosis was measured in intestinal tumors developed in UNC5C/APC1638N mutant mice. RESULTS: We show here that UNC5C expression is down-regulated in a large fraction of human colorectal cancers, mainly through promoter methylation. Moreover, in mice, inactivation of UNC5C is associated with increased intestinal tumor progression and a decrease in tumor cell apoptosis. CONCLUSIONS: The loss of UNC5C expression observed in human colorectal cancer is a selective advantage for tumor progression, in agreement with the dependence receptor hypothesis. Thus, the UNC5C dependence receptor is a tumor suppressor that regulates sporadic colorectal cancer