Distinct pathway for evolution of enhanced receptor binding and cell entry in SARS-like bat coronaviruses.

Understanding the zoonotic risks posed by bat coronaviruses (CoVs) is critical for pandemic preparedness. Herein, we generated recombinant vesicular stomatitis viruses (rVSVs) bearing spikes from divergent bat CoVs to investigate their cell entry mechanisms. Unexpectedly, the successful recovery of rVSVs bearing the spike from SHC014, a SARS-like bat CoV, was associated with the acquisition of a novel substitution in the S2 fusion peptide-proximal region (FPPR).

A general method for quantitative fractionation of mammalian cells.

Subcellular fractionation in combination with mass spectrometry-based proteomics is a powerful tool to study localization of key proteins in health and disease. Here we offered a reliable and rapid method for mammalian cell fractionation, tuned for such proteomic analyses. This method proves readily applicable to different cell lines in which all the cellular contents are accounted for, while maintaining nuclear and nuclear envelope integrity.

Human hepatocyte PNPLA3-148M exacerbates rapid non-alcoholic fatty liver disease development in chimeric mice.

Advanced non-alcoholic fatty liver disease (NAFLD) is a rapidly emerging global health problem associated with pre-disposing genetic polymorphisms, most strikingly an isoleucine to methionine substitution in patatin-like phospholipase domain-containing protein 3 (PNPLA3-I148M). Here, we study how human hepatocytes with PNPLA3 148I and 148M variants engrafted in the livers of broadly immunodeficient chimeric mice respond to hypercaloric diets. As early as four weeks, mice developed dyslipidemia, impaired glucose tolerance, and steatosis with ballooning degeneration selectively in the human graft, followed by pericellular fibrosis after eight weeks of hypercaloric feeding.

Evidence for a Hepatitis B Virus Short RNA Fragment Directly Targeting the Cellular RRM2 Gene.

The hepatitis B virus (HBV) is one of the smallest but most highly infectious human pathogens. With a DNA genome of only 3.2 kb and only four genes, HBV successfully completes its life cycle by using intricate processes to hijack the host machinery.

RNR-R2 Upregulation by a Short Non-Coding Viral Transcript.

DNA viruses require dNTPs for replication and have developed different strategies to increase intracellular dNTP pools. Hepatitis B virus (HBV) infects non-dividing cells in which dNTPs are scarce and the question is how viral replication takes place. Previously we reported that the virus induces the DNA damage response (DDR) pathway culminating in RNR-R2 expression and the generation of an active RNR holoenzyme, the key regulator of dNTP levels, leading to an increase in dNTPs.

Replication and single-cycle delivery of SARS-CoV-2 replicons.

Molecular virology tools are critical for basic studies of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and for developing new therapeutics. Experimental systems that do not rely on viruses capable of spread are needed for potential use in lower-containment settings. In this work, we use a yeast-based reverse genetics system to develop spike-deleted SARS-CoV-2 self-replicating RNAs.

Genome-Scale Identification of SARS-CoV-2 and Pan-coronavirus Host Factor Networks.

The coronavirus disease 2019 (COVID-19) pandemic has claimed the lives of over one million people worldwide. The causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a member of the Coronaviridae family of viruses that can cause respiratory infections of varying severity. The cellular host factors and pathways co-opted during SARS-CoV-2 and related coronavirus life cycles remain ill defined.

Functional interrogation of a SARS-CoV-2 host protein interactome identifies unique and shared coronavirus host factors.

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has devastated the global economy and claimed more than 1.7 million lives, presenting an urgent global health crisis. To identify host factors required for infection by SARS-CoV-2 and seasonal coronaviruses, we designed a focused high-coverage CRISPR-Cas9 library targeting 332 members of a recently published SARS-CoV-2 protein interactome.

Genome-scale identification of SARS-CoV-2 and pan-coronavirus host factor networks.

Unlabelled: The COVID-19 pandemic has claimed the lives of more than one million people worldwide. The causative agent, SARS-CoV-2, is a member of the family, which are viruses that cause respiratory infections of varying severity. The cellular host factors and pathways co-opted by SARS-CoV-2 and other coronaviruses in the execution of their life cycles remain ill-defined.

Functional interrogation of a SARS-CoV-2 host protein interactome identifies unique and shared coronavirus host factors.

Unlabelled: The ongoing SARS-CoV-2 pandemic has devastated the global economy and claimed nearly one million lives, presenting an urgent global health crisis. To identify host factors required for infection by SARS-CoV-2 and seasonal coronaviruses, we designed a focused high-coverage CRISPR-Cas9 library targeting 332 members of a recently published SARS-CoV-2 protein interactome. We leveraged the compact nature of this library to systematically screen four related coronaviruses (HCoV-229E, HCoV-NL63, HCoV-OC43 and SARS-CoV-2) at two physiologically relevant temperatures (33 °C and 37 °C), allowing us to probe this interactome at a much higher resolution relative to genome scale studies.

Expansion, in vivo-ex vivo cycling, and genetic manipulation of primary human hepatocytes.

Primary human hepatocytes (PHHs) are an essential tool for modeling drug metabolism and liver disease. However, variable plating efficiencies, short lifespan in culture, and resistance to genetic manipulation have limited their use. Here, we show that the pyrrolizidine alkaloid retrorsine improves PHH repopulation of chimeric mice on average 10-fold and rescues the ability of even poorly plateable donor hepatocytes to provide cells for subsequent ex vivo cultures.

Correction: miRNA independent hepacivirus variants suggest a strong evolutionary pressure to maintain miR-122 dependence.

[This corrects the article DOI: 10.1371/journal.ppat.

The nonreceptor tyrosine kinase c-Src attenuates SCF(β-TrCP) E3-ligase activity abrogating Taz proteasomal degradation.

The polyomavirus middle T antigen (PyMT) oncogene activates the cellular nonreceptor tyrosine kinase c-Src and recruits the Hippo pathway effectors, Yap (yes-associated protein) and Taz (transcriptional coactivator with PDZ-binding motif), as key steps in oncogenesis. Yap and Taz are transcription coactivators shuttling from the cytoplasm to the nucleus. The Hippo pathway kinase Lats1/2 (large tumor suppressor homolog) reduces Yap/Taz nuclear localization and minimizes their cytoplasmic levels by facilitating their ubiquitination by the E3 ligase SCF(β-TrCP).

Hepatitis B virus induces RNR-R2 expression via DNA damage response activation.

Background & Aims: Hepatitis B virus (HBV) infects and replicates in quiescent hepatocytes, which are deficient in dNTPs, the critical precursors of HBV replication. Most tumor viruses promote dNTP production in host cells by inducing cell proliferation. Although HBV is known as a major cause of hepatocellular carcinoma, it does not lead to cellular proliferation.