Ferulic acid derivatives block coronaviruses HCoV-229E and SARS-CoV-2 replication in vitro.

A novel coronavirus, SARS-CoV-2, emerged in China at the end of 2019 causing a large global outbreak. As treatments are of the utmost importance, drugs with broad anti-coronavirus activity embody a rich and rapid drug discovery landscape, where candidate drug compounds could be identified and optimized. To this end, we tested ten small-molecules with chemical structures close to ferulic acid derivatives (FADs) (n = 8), caffeic acid derivatives (CAFDs) (n = 1) and carboxamide derivatives (CAMDs) (n = 1) for their ability to reduce HCoV-229E replication, another member of the coronavirus family. Among these ten drugs tested, five of them namely MBA112, MBA33, MBA27-1, OS4-1 and MBA108-1 were highly cytotoxic and did not warrant further testing. In contrast, we observed a moderate cytotoxicity for two of them, MBA152 and 5c. Three drugs, namely MBA140, LIJ2P40, and MBA28 showed lower cytotoxicity. These candidates were then tested for their antiviral propreties against HCoV-229E and SARS-CoV2 replication. We first observed encouraging results in HCoV-229E. We then measured a reduction of the viral SARS-CoV2 replication by 46% with MBA28 (EC50 > 200 µM), by 58% with MBA140 (EC50 = 176 µM), and by 82% with LIJ2P40 (EC50 = 66.5 µM). Overall, the FAD LIJ2P40 showed a reduction of the viral titer on SARS-CoV-2 up to two logs with moderate cytotoxicity which opens the door to further evaluation to fight Covid-19.

Role of the cellular factor CTCF in the regulation of bovine leukemia virus latency and three-dimensional chromatin organization.

Bovine leukemia virus (BLV)-induced tumoral development is a multifactorial phenomenon that remains incompletely understood. Here, we highlight the critical role of the cellular CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the provirus. Next, we showed that CTCF localized to regions of transitions in the histone modifications profile along the BLV genome and that it is implicated in the repression of the 5'Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3'LTR promoter activity. Finally, we demonstrated that BLV integration deregulated the host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.

HIV-1 Env induces pexophagy and an oxidative stress leading to uninfected CD4+ T cell death.

The immunodeficiency observed in HIV-1-infected patients is mainly due to uninfected bystander CD4+ T lymphocyte cell death. The viral envelope glycoproteins (Env), expressed at the surface of infected cells, play a key role in this process. Env triggers macroautophagy/autophagy, a process necessary for subsequent apoptosis, and the production of reactive oxygen species (ROS) in bystander CD4+ T cells. Here, we demonstrate that Env-induced oxidative stress is responsible for their death by apoptosis. Moreover, we report that peroxisomes, organelles involved in the control of oxidative stress, are targeted by Env-mediated autophagy. Indeed, we observe a selective autophagy-dependent decrease in the expression of peroxisomal proteins, CAT and PEX14, upon Env exposure; the downregulation of either BECN1 or SQSTM1/p62 restores their expression levels. Fluorescence studies allowed us to conclude that Env-mediated autophagy degrades these entire organelles and specifically the mature ones. Together, our results on Env-induced pexophagy provide new clues on HIV-1-induced immunodeficiency.Abbreviations: Ab: antibodies; AF: auranofin; AP: anti-proteases; ART: antiretroviral therapy; BafA1: bafilomycin A1; BECN1: beclin 1; CAT: catalase; CD4: CD4 molecule; CXCR4: C-X-C motif chemokine receptor 4; DHR123: dihydrorhodamine 123; Env: HIV-1 envelope glycoproteins; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; GFP-SKL: GFP-serine-lysine-leucine; HEK: human embryonic kidney; HIV-1: type 1 human immunodeficiency virus; HTRF: homogeneous time resolved fluorescence; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NAC: N-acetyl-cysteine; PARP: poly(ADP-ribose) polymerase; PEX: peroxin; ROS: reactive oxygen species; siRNA: small interfering ribonucleic acid; SQSTM1/p62: sequestosome 1.

HIV-1 Vpr inhibits autophagy during the early steps of infection of CD4 T cells.

BACKGROUND INFORMATION: Autophagy is induced during HIV-1 entry into CD4 T cells by the fusion of the membranes triggered by the gp41 envelope glycoprotein. This anti-HIV-1 mechanism is inhibited by the viral infectivity factor (Vif) neosynthesized after HIV-1 integration to allow viral replication. However, autophagy is very rapidly controlled after HIV-1 entry by a still unknown mechanism. As HIV-1 viral protein R (Vpr) is the only auxiliary protein found within the virion in substantial amount, we studied its capability to control the early steps of HIV-1 envelope-mediated autophagy. RESULTS: We demonstrated that ectopic Vpr inhibits autophagy in both the Jurkat CD4 T cell line and HEK.293T cells. Interestingly, Vpr coming from the virus also blocks autophagy in CD4 T cells, the main cell target of HIV-1. Furthermore, Vpr decreases the expression level of two essential autophagy proteins (ATG), LC3B and Beclin-1, and an important autophagy-related protein, BNIP3 as well as the level of their mRNA. We also demonstrated in HEK.293T cells that Vpr degrades the FOXO3a transcription factor through the ubiquitin proteasome system. CONCLUSION: Vpr, the only well-expressed HIV-1 auxiliary protein incorporated into viruses, is able to negatively control autophagy induced during HIV-1 entry into CD4 T cells. SIGNIFICANCE: We provide insights of how HIV-1 controls autophagy very early after its entry into CD4 T cells and discovered a new function of Vpr. These results open the route to a better understanding of the roles of Vpr during HIV-1 infection through FOXO3a degradation and could be important to consider additional therapies that counteract the role of Vpr on autophagy.

[LAP (LC3-associated phagocytosis): phagocytosis or autophagy?] / La phagocytose associée à LC3 (LAP) - Phagocytose ou autophagie ?

Phagocytosis and macroautophagy, named here autophagy, are two essential mechanisms of lysosomal degradation of diverse cargos into membrane structures. Both mechanisms are involved in immune regulation and cell survival. However, phagocytosis triggers degradation of extracellular material whereas autophagy engulfs only cytoplasmic elements. Furthermore, activation and maturation of these two processes are different. LAP (LC3-associated phagocytosis) is a form of phagocytosis that uses components of the autophagy pathway. It can eliminate (i) pathogens, (ii) immune complexes, (iii) threatening neighbouring cells, dead or alive, and (iv) cell debris, such as POS (photoreceptor outer segment) and the midbody released at the end of mitosis. Cells have thus optimized their means of elimination of dangerous components by sharing some fundamental elements coming from the two main lysosomal degradation pathways.

TITLE: La phagocytose associée à LC3 (LAP) - Phagocytose ou autophagie ? ABSTRACT: Phagocytose et macroautophagie, appelée ici autophagie, sont deux mécanismes essentiels de dégradation lysosomale de divers cargos englobés dans des structures membranaires. Ils sont tous deux impliqués dans la régulation du système immunitaire et la survie cellulaire. Cependant, la phagocytose permet l'ingestion de matériel extracellulaire alors que l'autophagie dégrade des composants intra-cytoplasmiques, avec des mécanismes d'activation et de maturation différents. La LAP (LC3-associated phagocytosis) est une forme particulière de phagocytose qui utilise certains éléments de l'autophagie. Elle permet l'élimination de pathogènes, de complexes immuns, de cellules avoisinantes, mortes ou vivantes, constituant un danger pour l'organisme, et de débris cellulaires, tels que les segments externes des photorécepteurs (POS, photoreceptor outer segment), ou la pièce centrale du pont intercellulaire produit en fin de mitose. Les cellules ont ainsi « optimisé ¼ leurs moyens d'éliminer les composés potentiellement dangereux en partageant certains éléments essentiels des deux voies de dégradation lysosomale.