Biology subjects

Lupashin, V. V.

Publications and source records attributed to Lupashin, V. V..

2 recordsLinked to original sources

bioRxiv2023

Essential role of the Conserved Oligomeric Golgi complex in Toxoplasma gondii

Survival of the apicomplexan parasite Toxoplasma gondii depends on the proper functioning of many glycosylated proteins. Glycosylation is performed in the major membranous organelles ER and Golgi apparatus that constitute a significant portion of the intracellular secretory system. The secretory pathway is bidirectional: cargo is delivered to target organelles in the anterograde direction, while the retrograde flow maintains the membrane balance and proper localization of glycosylation machinery. Despite the vital role of the Golgi in parasite infectivity, little is known about its biogenesis in apicomplexan parasites. In this study we examined T. gondii Conserved Oligomeric Golgi (COG) complex and determined that, contrary to predictions, T. gondii expresses the entire eight-subunit complex and each complex subunit is essential for tachyzoite growth. Deprivation of the COG complex induces a pronounced effect on Golgi and ER membranes, which suggests the T. gondii COG complex has wider role in intracellular membrane trafficking. We demonstrated that besides its conservative role in protein glycosylation and retrograde intra-Golgi trafficking, the COG complex also interacted with anterograde and novel transport machinery. Furthermore, we identified coccidian-specific components of the Golgi transport system: TgUlp1 and TgGlp1. Protein structure and phylogenetic analyses revealed that TgUlp1 is an adaptation of the conservative Golgi tethering factor Uso1/p115, and together with Golgi-localized TgGlp1, TgUlp1 showed dominant interactions with the trafficking machinery that predicted to operate the endosome-to-Golgi recycling. Together, our study showed that T. gondii has expanded function of the conservative Golgi tethering COG complex and evolved additional regulators of the transport likely to serve parasite-specific secretory organelles.

cell biology↗

bioRxiv2020

Genome-wide CRISPR-Cas9 screen reveals common factors in dsRNA and Sindbis virus-induced cell death

Double stranded RNA (dsRNA) is the hallmark of many viral infections. dsRNA is produced either by RNA viruses during replication or by DNA viruses upon convergent transcription. Synthetic dsRNA is also able to mimic viral-induced activation of innate immune response and cell death. In this study, we employed a genome-wide CRISPR-Cas9 loss of function screen based on cell survival in order to identify genes implicated in the host response to dsRNA. By challenging HCT116 human cells with either synthetic dsRNA or Sindbis virus (SINV), we identified the heparan sulfate (HS) pathway as a crucial factor for dsRNA entry and we validated SINV dependency on HS. Interestingly, we uncovered a novel role for COG4, a component of the Conserved Oligomeric Golgi (COG) complex, as a factor involved in cell survival to both dsRNA and SINV in human cells. We showed that COG4 knock-out led to a decrease of extracellular HS, specifically affected dsRNA transfection efficiency and reduced viral production, explaining the increased cell survival of these mutants. ImportanceWhen facing a viral infection, the organism has to put in place a number of defense mechanisms in order to clear the pathogen from the cell. At the early phase of this preparation for fighting against the invader, the innate immune response is triggered by the sensing of danger signals. Among those molecular cues, double-stranded (dsRNA) is a very potent inducer of different reactions at the cellular level that can ultimately lead to cell death. Using a genome-wide screening approach, we set to identify genes involved in dsRNA entry, sensing and apoptosis induction in human cells. This allowed us to determine that the heparan sulfate pathway and the Conserved Oligomeric Golgi complex are key determinants allowing entry of both dsRNA and viral nucleic acid leading to cell death.

microbiology↗