Biology subjects

Huttunen, M.

Publications and source records attributed to Huttunen, M..

3 recordsLinked to original sources

bioRxiv2021

Vaccinia virus subverts xenophagy through phosphorylation and nuclear targeting of p62

Autophagy is an essential degradation program required to maintain cell homeostasis. Amongst its many functions is the engulfment and destruction of cytosolic pathogens, termed Xenophagy. Not surprisingly, many pathogens have adapted various strategies to circumvent or co-opt autophagic degradation during infection. For poxviruses, it is known that infection activates autophagy, which however is not required for successful replication. Despite the fact that these complex viruses replicate exclusively in the cytoplasm, autophagy-mediated control of poxvirus infection has not been explored. Using the prototypic poxvirus, vaccinia virus (VACV), we show that over-expression of the xenophagy receptors p62, NDP52 and Tax1Bp1 restricts poxvirus infection. While NDP52 and Tax1Bp1 were degraded, p62 was found to initially target cytoplasmic virions before being shunted to the nucleus. Nuclear translocation of p62 during infection was dependent upon p62 NLS2, and VACV kinase mediated phosphorylation of associated p62 residues T269/S272. These results indicate that VACV actively targets the xenophagy receptor p62 during the early stages of infection to avoid destruction, and further suggest that poxviruses exhibit a unique multi-layered control of autophagy in order to facilitate cytoplasmic replication.

microbiology↗

bioRxiv2020

Vaccinia virus hijacks ESCRT-mediated multivesicular body formation for virus egress

Unlike most enveloped viruses, poxvirus egress is a complex process whereby cytoplasmic single membrane-bound virions are wrapped in a cell-derived double membrane. These triple membrane-bound particles, termed intracellular enveloped virions (IEVs), are then released from infected cells by fusion. While the wrapping double membrane is thought to be derived from virus-modified trans-Golgi or early endosomal cisternae, the cellular factors that regulate virus wrapping remain largely undefined. To identify novel cell factors required for this process the prototypic poxvirus, vaccinia virus (VACV), was subjected to a high-throughput RNAi screen directed against cellular membrane trafficking proteins. Focusing on the endosomal sorting complexes required for transport (ESCRT), we demonstrate that ESCRT-III and VPS4 are required for packaging of virus into multivesicular bodies (MVBs). EM-based characterization of these MVB-IEVs showed that they account for half of IEV production indicating that MVBs serve as a second major source of VACV wrapping membrane. These data support a model whereby, in addition to cisternae-based wrapping, VACV hijacks ESCRT-mediated MVB formation to facilitate virus egress and spread.

cell biology↗

bioRxiv2019

Mimicry embedding for advanced neuralnetwork training of 3D biomedical micrographs

The use of deep neural networks (DNNs) for analysis of complex biomedical images shows great promise but is hampered by a lack of large verified datasets for rapid network evolution. Here we present a novel \"mimicry embedding\" strategy for rapid application of neural network architecture-based analysis of biomedical imaging datasets. Embedding of a novel biological dataset, such that it mimics a verified dataset, enables efficient deep learning and seamless architecture switching. We apply this strategy across various microbiological phenotypes; from super-resolved viruses to in vivo parasitic infections. We demonstrate that mimicry embedding enables efficient and accurate analysis of three-dimensional microscopy datasets. The results suggest that transfer learning from pre-trained network data may be a powerful general strategy for analysis of heterogeneous biomedical imaging datasets.

bioinformatics↗