Biology subjects

Messerle, M.

Publications and source records attributed to Messerle, M..

4 recordsLinked to original sources

bioRxiv2025

Chromosome-associated spot formation by human cytomegalovirus immediate early 1 (IE1) protein

HCMV is associated with severe disease in immunocompromised patients and is a cause of congenital disease. Already more than 30 years ago, IE1 was described to bind to mitotic chromosomes, however the implications of this finding have yet to be determined. HCMV can infect a wide range of cell types and was also detected in different tumours; however, the majority of molecular studies relating to this virus are performed in fibroblasts or monocytic cells. We examined the localization of HCMV IE1 across multiple cell types, including tumour cell lines, to better understand how the protein behaves in these cellular contexts. IE1 is one of the first HCMV genes expressed after lytic infection of the cell and it was observed to distribute evenly over the chromosomes in so-called "chromosome painting" pattern. In leukemia and glioblastoma cells we detected a novel mitotic localization pattern of IE1 - in chromosome-associated spots (CAS), in addition to "painting the chromosomes", as reported before. We demonstrate that the IE1 core domain mediates CAS localization and that the distribution pattern of IE1 on mitotic chromosomes is influenced by both the cell type being infected and the level of IE1 expression. The novel CAS localization of IE1 suggests a new, possibly cell-type specific function of this protein, distinct from its role in transcriptional regulation.

microbiology↗

bioRxiv2024

Protective function of ex vivo expanded CD8 T cells in a mouse model of adoptive therapy for cytomegalovirus infection depends on integrin beta 1 but not CXCR3, CTLA4, or PD-1 expression

The adoptive transfer of virus-specific T cells (VSTs) represents a therapeutic option for viral infection treatment in immunocompromised patients. Before administration, ex vivo culture enables VST expansion. However, it is unclear how ex vivo expansion affects the circulation, homing, and intra-tissue migration of administered VSTs. We established a model of VST immunotherapy of acute cytomegalovirus infection using adoptive transfer of ex vivo expanded OT-I CD8 T cells (recognizing SIINFEKL peptide) into Rag2-/- mice infected with murine cytomegalovirus (MCMV) encoding for the SIINFEKL peptide. Ex vivo expansion induced an effector T cell phenotype and affected the expression of integrins and chemokine receptors. CRISPR/Cas9-mediated gene deletions enabled us to address the role of selected genes in the homing of VSTs following intravenous administration. We found that deletion of Itgb1, encoding for integrin beta 1, prevented OT-I cells from entering infected organs and drastically reduced their number in blood, suggesting that adoptively transferred VSTs primarily expand in the infected tissues. In contrast, Cxcr3-/- OT-I cells provided equal protection as their Cxcr3+/+ counterparts, indicating that this chemokine receptor does not contribute to VST entry into infected organs. Further, Pdcd1 and Ctla4 deletion did not impair the transferred OT-I cells ability to protect mice from MCMV, arguing against quick exhaustion of VSTs with an effector T cell phenotype. Together, these data indicate that ex vivo expansion affects migration and activation properties of VSTs and suggest that future clinical evaluation of adoptive T cell therapy efficacy should include homing molecule expression assessment.

immunology↗

bioRxiv2022

MHC class Ia molecules facilitate MCK2-dependent MCMV infection of macrophages and virus dissemination to the salivary gland

Murine cytomegalovirus (MCMV) infection of macrophages relies on MCMV-encoded chemokine 2 (MCK2) through one or more unknown cellular receptors while infection of fibroblast occurs independent of MCK2 and is mediated by cell-expressed neuropilin 1. Applying a CRISPR screen, we now identified that the MHC-Ia/Beta-2-microglobulin (B2m) complex serves as an entry port for MCK2-mediated infection of macrophages. Further analyses revealed that MCK2-dependent infection requires expression of the MHC-Ia haplotypes H-2b and H-2d but not H-2k. The importance of the MCK2-MHC-I-pathway for primary infection and viral dissemination was highlighted by experiments with B2m-deficient mice, which lack surface expression of MHC-I molecules. In those mice, intranasally administered MCK2-proficient MCMV could not infect alveolar macrophages and subsequently failed to disseminate into the salivary glands. The identified molecular pathway used by MCMV to infect lung resident macrophages provides essential knowledge for understanding cytomegalovirus-induced pathogenesis, tissue targeting, and virus dissemination.

immunology↗

bioRxiv2019

Human cytomegalovirus nuclear capsid motility is non-directed and independent of nuclear actin bundles

Herpesvirus genome replication, capsid assembly and packaging take place in the host cell nucleus. Matured capsids leave the nucleus through a unique envelopment-de-envelopment process at the nuclear membranes called nuclear egress. How assembled and DNA-containing herpesvirus capsids reach the sites of nuclear egress is however still controversially discussed, as host chromatin that marginalizes during infection might constitute a major barrier. For alphaherpesviruses, previous work has suggested that nuclear capsids use active transport mediated by nuclear filamentous actin (F-actin). However, direct evidence for nuclear capsid motility on nuclear F-actin was missing. Our subsequent work did not detect nuclear F-actin associated with motile capsids, but instead found evidence for chromatin remodeling to facilitate passive capsid diffusion. A recent report described that human cyto-megalovirus, a betaherpesvirus, induces nuclear F-actin and that the motor protein myosin V localizes to these structures. Direct evidence of capsid recruitment to these structures and motility on them was however missing. In this study, we tested the functional role of HCMV-induced, nuclear actin assemblies for capsid transport. We did not observe transport events along nuclear F-actin. Instead, reproduction of nuclear F-actin was only possible using strong overexpression of the fluorescent marker LifeAct-mCherry-NLS. Also, two alternative fluo-rescent F-actin markers did not detect F-actin in HCMV-infected cells. Furthermore, single particle tracking of nuclear HCMV capsids showed no indication for active transport, which is in line with previous work on alphaherpesviruses.

microbiology↗