Biology subjects

Henriques, J.

Publications and source records attributed to Henriques, J..

4 recordsLinked to original sources

bioRxiv2024

The cortical heartbeat-evoked potential is modulated by heart rate in a task and mental effort dependent manner

Cardiac cycle duration, or interbeat interval (IBI), is the period from one heartbeat to the next. IBI changes from cycle to cycle. Periods with longer IBI are associated with higher sensitivity to external sensory stimuli (exteroception). Warning cues induce a state of attentive anticipation characterized by an increase in IBI (anticipatory cardiac deceleration) and faster reaction times. Ageing reduces the increase in IBI induced by warning cues and response speed. However, it is unclear which mechanism, if any, connects IBI with reaction time. The heartbeat-evoked potential (HEP) is a cortical response evoked by the heartbeat, modulated by attention and associated with sensitivity to external sensory stimuli. HEP might be affected by IBI and mediate the association between cardiac output and cortical processing. We investigated if the HEP was affected by warning cues as well as spontaneous fluctuations in IBI. To explore the impact of age-related changes in cardiac responses, we included young and older people [N = 33/29; 26/23 women; mean age 23/61 years]. We analysed the electroencephalograms and electrocardiograms simultaneously acquired during auditory cued simple reaction time and go/no-go tasks. The warning cue did not induce significant changes in the HEP. Yet, fluctuations in IBI (not locked with the warning cue) affected the HEP and HEP amplitude was associated with average reaction time in the older group. However, on a trial-by-trial basis, reaction time was independent from IBI fluctuations. In conclusion, we found no evidence that the HEP mediates the effect of attention orienting on reaction time.

neuroscience↗

bioRxiv2020

Identification of oncolytic vaccinia restriction factors in canine high-grade mammary tumor cells using single-cell transcriptomics

Mammary carcinoma, including triple-negative breast carcinomas (TNBC) are tumor-types for which human and canine pathologies are closely related at the molecular level. Low-passage, primary carcinoma cells from TNBC versus non-TNBC were used to compare the efficacy of an oncolytic vaccinia virus (VV). We show that non-TNBC cells are 28 times more sensitive to VV than TNBC cells in which VV replication is impaired. Single-cell RNA-seq performed on two different TNBC cell samples infected or not with VV highlighted three distinct populations: naive cells, bystander cells, defined as cells exposed to the virus but not infected and infected cells. The transcriptome of these three populations showed striking variations in the modulation of pathways regulated by cytokines and growth factors. We hypothesized that the pool of genes expressed in the bystander populations was enriched in antiviral genes. Bio-informatic analysis suggested that the reduced activity of the virus was associated with a higher mesenchymal status of the cells. In addition, we demonstrate experimentally that high expression of one gene, DDIT4, is detrimental to VV production. Considering that DDIT4 is associated with a poor prognosis in various cancers including TNBC, out data highlight DDIT4 as a candidate resistance marker for oncolytic poxvirus therapy. This information could be used to design new generations of oncolytic poxviruses. Beyond the field of gene therapy, this study demonstrate that single-cell transcriptomics can be used to identify cellular factors influencing viral replication. Author summaryThe identification of cellular genes influencing viral replication/propagation have been studied using hypothesis-driven approaches and/or high-throughput RNA interference screens. In the present report, we propose a methodology based on single-cell transcriptomic. We have studied, in the context of oncolytic virothepary, the susc eptibility of primary, low-passage mammary carcinoma cells of canine origin from different grades to an oncolytic vaccinia virus (VV). We highlight a fault in replication of VV in cells originated from high-grade triple-negative breast carcinomas (TNBC). Single-cell RNA-seq performed on TNBC cell samples infected with VV suggested that the reduced activity of the virus was associated with a higher mesenchymal status of the cells. We also demonstrate that high expression of one gene, DDIT4, is detrimental to VV production. Considering that DDIT4 is associated with a poor prognosis in various cancers including TNBC, out data highlight DDIT4 as a candidate resistance marker for oncolytic poxvirus therapy. Beyond the field of cancer gene therapy, we demonstrate here that single-cell transcriptomics increases the arsenal of tools available to identify cellular factors influencing viral replication.

cancer biology↗

bioRxiv2020

Protein dynamics enables phosphorylation of buried residues in Cdk2/Cyclin A-bound p27

Proteins carry out a wide range of functions that are tightly regulated in space and time. Protein phosphorylation is the most common post-translation modification of proteins and plays key roles in the regulation of many biological processes. The finding that many phosphorylated residues are not solvent exposed in the unphosphorylated state opens several questions for understanding the mechanism that underlies phosphorylation and how phosphorylation may affect protein structures. First, since kinases need access to the phosphorylated residue, how do such buried residues become modified? Second, once phosphorylated, what are the structural effects of phosphorylation of buried residues and do they lead to changed conformational dynamics. We have used the ternary complex between p27, Cdk2 and Cyclin A to study these questions using enhanced sampling molecular dynamics simulations. In line with previous NMR and single-molecule fluorescence experiments we observe transient exposure of Tyr88 in p27, even in its unphosphorylated state. Once Tyr88 is phosphorylated, we observe a coupling to a second site, thus making Tyr74 more easily exposed, and thereby the target for a second phosphorylation step. Our observations provide atomic details on how protein dynamics plays a role in modulating multi-site phosphorylation in p27, thus supplementing previous experimental observations. More generally, we discuss how the observed phenomenon of transient exposure of buried residues may play a more general role in regulating protein function. Significance StatementProtein phosphorylation is a common post-translation modification and is carried out by kinases. While many phosphorylation sites are located in disordered regions of proteins or in loops, a surprisingly large number of modification sites are buried inside folded domains. This observation led us to ask the question of how kinases gain access to such buried residues. We used the complex between p27, a regulator of cell cycle progression, and Cyclin-dependent kinase 2/Cyclin A to study this problem. We hypothesized that transient exposure of buried tyrosines in p27 to the solvent would make them accessible to kinases, explaining how buried residues get modified. We provide an atomic-level description of these dynamic processes revealing how protein dynamics plays a role in regulation.

biophysics↗

bioRxiv2017

Genetic ablation of RhoA in adult microglia causes synapse and neuronal loss

Nervous tissue homeostasis requires regulation of microglia activity. Using conditional gene targeting in mice, we demonstrate that genetic ablation of the small GTPase Rhoa in adult microglia is sufficient to trigger spontaneous microglia activation producing a neurological phenotype (including synapse and neuron loss, impairment of LTP, formation of {beta}-amyloid plaques and memory deficits). Mechanistically, loss of Rhoa in microglia triggers Src activation and Src-mediated Tnf production, leading to excitotoxic glutamate secretion. Inhibiting Src in microglia Rhoa-deficient mice attenuates microglia dysregulation and the ensuing neurological phenotype. We also found that the Rhoa/Src signaling pathway was disrupted in microglia of the APP/PS1 mouse model of Alzheimers disease and that low doses of A{beta} oligomers triggered microglia neurotoxic polarization through the disruption of Rhoa-to-Src signaling. Overall, our results indicate that disturbing RhoGTPase signaling in microglia can directly cause neurodegeneration.

neuroscience↗