Biology subjects

Henckaerts, E.

Publications and source records attributed to Henckaerts, E..

4 recordsLinked to original sources

bioRxiv2026

Optimized AAV to express the unfolded protein response transcription factor XBP1s ameliorates Alzheimer's disease features in mouse models

Proteostasis impairment at the level of the endoplasmic reticulum (ER) is a salient feature of Alzheimers disease (AD). The unfolded protein response (UPR) is the main pathway to cope with ER stress, where the expression of the transcription factor X-Box binding protein 1 (XBP1) is central to establish repair programs. To artificially enforce the adaptive capacity of the UPR in the AD brain, we recently reported the protective effects of overexpressing active XBP1 in the brain using adeno-associated vectors (AAVs) of AD mice, in addition to aged animals. Here we have generated a next generation vector suitable for clinical testing by (i) expressing codon-optimized human XBP1s without artificial tags, (ii) the use of the synapsin promoter to restrict expression to neurons, and (iii) incorporating a novel variant of AAV2 (AAV-TT) with greater biodistribution (here termed Proteostaser-1). Treatment of 5xFAD mice with Proteostaser-1 improved spatial learning and synaptic plasticity, and reduced the deposition of amyloid plaques in the brain. Proteostaser-1 administration also improved cognition in a model of sporadic AD based on the intracerebral injection of amyloid {beta} oligomers. Our results further support the therapeutic potential of the UPR as a strategy to ameliorate AD features and sustain synaptic function.

cell biology↗

bioRxiv2025

The adeno-associated virus Rep proteins target PP4:SMEK1 by preventing substrate-recruitment

Adeno-associated virus (AAV) vectors are widely used for in vivo gene therapy, but their clinical effectiveness and scalable production remain limited by gaps in our understanding of AAV biology. In particular, the host-virus interactions that regulate AAV gene expression and replication are not fully defined, yet they hold key insights for engineering improved recombinant AAV (rAAV) vectors. Here, we identify the PP4:SMEK1/2 phosphatase complex as a host restriction factor that suppresses wildtype AAV replication. Active replication and Rep expression correlates with hyperphosphorylation of KAP1S824 and RPA2S4/8/33, known PP4 substrates. Rep proteins directly bind the HEAT/Arm domain of the SMEK1 regulatory subunit of PP4. We further reveal that the KAP1:SMEK1 interaction is mediated by a MAPP short linear motif (SLiM) that interacts with the substrate recruitment groove of the SMEK1 EVH1 domain. Rep68 disrupts this interaction and interferes with substrate recruitment by the PP4:SMEK1/2 complex, leading to substrate hyperphosphorylation. We also uncover a multifunctional complex containing PP4:SMEK1 and PP1:NIPP1, both implicated in KAP1S824 dephosphorylation. Together, these findings reveal a substrate-recruitment interference mechanism by which AAV Rep proteins inhibit host phosphatase activity. This mechanistic insight provides a blueprint for enhancing rAAV vector potency and production in gene therapy applications.

cell biology↗

bioRxiv2020

The Cryo-EM structure of AAV2 Rep68 in complex with ssDNA reveals a malleable AAA+ machine that can switch between oligomeric states.

The adeno-associated virus (AAV) Rep proteins use a unique AAA+ domain to catalyze DNA replication, transcription regulation, and genome packaging. Also, they mediate site-specific integration during a latent phase. To understand the mechanisms underlying AAV Rep function, we investigated the cryo-EM and X-ray structures of Rep68-ssDNA complexes. Surprisingly, Rep68 generates hybrid ring structures where the Origin-Binding-Domain (OBD) forms octameric rings while the helicase domain (HD) forms heptamers. Moreover, the binding to ATP{gamma}S promotes a large conformational change in the entire AAA+ domain that leads the HD to form both heptamer and hexamers. The HD oligomerization is driven by an interdomain linker region that acts as a latch to catch the neighboring HD subunit and is flexible enough to permit the formation of different stoichiometric ring structures. Overall, our studies show the structural basis of AAV Reps structural flexibility required to fulfill its multifunctional role during the AAV life cycle.

biochemistry↗

bioRxiv2018

Generation of light-producing somatic-transgenic mice using adeno-associated virus vectors

We have previously designed a library of lentiviral vectors to generate somatic-transgenic rodents to monitor signalling pathways in diseased organs using whole-body bioluminescence imaging, in conscious, freely moving rodents. We have now expanded this technology to adeno-associated viral vectors. We first explored bio-distribution by assessing GFP expression after neonatal intravenous delivery of AAV8. We observed widespread gene expression in, central and peripheral nervous system, liver, kidney and skeletal muscle. Next, we selected a constitutive SFFV promoter and NF{kappa}B binding sequence for bioluminescence and biosensor evaluation.\n\nAn intravenous injection of AAV8 containing firefly luciferase and eGFP under transcriptional control of either element resulted in strong and persistent widespread luciferase expression. A single dose of LPS-induced a 10-fold increase in luciferase expression in AAV8-NF{kappa}B mice and immunohistochemistry revealed GFP expression in cells of astrocytic and neuronal morphology. Importantly, whole-body bioluminescence persisted up to 240 days.\n\nTo further restrict biosensor activity to the CNS, we performed intracerebroventricular injection of each vector. We observed greater restriction of bioluminescence to the head and spine with both vectors. Immunohistochemistry revealed strongest expression in cells of neuronal morphology. LPS administration stimulated a 4-fold increase over baseline bioluminescence.\n\nWe have validated a novel biosensor technology in an AAV system by using an NF{kappa}B response element and revealed its potential to monitor signalling pathway in a non-invasive manner using a model of LPS-induced inflammation. This technology employs the 3Rs of biomedical animal research, complements existing germline-transgenic models and may be applicable to other rodent disease models with the use of different response elements.

genomics↗