Biology subjects

Gijsbers, R.

Publications and source records attributed to Gijsbers, R..

6 recordsLinked to original sources

bioRxiv2026

A druggable ATP13A3-antizyme switch controls adaptive polyamine uptake in cancer

Cellular polyamine depletion is a promising anticancer strategy, but compensatory polyamine uptake limits efficacy when synthesis is blocked by DFMO (difluoromethylornithine), a clinically approved inhibitor of ornithine decarboxylase. The transporter and feedback mechanism driving this adaptive response have remained unclear. Despite their similar biochemical properties, we identify ATP13A3, rather than ATP13A2, as the principal DFMO-responsive polyamine importer, suggesting that these isoforms regulate distinct polyamine fluxes. Mechanistically, the polyamine sensor antizyme not only restrains polyamine biosynthesis but also selectively inhibits ATP13A3-mediated uptake, a brake that is relieved upon DFMO treatment. This regulatory circuit exposes distinct polyamine-acquisition states across cancers, defining synthesis- and/or uptake-biased subtypes that can shift during disease progression. Melanoma metastasis and vemurafenib resistance evolve toward increased ATP13A3-dependent uptake. The polyamine uptake branch controlled by ATP13A3-antizyme regulation can be pharmacologically blocked by AMXT 1501, which directly inhibits ATP13A3. Together, our findings explain DFMO adaptation through ATP13A3-antizyme control and establish ATP13A3 as a targetable node for polyamine depletion strategies in multiple cancers, supporting ongoing clinical evaluation of combined DFMO/AMXT 1501 therapy.

cell biology↗

bioRxiv2025

From injury to recovery: Functional neuronal regeneration after traumatic brain injury in the telencephalon of the young adult African turquoise killifish

Neuronal loss caused by neurodegenerative diseases and traumatic brain injuries (TBI) often results in long-term disabilities, highlighting the urgent need for further research and effective regenerative strategies. In mammals, neurogenic capacity is inherently limited and declines further with age. In contrast, the young adult killifish demonstrates a remarkable ability to regenerate neurons in the telencephalon following TBI. However, it remains unknown whether and when these newly generated neurons functionally integrate into existing circuits, as traditional histological analysis of fixed tissue offers only static insights into this dynamic process. To this end, we optimized a retroviral vector strategy to label dividing stem cells and their progeny, including newborn neurons. By introducing a combination of novel approaches i.e., retroviral vector labeling, electrophysiology and a conditioned place avoidance test, we investigated the generation, morphology, and synaptic integration of newborn neurons following TBI in the dorsomedial (Dm) zone of the telencephalon, a region homologous to the mammalian amygdala in other teleost fish. Our results show that injury-induced adult-born neurons functionally integrate into existing circuits, and that killifish can achieve functional behavioral recovery after TBI. While previous histological assessments using a stab-wound injury suggested a 30-day recovery period, our functional data reveal that full behavioral recovery requires approximately 50 days. At this point, fish successfully relearn to avoid a conditioned place, and the new neurons exhibit mature morpho-electric characteristics, including abundant dendritic spines. Electrophysiological analysis revealed that newborn neurons in an injured environment take longer to mature when compared to neurons in naive killifish. Together, our findings demonstrate that structural regeneration aligns with functional recovery, and establish retroviral vectors as a powerful tool for birth dating injury-induced neurogenesis in teleosts. Killifish thus represent a promising model for studying interventions aimed at enhancing neuronal maturation and integration after brain injury. Key pointsO_LIA retroviral vector strategy allows specific and sparse labeling of adult-born neurons in the killifish brain. C_LIO_LIThe Dm zone in the telencephalon of the killifish is responsible for avoidance learning and memory and thus homologous to the mammalian amygdala. C_LIO_LIIn young adult killifish, upon Dm injury, adult-born neurons mature morphologically and functionally in 50 days, which is slower than in constitutive neurogenesis. C_LIO_LIThe timing and extent of behavioral recovery from such injury aligns with morpho-electric observations. C_LI

neuroscience↗

bioRxiv2023

CTNS mRNA as a potential treatment for nephropathic cystinosis

Messenger RNA (mRNA) therapies are emerging in different disease areas, but have not yet reached the kidney field. Our aim was to study the feasibility to correct the genetic defect in nephropathic cystinosis using synthetic mRNA. Cystinosis is a prototype disorder of proximal tubular dysfunction caused by mutations in the CTNS gene, encoding the lysosomal cystine-H+ symporter cystinosin, and leading to cystine accumulation in all cells of the body. The kidneys are the first and most severely affected organs, presenting glomerular and proximal tubular dysfunction. Cysteamine is the current therapeutic standard that reduces cellular cystine levels, but has many side effects and does not restore kidney function. Here, we show that synthetic mRNA is safe and effective to reintroduce functional cystinosin using lipofection in CTNS-/- kidney cells and following direct injection in ctns-/- zebrafish larvae. CTNS mRNA therapy results in prompt lysosomal expression of the functional protein and decreases cellular cystine accumulation for up to 14 days. In the ctns-/- zebrafish, CTNS mRNA therapy improves proximal tubular reabsorption, reduces proteinuria, and restores brush border expression of the multi-ligand receptor megalin. We propose that mRNA-based therapy, if sufficient kidney targeting can be achieved, may be a new approach to treat cystinosis. Translational statementCystinosis is a systemic lysosomal storage disease caused by mutations in the CTNS (cystinosin) gene. It initially affects the kidneys and leads to kidney failure, if left untreated. The current standard therapy, cysteamine, is not curative and has many side-effects. Here we demonstrate the potential of mRNA-based therapy to swiftly restore cystinosin function and ameliorate the kidney phenotype. Future research will focus on mRNA delivery methods and targeting kidney cells in cystinosis rodent models.

genetics↗

bioRxiv2022

LARP1 regulates metabolism and mTORC1 activity in cancer

The protein mammalian target of rapamycin (mTOR) is a master regulator of cell homeostasis. Although mTOR is aberrantly overactivated in 70% ovarian cancers, mTOR cascade inhibitors (such as those blocking the kinase activity of mTOR itself or upstream kinases PI3K/AKT) have demonstrated disappointing activity in ovarian cancer clinical trials. These findings indicate that, despite its pivotal role in normal cells, hyperactivated mTOR does not act as a master regulator of metabolism in this cancer context. Surprisingly, we have identified that the RNA binding protein LARP1, a known phospho-target of mTORC1 and activator of ribosomal biogenesis, is responsible for metabolic reprogramming in mTOR-dysregulated cancers. LARP1 post-transcriptionally regulates the expression of several hundred rate-limiting enzymes involved in multiple aspects of metabolism, including glycolysis and oxidative phosphorylation. Through this mechanism LARP1 sustains ATP production and mTORC1 localisation on the lysosome, thereby activating cell proliferation despite the scarcity of extracellular nutrients. Our findings show that, by sustaining global cellular metabolism in response to growth factor signalling, LARP1 has a central post-transcriptional role in controlling mTORC1 localisation and driving cancer progression, a key cancer hallmark.

cancer biology↗

bioRxiv2022

Nanoblades allow high-level genome editing in organoids

Genome engineering has become more accessible thanks to the RNA programmable endonucleases such as the CRISPR/Cas9 system. However, using this editing technology in synthetic organs called organoids is still very inefficient. This is due to the delivery methods used for the CRISPR-Cas9 machinery, which include electroporation of CRISPR/Cas9 DNA, mRNA or ribonucleoproteins (RNPs) containing the CAS9-gRNA complex. However, these procedures are toxic to some extent for the organoids. Here we describe the use of the Nanoblade technology, which outperformed by far knock-out (KO) levels achieved to date by gene editing in murine and human tissue derived organoids. We reached up to 80% of gene KO in organoids after treatment with nanoblades. Indeed, high-level nanoblade-mediated KO for the androgen receptor (AR) encoding gene and the cystic fibrosis transmembrane conductance regulator (CFTR) gene was achieved with single gRNA or dual gRNA containing nanoblades in murine prostate and colon organoids. Likewise, nanoblades achieved high levels of gene editing in human organoids ranging between 20% and 50%. Most importantly, in contrast to other gene editing methods, this was obtained without toxicity for the organoids. Only four weeks are required to obtain stable gene KO in organoids and nanoblades simplify and allow rapid genome editing in organoids with little to no side-effects such as possible unwanted INDELS in off-target sites.

bioengineering↗

bioRxiv2022

BET-independent MLV integration is retargeted in vivo and selects distinct genomic elements for lymphomagenesis

Moloney murine leukemia virus (MLV) infects BALB/c mice and induces T-cell lymphoma in mice. Retroviral integration is mediated by the interaction of the MLV integrase (IN) with members of the bromodomain and extra-terminal motif (BET) protein family (BRD2, BRD3 and BRD4). Introduction of the W390A mutation in MLV IN abolishes BET interaction. Here we compared the replication of W390A MLV and WT MLV in adult BALB/c mice to study the role of BET proteins in replication, integration and tumorigenesis in vivo. Comparing WT and W390A MLV infection revealed similar viral loads in blood, thymus and spleen cells. Interestingly, W390A MLV integration was retargeted away from GC-enriched genomic regions. However, both WT MLV and W390A MLV developed T cell lymphoma after a similar latency represented by an enlarged thymus and spleen and multi-organ tumor infiltration. Integration site sequencing from splenic tumor cells revealed clonal expansion in all WT MLV- and W390A MLV-infected mice. However, the integration profile of W390A MLV and WT MLV differed significantly. Integrations were enriched in enhancers and promoters but compared to WT, W390A MLV integrated less frequently into enhancers and more into oncogene bodies, such as Notch1 and Ppp1r16b. We conclude that host factors direct MLV in vivo integration site selection. Although, BET proteins target WT MLV integration preferentially towards enhancers and promoters, insertional lymphomagenesis can occur independently from BET, likely due to the intrinsically strong enhancer/promoter of the MLV LTR.

microbiology↗