Biology subjects

Wilhelm, T.

Publications and source records attributed to Wilhelm, T..

8 recordsLinked to original sources

bioRxiv2026

Structure-Property-Performance Engineering of Hydrogel Depots for Long-Acting Peptide Delivery

Controlled release systems for subcutaneous peptide delivery often exhibit a pronounced initial burst release followed by inadequate maintenance of therapeutic exposure, limiting depot lifetime and increasing pharmacokinetic variability. Here, we engineer a dynamic, injectable hydrogel depot technology for months-long delivery of lipidated peptides. Using semaglutide as a model, we establish a modular formulation framework integrating: (i) formulation-driven tuning of depot mechanics to control release kinetics, (ii) cargo complexation strategies leveraging hydrophobic and multivalent ion-mediated interactions, and (iii) oxidative stabilization through sacrificial antioxidant excipients. We evaluated depot performance by rheology, in vitro cargo release, and in vivo pharmacokinetic and pharmacodynamic studies in rodents. Optimized formulations sustained semaglutide exposure for over six weeks from a single administration with two-fold reduction in peak-to-trough exposure and comparable total bioavailability relative to daily dosing, resulting in improved glucose control, weight regulation, and preservation of pancreatic islet content. These results suggest potential for quarterly dosing in humans. Together, this work establishes integrated and generalizable structure-property-performance relationships that account for cargo-matrix and cargo-excipient interactions across burst, diffusion, and erosion regimes to inform a practical formulation framework for engineering long-acting depots for sustained peptide delivery.

bioengineering↗

bioRxiv2025

An intergenerational lipid memory of the social environment in C. elegans

Information about the environment can, in some cases, be transmitted to an organisms offspring by epigenetic inheritance. Here, we describe a novel form of epigenetics in C. elegans where information is transmitted between generations not by alterations in DNA, chromatin, or RNA, but by changes in the composition of lipids. Specifically, we delineate an environment-to-neuron-to-intestine-to-oocyte signalling axis that alters progeny thermotolerance by remodelling lipid provisioning to oocytes when animals detect social pheromones. Intergenerational information transmission via lipid memories may represent an underappreciated form of epigenetics.

genetics↗

bioRxiv2024

KIRA6 is an effective and versatile mast cell inhibitor of IgE-mediated activation

Incidents of IgE-mediated, mast cell (MC)-driven allergic diseases are constantly rising and there is an urgent need for the development of novel pharmacological MC stabilizers. Allergen/antigen (Ag)-triggered activation of MCs via crosslinking of the high-affinity receptor for IgE (Fc{varepsilon}RI) is regulated, amongst others, by the coordinated action of various cytosolic tyrosine kinases of the SRC family, e.g. LYN and FYN, which exert positive as well as negative functions. We report that KIRA6, an inhibitor developed for the endoplasmic reticulum (ER) stress sensor IRE1, suppresses IgE-mediated pro-inflammatory MC activation by inhibiting both LYN and FYN. KIRA6 dose-dependently and effectively attenuates Ag-stimulated early signaling (e.g. substrate tyrosine phosphorylation, Ca2+ mobilization, and activation of MAPK pathways) as well as effector functions such as degranulation and pro-inflammatory cytokine production/secretion in murine bone marrow-derived MCs (BMMCs). Moreover, Ag-triggered bronchoconstriction in an ex vivo model of precision-cut lung slices (PCLS), and IgE-mediated stimulation of human MCs were repressed by KIRA6. To get in-depth inside into KIRA6 interaction with three MC-relevant tyrosine kinases, LYN, FYN, and KIT, and to elicit the potential of KIRA6 structure to serve as pharmacophore for the development of respective single-, dual-, or triple-specificity inhibitors, we modeled and evaluated the binding of KIRA6 on the three kinases by applying homology modeling and molecular dynamics simulations, as well as MM GBSA calculations. We found that KIRA6 has a high propensity to bind the inactive state of LYN, FYN, and KIT with comparable affinities. In conclusion, our data suggest the use of novel inhibitors based on the KIRA6 pharmacophore as effective MC stabilizers to improve treatment of pro-inflammatory diseases with MC involvement in need of effective pharmacological interventions.

immunology↗

bioRxiv2022

Aberrant DNA repair is a vulnerability in histone H3.3-mutant brain tumors

Pediatric high-grade gliomas (pHGG) are devastating and incurable brain tumors with recurrent mutations in histone H3.3. These mutations promote oncogenesis by dysregulating gene expression through alterations of histone modifications. We identify aberrant DNA repair as an independent oncogenic mechanism, which fosters genome instability and tumor cell growth in H3.3 mutant pHGG, thus opening new therapeutic options. The two most frequent H3.3 mutations in pHGG, K27M and G34R, drive aberrant repair of replication-associated damage by non-homologous end joining (NHEJ). Aberrant NHEJ is mediated by the DNA repair enzyme Polynucleotide Kinase 3-Phosphatase (PNKP), which shows increased association with mutant H3.3 at damaged replication forks. PNKP sustains the proliferation of cells bearing H3.3 mutations, thus conferring a molecular vulnerability, specific to mutant cells, with potential for therapeutic targeting.

cancer biology↗

bioRxiv2021

A method to enrich and purify centromeric DNA from human cells

Centromeres are key elements for chromosome segregation. Canonical centromeres are built over long-stretches of tandem repetitive arrays. Despite being quite abundant compared to other loci, centromere sequences overall still represent only 2 to 5% of the human genome, therefore studying their genetic and epigenetic features is a major challenge. Furthermore, sequencing of centromeric regions requires high coverage to fully analyze length and sequence variations, which can be extremely costly. To bypass these issues, we have developed a technique based on selective restriction digestion and size fractionation to enrich for centromeric DNA from human cells. Combining enzymes capable of cutting at high frequency throughout the genome, except within most human centromeres, with size-selection of >20 kb fragments resulted in over 25-fold enrichment in centromeric DNA. Sequencing of the enriched fractions revealed that up to 60% of the enriched material is made of centromeric DNA. This approach has great potential for making sequencing of centromeric DNA more affordable and efficient and for single DNA molecule studies.

molecular biology↗

bioRxiv2020

CENP-A chromatin prevents replication stress at centromeres to avoid structural aneuploidy

Chromosome segregation relies on centromeres, yet their repetitive DNA is often prone to aberrant rearrangements under pathological conditions. Factors that maintain centromere integrity to prevent centromere-associated chromosome translocations are unknown. Here, we demonstrate the importance of the centromere-specific histone H3 variant CENP-A in safeguarding DNA replication of alpha-satellite repeats to prevent structural aneuploidy. Rapid removal of CENP-A in S-phase, but not other cell cycle stages, caused accumulation of R-loops with increased centromeric transcripts, and interfered with replication fork progression. Replication without CENP-A causes recombination at alpha-satellites in an R-loop-dependent manner, unfinished replication and anaphase bridges. In turn, chromosome breakage and translocations arise specifically at centromeric regions. Our findings provide insights into how specialized centromeric chromatin maintains the integrity of transcribed noncoding repetitive DNA during S-phase. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/277103v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@4e6dc4org.highwire.dtl.DTLVardef@1089c90org.highwire.dtl.DTLVardef@5ee5c2org.highwire.dtl.DTLVardef@3e300d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2020

Capitalizing on paradoxical activation of the MAPK pathway for treatment of Imatinib-resistant mast cell leukemia and chronic myelogenous leukemia

Prevention of fatal side effects during cancer therapy of cancer patients with high-dosed pharmacological inhibitors is to date a major challenge. Moreover, the development of drug resistance poses severe problems for the treatment of patients with leukemia or solid tumors. Particularly drug-mediated dimerization of RAF kinases can be the cause of acquired resistance, also called "paradoxical activation". Here we re-analyzing the effects of different tyrosine kinase inhibitors (TKIs) on the proliferation, metabolic activity, and survival of the Imatinib-resistant, KITV560G,D816V-expressing human mast cell (MC) leukemia (MCL) cell line HMC-1.2. We observed that low concentrations of the TKIs Nilotinib and Ponatinib resulted in enhanced proliferation, suggesting paradoxical activation of the MAPK pathway. Indeed, these TKIs caused BRAF-CRAF dimerization, resulting in ERK1/2 activation. The combination of Ponatinib with the MEK inhibitor Trametinib, at nanomolar concentrations, effectively suppressed HMC-1.2 proliferation, metabolic activity, and induced apoptotic cell death. Effectiveness of this drug combination was recapitulated in the human KIT D816V MC line ROSA KITD816V and in KIT D816V hematopoietic progenitors obtained from in patient-derived induced pluripotent stem cells (iPS cells). In conclusion, mutated KIT-driven Imatinib resistance can be efficiently bypassed by a low concentration combination of the TKI Ponatinib and the MEK inhibitor Trametinib, potentially reducing the negative side effects associated to MCL therapy.

cancer biology↗

bioRxiv2017

Neuronal Inhibition Of The Autophagy Nucleation Complex Extends Lifespan In Post-Reproductive C. elegans

Autophagy is a ubiquitous catabolic process, which causes cellular bulk degradation of cytoplasmic components and thereby regulates cellular homeostasis. Inactivation of autophagy has been linked with detrimental effects to cells and organisms. The antagonistic pleiotropy theory postulates that fitness promoting genes during youth are harmful during aging (Williams 1957). On this basis we examined genes mediating post-reproductive longevity using an RNA interference screen. From this screen we identified 30 novel regulators of post-reproductive longevity including pha-4. Through downstream analysis of pha-4 we identify that genes governing the early stages of autophagy up until the stage of vesicle nucleation, such as bec-1, strongly extend both lifespan and healthspan. Further, our data demonstrates that the improvements in health and longevity are mediated through the neurons - resulting in reduced neurodegeneration and sarcopenia. We propose that autophagy switches from advantageous to harmful in the context of an age-associated dysfunction.

molecular biology↗