Biology subjects

Bodamer, O.

Publications and source records attributed to Bodamer, O..

4 recordsLinked to original sources

bioRxiv2026

Technical Note: Focused ultrasound-mediated blood-brain barrier opening for delivery of LNP-packaged modRNA therapy in a mouse model of Niemann-Pick Disease Type C

Efficient delivery of molecular therapies to the central nervous system (CNS) remains a major barrier to treating neurogenetic disorders such as Niemann-Pick type C (NPC) disease. Focused ultrasound-mediated blood-brain barrier opening (FUS-BBBO) has emerged as a non-invasive strategy to enhance delivery of systemically administered therapeutics. In this study, we evaluated whether FUS-BBBO could enable delivery of lipid nanoparticle (LNP)-packaged modified mRNA (modRNA) to the cerebellum in an NPC mouse model. A pilot study in wild-type mice demonstrated successful FUS-mediated BBB opening, delivery of LNP-packaged GFP mRNA, and subsequent protein expression in the cerebellum. We then performed a controlled study in NPC mice comparing delivery of LNP-GFP and LNP-NPC modRNA using intravenous administration with and without FUS-BBBO. BBB opening was confirmed by contrast-enhanced MRI in FUS-treated animals. Quantitative PCR revealed the presence of GFP mRNA in the cerebellum following FUS-BBBO, whereas NPC mRNA was minimal or undetectable across groups. However, no GFP or NPC1 protein expression was detected in the cerebellum by western blot in any experimental group. Consistent with this, no therapeutic effect on Purkinje cell survival was observed. These results demonstrate that while FUS-BBBO reliably induces BBB opening and can facilitate limited delivery of LNP-packaged mRNA to the brain, this did not translate into detectable protein expression or therapeutic benefit in the NPC model under the conditions tested. This discrepancy between successful delivery in wild-type mice and lack of efficacy in diseased animals points to potential important biological and/or formulation-dependent barriers that must be addressed to enable effective CNS delivery of LNP-based mRNA therapies.

bioengineering↗

bioRxiv2022

KMT2D regulates thymic egress by modulating maturation and integrin expression

ObjectiveThere is a clinical need to understand how dysregulated thymocyte development, caused by pathogenic variants in the gene encoding the histone-modifying enzyme, lysine methyltransferase 2D (KMT2D), contributes to immune dysfunction, including immune deficiency, autoimmunity, and lymphoproliferative sequela, and immune-driven mortality in individuals with Kabuki syndrome type 1 (KS1). MethodsWe studied peripheral T cells and thymocytes in both individuals with KS1 and murine constitutive and conditional targeted Kmt2d in T cells and hematopoietic lineages. KMT2D target genes, identified by RNA-sequencing of murine Kmt2d-knockout single-positive thymocytes, were validated with H3K4me3 ChIP-PCR and flow cytometry. ResultsRecent thymic emigrant (RTE) and naive T cells were reduced, and memory and double-negative (DN)-T cells were expanded in human KS1 and murine models. Kmt2d loss led to Mature 1 CD8+-single positive (SP) thymocyte accumulation and a decrease in SP thymocyte egress licensing expression (normally associated with the Mature 2 phenotype). Splenomegaly is associated with hematopoietic-driven Kmt2d loss and brings to light potential overlapping phenotypes with lymphoproliferative syndromes. Finally, we identified a KMT2D-regulated cluster of integrins which likely mediates aspects of the T cell egression. ConclusionsSingle-positive thymocyte populations deficient in Kmt2d display less integrin, less maturation, and less egress licensing gene expression; thereby, altering the downstream peripheral T cell composition that contribute to the observed KS1-associated immune deficiency. T cell intrinsic Kmt2d loss increases the percentage of peripheral DNT cells potentially through dysregulated apoptotic signaling, while hematopoietic-driven Kmt2d loss predisposes to splenomegaly; therefore, loss of Kmt2d recapitulates several distinct features of lymphoproliferative syndromes.

immunology↗

bioRxiv2019

Characterization of SETD1A haploinsufficiency in humans and Drosophila defines a novel neurodevelopmental syndrome.

Defects in histone methyltransferases (HMTs) are major contributing factors in neurodevelopmental disorders (NDDs). Heterozygous variants of SETD1A involved in histone H3 lysine 4 (H3K4) methylation were previously identified in individuals with schizophrenia. Here, we define the clinical features of the Mendelian syndrome associated with haploinsufficiency of SETD1A by investigating 15 predominantly pediatric individuals who all have de novo SETD1A variants. These individuals present with a core set of symptoms comprising global developmental delay and/or intellectual disability, subtle facial dysmorphisms, behavioral and psychiatric problems. We examined cellular phenotypes in three patient derived lymphoblastoid cell lines with three variants: p.Gly535Alafs*12, c.4582-2_4582delAG, and p.Tyr1499Asp. These patient cell lines displayed DNA damage repair defects that were comparable to previously observed RNAi-mediated depletion of SETD1A. This suggested that these variants, including the p.Tyr1499Asp in the catalytic SET domain, behave as Loss-of-Function (LoF) alleles. Previous studies demonstrated a role for SETD1A in cell cycle control and differentiation. However, individuals with SETD1A variants do not show major structural brain defects or severe microcephaly, suggesting that defective proliferation and differentiation of neural progenitors is unlikely the single underlying cause of the disorder. We show here that the Drosophila Melanogaster SETD1A orthologue is required in postmitotic neurons of the fly brain for normal memory, suggesting a role in post development neuronal function. Together, this study defines a neurodevelopmental disorder caused by dominant de novo LoF variants in SETD1A and further supports a role for H3K4 methyltransferases in the regulation of neuronal processes underlying normal cognitive functioning.

genetics↗

bioRxiv2017

Molecular map of GNAO1-related disease phenotypes and reactions to treatment

The GNAO1 gene codes for the most commonly expressed G protein in the central nervous system. Pathogenic GNAO1 variants result in early-onset neurological phenotypes, sometimes with distinct epilepsy or movement disorder, and sometimes with both mani-festations in the same patient. The existing extensive knowledge about G-protein coupled receptor (GPCR) signaling provides the input needed to describe quantitatively how mutations modify the GPCR signal. This in turn allows rational interpretation of distinct phenotypes arising from mutations in GNAO1. In this work we outline a model that enables understanding of clinical phenotypes at a molecular level. The mutations affecting the catalytic pocket of GNAO1, we show, result in the improper withdrawal of the signal, and give rise to epileptic phenotypes (EPs). The converse is not true - some pure EPs are caused by mutations with no obvious impact on catalysis. Mutations close to the interface with GNAO1s downstream effector block the signal propagation in that direction, and manifest as a movement disorder phenotype without epilepsy. Quantifying the reported reaction to therapy highlights the tendency of the latter group to be unresponsive to the therapies currently in use. We argue, however, that the majority of clinically described mutations can impact several aspects of GNAO1 function at once, resulting in the continuum of phenotypes observed in patients. The reasoning based on GNAO1 signaling model provides a precision medicine paradigm to aid clinicians in selecting effective categories of medication, and in addition, can suggest pragmatic targets for future therapies.

molecular biology↗