Biology subjects

Holm, A.

Publications and source records attributed to Holm, A..

10 recordsLinked to original sources

bioRxiv2026

Vertical climbing in mice: a translationally relevant measure of pain-related impact on natural behaviour

Despite urgent need for better analgesics, drug development has been complicated by incomplete bench-to-bedside translation. A likely contributing factor is the poor connection between the experimenter-evoked pain-related measures often used in preclinical models, and the clinical symptoms, like broader functional impairment, reported by patients. Here, we asked whether vertical climbing, a species-specific elective behaviour in mice, could serve as a measure of pain-related impairment. We tested male and female mice in a wide range of pain-related models including models of post-operative pain, inflammatory injury, osteoarthritis, rheumatoid arthritis, cancer-induced bone pain, fibrous dysplasia, neuropathic pain, migraine-related pain and facial neuropathy. Vertical climbing was reduced in all models, across five different laboratories, demonstrating the robustness and consistency of this type of behaviour as a novel pain-related outcome measure. Reduced climbing correlated significantly with established pain-related measures, but its time course diverged from that of evoked mechanical allodynia, while aligned more closely with other non-evoked behaviours, like burrowing, home cage activity, wheel running or weight bearing. Pharmacological validation was bidirectional: gabapentin restored climbing in mice with neuropathic injury, and naltrexone reinstated the climbing deficit in mice that had recovered from intraplantar CFA, consistent with persistent pain held in remission by endogenous opioid signalling. Overall, our results indicate that voluntary vertical climbing is a stable, elective behaviour that provides a robust and translationally relevant measure of pain-related functional impairment in mice.

neuroscience↗

bioRxiv2026

A de novo GABPA Variant in a Patient with Multifocal Cutaneous Vascular Tumors of an Unclassified Entity

We investigated the genetic basis of a previously unclassified congenital vascular anomaly in a patient with multifocal cutaneous vascular tumors. Through genomic analysis, we identified a novel heterozygous de novo germline variant in GA-binding protein-alpha (GABPA), an ETS family transcription factor. Histopathologic evaluation demonstrated capillary-venous lesions lacking glucose transporter 1 expression, distinguishing this entity from common infantile hemangioma. Notably, the tumor vasculature exhibited a prominent alpha-SMA-positive perivascular cell layer, with nuclear localized GABPA detected in endothelial and perivascular cells. The GABPA c.509T>G (p.L170R) variant is absent from large population databases, including gnomAD, DeCAF, and RGC-MCPS databases, indicating it is extremely rare. The affected leucine residue is highly conserved across species and located within the Pointed (PNT) domain, a critical region mediating GABPA protein-protein interactions. AlphaMissense predicts this substitution to be highly damaging. Structure-based analysis using an AlphaFold-predicted approach, combined with in silico mutagenesis and molecular interaction analyses, revealed that the L170R substitution introduces new electrostatic interactions while disrupting native hydrophobic contacts within the PNT domain. Functional assessment in zebrafish demonstrated that mosaic stromal expression of GABPA-L170R caused abnormal vascular architecture compared with GABPA-wild-type controls, establishing a direct link between this variant and disrupted vascular development. Collectively, the genetic rarity, evolutionary conservation, predicted structural perturbation, and disruptive effects on vascular development establish GABPA-L170R as likely disease-causing variant. These findings define a new molecular mechanism underlying congenital vascular tumor formation and expand the role for ETS-family transcriptional regulation in human vascular anomalies.

genetics↗

bioRxiv2026

The NBSGW RIP-DTR Mouse: An Integrated Platform for Diabetes Induction, Human Immune Reconstitution and Transplantation Studies

Using toxin receptor-mediated cell ablation, a diabetes mouse model was generated that supports engraftment of human hematopoietic stem/progenitor cells (HSPCs) without the need for irradiation. The NBSGW immunodeficient strain was crossed with the NSG RIP-DTR which carries the diphtheria toxin receptor (hDTR) under the control of the rat insulin promoter to generate the NBSGW RIP-DTR mouse. This model enables controlled {beta}-cell ablation, robust human immune system reconstitution without myeloablative conditioning, and evaluation of human immune-mediated graft rejection within a single platform. NBSGW RIP-DTR mice exhibited reproducible and titratable diabetes induction, supported durable human islet engraftment and glycemic correction, and retained efficient human hematopoietic reconstitution comparable to the parental NBSGW strain. In humanized mice, diphtheria toxin-mediated diabetes induction was well tolerated and enabled assessment of human immune responses to allogeneic islet grafts. Collectively, these findings establish the NBSGW RIP-DTR mouse as an integrated and clinically relevant platform for studying {beta}-cell replacement therapies and human immune-mediated graft rejection. Article HighlightsO_LICurrent preclinical models do not simultaneously support controlled diabetes induction, human islet transplantation, and durable human immune reconstitution without irradiation. C_LIO_LIThis study asked whether the NBSGW RIP-DTR mouse could integrate diphtheria toxin-mediated {beta}-cell ablation with irradiation-free humanization in a single platform. C_LIO_LINBSGW RIP-DTR mice demonstrated reproducible diabetes induction, supported functional human islet engraftment, and retained robust human hematopoietic reconstitution comparable to parental strains. C_LIO_LIThese findings establish the NBSGW RIP-DTR model as a clinically relevant platform for studying {beta}-cell replacement and human immune response to islet allografts, xenografts and stem cell-derived islets. C_LI

immunology↗

bioRxiv2025

Inhibiting SOX18 with propranolol restores vascular integrity in NR2F2-driven malformations

Translating genomic discoveries into therapies for rare genetic disorders remains a significant challenge, particularly for variants of unknown significance (VUS) where molecular mechanisms are unclear. This is particularly relevant in vascular malformations, where venous differentiation remains poorly understood, and the role of transcription factors in specifying venous identity is only beginning to be elucidated. Here, we combine live-cell single-molecule imaging with genomics-based approaches to uncover a biophysical mechanism of transcription factor antagonism that underpins venous identity. We show that SOX18 and NR2F2 antagonistically co-regulate venous differentiation through dynamic feedback between their nuclear populations. This interaction is disrupted in vascular malformation syndrome caused by a de novo heterozygous NR2F2 mutation, presenting with aberrant vascular integrity and bleeding. Treatment with an FDA-approved drug--known to inhibit SOX18--led to marked clinical improvement in the proband. To dissect the molecular mechanism underlying this mutation and the drug response, we used human embryonic stem cells (hESCs) engineered to carry the probands NR2F2 variant. These cells exhibited impaired hESC to venous differentiation with no effect on artery EC differentiation. In silico modelling and live-cell molecular imaging revealed that the NR2F2 variant is hyper-mobile, fails to form homodimers, and cannot recruit SOX18, thereby disrupting a critical transcriptional antagonism that underpins venous endothelial identity. We demonstrate that targeted pharmacological inhibition of SOX18 restores this regulatory balance in hESC-derived venous endothelial cells, rescuing both gene expression and NR2F2 binding dynamics at the single-molecule level. Together, this study uncovers a biophysical mechanism of transcription factor antagonism that governs venous differentiation and offers a framework for developing targeted therapies for rare vascular malformations.

developmental biology↗

bioRxiv2024

Touchscreen response precision is sensitive to the explore/exploit tradeoff

The explore/exploit tradeoff is a fundamental property of choice selection during reward-guided decision making. In perceptual decision making, higher certainty decisions are more motorically precise, even when the decision does not require motor accuracy. However, while we can parametrically control uncertainty in perceptual tasks, we do not know what variables - if any - shape motor precision and reflect subjective certainty during reward-guided decision making. Touchscreens are increasingly used across species to measure choice, but provide no tactile feedback on whether an action is precise or not, and therefore provide a valuable opportunity to determine whether actions differ in precision due to explore/exploit state, reward, or individual variables. We find all three of these factors exert independent drives towards increased precision. During exploit states, successive touches to the same choice are closer together than those made in an explore state, consistent with exploit states reflecting higher certainty and/or motor stereotypy in responding. However, exploit decisions might be expected to be rewarded more frequently than explore decisions. We find that exploit choice precision is increased independently of a separate increase in precision due to immediate past reward, suggesting multiple mechanisms regulating choice precision. Finally, we see evidence that male mice in general are less precise in their interactions with the touchscreen than females, even when exploiting a choice. These results suggest that as exploit behavior emerges in reward-guided decision making, individuals become more motorically precise reflecting increased certainty, even when decision choice does not require additional motor accuracy, but this is influenced by individual differences and prior reward. These data uncover the hidden potential for touchscreen tasks in any species to uncover the latent neural states that unite cognition and movement.

animal behavior and cognition↗

bioRxiv2024

R(+) Propranolol decreases lipid accumulation in hemangioma-derived stem cells

BackgroundInfantile hemangioma (IH) is a benign vascular tumor that undergoes an initial rapid growth phase followed by spontaneous involution. A fibrofatty residuum remains in many tumors and often necessitates resection. We recently discovered that R(+) propranolol, the non-{beta} blocker enantiomer, inhibits blood vessel formation of IH patient-derived hemangioma stem cells (HemSC) xenografted in mice. HemSC are multipotent cells with the ability to differentiate into endothelial cells, pericytes, and adipocytes. ObjectivesWe investigated how R(+) propranolol affects HemSC adipogenic differentiation and lipid accumulation, in vitro and in a preclinical murine model for IH. MethodsWe conducted a 10-day adipogenesis assay on 4 IH patient-derived HemSCs. Oil Red O (ORO) staining was used to identify the onset and level of lipid accumulation in HemSC while quantitative real-time polymerase chain reaction was conducted to determine the temporal expression of key factors implicated in adipogenesis. 5-20{micro}M R(+) propranolol treatment was added to HemSC induced to undergo adiogenesis for 4 and 8 days, followed by quantification of lipid-stained areas and transcript levels of key adipogenic factors. We immunostained for lipid droplet-associated protein Perilipin 1 (PLIN1) in HemSC-xenograft sections from mice treated with R(+) propranolol and quantified the area using ImageJ. ResultsWe found that different patient-derived HemSC exhibit a robust and heterogenous adipogenic capacity when induced for adipogenic differentiation in vitro. Consistently across four IH patient-derived HemSC isolates, R(+) propranolol reduced ORO-stained areas and lipoprotein lipase (LPL) transcript levels in HemSC after 4 and 8 days of adipogenic induction. In contrast, R(+) propranolol had no significant inhibitory effect on transcript levels encoding adipogenic transcription factors. In a pre-clinical HemSC xenograft model, PLIN1-positive area was significantly reduced in xenograft sections from mice treated with R(+) propranolol, signifying reduced lipid accumulation. ConclusionsOur findings suggest a novel regulatory role for the R(+) enantiomer of propranolol in modulating lipid accumulation in HemSC. This highlights a novel role of R(+) propranolol in the involuting phase of IH and a strategy to reduce fibrofatty residua in IH. What is already known about this topic?O_LIPropranolol is the mainstay treatment for infantile hemangioma (IH), the most common tumor of infancy, but its use can be associated with concerning {beta}-blocker side effects. C_LIO_LIR(+) propranolol, the enantiomer largely devoid of {beta}-blocker activity, was recently shown to inhibit endothelial differentiation of hemangioma-derived stem cells (HemSC) in vitro and reduce blood vessel formation in a HemSC-derived xenograft murine model of IH. C_LI What does this study add?O_LIR(+) propranolol inhibits lipid accumulation in HemSC in vitro. C_LIO_LIR(+) propranolol does not affect mRNA transcript levels of key adipogenic transcription factors in differentiating HemSC in vitro. C_LIO_LIR(+) propranolol reduces lipid accumulation in a pre-clinical xenograft murine model of IH. C_LI What is the translational message?O_LIThe R(+) enantiomer of propranolol could be advantageous in terms of reduction in {beta}-adrenergic side effects and fibrofatty tissue formation in the involuting phase of IH. C_LIO_LILess fibrofatty residua might reduce the need for surgical resection. C_LIO_LIDisfigurement and associated psychosocial impacts might be improved in this young patient cohort. C_LI

molecular biology↗

bioRxiv2024

An endothelial SOX18-mevalonate pathway axis enables repurposing of statins for infantile hemangioma

Infantile hemangioma (IH) is the most common tumor in children and a paradigm for pathological vasculogenesis, angiogenesis and regression. Propranolol is the mainstay of treatment for IH. It inhibits hemangioma vessel formation via a {beta}-adrenergic receptor independent off-target effect of its R(+) enantiomer on the endothelial specific transcription factor sex-determining region Y (SRY) box transcription factor 18 (SOX18). Transcriptomic profiling of patient-derived hemangioma stem cells uncovered the mevalonate pathway (MVP) as a target of R(+) propranolol. Loss of SOX18 function confirmed R(+) propranolol mode of action on the MVP. Functional validation in preclinical IH models revealed that statins - targeting the MVP - are potent inhibitors of hemangioma vessel formation. We propose a novel SOX18-MVP-axis as a central regulator of IH pathogenesis and suggest statin repurposing to treat IH. Our findings reveal novel pleiotropic effects of beta-blockers and statins acting on the SOX18-MVP axis to disable an endothelial specific program in IH, which may impact other scenarios involving pathological vasculogenesis and angiogenesis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/577829v2_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@f02b2corg.highwire.dtl.DTLVardef@1a2790forg.highwire.dtl.DTLVardef@1ba0318org.highwire.dtl.DTLVardef@1213522_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2020

Regulation of Decay Accelerating Factor primes human germinal center B cells for phagocytosis

Germinal centers (GC) are sites for extensive B cell proliferation and homeostasis is maintained by programmed cell death. The complement regulatory protein Decay Accelerating Factor (DAF) blocks complement deposition host cells and therefore also phagocytosis of cells. Here, we show that B cells downregulate DAF upon BCR engagement and that T cell-dependent stimuli preferentially led to activation of DAFlo B cells. Consistent with this, a majority of light and dark zone GC B cells were DAFlo and susceptible to complement-dependent phagocytosis, as compared with DAFhi GC B cells. We could also show that the DAFhi GC B cell subset had increased expression of the plasma cell marker Blimp-1. DAF expression was also modulated during B cell hematopoiesis in the human bone marrow. Collectively, our results reveal a novel role of DAF to pre-prime activated human B cells for phagocytosis prior to apoptosis.

immunology↗

bioRxiv2020

Development of non-transgenic glyphosate tolerant wheat by TILLING

Glyphosate (N-phosphonomethyl-glycine) is the worlds most widely used broad spectrum, post-emergence herbicide. It inhibits the chloroplast-targeted enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS; EC 2.5.1.19), a component of the plant and microorganism-specific shikimate pathway and a key catalyst in the production of aromatic amino acids. Variants of EPSPS that are not inhibited by glyphosate due to particular amino acid alterations in the active site of the enzyme are known. Some of these variants have been identified in weed species that have developed resistance to glyphosate because of the strong selective pressure of continuous, heavy glyphosate use. We have used TILLING (Targeting Induced Local Lesions in Genomes), a non-transgenic, target-selected, reverse genetics mutation breeding technique, and conventional genetic crosses, to identify and combine, through two rounds of mutagenesis, wheat lines having both T102I and P106S (so-called TIPS enzyme) mutations in both the A and the D sub-genome homoeologous copies of the wheat EPSPS gene. The combined effects of the T102I and P106S mutations are known from previous work in multiple species to minimize the binding of the herbicide while maintaining the affinity of the catalytic site for its native substrates. These novel wheat lines exhibit substantial tolerance to commercially relevant levels of glyphosate.

plant biology↗

bioRxiv2018

Development of reduced gluten wheat enabled by determination of the genetic basis of the lys3a low hordein barley mutant

Celiac disease is the most common food-induced enteropathy in humans with a prevalence of approximately 1% world-wide [1]. It is induced by digestion-resistant, proline- and glutamine-rich seed storage proteins, collectively referred to as \"gluten,\" found in wheat. Related prolamins are present in barley and rye. Both celiac disease and a related condition called non-celiac gluten sensitivity (NCGS) are increasing in incidence [2] [3]. This has prompted efforts to identify methods of lowering gluten in wheat, one of the most important cereal crops. Here we used BSR-seq (Bulked Segregant RNA-seq) and map-based cloning to identify the genetic lesion underlying a recessive, low prolamin mutation (lys3a) in diploid barley. We confirmed the mutant identity by complementing the lys3a mutant with a transgenic copy of the wild type barley gene and then used TILLING (Targeting Induced Local Lesions in Genomes) [4] to identify induced SNPs (Single Nucleotide Polymorphisms) in the three homoeologs of the corresponding wheat gene. Combining inactivating mutations in the three sub-genomes of hexaploid bread wheat in a single wheat line lowered gliadin and low molecular weight glutenin accumulation by 50-60% and increased free and protein-bound lysine by 33%. This is the first report of the combination of mutations in homoeologs of a single gene that reduces gluten in wheat.

plant biology↗