Biology subjects

Wegner, J.

Publications and source records attributed to Wegner, J..

7 recordsLinked to original sources

bioRxiv2026

NMR assignment and functional characterization of biotechnologically modified xanthan

Xanthan gum is one of the most important industrial microbial polysaccharides, yet comprehensive molecular-level structural characterization remains limited because of its high molecular weight, conformational rigidity, and severe spectral overlap in nuclear magnetic resonance spectroscopy. Here, we present a near-complete 1H/13C NMR chemical shift assignment of the xanthan repeating unit by combining multidimensional NMR spectroscopy with targeted glycosyltransferase knockout strains and controlled enzymatic depolymerization. Comparative analysis of wild-type xanthan and{Delta} gumI and{Delta} gumK variants enabled the unambiguous assignment of {beta}-mannose and glucuronic acid resonances, and, by extension, of the remaining sugars, supporting future structural studies of engineered xanthan variants. In addition, we investigated how side-chain composition affects xanthan properties by analyzing genetically modified variants lacking specific acetyl, pyruvyl, or sugar residues. Temperature-dependent 1H NMR determined order-disorder transition temperatures and revealed that removing pyruvate or negatively charged side-chain components increased thermal stability, whereas losing the terminal {beta}-mannose destabilized the ordered conformation. Together, these results establish a robust NMR assignment for xanthan and provide new insights into how individual side-chain substituents influence the structural stability of this polysaccharide, facilitating the rational characterization of engineered xanthan variants and structurally closely related polysaccharides.

biochemistry↗

bioRxiv2025

Mini-Pcdh15b Gene Therapy Rescues Visual Deficits in a Zebrafish Model of Usher Syndrome Type 1F

Usher syndrome type 1F (USH1F) is a severe inherited disorder caused by mutations in PCDH15, resulting in congenital deafness, vestibular dysfunction, and progressive retinal degeneration leading to blindness. While cochlear implantation can restore hearing, no therapeutic interventions currently exist for vision loss. Gene augmentation therapy represents a promising approach; however, the PCDH15 coding sequence ([~]5.3 kb) exceeds the packaging capacity of adeno-associated virus (AAV) vectors. To overcome this limitation, we previously engineered shortened "mini-PCDH15" constructs that retain key structural and functional domains while fitting within a single AAV. Among these, the mini-PCDH15-V4 variant successfully restored hearing in Pcdh15-deficient mice. Here, we investigated the ability of a cone-targeted mini-pcdh15b-V4 transgene to rescue vision in a zebrafish model of USH1F. Untreated pcdh15b-deficient zebrafish exhibited severe structural and functional defects of the retina, including disorganized and shortened photoreceptor outer segments, disrupted calyceal processes, and markedly reduced electroretinogram (ERG) and optokinetic response (OKR) performance. Targeted expression of mini-pcdh15b-V4 recapitulated typical localization of Pcdh15b to calyceal processes and outer segment membranes, rescued photoreceptor architecture, and re-established both structural organization and functional output. Treated mutants exhibited improved visual tracking behavior and full recovery of ERG a-wave and b-wave amplitudes, indicating restoration of photoreceptor and synaptic function. Importantly, mini-pcdh15b-V4 expression produced no adverse effects in wild-type or heterozygous fish, supporting the safety of cone-specific expression. Together, these findings demonstrate that mini-pcdh15b-V4 can restore both photoreceptor structure and visual function in pcdh15b-deficient zebrafish. This work establishes the pcdh15b mutant zebrafish as a powerful preclinical model for studying USH1F retinopathy and supports the translational potential of rationally engineered mini-PCDH15 constructs as a feasible gene therapy approach for preventing or reversing vision loss in individuals with USH1F.

neuroscience↗

bioRxiv2023

Hexafluoro slows retinal degeneration and improves visual function in zebrafish models of Usher syndrome 1F

Usher syndrome is the leading genetic cause of deafblindness, affecting hundreds of thousands of people worldwide. The deafness can be addressed with hearing aids or cochlear implants, but there is currently no treatment for the vision loss, which is due to progressive degeneration of retinal photoreceptors. Studies in animal models of Usher syndrome have shown that photoreceptor degeneration is exacerbated by exposure to bright light, and other studies have shown that light-induced photostress reduces mitochondrial function. We previously synthesized hexafluoro and showed that it is a potent Sirt3 activator that promotes mitochondrial respiration. Here we examined the efficacy of hexafluoro as a potential therapeutic for treatment of vison loss in a zebrafish model of Usher syndrome type 1F, which exhibits early and severe vision defects along with vestibular dysfunction as seen in Usher type 1 pathology. We find that hexafluoro improves visual function, reduces photoreceptor degeneration, and protects the retina against exposure to bright light in this USH1F model.

neuroscience↗

bioRxiv2023

hnRNPM and ELAVL1 control type I interferon induction by promoting IRF3 phosphorylation downstream of both cGAS and RIG-I

RIG-I and cGAS are crucial sensors of viral nucleic acids and induce type I IFNs via TBK1/IKK and IRF3. Here, we have identified hnRNPM as a novel positive regulator of IRF3 phosphorylation and type I IFN induction downstream of both cGAS and RIG-I. Combining interactome analysis and genome editing, we further identified ELAVL1 as an immune-relevant interactor of hnRNPM. Depletion of hnRNPM or ELAVL1 impaired type I IFN induction by HSV-1 and SeV. In addition, we found that hnRNPM and ELAVL1 interact with TBK1 and NF-kB p65. Confocal microscopy revealed cytosolic and perinuclear interactions between hnRNPM, ELAVL1, and TBK1. To our knowledge, hnRNPM and ELAVL1 represent the first non-redundant signaling components merging the cGAS-STING and RIG-I-MAVS pathways, thus representing a novel platform that fuels antiviral defense.

immunology↗

bioRxiv2020

COPB2 haploinsufficiency causes a coatopathy with osteoporosis and developmental delay

Coatomer complexes function in the sorting and trafficking of proteins between subcellular organelles. Pathogenic variants in coatomer subunits or associated factors have been reported in multi-systemic disorders, i.e., coatopathies, that can affect the skeletal and central nervous systems. We have identified loss-of-function variants in COPB2, a component of the coatomer complex I (COPI), in individuals presenting with osteoporosis, fractures and developmental delay of variable severity. Because the role of COPB2 in bone has not been characterized, we studied the effect of COPB2 deficiency on skeletal development in mice and zebrafish. Copb2+/- mice showed low bone mass and decreased bone strength. In zebrafish, larvae carrying a copb2 heterozygous frameshift variant showed delayed mineralization. copb2-null embryos showed endoplasmic reticulum (ER) and Golgi disorganization, and embryonic lethality. COPB2 siRNA-treated fibroblasts showed delayed collagen trafficking with retention of type I collagen in the ER and Golgi, and altered distribution of Golgi markers. Our data suggest that COPB2 haploinsufficiency leads to disruption of intracellular collagen trafficking and osteoporosis, which may improve with ascorbic acid supplementation. This work highlights the role of COPI complex as a critical regulator of bone mass and identifies a new form of coatopathy due to COPB2 deficiency.

genetics↗

bioRxiv2019

Platelet-neutrophil aggregates promote skin pathology in psoriasis

Psoriasis is a frequent systemic inflammatory autoimmune disease characterized primarily by skin lesions with massive infiltration of leukocytes but frequently also presents with cardiovascular comorbidities. Especially polymorphonuclear neutrophils (PMNs) abundantly infiltrate psoriatic skin but the cues that prompt PMNs to home to the skin are not well defined. To identify PMN surface receptors that may explain PMN skin homing in psoriasis patients, we screened 332 surface antigens on primary human blood PMNs from healthy donors and psoriasis patients. We identified platelet surface antigens as a defining feature of psoriasis PMNs, due to a significantly increased aggregation of neutrophils and platelets in the blood of psoriasis patients. Similarly, in the imiquimod-induced experimental in vivo model of psoriasis, disease induction promoted PMN-platelet aggregate formation. In psoriasis patients, disease directly correlated with blood platelet counts and platelets were detected in direct contact with PMNs in psoriatic but not healthy skin. Importantly, depletion of circulating platelets in vivo ameliorated disease severity significantly, indicating that the intimate relationship of PMNs and platelets may be relevant for psoriasis pathology and disease severity, and potentially for psoriasis-associated cardiovascular comorbidities. Key pointsO_LIHuman neutrophils in psoriasis patient blood show a distinct platelet signature of surface antigens C_LIO_LIPlatelets congregate with neutrophils in psoriatic skin lesions C_LIO_LICirculating platelets contribute to psoriasis skin pathology C_LI

immunology↗

bioRxiv2018

Spatially clustered loci with multiple enhancers are frequent targets of HIV-1

HIV-1 recurrently targets active genes that are positioned in the outer shell of the nucleus and integrates in the proximity of the nuclear pore compartment. However, the genomic features of these genes and the relevance of their transcriptional activity for HIV-1 integration have so far remained unclear. Here we show that recurrently targeted genes are delineated with super-enhancer genomic elements and that they cluster in specific spatial compartments of the T cell nucleus. We further show that these gene clusters acquire their location at the nuclear periphery during the activation of T cells. The clustering of these genes along with their transcriptional activity are the major determinants of HIV-1 integration in T cells. Our results show for the first time the relevance of the spatial compartmentalization of the genome for HIV-1 integration, thus further strengthening the role of nuclear architecture in viral infection.

genomics↗