Biology subjects

Reinhardt, F.

Publications and source records attributed to Reinhardt, F..

11 recordsLinked to original sources

bioRxiv2026

Octopamine receptors at a glance: from expression and anatomical maps to their role in development and behavior in the Drosophila melanogaster larva

Octopamine is involved in a variety of different physiological and behavioral mecha-nisms in Drosophila melanogaster. Throughout the life cycle of the fruit fly, from the larva to the adult, octopaminergic neurons in both the central and the peripheral nerv-ous system target a multitude of neurons and even non-neuronal tissues, making it challenging to analyze individual mechanisms of octopamine function. One approach to deconstructing this complex system is to examine the postsynaptic components of signal transmission. In Drosophila, octopamine interacts with six distinct G-protein-coupled receptors. For some of these receptors, expression maps and functional im-plications have been described. In contrast, other receptors have been neglected, partly due to the lack of suitable genetic tools. Here, for the first time, we compiled a complete set of mutant lines of all known octopamine receptors, all generated using the same genetic tool, the recently established Trojan Exon system. It integrates the Gal4/UAS binary expression strategy while simultaneously impairing receptor func-tion. This enabled us to generate a comprehensive anatomical map of receptor ex-pression in the larva and, at the same time, analyze the function of individual octopa-mine receptors during larval development, chemosensory perception and locomotion. All octopamine receptors (Oamb, Oct2R, Oct{beta}1R, Oct{beta}2R, Oct{beta}3R, and Oct-TyrR) showed extensive signal in the central nervous system. The same was found for the peripheral nervous system, with the exception of Oct{beta}2R, which showed pronounced expression in the somatic muscles. We also observed a previously undescribed role of Oct{beta}1R, Oct{beta}3R, and Oct-TyrR in larval hatching and in the survival of larvae and pupae. Molecular evaluation of the Trojan Exon octopamine lines supports our analy-sis. In addition, we combined the experimental results with gene expression data from the different development stages of Drosophila melanogaster and from different tis-sues and cell populations throughout the body. Overall, we compiled, analyzed and validated a complete set of octopamine lines which, together with gene expression analysis, provides a basis for further functional studies on the larval octopaminergic system.

neuroscience↗

bioRxiv2025

Telomerase RNA gene duplications drive telomeric repeatdiversity and evolution in Andrena bees

Most organisms in the animal kingdom require a non-coding telomerease RNA (TR) in conjunction with the telomerase reverse transcriptase (TERT) to add telomere tandem repeats to chromosome ends to genomic instability. Recent studies reported an extensive diversity in the sequence of telomeric repeats in some insect species. Our investigation of TR genes in the Andrena genus provides convincing evidence for the presence of multiple TR gene copies with different template sequences for synthesis of distinct telomeric repeat sequences in several species. In this study we describe the structure, genomic coordinates and abundance of these TR genes, and correlate our findings with the levels of tandem repeats found in DNAseq data. Based on an analysis of the synthenic context of these newly predicted TR genes, we show evidence for the existence of multiple TR paralogs that diverged during the evolution of the genus Andrena. To our knowledge this is the first time such a phenomenon is observed in animals, although recently reported for plants. Interestingly, the comprehensive annotation of all TERT genes found in yet unannotated Andrena species shows no corresponding evolutionary changes in related TERT proteins encoded by a single copy gene. Our study suggests an evolutionary mechanism for diversification of telomeric repeat sequences in certain insect species through telomerase RNA gene duplication.

bioinformatics↗

bioRxiv2024

CD47 predominates over CD24 as a macrophage immune checkpoint in cancer.

Macrophages hold tremendous promise as effectors of cancer immunotherapy, but the best strategies to provoke these cells to attack tumors remain unknown. Here, we evaluated the therapeutic potential of targeting two distinct macrophage immune checkpoints: CD47 and CD24. We found that antibodies targeting these antigens could elicit maximal levels of phagocytosis when combined together in vitro. However, to our surprise, via unbiased genome-wide CRISPR screens, we found that CD24 primarily acts as a target of opsonization rather than an immune checkpoint. In a series of in vitro and in vivo genetic validation studies, we found that CD24 was neither necessary nor sufficient to protect cancer cells from macrophage phagocytosis in most mouse and human tumor models. Instead, anti-CD24 antibodies exhibit robust Fc-dependent activity, and as a consequence, they cause significant on-target hematologic toxicity in mice. To overcome these challenges and leverage our findings for therapeutic purposes, we engineered a collection of 77 novel bispecific antibodies that bind to a tumor antigen with one arm and engage macrophages with the second arm. We discovered multiple novel bispecifics that maximally activate macrophage-mediated cytotoxicity and reduce binding to healthy blood cells, including bispecifics targeting macrophage immune checkpoint molecules in combination with EGFR, TROP2, and CD71. Overall, our findings indicate that CD47 predominates over CD24 as a macrophage immune checkpoint in cancer, and that the novel bispecifics we created may be optimal immunotherapies to direct myeloid cells to eradicate solid tumors.

cancer biology↗

bioRxiv2024

Ether lipids influence cancer cell fate by modulating iron uptake

Cancer cell fate has been widely ascribed to mutational changes within proteincoding genes associated with tumor suppressors and oncogenes. In contrast, the mechanisms through which the biophysical properties of membrane lipids influence cancer cell survival, dedifferentiation and metastasis have received little scrutiny. Here, we report that cancer cells endowed with high metastatic ability and cancer stem celllike traits employ ether lipids to maintain low membrane tension and high membrane fluidity. Using genetic approaches and lipid reconstitution assays, we show that these ether lipid-regulated biophysical properties permit non-clathrin-mediated iron endocytosis via CD44, resulting in significant increases in intracellular redox-active iron and enhanced ferroptosis susceptibility. Using a combination of in vitro threedimensional microvascular network systems and in vivo animal models, we show that loss of ether lipids from plasma membranes also strongly attenuates extravasation, metastatic burden and cancer stemness. These findings illuminate a mechanism whereby ether lipids in carcinoma cells serve as key regulators of malignant progression while conferring a unique vulnerability that can be exploited for therapeutic intervention.

cancer biology↗

bioRxiv2023

Chloroplasts lacking class I glutaredoxins are functional but show a delayed recovery of protein cysteinyl redox state after oxidative challenge

Redox status of protein cysteinyl residues is mediated via glutathione (GSH)/glutaredoxin (GRX) and thioredoxin (TRX)-dependent redox cascades. An oxidative challenge can induce post-translational protein modifications on thiols, such as protein S-glutathionylation. Class I GRX are small thiol-disulfide oxidoreductases that reversibly catalyse S-glutathionylation and protein disulfide formation. TRX and GSH/GRX redox systems can provide partial backup for each other in several subcellular compartments, but not in the plastid stroma where TRX/light-dependent redox regulation of primary metabolism takes place. While the stromal TRX system has been studied at detail, the role of class I GRX on plastid redox processes in vivo is still unknown. We generate knockout lines of GRXC5 as the only chloroplast class I GRX of the moss Physcomitrium patens. While we find that class I PpGRXC5 has high activities in glutathione-dependent oxidoreductase assays using hydroxyethyl disulfide or redox-sensitive GFP2 (roGFP2) as substrates in vitro, {Delta}grxc5 plants show no detectable growth defect or stress sensitivity, in contrast to mutants with a less negative stromal EGSH ({Delta}gr1). Using stroma-targeted roGFP2, we show increased protein Cys oxidation and decreased reduction rates after oxidative challenge in {Delta}grxc5 plants in vivo, indicating kinetic uncoupling of the protein Cys redox state from glutathione redox potential. Protein Cys disulfide and S-glutathionylation formation rates after H2O2 treatment remained unchanged. Lack of class I GRX function in the stroma did not result in impaired carbon fixation. Our observations suggest specific roles for class I GRX in the efficient redox equilibration between EGSH and protein Cys in the plastid stroma as well as negligible cross-talk with metabolic regulation via the TRX system. We propose a model for stromal class I GRX function as efficient kinetic couplers of protein Cys redox state to the dynamic stromal EGSH and highlight the importance of identifying in vivo target proteins of GRXC5. One sentence summaryRemoval of class I GRX activity in the chloroplast stroma of P. patens kinetically uncouples GRX-dependent cysteine redox changes from the local glutathione redox potential, without an effect on NPQ or photosynthetic carbon reactions.

plant biology↗

bioRxiv2023

Lysosomal acid lipase-activity as a novel target to efficiently address triple-negative breast cancer high malignancy

Increased metabolism of neutral lipids, e.g. triglycerides and cholesterol esters, is a hallmark of malignant cancers such as triple-negative breast cancer (TNBC). Predominantly, cancer cells with a high epigenetic stem cell-associated signature increasingly utilize neutral lipids to maintain their high degree of tumor stemness, linking metabolic aberrations to epigenetically dysregulated differentiation processes. Lysosomal acid lipase (LIPA) is a central enzyme in the cellular utilization of exogenous and endogenous neutral lipids; however, the role of LIPA-activity in TNBC remains unexplored. We here show for the first time that pharmacological inhibition of LIPA, highly expressed in TNBC, reduces the expression markers of breast cancer stemness in cell culture models of TNBC. A role of LIPA in maintaining TNBC high cellular stemness was stressed by specific siRNA knock-down. Furthermore, inhibition of LIPA sensitized TNBC cells to therapy with Paclitaxel and Doxorubicin, two important chemotherapeutics in current TNBC treatment. When LIPA-activity was inhibited in a three-dinensional (3D) patient derived organoid model, we observed a significant reduction in TNBC cellular viability. Importantly, LIPA inhibition prevented tumor metastasis in a TNBC-zebrafish xenograft model in vivo. These findings introduce LIPA-activity as a novel pharmacological target in TNBC therapy to specifically address its high cancer malignancy with a potential for implementation of LIPA inhibitors into personalized treatment in the future.

cancer biology↗

bioRxiv2023

DanioCTC: Injection of circulating tumor cells from metastatic breast cancer patients in zebrafish xenografts for analysis of metastasis

Circulating tumor cells (CTCs) are considered as metastatic precursor cells, and zebrafish xenografts provide an in vivo model to study cancer cell spread. Currently, the low number of patient-derived CTCs limits their analysis in animal models. We present DanioCTC, a xenograft workflow for injecting CTCs from metastatic breast cancer (MBC) patients into zebrafish embryos to study cell dissemination in vivo. The study successfully adapts existing workflows and combines diagnostic leukapheresis (DLA), the Parsortix microfluidic system, flow cytometry, and the automated cell micromanipulator CellCelector setup to enrich and isolate MBC-derived CTCs and to finally inject them into Zebrafish embryos, where their dissemination was tracked up to 3 days post-injection. MDA-MB-231 cells were used as a standard xenotransplantation control, and these cells were frequently found in the head and blood-forming regions of the tail. Using DLA aliquots spiked with MBA-MB-231 cells, the newly established DanioCTC workflow confirmed the dissemination of MDA-MB-231 cells into these regions. CTCs from an MBC patient were then enriched by DLA, Parsortix, and flow cytometry, isolated with the CellCelectorTM and xenografted into zebrafish embryos. CTCs were mainly detected in the head and trunk, unlike MDA-MB-231 cells, which were present in the head and tail. DanioCTC presents a significant breakthrough in the use of zebrafish embryos as a model to study CTC dissemination in vivo, which can be used for patient-derived CTCs instead of cell culture-derived cancer cells as a crucial step towards understanding the biology of metastatic breast cancer. Statement of significanceDanioCTC is a novel workflow to inject patient-derived CTCs into zebrafish, enabling studies on CTC dissemination and personalized treatment in vivo, therefore advancing our toolkit to fight metastatic cancer.

cancer biology↗

bioRxiv2023

Profiling extracellular vesicles in circulation enables the early detection of ovarian cancer

Ovarian cancer is a heterogeneous group of tumors in both cell type and natural history. While outcomes are generally favorable when detected early, the most common subtype, high-grade serous carcinoma (HGSOC), typically presents at an advanced stage and portends less favorable prognoses. Its aggressive nature has thwarted early detection efforts through conventional detection methods such as serum CA125 and ultrasound screening and thus inspired the investigation of novel biomarkers. Here, we report the systematic development of an extracellular-vesicle (EV)-based test to detect early-stage HGSOC. Our study is based on emerging insights into HGSOC biology, notably that it arises from precursor lesions within the fallopian tube before traveling to ovarian and/or peritoneal surfaces. To identify HGSOC marker candidates, we established murine fallopian tube (mFT) cells with oncogenic mutations in Brca1/2, Tp53, and Pten genes, and performed proteomic analyses on mFT EVs. The identified markers were then evaluated with an orthotopic HGSOC animal model. In serially-drawn blood samples of tumor-bearing mice, mFT-EV markers increased with tumor initiation, supporting their potential use in early cancer detection. A pilot human clinical study (n = 51) further narrowed EV markers to five candidates, EpCAM, CD24, VCAN, HE4, and TNC. Combined expression of these markers achieved high OvCa diagnostic accuracy (cancer vs. non-cancer) with a sensitivity of 0.89 and specificity of 0.93. The same five markers were also effective in a three-group classification: non-cancer, early-stage (I & II) HGSOC, and late-stage (III & IV) HGSOC. In particular, they differentiated early-stage HGSOC from the rest with a specificity of 0.91. Minimally invasive and repeatable, this EV-based testing could be a versatile and serial tool for informing patient care and monitoring women at high risk for ovarian cancer.

cancer biology↗

bioRxiv2022

Mitochondrial genomes in Perkinsus decode conserved frameshifts in all genes

Mitochondrial genomes of apicomplexans, dino-flagellates and chrompodellids, that collectively make up the Myzozoa, are uncommonly reduced in coding capacity and display divergent gene configuration and expression mechanisms. They encode only three proteins -- COB, COX1, COX3 -- contain rRNAs fragmented to [~]100-200 base pair elements, and employ extensive recombination, RNA trans-splicing, and RNA-editing for genome maintenance and expression. The early-diverging Perkinsozoa is the final major myzozoan lineage whose mitochondrial genomes remain poorly characterized. Previous reports of Perkinsus cox1 and cob partial gene sequences have indicated independent acquisition of non-canonical features, namely the occurrence of multiple frameshifts in both genes. To determine ancestral myzozoan mitochondrial genome features, as well as any novel ones in Perkinsozoa, we sequenced and assembled four Perkinsus species mitochondrial genomes. These data show a simple ancestral genome with the common reduced coding capacity, but one already prone to rearrangement. Moreover, we identified 75 frameshifts across the four species that are present in all genes, that are highly conserved in gene location, and that occur as four distinct types. A decoding mechanism apparently employs unused codons at the frameshift sites that advance translation either +1 or +2 frames to the next used codon. The locations of the frameshifts are seemingly positioned to regulate protein folding of the nascent protein as it emerges from the ribosome. COX3 is distinct in containing only one frameshift and showing strong selection against residues that are otherwise frequently encoded at the frameshift positions in COX3 and COB. All genes also lack cysteine codons implying a further constraint on these genomes with reduction to only 19 different amino acids. Furthermore, mitochondrion-encoded rRNA fragment complements are incomplete in Perkinsus spp. but some are found in the nuclear DNA, suggesting these may be imported into the organelle as for tRNAs. Perkinsus demonstrates additional remarkable trajectories of organelle genome evolution including pervasive integration of frameshift translation into genome expression.

molecular biology↗

bioRxiv2020

Vernalization alters sugar beet (Beta vulgaris) sink and source identities and reverses phloem translocation from taproots to shoots

During vegetative growth, biennial sugar beets maintain a steep gradient between the shoot (source) and the sucrose-storing taproot (sink). To shift from vegetative to generative growth, they require a chilling phase, called vernalization. Here, we studied sugar beet sink-source dynamics upon cold temperature-induced vernalization and revealed a pre-flowering taproot sink to source reversal. This transition is induced by transcriptomic and functional reprogramming of sugar beet tissue, resulting in a reversal of flux direction in long distance transport system, the phloem. As a key process for this transition, vacuolar sucrose importers and exporters, BvTST2;1 and BvSUT4, are oppositely regulated, leading to re-mobilization of sugars from taproot storage vacuoles. Concomitant changes in the expression of floral regulator genes suggest that the now deciphered processes are a prerequisite for bolting. Our data may thus serve dissecting metabolic and developmental triggers for bolting, which are potential targets for genome editing or breeding approaches.

plant biology↗

bioRxiv2019

Optimization of the experimental parameters of the ligase cycling reaction

The ligase cycling reaction (LCR) is a scarless and efficient method to assemble plasmids from fragments of DNA. This assembly method is based on the hybridization of DNA fragments with complementary oligonucleotides, so-called bridging oligos (BOs), and an experimental procedure of thermal denaturation, annealing and ligation. In this study, we explore the effect of molecular crosstalk of BOs and various experimental parameters on the LCR by utilizing a fluorescence-based screening system. The results indicate an impact of the melting temperatures of BOs on the overall success of the LCR assembly. Secondary structure inhibitors, such as DMSO and betaine, are shown to negatively impact the number of correctly assembled plasmids. Adjustments of the annealing, ligation and BO-melting temperature further improved the LCR. The optimized LCR was confirmed by validation experiments. Based on these findings, a step-by-step protocol is offered within this study to ensure a routine for high efficient LCR assemblies.

bioengineering↗