Biology subjects

Graf, E.

Publications and source records attributed to Graf, E..

7 recordsLinked to original sources

bioRxiv2025

Pro-endometriosis macrophage release of IL-33 is key for endometriosis pain and lesion formation

Endometriosis is a painful gynecological inflammatory disease affecting up to 10% of females. When released by sensory neurons, calcitonin gene-related peptide (CGRP) shapes immunity, a process known as neuroimmune communication. We previously showed that nociceptor-derived CGRP polarizes macrophages into pro-endometriosis macrophages (PEMs) that mediates endometrial epithelial (endo-epi) cell proliferation and pain. However, the key mediators involved in this PEM-induced cell proliferation were unknown. Using unbiased approaches, we discovered that nociceptor-derived CGRP induces PEMs to produce IL-33. IL-33 binding to its receptor ST2 is key for endometriotic lesion growth and pain during endometriosis in mice as anti-IL-33 antibody treatment reduced evoked and spontaneous pain as well as lesion size. Chemical or genetic ablation of nociceptors or macrophages also resulted in lower levels of lesion IL-33, demonstrating a neuroimmune-driven mechanism for IL-33 production during endometriosis. In humans, we found that IL-33 is correlated with increased number of glands and fibrosis in lesions and that IL-33 expression in macrophages is also associated with genetic risk of endometriosis. We also provided evidence that suggests a dual role for IL-33 in endometriosis, in which, it is initially required for lesion formation and later for lesion maintenance only, and associated pain. Therefore, targeting IL-33/ST2 signaling may effectively treat endometriosis pain.

neuroscience↗

bioRxiv2025

Apremilast improves cardiomyocyte cohesion and arrhythmia in different models for arrhythmogenic cardiomyopathy

BackgroundArrhythmogenic cardiomyopathy (ACM) is a genetically inherited desmosome heart disease leading to life-threatening arrhythmias and sudden cardiac death. Currently, ACM treatment paradigms are merely symptom targeting. Recently, apremilast was shown to stabilize keratinocyte adhesion in the desmosomal disease pemphigus vulgaris. Therefore, this study investigated whether apremilast can be a therapeutic option for ACM. MethodsHuman induced pluripotent stem cells from a healthy control (hiPSC) and an ACM index patient (ACM-hiPSC) carrying a heterozygous desmoplakin (DSP) gene mutation (c.2854G>T, p.Glu952Ter), confirmed by whole exome sequencing (WES), were established. Cyclic-AMP ELISA, dissociation assay, immunostaining, and Western blotting analyses were performed in human iPSC-derived cardiomyocytes (hiPSC-CMs), murine HL-1 cardiomyocytes, and cardiac slices derived from wild-type (WT) mice, plakoglobin (PG, Jup) knockout (Jup-/-) (murine ACM model) or PG Serine 665 phosphodeficient (JUP-S665A) mice. Microelectrode array (MEA) analyses in ventricular cardiac slices and Langendorff heart perfusion were performed to analyze heart rate variability and arrhythmia. ResultsACM-hiPSC derived cardiomyocytes (ACM-hiPSC-CMs) revealed a significant loss of cohesion, which was rescued by apremilast. Further, treatment with apremilast strengthened basal cardiomyocyte cohesion in HL-1 cells and WT murine cardiac slices, paralleled by phosphorylation of PG at Serine 665 in human and murine models. In HL-1 cells, apremilast in addition activated ERK1/2, inhibition of which abolished apremilast-enhanced cardiomyocyte cohesion. Further, dissociation assays in slice cultures from JUP-S665A and Jup-/- mice revealed that PG is crucial for apremilast-enhanced cardiomyocyte cohesion. In parallel to enhanced cell adhesion, MEA and Langendorff measurements from WT and Jup-/- mice demonstrated decreased heart rate variability and arrhythmia after apremilast treatment. ConclusionsApremilast improves loss of cardiomyocyte cohesion, enhances localization of DSG2, and reduces arrhythmia in human and murine models of ACM ex vivo and in vitro, providing a novel treatment strategy for ACM by preserving desmosome function. Translational perspectiveThe current therapeutic options for patients with arrhythmogenic cardiomyopathy (ACM) include lifestyle changes, treatment with anti-arrhythmic drugs, catheter ablation, implantable cardiac defibrillators, and ultimately, heart transplantation for patients who are having therapy refractory arrhythmia or developed heart failure. However, lifestyle changes, such as restraining from physical endurance activities and {beta}-blocker therapy, are most used in patients carrying genetic variants coding for proteins of the desmosomal complex. Recent advancements hint that strategies enhancing intracellular cAMP could be beneficial in treating desmosomal diseases and can be effective therapeutics, which would be highly relevant for ACM patients. In this study, we show that apremilast improves loss of cardiomyocyte cohesion, enhances localization of desmosomal proteins, and reduces arrhythmia in both human and murine models of ACM ex vivo and in vitro, providing a novel treatment strategy for ACM by preserving desmosome function.

cell biology↗

bioRxiv2020

Identification and characterization of distinct murine brown adipocyte lineages

Brown adipose tissue (BAT) plays an important role in the regulation of body weight and glucose homeostasis. While increasing evidence supports white adipose tissue heterogeneity, little is known about heterogeneity within murine BAT. Using single cell RNA sequencing of the stromal vascular fraction of murine BAT and analysis of 67 brown preadipocyte and adipocyte clones we unravel heterogeneity within brown preadipocytes. Statistical analysis of gene expression profiles from these clones identifies markers distinguishing brown adipocyte lineages. We confirm the presence of distinct brown adipocyte populations in vivo using three identified markers; Eif5, Tcf25, and Bin1. Functionally, we demonstrate that loss of Bin1 enhances UCP1 expression and mitochondrial respiration, suggesting that Bin1 marks a dormant brown adipocyte type. The existence of multiple brown adipocyte lineages suggests distinct functional properties of BAT depending on its cellular composition, with potentially distinct function in thermogenesis and the regulation of whole body energy homeostasis.

cell biology↗

bioRxiv2020

Adaptive mitochondrial regulation of the proteasome

The proteasome is the main proteolytic system for targeted protein degradation in the cell. Its function is fine-tuned according to cellular needs. Regulation of proteasome function by mitochondrial metabolism, however, is unknown. Here, we demonstrate that mitochondrial dysfunction reduces the assembly and activity of the 26S proteasome in the absence of oxidative stress. Impaired respiratory complex I function leads to metabolic reprogramming of the Krebs cycle and deficiency in aspartate. Aspartate supplementation activates assembly and activity of 26S proteasomes via transcriptional activation of the proteasome assembly factors p28 and Rpn6. This metabolic adaptation of 26S proteasome function involves sensing of aspartate via the mTORC1 pathway. Metformin treatment of primary human cells similarly reduced assembly and activity of 26S proteasome complexes, which was fully reversible and rescued by supplementation of aspartate or pyruvate. Of note, respiratory dysfunction conferred resistance towards the proteasome inhibitor Bortezomib. Our study uncovers a fundamental novel mechanism of how mitochondrial metabolism adaptively adjusts protein degradation by the proteasome. It thus unravels unexpected consequences of defective mitochondrial metabolism in disease or drug-targeted mitochondrial reprogramming for proteasomal protein degradation in the cell. As metabolic inhibition of proteasome function can be alleviated by treatment with aspartate or pyruvate, our results also have therapeutic implications.

cell biology↗

bioRxiv2020

Maintenance of epithelial traits and resistance to mesenchymal reprogramming promote proliferation in metastatic breast cancer

Despite important advances in the treatment of breast cancer, the 5-year survival rate for patients with distant metastasis remains less than 30%. Metastasis is a complex, multi-step process beginning with local invasion and ending with the outgrowth of systemically disseminated cells into actively proliferating metastases that ultimately cause the destruction of vital organs. It is this last step that limits patient survival and, at the same time, remains the least understood mechanistically. Here, we focus on understanding determinants of metastatic outgrowth using metastatic effusion biopsies from stage IV breast cancer patients. By modelling metastatic outgrowth through xenograft transplantation, we show that tumour initiation potential of patient-derived metastatic breast cancer cells across breast cancer subtypes is strongly linked to high levels of EPCAM expression. Breast cancer cells with high EPCAM levels are highly plastic and, upon induction of epithelial-mesenchymal transition (EMT), readily adopt mesenchymal traits while maintaining epithelial identity. In contrast, low EPCAM levels are caused by the irreversible reprogramming to a mesenchymal state with concomitant suppression of metastatic outgrowth. The ability of breast cancer cells to retain epithelial traits is tied to a global epigenetic program that limits the actions of EMT-transcription factor ZEB1, a suppressor of epithelial genes. Our results provide direct evidence that maintenance of epithelial identity is required for metastatic outgrowth while concomitant expression of mesenchymal markers enables plasticity. In contrast, loss of epithelial traits is characteristic of an irreversible mesenchymal reprogramming associated to a deficiency for metastatic outgrowth. Collectively, our data provide a framework for the intricate intercalation of mesenchymal and epithelial traits in metastatic growth.

cancer biology↗

bioRxiv2018

MAU2 and NIPBL variants in Cornelia de Lange syndrome reveal MAU2-independent loading of cohesin and uncover a protective mechanism against early truncating mutations in NIPBL

Cornelia de Lange syndrome (CdLS) is a rare developmental disorder caused by mutations in genes related to the cohesin complex. For its association with chromatin, cohesin depends on a heterodimer formed by NIPBL and MAU2, which interact via their respective N-termini. Variants in NIPBL are the main cause of CdLS and result in NIPBL haploinsufficiency.\n\nUsing CRISPR, we generated cells homozygous for an out-of-frame duplication in NIPBL. Remarkably, alternative translation initiation rescued NIPBL expression in these cells and produced an N-terminally truncated NIPBL that lacks MAU2-interaction domain, causing a dramatic reduction of MAU2 protein levels. Strikingly, this protective mechanism allows nearly normal amounts of cohesin to be loaded onto chromatin in a manner that is independent of functional NIPBL/MAU2 complexes and therefore in contrast to previous findings.\n\nWe also report the first pathogenic variant in MAU2, a deletion of seven amino acids important for wrapping the N-terminus of NIPBL within MAU2. The mutation causes dramatic reduction of MAU2 heterodimerization with NIPBL, hence undermining the stability of both proteins.\n\nOur data confirm NIPBL haploinsufficiency as the major pathogenic mechanism of CdLS and give new insights into the molecular mechanisms responsible for this neurodevelopmental disorder. Our work also unveils an alternative translation-based mechanism that protects cells from out-of-frame variants of NIPBL and that may be of relevance in other genetic conditions.

molecular biology↗

bioRxiv2018

An atlas of the aging lung mapped by single cell transcriptomics and deep tissue proteomics

Aging promotes lung function decline and susceptibility to chronic lung diseases, which are the third leading cause of death worldwide. We used single cell transcriptomics and mass spectrometry to quantify changes in cellular activity states of 30 cell types and the tissue proteome from lungs of young and old mice. Aging led to increased transcriptional noise, indicating deregulated epigenetic control. We observed highly distinct effects of aging on cell type level, uncovering increased cholesterol biosynthesis in type-2 pneumocytes and lipofibroblasts as a novel hallmark of lung aging. Proteomic profiling revealed extracellular matrix remodeling in old mice, including increased collagen IV and XVI and decreased Fraser syndrome complex proteins and Collagen XIV. Computational integration of the aging proteome and single cell transcriptomes predicted the cellular source of regulated proteins and created a first unbiased reference of the aging lung. The lung aging atlas can be accessed via an interactive user-friendly webtool at: https://theislab.github.io/LungAgingAtlas

systems biology↗