Biology subjects

Petzsch, P.

Publications and source records attributed to Petzsch, P..

8 recordsLinked to original sources

bioRxiv2026

MIC13-linked cristae disruption causes metabolic failure and early fibrotic remodelling in mitochondrial liver disease

Mitochondrial diseases are highly complex and heterogeneous, and nearly 20% of cases involve severe liver pathology. Here, we report an affected individual carrying a pathogenic MIC13 variant (c.260-2A>G) associated with early-onset mitochondrial hepato-encephalopathy. Such mitochondrial hepatopathies are rare, multisystemic disorders with major liver involvement, difficult to diagnose, lack effective treatment, and are poorly understood, in part due to the absence of faithful disease-relevant cellular models. To investigate hepatocyte-specific consequences of the MIC13 variant, we generated iPSCs carrying this disease-causing variant and differentiated them into induced hepatocytes (iHeps). MIC13, a key component of the MICOS complex required for cristae formation, was disrupted in these cells, and the resultant iHeps exhibited the same cristae defects observed in clinical samples. Integrated multi-omics and biochemical analyses revealed extensive metabolic rewiring, including disrupted amino acid turnover and accumulation of tricarboxylic acid (TCA) and urea cycle intermediates. Additionally, profound alterations in methionine cycle and transsulfuration pathways, along with enhanced bile acid synthesis, collectively affect methylation potential, redox homeostasis, and detoxification. Lipid metabolism was also impaired, with incomplete {beta}-oxidation, increased ketogenesis, and diminished lipid storage. At the cellular level, extensive extracellular matrix (ECM) remodelling, increased intracellular collagen accumulation and enhanced cell migration indicated an early fibrotic phenotype. Overall, this clinically relevant model uncovers mechanistically how cristae defects drive metabolic imbalance and hepatocyte dysfunction, ultimately leading to early fibrotic changes in mitochondrial liver disease. These findings provide a strong mechanistic foundation for understanding mitochondrial liver disease and developing targeted therapeutic strategies.

biochemistry↗

bioRxiv2025

Obesity and diabetes related disturbances in systemic metabolism induce a cardiometabolic heart failure with preserved ejection fraction phenotype in a combined high-fat, high sucrose diet and streptozotocin mouse model

BackgroundDiabetes and obesity are associated with an increased incidence of heart failure with preserved ejection fraction (HFpEF), but the underlying pathophysiological mechanisms are poorly understood. A shortage of appropriate preclinical mouse models reflecting different pathophysiological disease aspects might contribute to this inadequate understanding of the complex and diverse HFpEF pathophysiology. We conducted a comprehensive analysis of a non-genetic, inducible T2DM mouse model with regard to its suitability as a preclinical model of cardiometabolic, diabetes-induced HFpEF. MethodsT2DM was induced in C57Bl/6 mice by high-fat/high-sucrose diet (HFHSD) combined with low-dose streptozotocin (STZ) treatment (DIO-STZ), control animals received standard chow (chow). As additional control groups, animals of a DIO group were solely fed HFHSD throughout the study, and a STZ group received solely STZ injections while maintained on a standard chow. Cardiac function was assessed in vivo by echocardiography and left ventricular catheterization, as well as in vitro using the isolated perfused heart model. Structural, molecular and bioenergetic disturbances were analyzed by immunohistochemistry, RNA-seq, qPCR, western blot, and extracellular flux analysis of myocardial tissue, among others. ResultsBlood glucose, fatty acids and ketone body levels were elevated, and insulin plasma level were reduced in DIO-STZ animals compared to chow. DIO-STZ mice showed a strong cardiometabolic HFpEF phenotype with reduced cardiac output, end-diastolic volume, and increased filling pressure. Neither STZ nor DIO mice showed signs of HFpEF development. No difference in myocardial fibrosis nor in in vitro myocardial stiffness was detected between DIO-STZ and chow. Myocardial RNA-Seq clearly pointed towards disturbances in lipid and ketone metabolism. Extracellular flux analysis in intact cardiac tissue slices revealed an increased fatty acid oxidation capacity without differences in glucose metabolism. Mitochondrial respirometry revealed no indication of general mitochondrial dysfunction or mitochondrial uncoupling, but a reduced capacity for {beta}-hydroxybutyrate oxidation. ConclusionsThe diabetic DIO-STZ mouse model showed a pronounced functional HFpEF phenotype. However, we show clear evidence that the underlying mechanism differs remarkably from the other HFpEF models making the DIO-STZ model a relevant extension of the range of HFpEF mouse models, especially for investigating molecular mechanisms or therapeutical interventions in diabetes associated HFpEF.

physiology↗

bioRxiv2024

Permissive and instructive Hox codes govern limb positioning

The positioning of limbs along the anterior-posterior axis varies widely across vertebrates. The mechanisms controlling this feature remain to be fully understood. For over 30 years, it has been speculated that Hox genes play a key role in this process but evidence supporting this hypothesis has been largely indirect. In this study, we employed loss- and gain-of-function Hox gene variants in chick embryos to address this issue. Using this approach, we found that Hox4/5 genes are necessary but insufficient for forelimb formation. Within the Hox4/5 expression domain, Hox6/7 genes are sufficient for reprogramming of neck lateral plate mesoderm to form an ectopic limb bud, thereby inducing forelimb formation anterior to the normal limb field. Our findings demonstrate that the forelimb program depends on the combinatorial actions of these Hox genes. We propose that during the evolutionary emergence of the neck, Hox4/5 provide permissive cues for forelimb formation throughout the neck region, while the final position of the forelimb is determined by the instructive cues of Hox6/7 in the lateral plate mesoderm. Impact statementElucidation of the Hox code defining forelimb positioning provides novel insights in lateral plate mesoderm patterning and the integration of vertebrate column structure and limb positioning.

developmental biology↗

bioRxiv2024

BATF controls IFN I production via DC-SCRIPT in plasmacytoid dendritic cells

The basic leucine zipper ATF-like transcription factor (BATF) plays a pivotal role in coordinating various aspects of lymphoid cell biology, yet essential functions in dendritic cells (DCs) have not been reported. Here we demonstrate that BATF deficiency leads to increased interferon (IFN) I production in Toll-like receptor 9 (TLR9)-activated plasmacytoid dendritic cells (pDCs), while BATF overexpression has an inhibitory effect. BATF-deficient mice exhibit elevated IFN I serum levels early in lymphocytic choriomeningitis virus (LCMV) infection. Through ATAC-Seq analysis, BATF emerges as a pioneer transcription factor, regulating approximately one third of the known transcription factors in pDCs. Integrated transcriptomics and ChIP-Seq approaches identified the transcriptional regulator DC-SCRIPT as a direct target of BATF that suppresses IFN I promoter activity by interacting with the interferon regulatory factor 7 (IRF7). Genome-wide association study (GWAS) analyses further implicate BATF in pDC-mediated human diseases. Our findings establish a novel negative feedback axis in IFN I regulation in pDCs during anti-viral immune responses orchestrated by BATF and DC-SCRIPT, with broader implications for pDC and IFN I-mediated autoimmunity.

immunology↗

bioRxiv2023

Mitochondrial Apolipoprotein MIC26 is a metabolic rheostat regulating central cellular fuel pathways

Mitochondria play central roles in metabolism and metabolic disorders such as type 2 diabetes. MIC26, a MICOS complex subunit, was linked to diabetes and modulation of lipid metabolism. Yet, the functional role of MIC26 in regulating metabolism under hyperglycemia is not understood. We employed a multi-omics approach combined with functional assays using WT and MIC26 KO cells cultured in normoglycemia or hyperglycemia, mimicking altered nutrient availability. We show that MIC26 has an inhibitory role in glycolysis and cholesterol/lipid metabolism under normoglycemic conditions. Under hyperglycemia, this inhibitory role is reversed demonstrating that MIC26 is critical for metabolic adaptations. This is partially mediated by alterations of mitochondrial metabolite transporters. Furthermore, MIC26 deletion led to a major metabolic rewiring of glutamine utilization as well as oxidative phosphorylation. We propose that MIC26 acts as a metabolic rheostat, that modulates mitochondrial metabolite exchange via regulating mitochondrial cristae, allowing cells to cope with nutrient overload.

cell biology↗

bioRxiv2022

Deficiency in hyaluronan synthase 3 attenuates ruptures in a murine model of abdominal aortic aneurysms by reduced aortic monocyte infiltration

Abdominal aortic aneurysms (AAA) are a common vascular disorder with a high mortality due to the prevalence of aortic ruptures. The underlying pathomechanisms are complex and involve immune cell infiltration and degradation of the vascular extracellular matrix (ECM). Hyaluronan (HA), synthesized at the plasma membrane by three HA synthase isoenzymes (HAS1-3), is not only a major constituent of the ECM but also known to directly affect the phenotype of vascular smooth muscle cells as well as immunological responses. Specifically, the HAS3 isoenzyme has been reported to play a major role in various inflammatory conditions. Therefore, the aim of the present study was to elucidate the role of HAS3-derived HA in the pathogenesis of abdominal aortic aneurysm. To this end, we used a murine model of Angiotensin II (AngII)-induced abdominal aortic aneurysms and dissections (AAAs/AADs) and could demonstrate that genetic depletion of Has3 improves survival in Apoe/Has3 double deficient (Apoe/Has3-DKO) mice via the reduced occurrence of aortic ruptures. Mechanistically, fewer elastica breaks were observed in Apoe/Has3-DKO mice compared to Apoe-KO littermates. This was associated with a decreased infiltration of myeloid immune cells into the vessel wall of Has3-deficient mice while in parallel elevated numbers of circulating leukocytes were detected. RNA seq analysis from aortic tissue pointed towards a disturbed endothelial-myeloid cell communication as a cause for the diminished recruitment of immune cells to the aortic wall. While endothelial cells were unaffected, upregulation of adhesion receptors as well as the HA receptor CD44, known to mediate leukocyte adhesion to the endothelium, was blunted in monocytes from Apoe/Has3-DKO mice in response to AngII treatment. These findings underline the pivotal detrimental role of monocytes HAS3-dependent pericellular HA matrix for an exaggerated immune cell recruitment to inflammatory foci giving here rise for an increased incidence of ruptured aortic aneurysms.

immunology↗

bioRxiv2021

The transcription factor reservoir and chromatin landscape in activated plasmacytoid dendritic cells

Transcription factors (TFs) control gene expression by direct binding to regulatory regions of target genes but also by impacting chromatin landscapes and thereby modulating DNA accessibility for other TFs. To date, the global TF reservoir in plasmacytoid dendritic cells (pDCs), a cell type with the unique capacity to produce unmatched amounts of type I interferons, has not been fully characterized. To fill this gap, we have performed a comprehensive analysis in naive and TLR9-activated pDCs in a time course study covering early timepoints after stimulation (2h, 6h, 12h) integrating gene expression (RNA-Seq), chromatin landscape (ATAC-Seq) and Gene Ontology studies. We found that 70% of all described TFs are expressed in pDCs for at least one stimulation time point and that activation predominantly "turned on" the chromatin regions associated with TF genes. We hereby define the complete set of TLR9-regulated TFs in pDCs. Further, this study identifies the AP-1 family of TFs as potentially important but so far less well characterized regulators of pDC function.

molecular biology↗

bioRxiv2021

Lymphotoxin β receptor: A crucial role in innate and adaptive immune responses against Toxoplasma gondii

The LT{beta}R plays an essential role in the initiation of immune responses to intracellular pathogens. In mice, the LT{beta}R is crucial for surviving acute toxoplasmosis, however, up to now a functional analysis is largely incomplete. Here, we demonstrate that the LT{beta}R is a key regulator required for the intricate balance of adaptive immune responses. T. gondii infected LT{beta}R-/- mice show globally altered IFN{gamma} regulation, reduced IFN{gamma}-controlled host effector molecule expression, impaired T cell functionality and an absent anti-parasite specific IgG response resulting in a severe loss of immune control of the parasites. Reconstitution of LT{beta}R-/- mice with toxoplasma immune serum significantly prolongs the survival following T. gondii infection. Notably, analysis of RNAseq data clearly indicates a specific effect of T. gondii infection on the B cell response and isotype switching. This study unfolds the decisive role of the LT{beta}R in cytokine regulation and adaptive immune responses to control T. gondii.

immunology↗