Biology subjects

Goedecke, A.

Publications and source records attributed to Goedecke, A..

3 recordsLinked to original sources

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↗

bioRxiv2022

Full-length transcriptomic analysis in murine and human heart reveals diversity of PGC-1α promoters and isoforms regulated distinctly in myocardial ischemia and obesity

BackgroundPeroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1) acts as a transcriptional coactivator and regulates mitochondrial function. Various isoforms are generated by alternative splicing and differentially regulated promoters. In the heart, total PGC-1 deficiency knockout leads to dilatative cardiomyopathy, but knowledge on the complexity of cardiac isoform expression of PGC-1 remains sparse. Thus, this study aims to generate a reliable dataset on cardiac isoform expression pattern by long-read mRNA sequencing, followed by investigation of differential regulation of PGC-1 isoforms under metabolic and ischemic stress, using high-fat-high-sucrose-diet-induced obesity and a murine model of myocardial infarction. Methods and ResultsMurine (C57Bl/6J) or human heart tissue (obtained during LVAD-surgery), was used for long-read mRNA sequencing, resulting in full-length transcriptomes including 58,000 mRNA isoforms with 99% sequence accuracy. Automatic bioinformatic analysis as well as manual similarity search against exonic sequences lead to identification of putative coding PGC-1 isoforms, validated by PCR and Sanger-Sequencing. Thereby, 12 novel transcripts generated by hitherto unknown splicing events were detected. In addition, we postulate a novel promoter with homologous and strongly-conserved sequence in human heart. High-fat-diet as well as ischemia/reperfusion (I/R) injury transiently reduced cardiac expression of PGC-1-isoforms, with the most pronounced effect in the infarcted area. Recovery of PGC-1-isoform expression was even more decelerated when I/R was performed in diet-induced obese mice. ConclusionsWe deciphered for the first time a complete full-length-transcriptome of the murine and human heart, identifying novel putative PGC-1 coding transcripts including a novel promoter. These transcripts are differentially regulated in I/R and obesity suggesting transcriptional regulation and alternative splicing that may modulate PGC-1 function in the injured and metabolically challenged heart.

genetics↗

bioRxiv2018

Protein nitration is a physiological regulator of cardiac lactate dehydrogenase active site loop mobility and activity

Protein tyrosine nitration is a hallmark of oxidative stress related disease states, commonly detected as anti-nitrotyrosine immunoreactivity. The precise reactive oxygen sources, mechanisms of nitration as well as the modified target proteins and functional consequences, however, remain often unclear. Here we explore protein tyrosine nitration under basal conditions and find surprisingly physiologically nitrated proteins. Upon purifying a prominent physiologically nitrotyrosine immunopositive in hearts from mouse, rat and pig, we identify it as lactate dehydrogenase (LDH). Mechanistically, LDHs degree of basal nitration depended on two canonical sources, NO synthase (NOS) and myeloperoxidase (MPO), respectively. When validating the nitrated amino acid by MALDI-TOF mass spectrometry, we, surprisingly, located LDH nitration not to a tyrosine but the C-terminal tryptophan, Trp324. Molecular dynamics simulations suggested that Trp324 nitration restricts the interaction of the active site loop with the C-terminal -helix essential for activity. This prediction was confirmed by enzyme kinetics revealing an apparent lower Vmax of nitrated LDH, although yet unidentified concurrent oxidative modifications may contribute. Protein nitration is, thus, not a by definition disease marker but reflects also physiological signaling by eNOS/NO, MPO/nitrite and possibly other pathways. The commonly used assay of anti-nitrotyrosine immunoreactivity is apparently cross-reactive to nitrotryptophan requiring a reevaluation of the protein nitration literature. In the case of LDH, nitration of Trp324 is aggravated under cardiac metabolic stress conditions and functionally limits maximal enzyme activity. Trp324-nitrated LDH may serve both as a previously not recognized disease biomarker and possibly mechanistic lead to understand the metabolic changes under these conditions.

biochemistry↗