Biology subjects

Berwanger, C.

Publications and source records attributed to Berwanger, C..

4 recordsLinked to original sources

bioRxiv2025

The influence of power-training and aging on endomysium content and fiber cross-sectional area in the human soleus muscle

The Master Athletic Laboratory Study of Intramuscular Connective Tissue (MALICoT, DRKS00015764) set out to analyze the endomysium content of the human soleus muscle in response to athletic exercise and aging. Forty-three healthy male study participants were grouped into young (20-35 years) non-physically active controls (n=12), young power-trained athletes (n=10), older (60-75 years) non-physically active controls (n=11), and older power-trained athletes (n=10). A single biopsy was taken from the left soleus muscle of each participant, and cryo-sections were used for i) routine histological staining and myopathological evaluation, ii) deep learning-based image analysis of the H&E- and MHC-stained sections, iii) laminin-{gamma}-1/collagen IV double- and collagen I and III single-immunofluorescence staining, and iv) quantitative proteomic analysis. Examiner-based myopathological evaluation revealed normal skeletal muscle in 26 participants, while 11, 4, 1 and 1 biopsies showed unspecific myopathological changes, chronic neurogenic atrophy, type II fiber atrophy, and unspecific myositic changes, respectively. Analysis of the H&E- and MHC-stained sections as well as the laminin-{gamma}-1/collagen I-, collagen III- and collagen IV-immunostained sections revealed an approximately 1.3-fold increase in the mean fiber area in response to power-training in young participants and aging in unathletic participants. No significant change was detected in endomysium thickness or area. Furthermore, proteomic analysis did not reveal any group-specific change except for plasma membrane calcium-transporting ATPase 2 being less abundant in the soleus muscles of aged power-trained athletes. Overall, the data show that neither athletic exercise nor age significantly affected the content or composition of the endomysium in human soleus muscle tissue. New & NoteworthyMALICoT (DRKS00015764) set out to analyze the endomysium of soleus muscle in response to athletic exercise and aging. Myopathological evaluation of biopsies from 43 asymptomatic male study participants revealed normal skeletal muscle in only 26 of them. Neither exercise nor age significantly affected the endomysium content or proteomic profiles of human soleus muscle tissue. However, power-training in young participants and aging in unathletic participants were associated with significant increases in soleus muscle fiber cross-sectional area.

physiology↗

bioRxiv2024

Integrated data from R405W desmin knock-in mice highlight alterations of mitochondrial function, protein quality control, and myofibrillar structure in the initial stages of myofibrillar myopathy

BackgroundMutations in the desmin gene cause skeletal myopathies and cardiomyopathies. The objective of this study was to elucidate the molecular pathology induced by the expression of R405W mutant desmin in murine skeletal muscle tissue. MethodsA comprehensive characterization of the skeletal muscle pathology in hetero- and homozygous R405W desmin knock-in mice was performed, employing grip strength, blood acylcarnitine and amino acid, histological, ultrastructural, immunofluorescence, immunoblot, ribosomal stalling, RNA sequencing and proteomic analyses. ResultsBoth hetero- and homozygous R405W desmin knock-in mice showed classical myopathological features of a myofibrillar myopathy with desmin-positive protein aggregation, degenerative changes of the myofibrillar apparatus, increased autophagic build-up, and mitochondrial alterations. Muscle weakness and increased blood concentrations of acylcarnitines and amino acids were only present in homozygous animals. During its translation, mutant desmin does not induce terminal ribosomal stalling. Analyses of RNA sequencing and proteomic data from soleus muscle of 3-month-old mice depicted 59 up- and 2 down-regulated mRNAs and 101 up- and 18 down-regulated proteins that were shared between the heterozygous and homozygous genotypes in the respective omics datasets compared to the wild-type genotype. Combined analysis of the omics data demonstrated 187 significantly dysregulated candidates distributed across four groups of regulation. A down-regulation on the mRNA and protein levels was observed for a multitude of mitochondrial proteins including essential proton gradient-dependent carriers. Up-regulation on both omics levels was present for the transcription factor Mlf1, which is a binding partner of protein quality control related Dnajb6. Down-regulated on mRNA but up-regulated on the protein level was the sarcomeric lesion marker Xirp2 (xin actin-binding repeat-containing protein 2), whereas Ces2c (acylcarnitine hydrolase) was regulated in the opposite way. ConclusionsThe present study demonstrates that the expression of mutant desmin results in a myofibrillar myopathy in hetero- and homozygous R405W desmin knock-in mice. Combined morphological, transcriptomic and proteomic analyses helped to decipher the complex pattern of early pathological changes induced by the expression of mutant desmin. Our findings highlight the importance of major mitochondrial alterations, including essential proton gradient-dependent carriers as well as Dnajb6-related protein quality control and Xin-related myofibrillar damage, in the molecular pathogenesis of desminopathies.

neuroscience↗

bioRxiv2023

Immortalised murine R349P desmin knock-in myotubes exhibit a reduced proton leak and decreased ADP/ATP translocase levels in purified mitochondria

Desmin gene mutations cause myopathies and cardiomyopathies. Our previously characterised R349P desminopathy mice, which carry the ortholog of the common human desmin mutation R350P, showed marked alterations in mitochondrial morphology and function in muscle tissue. By isolating skeletal muscle myoblasts from offspring of R349P desminopathy and p53 knock-out mice, we established an immortalised cellular disease model. Heterozygous and homozygous R349P desmin knock-in and wild-type myoblasts could be well differentiated into multinucleated spontaneously contracting myotubes. The desminopathy myoblasts showed the characteristic disruption of the desmin cytoskeleton and desmin protein aggregation, and the desminopathy myotubes showed the characteristic myofibrillar irregularities. Long-term electrical pulse stimulation promoted myotube differentiation and markedly increased their spontaneous contraction rate. In both heterozygous and homozygous R349P desminopathy myotubes, this treatment restored a regular myofibrillar cross-striation pattern as seen in wild-type myotubes. High-resolution respirometry of mitochondria purified from myotubes by density gradient ultracentrifugation revealed normal oxidative phosphorylation capacity, but a significantly reduced proton leak in mitochondria from the homozygous R349P desmin knock-in cells. Consistent with a reduced proton flux across the inner mitochondrial membrane, our quantitative proteomic analysis of the purified mitochondria revealed significantly reduced levels of ADP/ATP translocases in the homozygous R349P desmin knock-in genotype. As this alteration was also detected in the soleus muscle of R349P desminopathy mice, which, in contrast to the mitochondria purified from cultured cells, showed a variety of other dysregulated mitochondrial proteins, we consider this finding to be an early step in the pathogenesis of secondary mitochondriopathy in desminopathy. HighlightsO_LIR349P desminopathy immortalised murine myoblasts as a cellular disease model C_LIO_LIElectrical stimulation improves myofibrillar maturation in desminopathy myotubes C_LIO_LIReduced proton leak in mitochondria of homozygous R349P desmin knock-in myotubes C_LIO_LIReduced ADP/ATP translocase levels in mitochondria of desminopathy myotubes C_LIO_LIEarly signs of secondary mitochondriopathy in desminopathy in cultured myotubes C_LI

cell biology↗

bioRxiv2023

Simulated microgravity during clino-rotation is disturbed by spurious fluid motion

To study processes related to weightlessness in ground-based cell biological research, a theoretically assumed microgravity environment is typically simulated using a clinostat - a small laboratory device that rotates cell culture vessels with the aim of averaging out the vector of gravitational forces. Here, we report that the rotational movement during fast clinorotation induces complex fluid motions in the cell culture vessel, which can trigger unintended cellular responses. Specifically, we demonstrate that suppression of myotube formation by 2D-clinorotation at 60 rpm is not an effect of the assumed microgravity but instead is a consequence of fluid motion. Therefore, cell biological results from fast clinorotation cannot be attributed to microgravity unless alternative explanations have been rigorously tested and ruled out. We consider two control experiments mandatory, i) a static, non-rotating control, and ii) a control for fluid motion. These control experiments are also highly recommended for other rotation speed settings and experimental conditions. Finally, we discuss strategies to minimize fluid motion in clinorotation experiments.

cell biology↗