Desmin Protein Research Articles

Desmin-related myopathy manifested by various types of arrhythmias: a case report and literature review.

Desmin is a type III intermediate filament protein specifically expressed in muscle cells, which is encoded by the DES gene. Defects in the desmin protein and cytoskeletal instability may interfere with cardiac muscle conduction signals, a fundamental mechanism for arrhythmias in patients with desmin-related myopathy. This current case report presents a female patient in her early 20s who presented with early-onset complete atrioventricular block and complete left bundle branch block over the previous decade. More recently, she had developed ventricular tachycardia, ventricular fibrillation, atrial fibrillation and other arrhythmias. Echocardiography revealed non-compaction of the ventricular myocardium and pulmonary hypertension. Whole-exome sequencing analysis identified a heterozygous missense mutation in the DES gene: c.1216C>T (p.Arg406Trp). She was eventually diagnosed with arrhythmias due to desmin-related myopathy. A literature review of international databases was undertaken to summarise the clinical characteristics of the cardiac involvement associated with this DES gene mutation.

Hepatic Stellate Cell-mediated Increase in CCL5 Chemokine Expression after X-ray Irradiation Determined In Vitro and In Vivo.

Radiation exposure causes hepatitis which induces hepatic steatosis and fibrosis. Although hepatic stellate cells (HSCs) have been considered potential pathological modulators for the development of hepatitis due to viral and microbial infections, their involvement in radiation-induced hepatitis is yet to be determined. This study aimed to clarify the relationship between radiation exposure and expressions of inflammatory cytokines and chemokines in HSCs in vitro and invivo. HSCs were obtained from 1-week-old mice, known to be highly sensitive to radiation-induced hepatocellular carcinoma, using a newly established method combining liver perfusion, cell dissociation, and density gradient centrifugation, followed by magnetic negative selection of hematopoietic and endothelial cells with anti-CD45.2 and CD146 antibodies. The isolated HSCs were confirmed by the expression of desmin and glial fibrillary acidic protein (GFAP). We demonstrated that primary cultured HSCs, exposed to X-ray irradiation (0, 1.9, and 3.8 Gy) and cultured for 3 and 7 days, produced elevated levels of C-C motif chemokine ligand 5 (CCL5, also known as RANTES) inflammatory chemokine in a dose-dependent manner. An invivo immunofluorescence method confirmed that increased CCL5 signals were observed in GFAP-positive HSCs in mouse livers 7 days after whole-body X-ray irradiation (1.9 and 3.8 Gy). Adequate expression of C-C motif chemokine receptor 5 (Ccr5), a receptor for CCL5, was also detected using real-time PCR in the liver of both irradiated and non-irradiated mice. Taken together, our data suggest that HSCs may drive hepatitis via CCL5/CCR5 axis in the liver under radiation-induced stress. Furthermore, this newly established experimental protocol can help evaluate the expression of other inflammatory cytokines in primary cultures of HSCs isolated from infant mice.

Phosphorylation of CRYAB Induces a Condensatopathy to Worsen Post-Myocardial Infarction Left Ventricular Remodeling.

Protein aggregates are emerging therapeutic targets in rare monogenic causes of cardiomyopathy and amyloid heart disease, but their role in more prevalent heart failure syndromes remains mechanistically unexamined. We observed mis-localization of desmin and sarcomeric proteins to aggregates in human myocardium with ischemic cardiomyopathy and in mouse hearts with post-myocardial infarction ventricular remodeling, mimicking findings of autosomal-dominant cardiomyopathy induced by R120G mutation in the cognate chaperone protein, CRYAB. In both syndromes, we demonstrate increased partitioning of CRYAB phosphorylated on serine-59 to NP40-insoluble aggregate-rich biochemical fraction. While CRYAB undergoes phase separation to form condensates, the phospho-mimetic mutation of serine-59 to aspartate (S59D) in CRYAB mimics R120G-CRYAB mutants with reduced condensate fluidity, formation of protein aggregates and increased cell death. Conversely, changing serine to alanine (phosphorylation-deficient mutation) at position 59 (S59A) restored condensate fluidity, and reduced both R120G-CRYAB aggregates and cell death. In mice, S59D CRYAB knock-in was sufficient to induce desmin mis-localization and myocardial protein aggregates, while S59A CRYAB knock-in rescued left ventricular systolic dysfunction post-myocardial infarction and preserved desmin localization with reduced myocardial protein aggregates. 25-Hydroxycholesterol attenuated CRYAB serine-59 phosphorylation and rescued post-myocardial infarction adverse remodeling. Thus, targeting CRYAB phosphorylation-induced condensatopathy is an attractive strategy to counter ischemic cardiomyopathy.

Abstract Mo093: Rescue of Desmin Insufficiency Restores Contractile Function in Cardiomyocytes with MYH7 E848G Dilated Cardiomyopathy Variant

Dilated cardiomyopathy (DCM), characterized by systolic dysfunction, is a significant cause of heart failure. Myosin heavy chain 7 ( MYH7 ) pathogenic variants are common causes of DCM; however, no specific disease-modifying therapy for MYH7 DCM exists. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) expressing the pathogenic MYH7 E848G DCM variant, we confirmed hypocontractility at the single cell level as assessed with traction force microscopy. hiPSC-CMs were cultured on polyacrylamide hydrogels with physiological stiffness in 15x100 µm patterned Matrigel-coated rectangles, each containing one cell. Upon 1 Hz electrical stimulation, contracting cells displaced fluorescent beads embedded within the gel, which were measured to estimate twitch force. MYH7 E848G/+ hiPSC-CMs had reduced maximum twitch force (97 ± 11 nN, n=46 cells) compared to MYH7 +/+ hiPSC-CMs (179 ± 18 nN, n=49 cells), recapitulating the disease phenotype. RNAseq analysis of MYH7 E848G/+ hiPSC-CMs compared to isogenic control MYH7 +/+ hiPSC-CMs found significant downregulation of desmin ( DES) (76.4 ± 8.2% reduction, n=4 bio reps), which encodes a muscle-specific type III intermediate filament. Desmin protein expression in MYH7 E848G/+ hiPSC-CMs was significantly attenuated relative to MYH7 +/+ hiPSC-CMs (90.9 ± 1.8% reduction, n=4 bio reps), matching gene expression data. Gene expression of the transcription factor MEF2C , a known transactivator of DES, was also reduced (40.4 ± 7.0% reduction, n=4 bio reps), suggesting MYH7 E848G/+ suppresses the MEF2C - DES signaling axis. We hypothesized restoring desmin protein levels may improve contractility in MYH7 E848G/+ hiPSC-CMs. To test this, we created an adeno-associated virus (AAV9) packaged with full-length desmin cDNA fused with a T2A self-cleaving peptide and mApple fluorescent reporter. hiPSC-CMs were transfected with this mApple-T2A-DES AAV at 1 MOI and contractility was assessed via traction force microscopy. mApple + MYH7 E848G/+ hiPSC-CMs had increased maximum twitch force (141 ± 11 nN, n=75 cells) relative to mApple - MYH7 E848G/+ hiPSC-CMs (65 ± 20 nN, n=21 cells), approaching the maximum twitch force of mApple + MYH7 +/+ hiPSC-CMs (165 ± 10 nN, n=87 cells). In conclusion, suppression of the MEF2C - DES signaling axis is a potential novel mechanism by which pathogenic MYH7 variants cause DCM. By leveraging this mechanistic insight, we found that rescuing desmin insufficiency can partially restore contractile function.

In vitro susceptibility of grass carp fish (Ctenopharyngodon idella) to oxidized myosin on structural change of protein secondary structure associated with reactive oxygen species (ROS) treatment

This study aimed to investigate the in vitro susceptibility of grass carp (Ctenopharyngodon idella) oxidized myosin, with the treatment of H2O2 levels being 0, 25, 50, and 100 μmol/L, respectively. The results showed that in vitro oxidation of myosin, reactive oxidative species promoted protein modifications that propagated the conformation changes on myosin secondary structure, leading to a significant increase (P < 0.05) in the protein carbonyl content in the high oxidation treatment, when compared to the low and medium treatments. The results of the Western blot analysis and sodium-polyacrylamide amide-dodecyl sulfate gel electrophoresis demonstrated that in vitro oxidation actively promoted the degradation of protein molecular weight and Desmin (53 kDa) deterioration in the sample with the highest concentration treatment of H2O2. Circular dichroism spectra showed a decrease in α-helix content from 70.1% to 29.8% and an increase in β-sheet percentage from 5.6% to 17.4%. Meanwhile, cysteine and methionine as the free amino acids were most susceptible to oxidative change due to their high sensitivity to the reaction of the sulfur group of amino acids. Protein degradation induced by oxidation resulted in significant changes to the protein secondary structure, as evidenced by the observation of oxidized myosin under different H2O2 levels.

Desmin gene expression is not ubiquitous in all upper airway myofibers and the pattern differs between healthy and sleep apnea subjects

BackgroundDesmin is a major cytoskeletal protein considered ubiquitous in mature muscle fibers. However, we earlier reported that a subgroup of muscle fibers in the soft palate of healthy subjects and obstructive sleep apnea patients (OSA) lacked immunoexpression for desmin. This raised the question of whether these fibers also lack messenger ribonucleic acid (mRNA) for desmin and can be considered a novel fiber phenotype. Moreover, some fibers in the OSA patients had an abnormal distribution and aggregates of desmin. Thus, the aim of the study was to investigate if these desmin protein abnormalities are also reflected in the expression of desmin mRNA in an upper airway muscle of healthy subjects and OSA patients.MethodsMuscle biopsies from the musculus uvulae in the soft palate were obtained from ten healthy male subjects and six male patients with OSA. Overnight sleep apnea registrations were done for all participants. Immunohistochemistry, in-situ hybridization, and reverse transcription–quantitative polymerase chain reaction (RT–qPCR) techniques were used to evaluate the presence of desmin protein and its mRNA.ResultsOur findings demonstrated that a group of muscle fibers lacked expression for desmin mRNA and desmin protein in healthy individuals and OSA patients (12.0 ± 5.6% vs. 23.1 ± 10.8%, p = 0.03). A subpopulation of these fibers displayed a weak subsarcolemmal rim of desmin accompanied by a few scattered mRNA dots in the cytoplasm. The muscles of OSA patients also differed from healthy subjects by exhibiting muscle fibers with reorganized or accumulated aggregates of desmin protein (14.5 ± 6.5%). In these abnormal fibers, the density of mRNA was generally low or concentrated in specific regions. The overall quantification of desmin mRNA by RT–qPCR was significantly upregulated in OSA patients compared to healthy subjects (p = 0.01).ConclusionsOur study shows evidence that muscle fibers in the human soft palate lack both mRNA and protein for desmin. This indicates a novel cytoskeletal structure and challenges the ubiquity of desmin in muscle fibers. Moreover, the observation of reorganized or accumulated aggregates of desmin mRNA and desmin protein in OSA patients suggests a disturbance in the transcription and translation process in the fibers of the patients.

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.

Downregulating lncRNA MIAT attenuates apoptosis of podocytes exposed to high glucose.

Diabetic nephropathy (DN), a destructive complication of diabetes mellitus (DM), is one of the leading causes of end-stage renal disease (ESRD). This study aimed to investigate the role of long non-coding RNA (lncRNA) MIAT in high-glucose (HG)-induced podocyte injury associated with DN. Three human kidney podocyte (HKP) cultures were treated with HG to mimic DN. Expression of lncRNA MIAT, podocyte-specific and injury-related proteins, and apoptosis were assessed before and after MIAT knockdown using MIAT shRNAs. MIAT expression was upregulated in HKPs in response to glucose stress. HG treatment resulted in a significant increase in the apoptotic rate, Bax level, and levels of injury-related proteins desmin, fibroblast-specific protein 1 (FSP-1), and smooth muscleα-actin (α-SMA), and a significant reduction in Bcl-2 levels and the levels of podocyte-specific proteins synaptopodin and podocin. Transfection of HKPs with shRNAs significantly reduced MIAT levels (p < 0.05) and attenuated apoptosis in HG-medium. Correspondingly, the levels of synaptopodin and podocin were upregulated, and desmin, FSP-1, and α-SMA were reduced (p < 0.05). Western blot analysis also showed that anti-apoptotic active caspase-3 and Bax and proapoptotic Bcl-2 were elevated and decreased, respectively, after MIAT knockdown, suggesting that apoptosis pathways are deactivated after MIAT downregulation. High glucose upregulates MIAT level in HKPs and induces cellular injury. Knockdown of MIAT alleviates the injury likely via deactivating apoptosis pathways.

Crocin Inhibits Orbital Fibroblasts Fibrosis in Thyroid-Associated Ophthalmopathy

Purpose To investigate the role of Crocin on proliferation, fibrosis, and migration of orbital fibroblasts, as well as the possible signaling pathway. Methods Immunofluorescence assay was performed to detect the expression of fibroblast marker proteins vimentin cytokeratin, desmin, and S-100. The quantity of 5‑ethynyl‑2′‑deoxyuridine-positive cells in orbital fibroblast was analyzed. Quantitative real-time PCR and western blots were performed to evaluate the expression level of fibrosis-related marker including alpha-smooth muscle actin, connective-tissue growth factor, collagen 1A1, and fibronectin. Scratch wound assays were performed to assess wound widths of orbital fibroblast. The expression and phosphorylation of extracellular signal-regulated kinase/signal transducer and activator of transcription 3 were evaluated using western blots. The phosphorylation of smad2 and smad3 was evaluated using immunofluorescence assay. Results Crocin treatment reduced 5‑ethynyl‑2′‑deoxyuridine-positive cells, indicating inhibitory effect on orbital fibroblast proliferation. The expression levels of alpha-smooth muscle actin, connective-tissue growth factor, collagen 1A1 and fibronectin were declined in Crocin treatment. Delayed wound closures were observed in Crocin treatment. Furthermore, Crocin did not affect the expression of extracellular signal-regulated kinase and signal transducer and activator of transcription 3, but weakened extracellular signal-regulated kinase and signal transducer and activator of transcription 3 phosphorylation in orbital fibroblast. The phosphorylation of smad2 and smad3 was attenuated by Crocin as well. Conclusion In conclusion, Crocin inhibits the phosphorylation of extracellular signal-regulated kinase and signal transducer and activator of transcription 3, contributing to the inhibitory effect on proliferation, fibrosis, and migration of orbital fibroblast, suggesting that Crocin has potential to be a novel therapeutic candidate for thyroid-associated ophthalmopathy treatment.

Genetic testing in inflammatory cardiomyopathy/myocarditis: a red flag for cardiomyopathy-like histologic findings

Abstract Background Myocarditis/inflammatory cardiomyopathy is characterized by the presence of an inflammatory infiltrate in the myocardium. Its etiology is heterogeneous, predominantly mediated by viral infection, as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Outcome could vary from a complete recovery to a residual myocardial injury with the subsequent development of dilated cardiomyopathy (DCM). The factors that play a role in the disease progression are not clear, but it has been shown that inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. Purpose To characterize the genetic background of inflammatory cardiomyopathy affected patients to determine the prevalence of pathogenic/likely pathogenic (P/LP) variants in cardiomyopathy-related genes and correlate to histopathologic findings in endomyocardial biopsies (EMB). Methods Eighty-nine myocarditis-affected patients (mean age 43±14, 55 males) underwent genetic screening of 200 genes related to inherited cardiomyopathies. Definite/moderate gene association with DCM and Arrhythmogenic Cardiomyopathy was based on the ClinGen framework. Variant prioritization was carried out using American College of Medical Genetics and Genomics rules. Correlation with histopathologic findings of the endomyocardial biopsy and family history was appraised. Results Twenty of the 89 suspected myocarditis patients (22%) carried a P/LP variant in cardiac-related genes: 8 in Titin, 3 in Myosin Heavy Chain 7, 2 in Desmoplakin, 2 in Lamin A/C; and Troponin T2, Filamin-C, Myosing Binding Protein C3, Desmin and Sodium Voltage-Gated Channel Alpha Subunit 5 carried one variant each. A re-analysis of the EMBs revealed that 82% of patients showed cardiomyopathy-like features at first histologic findings, with fibrosis in the myocardium and DCM-like phenotype at the second EMB. Further, 13 of the genotype-positive patients referred positive family history for cardiomyopathy and/or sudden cardiac death, whereas only 7 genotype-negative patients declared family history, showing a significant difference among both groups (p-value&amp;lt;0,0001). Conclusion The prevalence of P/LP variants in inflammatory cardiomyopathy/myocarditis patients is 22%, most of them associated with DCM. Cardiomyopathy-like features were already observed at the first EMB during the histologic re-evaluation in the majority of genotype-positive patients, and among them, high frequency of positive family history was observed. These findings suggest that genotype-positive inflammatory cardiomyopathy/myocarditis affected patients should be deeply clinically evaluated in order to guarantee an appropriate management for them and their families.

Establishment and characterization of a skeletal myoblast cell line of grass carp (Ctenopharyngodon idellus).

Skeletal muscle myoblastic cell lines can provide a valuable new in vitro model for the exploration of the mechanisms that control skeletal muscle development and its associated molecular regulation. In this study, the skeletal muscle tissues of grass carp were digested with trypsin and collagenase I to obtain the primary myoblast cell culture. Myoblast cells were obtained by differential adherence purification and further analyzed by cryopreservation and resuscitation, chromosome analysis, immunohistochemistry, and immunofluorescence. A continuous grass carp myoblast cell line (named CIM) was established from grass carp (Ctenopharyngodon idellus) muscle and has been subcultured > 100 passages in a year and more. The CIM cells revived at 79.78-95.06% viability after 1-6 months of cryopreservation, and shared a population doubling time of 27.24 h. The number of modal chromosomes of CIM cells was 48, and the mitochondrial 12S rRNA sequence of the CIM cell line shared 99% identity with those of grass carp registered in GenBank. No microorganisms (bacteria, fungi, or mycoplasma) were detected during the whole study. The cell type of CIM cells was proven to be myoblast by immunohistochemistry of specific myogenic protein markers, including CD34, desmin, MyoD, and MyHC, as well as relative expression of key genes. And the myogenic rate and fusion index of this cell line after 10 days of induced differentiation were 8.96 ~ 9.42% and 3-24%, respectively. The telomerase activity and transfection efficiency of CIM cell line were 0.027 IU/mgprot and 23 ~ 24%, respectively. These results suggest that a myoblast cell line named CIM with normal biological function has been successfully established, which may provide a valuable tool for related in vitro studies.

The Myocardial Accumulation of Aggregated Desmin Protein in a Case of Desminopathy with a de novo DES p.R406W Mutation.

Desminopathy is a cardiac and skeletal myopathy caused by disease-causing variants in the desmin (DES) gene and represents a subgroup of myofibrillar myopathies, where cytoplasmic desmin-postive immunoreactivity is the pathological hallmark. We herein report a 28-year-old Japanese man who was initially diagnosed with sporadic hypertrophic cardiomyopathy with atrioventricular block at 9 years old and developed weakness in the soft palate and extremities. The myocardial tissue dissected during implantation of the ventricular-assisted device showed a dilated phase of hypertrophic cardiomyopathy and intracellular accumulation of proteinase K-resistant desmin aggregates. Genetic testing confirmed a de novo mutation of DES, which has already been linked to desminopathy. As the molecular diagnosis of desminopathy is challenging, particularly if patients show predominantly cardiac signs and a routine skeletal muscle biopsy is unavailable, these characteristic pathological findings of endomyocardial proteinase K-resistant desmin aggregates might aid in clinical practice.

Capsaicin ameliorates myocardial injury in diabetic rats via upregulating Nrf-2, HO-1 and iNOS tissue concentrations besides normalizing the distribution of structural proteins desmin and α-SMA

Myocardial injury remains the leading cause of morbidity and mortality in diabetic patients. On the other hand, scientists have noticed that capsaicin has a distinctive pharmacological effect on the cardiovascular system. Hence, the present study aimed to investigate the potential ameliorative effects of capsaicin on the development of myocardial injury in diabetic rats and to identify the underlying mechanisms. Forty-eight animals were divided into four groups: control, diabetic, diabetic + rosuvastatin, and diabetic + capsaicin. Capsaicin was found to have a significant hypoglycemic and hypolipidemic effect compared to the other diabetic groups. Capsaicin also significantly increased the levels of the antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as reduced glutathione. This was likely due to the upregulation of the cytoplasmic content of its key regulators Nrf-2 and HO-1, as found by immunostaining and western blot analysis. Additionally, capsaicin significantly increased the levels of cardioprotective nitric oxide, which could be stimulated by the upregulation of iNOS. Capsaicin also had a significant anti-inflammatory effect by reducing the high levels of TNF-α and IL-1β. Capsaicin was able to significantly inhibit myocardial structural damage, as found by histopathological examination using Hematoxylin and eosin (H&E), Masson trichrome, and immunostaining of desmin and α-smooth actin. This was further confirmed on the biochemical level by the attenuation of cardiac enzymes, MDA, carbonyl content, and heat shock proteins (HSP) 70 upregulation. Finally, capsaicin was able to attenuate myocardial injury by decreasing the myocardial concentration of the apoptotic protein cleaved caspase-3. In conclusion, this study has introduced capsaicin as a promising naturally derived agent that can attenuate the development of myocardial damage in diabetics through its hypoglycemic, hypolipidemic, antioxidant, anti-inflammatory, and anti-apoptotic effects.

The novel role of IFITM1-3 in myogenic differentiation of C2C12 cells.

Interferon-induced transmembrane proteins (IFITMs 1, 2, and 3) play a critical role in preventing pathogen infection in vertebrates. They are also involved in the occurrence and prognosis of cancer. Myogenesis is a complex process regulated by several factors. This study disclosed that Ifitm1-3 were upregulated in the process of myogenic differentiation of C2C12 myoblasts on days 3, 5, and 7. This positively correlated with the expression of differentiation factors MyoD, myogenin, Mrf5, and desmin. Furthermore, knockdown of Ifitm1-3 by their individual siRNAs inhibited myogenesis of C2C12 myoblasts, with relative downregulation of MyoD, myogenin, Mrf5, and desmin. Subsequently, myotube formation and fusion percentage decreased. Co-immunoprecipitation combined with LC-MS/MS analysis uncovered the interaction proteins of IFITM1 and IFITM3 in C2C12 myoblasts. A total of 84 overlapped interaction proteins of IFITM1 and IFITM3 were identified, and one of the clusters was engaged in cytoskeletal and sarcomere proteins, including desmin, myosin, actin, vimentin, nestin, ankycorbin, and nucleolin. Hence, we hypothesize that these interacting proteins may function as scaffolds for IFITM1-3, possibly through the interaction protein desmin to initiate further interaction with other proteins to participate in myogenesis; however, the molecular mechanisms remain unclear. Our study may contribute to the development of novel therapeutics for myopathic diseases.

Nucleus Mechanosensing in Cardiomyocytes.

Cardiac muscle contraction is distinct from the contraction of other muscle types. The heart continuously undergoes contraction-relaxation cycles throughout an animal's lifespan. It must respond to constantly varying physical and energetic burdens over the short term on a beat-to-beat basis and relies on different mechanisms over the long term. Muscle contractility is based on actin and myosin interactions that are regulated by cytoplasmic calcium ions. Genetic variants of sarcomeric proteins can lead to the pathophysiological development of cardiac dysfunction. The sarcomere is physically connected to other cytoskeletal components. Actin filaments, microtubules and desmin proteins are responsible for these interactions. Therefore, mechanical as well as biochemical signals from sarcomeric contractions are transmitted to and sensed by other parts of the cardiomyocyte, particularly the nucleus which can respond to these stimuli. Proteins anchored to the nuclear envelope display a broad response which remodels the structure of the nucleus. In this review, we examine the central aspects of mechanotransduction in the cardiomyocyte where the transmission of mechanical signals to the nucleus can result in changes in gene expression and nucleus morphology. The correlation of nucleus sensing and dysfunction of sarcomeric proteins may assist the understanding of a wide range of functional responses in the progress of cardiomyopathic diseases.

Granulocyte-colony stimulating factor ameliorates di-ethylhexyl phthalate-induced cardiac muscle injury via stem cells recruitment, Desmin protein regulation, antifibrotic and antiapoptotic mechanisms.

Phthalates are common plasticizers present in medical-grade plastics and other everyday products. Di-ethylhexyl phthalate (DEHP) has been noted as a causative risk factor for the initiation and augmentation of cardiovascular functional disorders. G-CSF is a glycoprotein found in numerous tissues throughout the body and is currently applied in clinical practice and has been tested in congestive heart failure. We aimed to examine in depth the effect of DEHP on the histological and biochemical structure of the cardiac muscle in adult male albino rats and the mechanisms underlying the possible ameliorative effect of G-CSF. Forty-eight adult male albino rats were divided into control group, DEHP group, DEHP+ G-CSF group and DEHP-recovery group. We measured serum levels of aspartate aminotransferase (AST), creatine kinase MB isoenzyme (CK-MB) and lactate dehydrogenase (LDH). Left ventricular sections were processed for light and electron microscope examination, and immunohistochemical staining of Desmin, activated Caspase-3 and CD34. DEHP significantly increased enzyme levels, markedly distorted the normal architecture of cardiac muscle fibers, downregulated Desmin protein levels and enhanced fibrosis, and apoptosis. G-CSF treatment significantly decreased the enzyme levels compared to DEHP group. It enhanced CD34 positive stem cells recruitment to injured cardiac muscle, therefore improved the ultrastructural features of most cardiac muscle fibers via anti-fibrotic and anti-apoptotic effects in addition to increased Desmin protein expression levels. The recovery group showed partial improvement due to persistent DEHP effect. In conclusion, administration of G-CSF effectively corrected the histopathological, immunohistochemical and biochemical alterations in the cardiac muscle after DEHP administration by stem cells recruitment, Desmin protein regulation, antifibrotic and antiapoptotic mechanisms.

Immunolocalization of Desmin, Vimentin and S-100 proteins in testis and epididymis of African striped ground squirrel (Xerus erythropus)

The aim of the study was to immunolocalize desmin, vimentin and S-100 proteins in the testes and epididymis of African striped ground squirrel (Xerus erythropus) and establish their spatial distribution in the two organs. Formalin fixed-paraffin-embedded sections of the testis and epididymis obtained from ten apparently healthy adult male African striped ground squirrels were processed routinely for immunohistochemistry, using primary antibodies specific to desmin, vimentin and S-100. S-100The results showed that desmin reacted intensely in the myoid cells of the seminiferous tubules and smooth muscle cells of the epididymal ducts. It showed a moderate positive immunoreaction in the interstitial cells of Leydig, and the epididymal inter-ductal loose connective tissue. However, there was no immunoreaction of desmin in the spermatogonia or any other spermatogenic cell of the seminiferous tubule. Vimentin reacted intensely in the Leydig cells and spermatogonia. It showed moderate positive reaction in the myoid cells and the epididymal inter-ductal loose connective tissue. There was no immunoreaction of vimentin in the other spermatogenic cells (other than the spermatogonia). The S-100 proteins expressed a mild positive immunoreaction at the interstitial cells of Leydig, but negative immunoreaction in all other parts of testis and epididymis. Also, there was intense immunoreaction of desmin and vimentin and moderate immunoreaction of S-100 in the vascular endothelium in the testis and epididymis. In conclusion, the spatial distribution of desmin, vimentin and S-100 proteins in the testes and epididymis in the African striped ground squirrel showed some similarities and contrast with other mammals, giving insight into the functions of the proteins in these organs of the rodent.

Protective Effect of Astragaloside IV against Cadmium-Induced Damage on Mouse Renal Podocytes (MPC5).

In this study, we investigated the protective effect of Astragaloside IV (Ast) on mouse podocytes and its possible mechanism of action by constructing a cadmium-induced mouse renal podocytes model. We investigated the effects of cadmium (Cd) toxicity on cell number, morphology, the mitochondrial status of subcellular organelles, protein and gene levels, and the protective effects of Ast by constructing a model of Cd-induced damage to mouse renal podocytes (MPC5) and giving Ast protection at the same time. The results showed that exposure of MPC5 cells to CdCl2 culture medium containing 6.25 μM concentration acted with low cell mortality, but the mortality of MPC5 cells increased with the prolongation of cadmium exposure time. Given Ast, the death rate in the low dose group (12.5 μM) was significantly reduced, while the death rate in the medium dose group (25 μM) was extremely significantly reduced. In comparison to the control group, the Cd-exposed group exhibited a significant increase of 166.7% in malondialdehyde (MDA) content and a significant decrease of 17.1% in SOD activity. The mitochondrial membrane potential was also reduced to varying degrees. However, in the Ast-protected group compared to the Cd-exposed group, the MDA content significantly decreased by 20.8%, the SOD activity decreased by 7.14%, and the mitochondrial membrane potential showed a significant increase. Fluorescence staining of mitochondrial membrane potential indicated that Cd exposure caused mitochondrial apoptosis. In the 12-h cadmium-exposed group, the protein expression of Nephrin in mice significantly decreased by 33.4%. However, the expression of the Desmin protein significantly increased by 67.8%, and the expression of the autophagy protein LC3-II significantly increased by 55.5%. Meanwhile, the expression of PINK1, a mitochondrial autophagy pathway protein, was significantly increased in the 12 h and 24 h cadmium exposure groups. The mRNA level of PINK1 was significantly increased, and that of Parkin was decreased in the 48 h cadmium exposure group. Compared to the Cd-exposed group, the Ast group showed more significant improvements in the expression of podocyte structure, functional proteins, and mitochondrial autophagy pathway proteins. The immunological assay of mitochondrial autophagic pathway proteins further indicated that Cd-induced damage to MPC5 cells might be associated with the dysregulation of mitochondrial autophagy.

Intermediate filament proteins are reliable immunohistological biomarkers to help diagnose multiple tissue-specific diseases.

Cytoskeletal networks are proteins that effectively maintain cell integrity and provide mechanical support to cells by actively transmitting mechanical signals. Intermediate filaments, which are from the cytoskeleton family and are 10 nanometres in diameter, are unlike actin and microtubules, which are highly dynamic cytoskeletal elements. Intermediate filaments are flexible at low strain, harden at high strain and resist breaking. For this reason, these filaments fulfil structural functions by providing mechanical support to the cells through their different strain-hardening properties. Intermediate filaments are suitable in that cells both cope with mechanical forces and modulate signal transmission. These filaments are composed of fibrous proteins that exhibit a central α-helical rod domain with a conserved substructure. Intermediate filament proteins are divided into six groups. Type I and type II include acidic and basic keratins, type III, vimentin, desmin, peripheralin and glial fibrillary acidic protein (GFAP), respectively. Type IV intermediate filament group includes neurofilament proteins and a fourth neurofilament subunit, α-internexin proteins. Type V consists of lamins located in the nucleus, and the type VI group consists of lens-specific intermediate filaments, CP49/phakinin and filen. Intermediate filament proteins show specific immunoreactivity in differentiating cells and mature cells of various types. Various carcinomas such as colorectal, urothelial and ovarian, diseases such as chronic pancreatitis, cirrhosis, hepatitis and cataract have been associated with intermediate filaments. Accordingly, this section reviews available immunohistochemical antibodies to intermediate filament proteins. Identification of intermediate filament proteins by methodological methods may contribute to the understanding of complex diseases.

Structural and signaling proteins in the Z-disk and their role in cardiomyopathies.

The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.