Browsing by Subject "SKELETAL-MUSCLE"

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  • Hulmi, Juha J.; Hentila, Jaakko; DeRuisseau, Keith C.; Oliveira, Bernardo M.; Papaioannou, Konstantinos G.; Autio, Reija; Kujala, Urho M.; Ritvos, Olli; Kainulainen, Heikki; Korkmaz, Ayhan; Atalay, Mustafa (2016)
    Protein homeostasis in cells, proteostasis, is maintained through several integrated processes and pathways and its dysregulation may mediate pathology in many diseases including Duchenne muscular dystrophy (DMD). Oxidative stress, heat shock proteins, endoplasmic reticulum (ER) stress and its response, i.e. unfolded protein response (UPR), play key roles in proteostasis but their involvement in the pathology of DMD are largely unknown. Moreover, exercise and activin receptor IIB blocking are two strategies that may be beneficial to DMD muscle, but studies to examine their effects on these proteostasis pathways are lacking. Therefore, these pathways were examined in the muscle of mdx mice, a model of DMD, under basal conditions and in response to seven weeks of voluntary exercise and/or activin receptor IIB ligand blocking using soluble activin receptor-Fc (sAcvR2B-Fc) administration. In conjunction with reduced muscle strength, mdx muscle displayed greater levels of UPR/ER-pathway indicators including greater protein levels of IREloc, PERK and Atf6b mRNA. Downstream to IREloc and PERK, spliced Xbpl mRNA and phosphorylation of elF2oc, were also increased. Most of the cytoplasmic and ER chaperones and mitochondrial UPR markers were unchanged in mdx muscle. Oxidized glutathione was greater in mdx and was associated with increases in lysine acetylated proteome and phosphorylated sirtuin 1. Exercise increased oxidative stress when performed independently or combined with sAcvR2B-Fc administration. Although neither exercise nor sAcvR2B-Fc administration imparted a clear effect on ER stress/UPR pathways or heat shock proteins, sAcvR2B-Fc administration increased protein expression levels of GRP78/BiP, a triggering factor for ER stress/UPR activation and TxNIP, a redox-regulator of ER stress-induced inflammation. In conclusion, the ER stress and UPR are increased in mdx muscle. However, these processes are not distinctly improved by voluntary exercise or blocking activin receptor IIB ligands and thus do not appear to be optimal therapeutic choices for improving proteostasis in DMD. (C) 2016 Elsevier Inc. All rights reserved.
  • Omairi, Saleh; Matsakas, Antonios; Degens, Hans; Kretz, Oliver; Hansson, Kenth-Arne; Solbra, Andreas Vavang; Bruusgaard, Jo C.; Joch, Barbara; Sartori, Roberta; Giallourou, Natasa; Mitchell, Robert; Collins-Hooper, Henry; Foster, Keith; Pasternack, Arja; Ritvos, Olli; Sandri, Marco; Narkar, Vihang; Swann, Jonathan R.; Huber, Tobias B.; Patel, Ketan (2016)
    A central tenet of skeletal muscle biology is the existence of an inverse relationship between the oxidative fibre capacity and its size. However, robustness of this relationship is unknown. We show that superimposition of Estrogen-related receptor gamma (Erry) on the myostatin (Mtn) mouse null background (Mtn(-/-)Err gamma(Tg/+)) results in hypertrophic muscle with a high oxidative capacity thus violating the inverse relationship between fibre size and oxidative capacity. We also examined the canonical view that oxidative muscle phenotype positively correlate with Satellite cell number, the resident stem cells of skeletal muscle. Surprisingly, hypertrophic fibres from Mtn(-/-)Err gamma(Tg/+) mouse showed satellite cell deficit which unexpectedly did not affect muscle regeneration. These observations 1) challenge the concept of a constraint between fibre size and oxidative capacity and 2) indicate the important role of the microcirculation in the regenerative capacity of a muscle even when satellite cell numbers are reduced.
  • Soglia, F.; Zeng, Z.; Gao, J.; Puolanne, E.; Cavani, C.; Petracci, M.; Ertbjerg, P. (2018)
    In the past few yr, an emerging muscle abnormality termed wooden breast (WB) was found to affect broilers' Pectoralis major muscles. Although different studies have been performed in order to evaluate the effect of WB on meat quality, there is no evidence concerning its impact on the proteolytic processes taking place during meat aging. Thus, this study aimed at investigating the effect of a 7-day storage of broiler breast fillets on free calcium concentration, calpain activity, and proteolysis. Both the superficial and the deep layers of the Pectoralis major muscles were considered. Although similar electrophoretic profiles were observed by comparing the corresponding sampling positions, an evident lack of a high-molecular weight protein band, ascribed to nebulin, was found in the superficial layer of the WB fillets at 10 h postmortem. Compared to normal fillets (NB), both the superficial and the deep layer of WB exhibited a significantly higher amount of free calcium at 168 h postmortem (96 and 88 vs. 20 and 53 mu M; P
  • Huovinen, Ville; Bucci, Marco; Lipponen, Heta; Kiviranta, Riku; Sandboge, Samuel; Raiko, Juho; Koskinen, Suvi; Koskensalo, Kalle; Eriksson, Johan G.; Parkkola, Riitta; Iozzo, Patricia; Nuutila, Pirjo (2016)
    Bone marrow insulin sensitivity may be an important factor for bone health in addition to bone mineral density especially in insulin resistant conditions. First we aimed to study if prenatal maternal obesity plays a role in determining bone marrow insulin sensitivity in elderly female offspring. Secondly we studied if a four-month individualized resistance training intervention increases bone marrow insulin sensitivity in elderly female offspring and whether this possible positive outcome is regulated by the offspring's mother's obesity status. 37 frail elderly females (mean age 71.9 +/- 3.1 years) of which 20 were offspring of lean/normal-weight mothers (OLM, maternal BMI = 28.1 kg/m(2)) were studied before and after a four-month individualized resistance training intervention. Nine age-and sex-matched non-frail controls (maternal BMI
  • Petersen, Jessica L.; Mickelson, James R.; Rendahl, Aaron K.; Valberg, Stephanie J.; Andersson, Lisa S.; Axelsson, Jeanette; Bailey, Ernie; Bannasch, Danika; Binns, Matthew M.; Borges, Alexandre S.; Brama, Pieter; Machado, Artur da Camara; Capomaccio, Stefano; Cappelli, Katia; Cothran, E. Gus; Distl, Ottmar; Fox-Clipsham, Laura; Graves, Kathryn T.; Guerin, Gerard; Haase, Bianca; Hasegawa, Telhisa; Hemmann, Karin; Hill, Emmeline W.; Leeb, Tosso; Lindgren, Gabriella; Lohi, Hannes; Lopes, Maria Susana; McGivney, Beatrice A.; Mikko, Sofia; Orr, Nicholas; Penedo, M. Cecilia T.; Piercy, Richard J.; Raekallio, Marja; Rieder, Stefan; Røed, Knut H.; Swinburne, June; Tozaki, Teruaki; Vaudin, Mark; Wade, Claire M.; McCue, Molly E. (2013)
  • Chen, Y; Ma, YA; Feng, JJ; Wang, YH; Li, TF; Nurmi, K; Eklund, KK; Wen, JG (2021)
    NLRP3 inflammasome has been implicated in impaired post-injury muscle healing and in muscle atrophy. Histamine receptors play an important role in inflammation, but the role of histamine H-3 receptor (H3R) in myocyte regeneration and in the regulation of NLRP3 inflammasome is not known. We studied the effects of H3R signaling on C2C12 myocyte viability, apoptosis, and tumor necrosis factor alpha (TNF alpha)-induced NLRP3 inflammasome activation during striated myogenic differentiation at three time points (days 0, 3, and 6). Expression of Nlrp3, interleukin-1 beta (IL-1 beta), and myogenesis markers were determined. TNF alpha reduced overall viability of C2C12 cells, and exposure to TNF alpha induced apoptosis of cells at D6. Activation of H3R had no effect on viability or apoptosis, whereas inhibition of H3R increased TNF alpha-induced apoptosis. Stimulation of C2C12 cells with TNF alpha increased Nlrp3 mRNA expression at D3 and D6. Moreover, TNF alpha reduced the expression of myogenesis markers MyoD1, Myogenin, and Myosin-2 at D3 and D6. H3R attenuated TNF alpha-induced expression of Nlrp3 and further inhibited the myogenesis marker expression; while H3R -blockage enhanced the proinflammatory effects of TNF alpha and increased the myogenesis marker expression. TNF alpha-induced secretion of mature IL-1 beta was dependent on the activation of the NLRP3 inflammasome, as shown by the reduced secretion of mature IL-1 beta upon treatment of the cells with the small molecule inhibitor of the NLRP3 inflammasome (MCC950). The activation of H3R reduced TNF alpha-induced IL-1 beta secretion, while the H3R blockage had an opposite effect. In conclusion, the modulation of H3R activity regulates the effects of TNF alpha on C2C12 myocyte differentiation and TNF alpha-induced activation of NLRP3 inflammasome. Thus, H3R signaling may represent a novel target for limiting postinjury muscle inflammation and muscle atrophy.
  • Ross, Jacob A.; Levy, Yotam; Ripolone, Michela; Kolb, Justin S.; Turmaine, Mark; Holt, Mark; Lindqvist, Johan; Claeys, Kristl G.; Weis, Joachim; Monforte, Mauro; Tasca, Giorgio; Moggio, Maurizio; Figeac, Nicolas; Zammit, Peter S.; Jungbluth, Heinz; Fiorillo, Chiara; Vissing, John; Witting, Nanna; Granzier, Henk; Zanoteli, Edmar; Hardeman, Edna C.; Wallgren-Pettersson, Carina; Ochala, Julien (2019)
    Nemaline myopathy (NM) is a skeletal muscle disorder caused by mutations in genes that are generally involved in muscle contraction, in particular those related to the structure and/or regulation of the thin filament. Many pathogenic aspects of this disease remain largely unclear. Here, we report novel pathological defects in skeletal muscle fibres of mouse models and patients with NM: irregular spacing and morphology of nuclei; disrupted nuclear envelope; altered chromatin arrangement; and disorganisation of the cortical cytoskeleton. Impairments in contractility are the primary cause of these nuclear defects. We also establish the role of microtubule organisation in determining nuclear morphology, a phenomenon which is likely to contribute to nuclear alterations in this disease. Our results overlap with findings in diseases caused directly by mutations in nuclear envelope or cytoskeletal proteins. Given the important role of nuclear shape and envelope in regulating gene expression, and the cytoskeleton in maintaining muscle fibre integrity, our findings are likely to explain some of the hallmarks of NM, including contractile filament disarray, altered mechanical properties and broad transcriptional alterations.
  • Yuen, Michaele; Sandaradura, Sarah A.; Dowling, James J.; Kostyukova, Alla S.; Moroz, Natalia; Quinlan, Kate G.; Lehtokari, Vilma-Lotta; Ravenscroft, Gianina; Todd, Emily J.; Ceyhan-Birsoy, Ozge; Gokhin, David S.; Maluenda, Jerome; Lek, Monkol; Nolent, Flora; Pappas, Christopher T.; Novak, Stefanie M.; D'Amico, Adele; Malfatti, Edoardo; Thomas, Brett P.; Gabriel, Stacey B.; Gupta, Namrata; Daly, Mark J.; Ilkovski, Biljana; Houweling, Peter J.; Davidson, Ann E.; Swanson, Lindsay C.; Brownstein, Catherine A.; Gupta, Vandana A.; Medne, Livija; Shannon, Patrick; Martin, Nicole; Bick, David P.; Flisberg, Anders; Holmberg, Eva; Van den Bergh, Peter; Lapunzina, Pablo; Waddell, Leigh B.; Sioboda, Darcee D.; Bertini, Enrico; Chitayat, David; Telfer, William R.; Laquerriere, Annie; Gregorio, Carol C.; Ottenheijm, Coen A. C.; Boennemann, Carsten G.; Pelin, Katarina; Beggs, Alan H.; Hayashi, Yukiko K.; Romero, Norma B.; Laing, Nigel G.; Nishino, Ichizo; Wallgren-Pettersson, Carina; Melki, Judith; Fowler, Velia M.; MacArthur, Daniel G.; North, Kathryn N.; Clarke, Nigel F. (2014)
  • Sternby, Hanna; Mahle, Mariella; Linder, Nicolas; Erichson-Kirst, Laureen; Verdonk, Robert C.; Dimova, Alexandra; Ignatavicius, Povilas; Ilzarbe, Lucas; Koiva, Peeter; Penttilä, Anne; Regner, Sara; Bollen, Thomas L.; Brill, Richard; Stangl, Franz; Wohlgemuth, Walter A.; Singh, Vijay; Busse, Harald; Michl, Patrick; Beer, Sebastian; Rosendahl, Jonas (2019)
    Background: Acute pancreatitis (AP) is a frequent disorder with considerable morbidity and mortality. Obesity has previously been reported to influence disease severity. Objective The aim of this study was to investigate the association of adipose and muscle parameters with the severity grade of AP. Methods: In total 454 patients were recruited. The first contrast-enhanced computed tomography of each patient was reviewed for adipose and muscle tissue parameters at L3 level. Associations with disease severity were analysed through logistic regression analysis. The predictive capacity of the parameters was investigated using receiver operating characteristic (ROC) curves. Results: No distinct variation was found between the AP severity groups in either adipose tissue parameters (visceral adipose tissue and subcutaneous adipose tissue) or visceral muscle ratio. However, muscle mass and mean muscle attenuation differed significantly with p-values of 0.037 and 0.003 respectively. In multivariate analysis, low muscle attenuation was associated with severe AP with an odds ratio of 4.09 (95% confidence intervals: 1.61-10.36, p-value 0.003). No body parameter presented sufficient predictive capability in ROC-curve analysis. Conclusions: Our results demonstrate that a low muscle attenuation level is associated with an increased risk of severe AP. Future prospective studies will help identify the underlying mechanisms and characterise the influence of body composition parameters on AP.
  • Kangas, Reeta; Morsiani, Cristina; Pizza, Grazia; Lanzarini, Catia; Aukee, Pauliina; Kaprio, Jaakko; Sipilä, Sarianna; Franceschi, Claudio; Kovanen, Vuokko; Laakkonen, Eija K.; Capri, Miriam (2018)
    Tissue-specific effects of 17 beta-estradiol are delivered via both estrogen receptors and microRNAs (miRs). Menopause is known to affect the whole-body fat distribution in women. This investigation aimed at identifying menopause-and hormone replacement therapy (HRT)-associated miR profiles and miR targets in subcutaneous abdominal adipose tissue and serum from the same women. A discovery phase using array technology was performed in 13 women, including monozygotic twin pairs discordant for HRT and premenopausal young controls. Seven miRs, expressed in both adipose tissue and serum, were selected for validation phase in 34 women from a different cohort. An age/menopause-related increase of miRs-16-5p, -451a, -223-3p, -18a-5p, -19a-3p,-486-5p and -363-3p was found in the adipose tissue, but not in serum. MiR-19a-3p, involved in adipocyte development and estrogen signaling, resulted to be higher in HRT users in comparison with non-users. Among the identified targets, AKT1, BCL-2 and BRAF proteins showed lower expression in both HRT and No HRT users in comparison with premenopausal women. Unexpectedly, ESR1 protein expression was not modified although its mRNA was lower in No HRT users compared to premenopausal women and HRT users. Thus, both HRT and menopause appear to affect adipose tissue homeostasis via miR-mediated mechanism.
  • Hyytiäinen, Heli K.; Mykkänen, Anna K.; Hielm-Björkman, Anna K.; Stubbs, Narelle C.; McGowan, Catherine M. (2014)
  • Ertbjerg, Per; Puolanne, Eero (2017)
    The basic contractile unit of muscle, the sarcomere, will contract as the muscle goes into rigor post-mortem. Depending on the conditions, such as the rate of pH decline, the cooling rate and the mechanical restraints on the muscles, this longitudinal shortening will result in various post-mortem sarcomere lengths as well as lateral differences in the distances between the myosin and actin filaments. This shortening is underlying the phenomena described as rigor contraction, thaw rigor, cold shortening and heat shortening. The shortening in combination with the molecular architecture of the sarcomere as defined by the myosin filaments and their S-1 and S-2 units, the interaction with the actin filaments, and the boundaries formed by the 2-disks will subsequently influence basic meat quality traits including tenderness and water-holding capacity. Biochemical reactions from proteolysis and glycogen metabolism interrelate with the sarcomere length in a complex manner. The sarcomere length is also influencing the eating quality of cooked meat and the water-holding in meat products.
  • Marttila, Minttu; Mubashir, Hanif; Lemola, Elina; Nowak, Kristen J.; Laitila, Jenni; Gronholm, Mikaela; Wallgren-Pettersson, Carina; Pelin, Katarina (2014)
    Background: Nemaline myopathy (NM) is a rare genetic muscle disorder, but one of the most common among the congenital myopathies. NM is caused by mutations in at least nine genes: Nebulin (NEB), alpha-actin (ACTA1), alpha-tropomyosin (TPM3), beta-tropomyosin (TPM2), troponin T (TNNT1), cofilin-2 (CFL2), Kelch repeat and BTB (POZ) domain-containing 13 (KBTBD13), and Kelch-like family members 40 and 41 (KLHL40 and KLHL41). Nebulin is a giant (600 to 900 kDa) filamentous protein constituting part of the skeletal muscle thin filament. Around 90% of the primary structure of nebulin is composed of approximately 35-residue alpha-helical domains, which form super repeats that bind actin with high affinity. Each super repeat has been proposed to harbor one tropomyosin-binding site. Methods: We produced four wild-type (WT) nebulin super repeats (S9, S14, S18, and S22), 283 to 347 amino acids long, and five corresponding repeats with a patient mutation included: three missense mutations (p.Glu2431Lys, p.Ser6366Ile, and p.Thr7382Pro) and two in-frame deletions (p.Arg2478_Asp2512del and p.Val3924_Asn3929del). We performed F-actin and tropomyosin-binding experiments for the nebulin super repeats, using co-sedimentation and GST (glutathione-S-transferase) pull-down assays. We also used the GST pull-down assay to test the affinity of WT nebulin super repeats for WT alpha- and beta-tropomyosin, and for beta-tropomyosin with six patient mutations: p.Lys7del, p. Glu41Lys, p.Lys49del, p.Glu117Lys, p.Glu139del and p.Gln147Pro. Results: WT nebulin was shown to interact with actin and tropomyosin. Both the nebulin super repeats containing the p.Glu2431Lys mutation and nebulin super repeats lacking exon 55 (p.Arg2478_Asp2512del) showed weak affinity for F-actin compared with WT fragments. Super repeats containing the p.Ser6366Ile mutation showed strong affinity for actin. When tested for tropomyosin affinity, super repeats containing the p.Glu2431Lys mutation showed stronger binding than WT proteins to tropomyosin, and the super repeat containing the p.Thr7382Pro mutation showed weaker binding than WT proteins to tropomyosin. Super repeats containing the deletion p. Val3924_Asn3929del showed similar affinity for actin and tropomyosin as that seen with WT super repeats. Of the tropomyosin mutations, only p.Glu41Lys showed weaker affinity for nebulin (super repeat 18). Conclusions: We demonstrate for the first time the existence of direct tropomyosin-nebulin interactions in vitro, and show that nebulin interactions with actin and tropomyosin are altered by disease-causing mutations in nebulin and tropomyosin.
  • Sewry, Caroline A.; Laitila, Jenni M.; Wallgren-Pettersson, Carina (2019)
    Nemaline myopathies are a heterogenous group of congenital myopathies caused by de novo, dominantly or recessively inherited mutations in at least twelve genes. The genes encoding skeletal α-actin (ACTA1) and nebulin (NEB) are the commonest genetic cause. Most patients have congenital onset characterized by muscle weakness and hypotonia, but the spectrum of clinical phenotypes is broad, ranging from severe neonatal presentations to onset of a milder disorder in childhood. Most patients with adult onset have an autoimmune-related myopathy with a progressive course. The wide application of massively parallel sequencing methods is increasing the number of known causative genes and broadening the range of clinical phenotypes. Nemaline myopathies are identified by the presence of structures that are rod-like or ovoid in shape with electron microscopy, and with light microscopy stain red with the modified Gömöri trichrome technique. These rods or nemaline bodies are derived from Z lines (also known as Z discs or Z disks) and have a similar lattice structure and protein content. Their shape in patients with mutations in KLHL40 and LMOD3 is distinctive and can be useful for diagnosis. The number and distribution of nemaline bodies varies between fibres and different muscles but does not correlate with severity or prognosis. Additional pathological features such as caps, cores and fibre type disproportion are associated with the same genes as those known to cause the presence of rods. Animal models are advancing the understanding of the effects of various mutations in different genes and paving the way for the development of therapies, which at present only manage symptoms and are aimed at maintaining muscle strength, joint mobility, ambulation, respiration and independence in the activities of daily living.
  • Amini, Poorya; Stojkov, Darko; Felser, Andrea; Jackson, Christopher B.; Courage, Carolina; Schaller, Andre; Gelman, Laurent; Soriano, Maria Eugenia; Nuoffer, Jean-Marc; Scorrano, Luca; Benarafa, Charaf; Yousefi, Shida; Simon, Hans-Uwe (2018)
    Optic atrophy 1 (OPA1) is a mitochondrial inner membrane protein that has an important role in mitochondrial fusion and structural integrity. Dysfunctional OPA1 mutations cause atrophy of the optic nerve leading to blindness. Here, we show that OPA1 has an important role in the innate immune system. Using conditional knockout mice lacking Opa1 in neutrophils (Opa1(N Delta)), we report that lack of OPA1 reduces the activity of mitochondrial electron transport complex I in neutrophils. This then causes a decline in adenosine-triphosphate (ATP) production through glycolysis due to lowered NAD(+) availability. Additionally, we show that OPA1-dependent ATP production in these cells is required for microtubule network assembly and for the formation of neutrophil extracellular traps. Finally, we show that Opa1(N Delta) mice exhibit a reduced antibacterial defense capability against Pseudomonas aeruginosa.
  • Rissanen, Antti-Pekka; Tikkanen, Heikki Olavi; Koponen, Anne S.; Aho, Jyrki M.; Peltonen, Juha E. (2018)
    Adaptations to long-term exercise training in type 1 diabetes are sparsely studied. We examined the effects of a 1-year individualized training intervention on cardiorespiratory fitness, exercise-induced active muscle deoxygenation, and glycemic control in adults with and without type 1 diabetes. Eight men with type 1 diabetes (T1D) and 8 healthy men (CON) matched for age, anthropometry, and peak pulmonary O-2 uptake, completed a 1-year individualized training intervention in an unsupervised real-world setting. Before and after the intervention, the subjects performed a maximal incremental cycling test, during which alveolar gas exchange (volume turbine and mass spectrometry) and relative concentration changes in active leg muscle deoxygenated (Delta[HHb]) and total (Delta[tHb]) hemoglobin (near-infrared spectroscopy) were monitored. Peak O-2 pulse, reflecting peak stroke volume, was calculated (peak pulmonary O-2 uptake/peak heart rate). Glycemic control (glycosylated hemoglobin A(1c) (HbA(1c))) was evaluated. Both T1D and CON averagely performed 1 resistance-training and 3-4 endurance-training sessions per week (similar to 1 h/session at similar to moderate intensity). Training increased peak pulmonary O-2 uptake in T1D (p = 0.004) and CON (p = 0.045) (group x time p = 0.677). Peak O-2 pulse also rose in T1D (p = 0.032) and CON (p = 0.018) (group x time p = 0.880). Training increased leg Delta[HHb] at peak exercise in CON (p = 0.039) but not in T1D (group x time p = 0.052), while no changes in leg Delta[tHb] at any work rate were observed in either group (p > 0.05). HbA(1c) retained unchanged in T1D (from 58 +/- 10 to 59 +/- 11 mmol/mol, p = 0.609). In conclusion, 1-year adherence to exercise training enhanced cardiorespiratory fitness similarly in T1D and CON but had no effect on active muscle deoxygenation or glycemic control in T1D.
  • Nathan, K.; Lu, L. Y.; Lin, T.; Pajarinen, J.; Jämsen, E.; Huang, J-F; Romero-Lopez, M.; Maruyama, M.; Kohno, Y.; Yao, Z.; Goodman, S. B. (2019)
    Objectives Up to 10% of fractures result in undesirable outcomes, for which female sex is a risk factor. Cellular sex differences have been implicated in these different healing processes. Better understanding of the mechanisms underlying bone healing and sex differences in this process is key to improved clinical outcomes. This study utilized a macrophage-mesenchymal stem cell (MSC) coculture system to determine: 1) the precise timing of proinflammatory (M1) to anti-inflammatory (M2) macrophage transition for optimal bone formation; and 2) how such immunomodulation was affected by male versus female cocultures. Methods A primary murine macrophage-MSC coculture system was used to demonstrate the optimal transition time from M1 to M2 (polarized from M1 with interleukin (IL)-4) macrophages to maximize matrix mineralization in male and female MSCs. Outcome variables included Alizarin Red staining, alkaline phosphatase (ALP) activity, and osteocalcin protein secretion. Results We found that 96 hours of M1 phenotype in male cocultures allowed for maximum matrix mineralization versus 72 hours in female cocultures. ALP activity and osteocalcin secretion were also enhanced with the addition of IL-4 later in male versus female groups. The sex of the cells had a statistically significant effect on the optimal IL-4 addition time to maximize osteogenesis. Conclusion These results suggest that: 1) a 72- to 96-hour proinflammatory environment is critical for optimal matrix mineralization; and 2) there are immunological differences in this coculture environment due to sex. Optimizing immunomodulation during fracture healing may enhance and expedite the bone regeneration response. These findings provide insight into precise immunomodulation for enhanced bone healing that is sex-specific.
  • Sellier, Chantal; Cerro-Herreros, Estefania; Blatter, Markus; Freyermuth, Fernande; Gaucherot, Angeline; Ruffenach, Frank; Sarkar, Partha; Puymirat, Jack; Udd, Bjarne; Day, John W.; Meola, Giovanni; Bassez, Guillaume; Fujimura, Harutoshi; Takahashi, Masanori P.; Schoser, Benedikt; Furling, Denis; Artero, Ruben; Allain, Frederic H. T.; Llamusi, Beatriz; Charlet-Berguerand, Nicolas (2018)
    Myotonic dystrophy type 1 and type 2 (DM1, DM2) are caused by expansions of CTG and CCTG repeats, respectively. RNAs containing expanded CUG or CCUG repeats interfere with the metabolism of other RNAs through titration of the Muscleblind-like (MBNL) RNA binding proteins. DM2 follows a more favorable clinical course than DM1, suggesting that specific modifiers may modulate DM severity. Here, we report that the rbFOX1 RNA binding protein binds to expanded CCUG RNA repeats, but not to expanded CUG RNA repeats. Interestingly, rbFOX1 competes with MBNL1 for binding to CCUG expanded repeats and overexpression of rbFOX1 partly releases MBNL1 from sequestration within CCUG RNA foci in DM2 muscle cells. Furthermore, expression of rbFOX1 corrects alternative splicing alterations and rescues muscle atrophy, climbing and flying defects caused by expression of expanded CCUG repeats in a Drosophila model of DM2.
  • Zeng, Zhen; Li, Cheng; Ertbjerg, Per (2017)
    The purpose of this study was to increase the knowledge on the relationship between proteolysis of myofibrillar proteins and the water-holding of meat. Myofibrils isolated from porcine longissimus thoracic et lumborum muscle were used as a model system. Myofibrils were incubated with either calpain-2, the proteasome or a lysosomal extract at 25 degrees C for 2 h. All three proteolytic systems improved the relative water-holding and generally there was a larger effect with increasing amount of enzymes in the incubation. The improved water-holding occurred in parallel to degradation of myofibrillar proteins. Desmin was degraded by calpain-2 as well as by lysosomal enzymes and a-actinin was released by the proteasome. We here propose a model in which degradation of proteins in and around the Z-disk allows overall swelling of the filament lattice and more specifically in the I band area. In conclusion, proteolytic degradation of myofibrillar proteins by calpain-2, the proteasome or lysosomal enzymes improves the water-holding of myofibrils.
  • Soglia, Francesca; Petracci, Massimiliano; Puolanne, Eero (2020)
    The present study aims to measure the sarcomere lengths in normal broiler muscles and in non-lesion sites of breast muscles focally affected by Wooden Breast (WB). For this purpose, twenty Pectoralis major muscles (10 unaffected and 10 WB-focally affected cases) were sampled and used to measure sarcomere length by laser diffraction method. When compared with their unaffected counterpart, WB cases exhibited 13% longer sarcomeres (1.91 vs. 1.69 mu m; p <.001) measured within the non-lesioned site of the muscle. Although it is not simple to draw conclusions about the lesion properties based on the non-lesion area, but as the fibres are bound to each other, it may be reasonable to anticipate that the hardened consistency observed in WB is not ascribable to a more intense contraction of the sarcomeres. In addition, considering the current knowledge concerning this condition, it might be assumed that the longer sarcomeres observed in WB are not triggering the development of this condition but are rather a consequence of the profound alteration in the muscular structure resulting from it. Indeed, despite the outstanding improvements in the live and slaughtering traits, the selection programmes carried out in the past years have resulted in a reduced capillarization and impaired oxygen supply to the Pectoralis major of fast-growing hybrids thus affecting the physiology of its constituting fibres as well as maybe impairing their ability to synthetise new sarcomeres. This may result in a skeletal muscle injury, which would ultimately lead to necrosis and fibrosis.