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Zhongguo Ying Yong Sheng Li Xue Za Zhi... Nov 2022To investigate the protective effects of erythropoietin derived peptide, also known as spiral B surface peptide (HBSP), on kidney and aggregated proteins (Agrin) levels...
To investigate the protective effects of erythropoietin derived peptide, also known as spiral B surface peptide (HBSP), on kidney and aggregated proteins (Agrin) levels in acute skeletal muscle strain rats. Forty SPF grade SD male rats were randomly divided into control group, injury group, HBSP group and EPO group, with 10 rats in each group. Acute skeletal muscle strain animal models were established except the control group. After successful modeling, the rats in HBSP group and EPO group were intraperitoneally injected with 60 μg/kg HBSP and 5 000 U/kg recombinant human erythropoietin (rhEPO), and the rats in the control group and the injured group were intraperitoneally injected with 0.9% normal saline. Renal function was monitored with relevant kits; Hematoxylin-eosin staining was used to observe the pathological morphology of kidney tissue and skeletal muscle strain tissue. The apoptosis rate of renal tissue cells was detected by in situ terminal transferase labeling (TUNEL). Western blot and quantitative polymerase chain reaction (Q-PCR) were used to determine the expressions of Agrin and muscular-specific kinase (MuSK) in the injured skeletal muscle of rats in each group. Compared with the control group, the renal function indexes serum creatinine (Cr), urea nitrogen (BUN) and 24 h urinary protein (UP24) levels of rats in injured group were increased (< 0.05), but the levels of BUN, Cr and UP24 of rats in HBSP group were decreased (<0.05). Compared with HBSP group, there were no significant differences in the above indexes in EPO group (>0.05). In the control group, the muscle fiber structure was intact, the shape and structure of the fiber bundles were normal, and there was no infiltration of red blood cells and inflammatory cells in the interstitium, and no fibrohyperplasia. In the injured group, the muscle tissue showed sparse and irregular arrangement, and the interstitial widened with a large number of inflammatory cells and red blood cell infiltration. Erythrocytes and inflammatory cells were reduced in HBSP group and EPO group, and the transverse and longitudinal lines of muscle were clear. The glomerular structure of the rats in the fibrohyperplasia control group was intact and no lesions were observed. In the injured group, glomerular hypertrophy and significant matrix hyperplasia were observed, as well as the expansion of renal cysts with vacuolar and significant inflammatory infiltration were observed, and the inflammatory infiltration was reduced in the HBSP and EPO groups. Glomerular hypertrophy and hyperplasia were alleviated. The apoptosis rates of kidney cells in control group, injured group, HBSP group and EPO group were (4.05±0.51) %, (26.30±2.05) %, (14.28±1.62) % and (16.03±1.77) %, respectively, and there were significant differences among these groups (<0.05). Compared with control group, the levels of Agrin and MuSK in skeletal muscle pulled tissue were significantly decreased (<0.05), and those of HBSP group and EPO group were significantly increased compared with injured group (<0.05), but there was no significant difference between HBSP group and EPO group (>0.05). Erythropoietin derived peptide (HBSP) has obvious intervention effects on renal function injury in rats with acute skeletal muscle strain, and its mechanisms may be related to reducing the apoptosis rate of renal tissue cells and activating Agrin and MuSK expression.
Topics: Humans; Male; Animals; Rats; Hyperplasia; Agrin; Erythropoietin; Kidney; Muscle, Skeletal; Peptides
PubMed: 37308405
DOI: 10.12047/j.cjap.6348.2022.112 -
Proceedings of the National Academy of... Jun 2023MuSK is a receptor tyrosine kinase (RTK) that plays essential roles in the formation and maintenance of the neuromuscular junction. Distinct from most members of RTK...
MuSK is a receptor tyrosine kinase (RTK) that plays essential roles in the formation and maintenance of the neuromuscular junction. Distinct from most members of RTK family, MuSK activation requires not only its cognate ligand agrin but also its coreceptors LRP4. However, how agrin and LRP4 coactivate MuSK remains unclear. Here, we report the cryo-EM structure of the extracellular ternary complex of agrin/LRP4/MuSK in a stoichiometry of 1:1:1. This structure reveals that arc-shaped LRP4 simultaneously recruits both agrin and MuSK to its central cavity, thereby promoting a direct interaction between agrin and MuSK. Our cryo-EM analyses therefore uncover the assembly mechanism of agrin/LRP4/MuSK signaling complex and reveal how MuSK receptor is activated by concurrent binding of agrin and LRP4.
Topics: Receptors, Cholinergic; Agrin; LDL-Receptor Related Proteins; Signal Transduction; Neuromuscular Junction; Receptor Protein-Tyrosine Kinases
PubMed: 37252960
DOI: 10.1073/pnas.2300453120 -
Scientific Reports May 2023The study aimed to evaluate the impact of selected exerkines concentration induced by folk-dance and balance training on physical performance, insulin resistance, and... (Randomized Controlled Trial)
Randomized Controlled Trial
The study aimed to evaluate the impact of selected exerkines concentration induced by folk-dance and balance training on physical performance, insulin resistance, and blood pressure in older adults. Participants (n = 41, age 71.3 ± 5.5 years) were randomly assigned to folk-dance (DG), balance training (BG), or control group (CG). The training was performed 3 times a week for 12 weeks. Physical performance tests-time up and go (TUG) and 6-min walk test (6MWT), blood pressure, insulin resistance, and selected proteins induced by exercise (exerkines) were assessed at baseline and post-exercise intervention. Significant improvement in TUG (p = 0.006 for BG and 0.039 for DG) and 6MWT tests (in BG and DG p = 0.001), reduction of systolic blood pressure (p = 0.001 for BG and 0.003 for DG), and diastolic blood pressure (for BG; p = 0.001) were registered post-intervention. These positive changes were accompanied by the drop in brain-derived neurotrophic factor (p = 0.002 for BG and 0.002 for DG), the increase of irisin concentration (p = 0.029 for BG and 0.022 for DG) in both groups, and DG the amelioration of insulin resistance indicators (HOMA-IR p = 0.023 and QUICKI p = 0.035). Folk-dance training significantly reduced the c-terminal agrin fragment (CAF; p = 0.024). Obtained data indicated that both training programs effectively improved physical performance and blood pressure, accompanied by changes in selected exerkines. Still, folk-dance had enhanced insulin sensitivity.
Topics: Humans; Aged; Dancing; Insulin Resistance; Physical Functional Performance; Homeostasis; Glucose
PubMed: 37237034
DOI: 10.1038/s41598-023-35583-w -
Molecular and Cellular Neurosciences Jun 2023One of the effects of hypercholesterolemia (Hch) exerted on the central nervous system (CNS) is damage to the blood-brain barrier (BBB). Increased permeability of BBB...
The extent of damage to the blood-brain barrier in the hypercholesterolemic LDLR/Apo E double knockout mice depends on the animal's age, duration of pathology and brain area.
One of the effects of hypercholesterolemia (Hch) exerted on the central nervous system (CNS) is damage to the blood-brain barrier (BBB). Increased permeability of BBB results from structural changes in the vascular wall, loss of the tight junctions and barrier function, as well as alterations in the concentration of proteins located in the layers of the vascular wall. These changes occur in the course of metabolic and neurodegenerative diseases. The important role in the course of these processes is attributed to agrin, matrix metalloproteinase-9, and aquaporin-4. In this study, we aimed to determine: 1) the extent of Hch-induced damage to the BBB during maturation, and 2) the distribution of the above-mentioned markers in the vascular wall. Immunohistochemical staining and confocal microscopy were used for vascular wall protein assessment. The size of BBB damage was studied based on perivascular leakage of fluorescently labeled dextran. Three- and twelve-month-old male LDLR/Apo E double knockout mice (EX) developing Hch were used in the study. Age-matched male wild-type (WT) C57BL/6 mice were used as a control group. Differences in the concentration of studied markers coexisted with BBB disintegration, especially in younger mice. A relationship between the maturation of the vascular system and reduction of the BBB damage was also observed. We conclude that the extent of BBB permeability depends on animal age, duration of Hch, and brain region. These may explain different susceptibility of various brain areas to Hch, and different presentation of this pathology depending on age and its duration.
Topics: Animals; Male; Mice; Apolipoproteins E; Blood-Brain Barrier; Brain; Mice, Inbred C57BL; Mice, Knockout; Receptors, LDL
PubMed: 37182573
DOI: 10.1016/j.mcn.2023.103860 -
Cells May 2023Recent studies demonstrate the adverse effects of cannabinoids on development, including via pathways shared with ethanol exposure. Our laboratory has shown that both...
Recent studies demonstrate the adverse effects of cannabinoids on development, including via pathways shared with ethanol exposure. Our laboratory has shown that both the nervous system and cardiac development are dependent on agrin modulation of sonic hedgehog (shh) and fibroblast growth factor (Fgf) signaling pathways. As both ethanol and cannabinoids impact these signaling molecules, we examined their role on zebrafish heart development. Zebrafish embryos were exposed to a range of ethanol and/or cannabinoid receptor 1 and 2 agonist concentrations in the absence or presence of morpholino oligonucleotides that disrupt or expression. In situ hybridization was employed to analyze cardiac marker gene expression. Exposure to cannabinoid receptor agonists disrupted midbrain-hindbrain boundary development, but had no effect on heart development, as assessed by the presence of cardiac edema or the altered expression of cardiac marker genes. In contrast, exposure to 1.5% ethanol induced cardiac edema and the altered expression of cardiac marker genes. Combined exposure to or morpholino and 0.5% ethanol disrupted the gene expression pattern, with the restoration of the normal expression following mRNA overexpression. These studies provide evidence that signaling pathways critical to heart development are sensitive to ethanol exposure but not cannabinoid during early zebrafish embryogenesis.
Topics: Animals; Zebrafish; Ethanol; Hedgehog Proteins; Agrin; Cannabinoids; Edema, Cardiac; Morpholinos; Heart
PubMed: 37174727
DOI: 10.3390/cells12091327 -
International Journal of Molecular... Apr 2023The porcine ocular surface is used as a model of the human ocular surface; however, a detailed characterization of the porcine ocular surface has not been documented....
The porcine ocular surface is used as a model of the human ocular surface; however, a detailed characterization of the porcine ocular surface has not been documented. This is due, in part, to the scarcity of antibodies produced specifically against the porcine ocular surface cell types or structures. We performed a histological and immunohistochemical investigation on frozen and formalin-fixed, paraffin-embedded ocular surface tissue from domestic pigs using a panel of 41 different antibodies related to epithelial progenitor/differentiation phenotypes, extracellular matrix and associated molecules, and various niche cell types. Our observations suggested that the Bowman's layer is not evident in the cornea; the deep invaginations of the limbal epithelium in the limbal zone are analogous to the limbal interpalisade crypts of human limbal tissue; and the presence of goblet cells in the bulbar conjunctiva. Immunohistochemistry analysis revealed that the epithelial progenitor markers cytokeratin (CK)15, CK14, p63α, and P-cadherin were expressed in both the limbal and conjunctival basal epithelium, whereas the basal cells of the limbal and conjunctival epithelium did not stain for CK3, CK12, E-cadherin, and CK13. Antibodies detecting marker proteins related to the extracellular matrix (collagen IV, Tenascin-C), cell-matrix adhesion (β-dystroglycan, integrin α3 and α6), mesenchymal cells (vimentin, CD90, CD44), neurons (neurofilament), immune cells (HLA-ABC; HLA-DR, CD1, CD4, CD14), vasculature (von Willebrand factor), and melanocytes (SRY-homeobox-10, human melanoma black-45, Tyrosinase) on the normal human ocular surface demonstrated similar immunoreactivity on the normal porcine ocular surface. Only a few antibodies (directed against N-cadherin, fibronectin, agrin, laminin α3 and α5, melan-A) appeared unreactive on porcine tissues. Our findings characterize the main immunohistochemical properties of the porcine ocular surface and provide a morphological and immunohistochemical basis useful to research using porcine models. Furthermore, the analyzed porcine ocular structures are similar to those of humans, confirming the potential usefulness of pig eyes to study ocular surface physiology and pathophysiology.
Topics: Swine; Humans; Animals; Limbus Corneae; Cornea; Conjunctiva; Extracellular Matrix; Sus scrofa; Epithelial Cells
PubMed: 37108705
DOI: 10.3390/ijms24087543 -
International Journal of Molecular... Apr 2023Agrin is a heparan sulfate proteoglycan essential for the clustering of acetylcholine receptors at the neuromuscular junction. Neuron-specific isoforms of agrin are...
Agrin is a heparan sulfate proteoglycan essential for the clustering of acetylcholine receptors at the neuromuscular junction. Neuron-specific isoforms of agrin are generated by alternative inclusion of three exons, called Y, Z8, and Z11 exons, although their processing mechanisms remain elusive. We found, by inspection of splicing -elements into the human gene, that binding sites for polypyrimidine tract binding protein 1 (PTBP1) were extensively enriched around Y and Z exons. -silencing enhanced the coordinated inclusion of Y and Z exons in human SH-SY5Y neuronal cells, even though three constitutive exons are flanked by these alternative exons. Deletion analysis using minigenes identified five PTBP1-binding sites with remarkable splicing repression activities around Y and Z exons. Furthermore, artificial tethering experiments indicated that binding of a single PTBP1 molecule to any of these sites represses nearby Y or Z exons as well as the other distal exons. The RRM4 domain of PTBP1, which is required for looping out a target RNA segment, was likely to play a crucial role in the repression. Neuronal differentiation downregulates PTBP1 expression and promotes the coordinated inclusion of Y and Z exons. We propose that the reduction in the PTPB1-RNA network spanning these alternative exons is essential for the generation of the neuron-specific agrin isoforms.
Topics: Humans; RNA; Agrin; Neuroblastoma; Neurons; Protein Isoforms; Alternative Splicing; Polypyrimidine Tract-Binding Protein; Heterogeneous-Nuclear Ribonucleoproteins
PubMed: 37108583
DOI: 10.3390/ijms24087420 -
Annals of Translational Medicine Apr 2023Myasthenia gravis (MG) is the most common immune-mediated disorder of the neuromuscular junction. Anti-acetylcholine receptor (anti-AChR), anti-muscle-specific kinase... (Review)
Review
Myasthenia gravis (MG) is the most common immune-mediated disorder of the neuromuscular junction. Anti-acetylcholine receptor (anti-AChR), anti-muscle-specific kinase (anti-MuSK), and anti-lipoprotein receptor-related protein 4 (anti-LRP4) antibodies are the three well-defined pathogenic antibodies. Patients with MG can also have other antibodies, such as anti-titin, anti-ryanodine receptor (anti-RyR), anti-Agrin and anti-KV1.4 antibodies. Since MG is heterogeneous in terms of pathophysiology, antibody status, and other factors, serological tests are crucial for clinical diagnosis confirmation and treatment choice. Herein, we review the different methods for detection of various antibodies involved in MG and their sensitivity and specificity. The understanding of these elements should be useful for improving the diagnosis and determining how to adapt the existing therapies to the requirements of each patient.
PubMed: 37090043
DOI: 10.21037/atm-19-363 -
PNAS Nexus Apr 2023-related muscular dystrophy (LAMA2 MD or MDC1A) is a devastating congenital muscular dystrophy that is caused by mutations in the gene encoding laminin-α2, the long...
-related muscular dystrophy (LAMA2 MD or MDC1A) is a devastating congenital muscular dystrophy that is caused by mutations in the gene encoding laminin-α2, the long chain of several heterotrimeric laminins. Laminins are essential components of the extracellular matrix that interface with underlying cells. The pathology of LAMA2 MD patients is dominated by an early-onset, severe muscular dystrophy that ultimately leads to death by respiratory insufficiency. However, pathology in nonmuscle tissues has been described. Prior work in the / mouse model for LAMA2 MD has shown that two linker proteins, mini-agrin and αLNNd, when expressed in skeletal muscle fibers, greatly increase survival from a few months up to more than 2 years. However, the restoration of skeletal muscle function accentuates the pathology in nonmuscle tissue in / mice, first and foremost in the peripheral nerve resulting in paralysis of the hind limbs. We now show that the expression of the two linker proteins in all tissues ameliorates the muscular dystrophy and prevents the appearance of the hind limb paralysis. Importantly, the same ameliorating effect of the linker proteins was seen in / mice, which represent the most severe mouse model of LAMA2 MD. In summary, these data show that the two linker proteins can compensate the loss of laminin-α2 in muscle and peripheral nerve, which are the two organs most affected in LAMA2 MD. These results are of key importance for designing appropriate expression constructs for mini-agrin and αLNNd to develop a gene therapy for LAMA2 MD patients.
PubMed: 37038437
DOI: 10.1093/pnasnexus/pgad083 -
Aging Clinical and Experimental Research Jun 2023C-terminal Agrin Fragment (CAF) has emerged as a potent biomarker for identifying sarcopenia. However, the effect of interventions on CAF concentration and the...
BACKGROUND
C-terminal Agrin Fragment (CAF) has emerged as a potent biomarker for identifying sarcopenia. However, the effect of interventions on CAF concentration and the association of CAF with sarcopenia components are unclear.
OBJECTIVE
To review the association between CAF concentration and muscle mass, muscle strength, and physical performance among individuals with primary and secondary sarcopenia and to synthesize the effect of interventions on the change in the level of CAF concentration.
METHODS
A systematic literature search was conducted in six electronic databases, and studies were included if they met the selection criteria decided a priori. The data extraction sheet was prepared, validated, and extracted relevant data.
RESULTS
A total of 5,158 records were found, of which 16 were included. Among studies conducted on individuals with primary sarcopenia, muscle mass was significantly associated with CAF levels, followed by hand grip strength (HGS) and physical performance, with more consistent findings in males. While in secondary sarcopenics, the strongest association was found for HGS and CAF levels, followed by physical performance and muscle mass. CAF concentration was reduced in trials that used functional, dual task, and power training, whereas resistance training and physical activity raised CAF levels. Hormonal therapy did not affect serum CAF concentration.
CONCLUSION(S)
The association between CAF and sarcopenic assessment parameters varies in primary and secondary sarcopenics. The findings would help practitioners and researchers choose the best training mode/parameters/exercises to reduce CAF levels and, eventually, manage sarcopenia.
Topics: Humans; Male; Agrin; Hand Strength; Muscle Strength; Sarcopenia
PubMed: 36977974
DOI: 10.1007/s40520-023-02396-w