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Journal of Receptor and Signal... Aug 2021Rectal cancer is the most common malignant tumor in the digestive system with rapidly metastasis and highly recurrence. Agrin (AGRN) is a proteoglycan involving in a...
Rectal cancer is the most common malignant tumor in the digestive system with rapidly metastasis and highly recurrence. Agrin (AGRN) is a proteoglycan involving in a large number of human cancers. However, how AGRN regulates the progression of rectal cancer remains largely unknown. We aimed to determine the biological role of AGRN and its mechanism in rectal cancer. AGRN expression in rectal cancer tissues was detected based on TCGA. The survival curve was plotted using the Kaplan-Meier method. qRT-PCR and western blot were utilized to examine the expression level of AGRN in cells. Cell proliferation, clonogenic ability, invasion, and migration of rectal cancer cells were analyzed by CCK-8, colony formation and transwell experiments. GSEA was employed for the analysis of the potential pathways-related with AGRN in rectal cancer. The activity of WNT pathway was determined by western blot. AGRN expression was dramatically increased in rectal cancer, and its up-regulation was associated with poorer prognosis of rectal cancer patients. AGRN expression was an independent factor for the prognosis of rectal cancer. AGRN inhibition suppressed rectal cancer cell growth, invasion, and migration, whereas AGRN overexpression facilitated these behaviors of rectal cancer cells . Mechanistically, WNT signaling pathway was enriched in high AGRN-expressing patients with rectal cancer. AGRN elevated the activity of WNT pathway through increasing Cyclin D1, C-Myc, p-GSK-3β, and p-β-catenin expression. Our present study indicated that AGRN might function as an oncogenic indicator in rectal cancer activating the WNT pathway, which would help develop optimized therapeutic therapies for rectal cancer.
Topics: Agrin; Cell Line, Tumor; Cell Movement; Cell Proliferation; Disease Progression; Gene Expression Regulation, Neoplastic; Humans; Neoplasm Invasiveness; Prognosis; RNA, Small Interfering; Rectal Neoplasms; Signal Transduction; Up-Regulation; Wnt Proteins; Wnt Signaling Pathway
PubMed: 32862766
DOI: 10.1080/10799893.2020.1811325 -
JCI Insight Apr 2020Congenital myasthenic syndromes (CMS) are caused by mutations in molecules expressed at the neuromuscular junction. We report clinical, structural, ultrastructural, and...
Congenital myasthenic syndromes (CMS) are caused by mutations in molecules expressed at the neuromuscular junction. We report clinical, structural, ultrastructural, and electrophysiologic features of 4 CMS patients with 6 heteroallelic variants in AGRN, encoding agrin. One was a 7.9-kb deletion involving the N-terminal laminin-binding domain. Another, c.4744G>A - at the last nucleotide of exon 26 - caused skipping of exon 26. Four missense mutations (p.S1180L, p.R1509W, p.G1675S, and p.Y1877D) expressed in conditioned media decreased AChR clusters in C2C12 myotubes. The agrin-enhanced phosphorylation of MuSK was markedly attenuated by p.Y1877D in the LG3 domain and moderately attenuated by p.R1509W in the LG1 domain but not by the other 2 mutations. The p.S1180L mutation in the SEA domain facilitated degradation of secreted agrin. The p.G1675S mutation in the LG2 domain attenuated anchoring of agrin to the sarcolemma by compromising its binding to heparin. Anchoring of agrin with p.R1509W in the LG1 domain was similarly attenuated. Mutations of agrin affect AChR clustering by enhancing agrin degradation or by suppressing MuSK phosphorylation and/or by compromising anchoring of agrin to the sarcolemma of the neuromuscular junction.
Topics: Agrin; Amino Acid Substitution; Animals; HEK293 Cells; Humans; Mice; Mutation, Missense; Myasthenic Syndromes, Congenital; Neuromuscular Junction; Receptors, Nicotinic; Sarcolemma
PubMed: 32271162
DOI: 10.1172/jci.insight.132023 -
Nature Neuroscience Jul 2003
Topics: Adaptor Proteins, Signal Transducing; Agrin; Animals; Cytoskeletal Proteins; Homeodomain Proteins; Mice; Neuromuscular Junction; Receptor Protein-Tyrosine Kinases; Receptors, Cholinergic; Signal Transduction
PubMed: 12830150
DOI: 10.1038/nn0703-653 -
Experimental Neurology Nov 2014Agrin, a heparan sulfate proteoglycan functioning as a neuro-muscular junction inducer, has been shown to inhibit neuropathic pain in sciatic nerve injury rat models,...
Agrin, a heparan sulfate proteoglycan functioning as a neuro-muscular junction inducer, has been shown to inhibit neuropathic pain in sciatic nerve injury rat models, via phosphorylation of N-Methyl-d-aspartate receptor NR1 subunits in gamma-aminobutyric acid neurons. However, its effects on spinal cord injury-induced neuropathic pain, a debilitating syndrome frequently encountered after various spine traumas, are unknown. In the present investigation, we studied the 50kDa agrin isoform effects in a quisqualic acid dorsal horn injection rat model mimicking spinal cord injury-induced neuropathic pain. Our results indicate that 50kDa agrin decreased only in the dorsal horn of neuropathic animals and increased 50kDa agrin expression in the dorsal horn, via intra-spinal injection of adeno-associated virus serum type two, suppressed spinal cord injury-induced neuropathic pain. Also, the reason why 50kDa agrin only activates the N-Methyl-d-aspartate receptor NR1 subunits in the GABA neurons, but not in sensory neurons, is unknown. Using immunoprecipitation and Western-blot analysis, two dimensional gel separation, and mass spectrometry, we identified several specific proteins in the reaction protein complex, such as neurofilament 200 and mitofusin 2, that are required for the activation of the NR1 subunits of gamma-aminobutyric acid inhibitory neurons by 50kDa agrin. These findings indicate that 50kDa agrin is a promising agent for neuropathic pain treatment.
Topics: Adenoviridae; Agrin; Animals; Disease Models, Animal; Excitatory Amino Acid Agonists; Gene Expression Regulation; Hyperalgesia; Injections, Spinal; Male; Molecular Weight; Neuralgia; Pain Measurement; Pain Threshold; Quisqualic Acid; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Time Factors; gamma-Aminobutyric Acid
PubMed: 25151458
DOI: 10.1016/j.expneurol.2014.08.014 -
The Journal of Cell Biology Sep 2002Agrin is a nerve-derived factor that directs neuromuscular synapse formation, however its role in regulating interneuronal synaptogenesis is less clear. Here, we examine... (Comparative Study)
Comparative Study
Agrin is a nerve-derived factor that directs neuromuscular synapse formation, however its role in regulating interneuronal synaptogenesis is less clear. Here, we examine agrin's role in synapse formation between cholinergic preganglionic axons and sympathetic neurons in the superior cervical ganglion (SCG) using agrin-deficient mice. In dissociated cultures of SCG neurons, we found a significant decrease in the number of synapses with aggregates of presynaptic synaptophysin and postsynaptic neuronal acetylcholine receptor among agrin-deficient neurons as compared to wild-type neurons. Moreover, the levels of pre- and postsynaptic markers at the residual synapses in agrin-deficient SCG cultures were also reduced, and these defects were rescued by adding recombinant neural agrin to the cultures. Similarly, we observed a decreased matching of pre- and postsynaptic markers in SCG of agrin-deficient embryos, reflecting a decrease in the number of differentiated synapses in vivo. Finally, in electrophysiological experiments, we found that paired-pulse depression was more pronounced and posttetanic potentiation was significantly greater in agrin-deficient ganglia, indicating that synaptic transmission is also defective. Together, these findings indicate that neural agrin plays an organizing role in the formation and/or differentiation of interneuronal, cholinergic synapses.
Topics: Action Potentials; Agrin; Animals; Animals, Newborn; Biomarkers; Cell Count; Cells, Cultured; Cholinergic Fibers; Electrophysiology; Ganglia, Sympathetic; Mice; Mice, Inbred Strains; Mice, Mutant Strains; Rats; Rats, Sprague-Dawley; Receptors, Cholinergic; Receptors, Nicotinic; Superior Cervical Ganglion; Synapses; Synaptophysin
PubMed: 12221070
DOI: 10.1083/jcb.200203012 -
PloS One 2014Oral squamous cell carcinoma is the most common type of cancer in the oral cavity, representing more than 90% of all oral cancers. The characterization of altered...
Oral squamous cell carcinoma is the most common type of cancer in the oral cavity, representing more than 90% of all oral cancers. The characterization of altered molecules in oral cancer is essential to understand molecular mechanisms underlying tumor progression as well as to contribute to cancer biomarker and therapeutic target discovery. Proteoglycans are key molecular effectors of cell surface and pericellular microenvironments, performing multiple functions in cancer. Two of the major basement membrane proteoglycans, agrin and perlecan, were investigated in this study regarding their role in oral cancer. Using real time quantitative PCR (qRT-PCR), we showed that agrin and perlecan are highly expressed in oral squamous cell carcinoma. Interestingly, cell lines originated from distinct sites showed different expression of agrin and perlecan. Enzymatically targeting chondroitin sulfate modification by chondroitinase, oral squamous carcinoma cell line had a reduced ability to adhere to extracellular matrix proteins and increased sensibility to cisplatin. Additionally, knockdown of agrin and perlecan promoted a decrease on cell migration and adhesion, and on resistance of cells to cisplatin. Our study showed, for the first time, a negative regulation on oral cancer-associated events by either targeting chondroitin sulfate content or agrin and perlecan levels.
Topics: Agrin; Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Adhesion; Cell Line, Tumor; Cell Movement; Cisplatin; Drug Resistance, Neoplasm; Gene Expression; Gene Knockdown Techniques; Heparan Sulfate Proteoglycans; Humans; Mouth Neoplasms
PubMed: 25506919
DOI: 10.1371/journal.pone.0115004 -
Developmental Biology Jan 1997Agrin is a secreted glycoprotein with the ability to cluster cell surface molecules, including the nicotinic acetylcholine receptor (AchR) on muscle cells. Alternate...
Agrin is a secreted glycoprotein with the ability to cluster cell surface molecules, including the nicotinic acetylcholine receptor (AchR) on muscle cells. Alternate splicing of agrin mRNA results in a family of agrin proteins which differ in their clustering potency. Neuronal-specific isoforms with the highest clustering activity play a role in clustering postsynaptic proteins at the neuromuscular junction. However, the function of agrin isoforms expressed in many nonneuronal tissues, and only weakly active in clustering assays, remains obscure. Monolayer cultures of Chinese hamster ovary (CHO) cells expressing a neuronal (agrin-19) or a nonneuronal (agrin-0) form of agrin were used to assay the effect of agrin on neurite outgrowth and cell attachment. These results were compared to outgrowth on control CHO cells expressing only drug resistance and on regions of CHO-agrin monolayers not expressing detectable levels of agrin. Neurite extension on confluent monolayers of agrin-0- or -19-expressing CHO cells was reduced substantially below that of controls. In one experiment neurite lengths were compared at 2 and 3 days after plating and suggested that neurite outgrowth may be stopped and not simply retarded. Attachment of sensory or motoneurons was nearly twofold higher to agrin monolayers than to control cells, showing that the inhibition is not a result of a nonpermissive environment. An agrin construct missing the C-terminal half, removing the major site of variability and clustering activity, was also tested. This construct did not reduce outgrowth, suggesting that the C-terminal half of the protein may be important in stopping growth as well as inducing clustering. These results expand the role of agrin in synaptogenesis as it may provide a stop signal at the myofiber surface and may anchor the presynaptic fibers to the eventual motor endplate .
Topics: Agrin; Animals; CHO Cells; Cell Adhesion; Cells, Cultured; Chick Embryo; Cricetinae; Drug Resistance; Ganglia, Parasympathetic; Morphogenesis; Motor Neurons; Nerve Regeneration; Neurites; Neurons, Afferent; Organ Specificity; RNA Splicing; Rats; Recombinant Proteins; Spinal Cord; Synapses; Transfection
PubMed: 9015262
DOI: 10.1006/dbio.1996.8435 -
Muscle & Nerve May 2018Agrin is essential for the formation and maintenance of neuromuscular junctions (NMJs). NT-1654 is a C-terminal fragment of mouse neural agrin. In this study, we...
INTRODUCTION
Agrin is essential for the formation and maintenance of neuromuscular junctions (NMJs). NT-1654 is a C-terminal fragment of mouse neural agrin. In this study, we determined the effects of NT-1654 on the severity of experimental autoimmune myasthenia gravis (EAMG).
METHODS
EAMG was induced in female Lewis rats by immunization with the Torpedo acetylcholine receptor (tAChR) and complete Freund's adjuvant (CFA). NT-1654 was dissolved in phosphate-buffered saline (PBS) and injected daily subcutaneously into tAChR immunized rats during the first 10 days after immunization, and then every other day for the following 20 days.
RESULTS
We showed that NT-1654 attenuated clinical severity, effectively promoted the clustering of AChRs at NMJs, and alleviated the impairment of NMJ transmission and the reduction of muscle-specific kinase (MuSK) in EAMG rats.
DISCUSSION
We demonstrated that NT-1654 attenuated clinical severity, effectively promoted the clustering of AChRs at NMJs, and alleviated the impairment of NMJ transmission and the reduction of muscle-specific kinase (MuSK) in EAMG rats. Muscle Nerve 57: 814-820, 2018.
Topics: Action Potentials; Agrin; Animals; Autoantibodies; Disease Models, Animal; Dose-Response Relationship, Drug; Electromyography; Female; Freund's Adjuvant; Gene Expression Regulation; Immunization; Membrane Glycoproteins; Muscle, Skeletal; Muscular Atrophy; Myasthenia Gravis, Autoimmune, Experimental; Nerve Tissue Proteins; Neurofibromin 1; Neuromuscular Junction; Peptide Fragments; Rats; Rats, Inbred Lew; Receptors, Cholinergic
PubMed: 29193204
DOI: 10.1002/mus.26025 -
The Journal of Biological Chemistry Jan 1998Agrin is a basement membrane-associated proteoglycan that induces the formation of postsynaptic specializations at the neuromuscular junction. This activity is modulated...
Agrin is a basement membrane-associated proteoglycan that induces the formation of postsynaptic specializations at the neuromuscular junction. This activity is modulated by alternative splicing and is thought to be mediated by receptors expressed in muscle fibers. An isoform of agrin that does not induce postsynaptic specializations binds with high affinity to dystroglycan, a component of the dystrophin-glycoprotein complex. Transcripts encoding this agrin isoform are expressed in a variety of non-muscle tissues. Here, we analyzed the tissue distribution of agrin and dystroglycan on the protein level and determined their binding affinities. We found that agrin is most abundant in lung, kidney, and brain. Only a little agrin was detected in skeletal muscle, and no agrin was found in liver. Dystroglycan was highly expressed in all tissues examined except in liver. In a solid-phase radioligand binding assay, agrin bound to dystroglycan from lung, kidney, and skeletal muscle with a dissociation constant between 1.8 and 2.2 nM, while the affinity to brain-derived dystroglycan was 4.6 nM. In adult kidney and lung, agrin co-purified and co-immunoprecipitated with dystroglycan, and both molecules were co-localized in embryonic tissue. These data show that the agrin isoform expressed in non-muscle tissue is a high-affinity binding partner of dystroglycan and they suggest that this interaction, like that between laminin and dystroglycan, may be important for the mechanical integrity of the tissue.
Topics: Agrin; Animals; COS Cells; Chickens; Cytoskeletal Proteins; Dystroglycans; Kidney; Lung; Membrane Glycoproteins; Muscle, Skeletal; Protein Binding
PubMed: 9417121
DOI: 10.1074/jbc.273.1.600 -
Cell and Tissue Research Apr 2005The formation of somatic neuromuscular junctions in skeletal muscle is regulated by an extracellular matrix protein called agrin. Here, we have examined the expression... (Comparative Study)
Comparative Study
The formation of somatic neuromuscular junctions in skeletal muscle is regulated by an extracellular matrix protein called agrin. Here, we have examined the expression and localization of agrin during development of the rodent urinary bladder, as a first step to examining its possible role at autonomic neuroeffector junctions in smooth muscle. We have found that agrin is expressed on the surface of developing smooth muscle cells and in the basement membrane underlying the urothelium. More importantly, agrin is progressively concentrated at parasympathetic varicosities during postnatal development and is present at virtually all junctions in mature muscle. Reverse transcription/polymerase chain reaction analysis has shown that pelvic ganglion neurons that innervate the bladder express LN/z8 agrin, whereas bladder smooth muscle expresses LN/z- agrin. Together, these results demonstrate that nerve and/or muscle agrin becomes localized at cholinergic parasympathetic varicosities in smooth muscle, where it could play a role in the maturation of the neuroeffector junction.
Topics: Agrin; Animals; Animals, Newborn; Basement Membrane; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Neuroeffector Junction; Neuromuscular Junction; Protein Isoforms; Rats; Rats, Sprague-Dawley; Synapses; Urinary Bladder
PubMed: 15711988
DOI: 10.1007/s00441-004-1045-9