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Clinical Cancer Research : An Official... Mar 2020Sessile serrated lesions (SSL) are precursors to colon carcinoma, and their distinction from other polyps, in particular hyperplastic polyps (HP), presents significant...
PURPOSE
Sessile serrated lesions (SSL) are precursors to colon carcinoma, and their distinction from other polyps, in particular hyperplastic polyps (HP), presents significant diagnostic challenges. We evaluated expression patterns in colonic polyps of previously identified colon carcinoma-associated extracellular matrix (ECM) proteins to identify markers distinguishing SSLs from other polyps.
EXPERIMENTAL DESIGN
Gene-expression analyses of ECM proteins were performed using publicly available data on preneoplastic colonic polyps. In parallel, we evaluated by IHC the expression of agrin (AGRN) in over 400 colonic polyps, including HP, SSL with and without dysplasia, traditional serrated adenomas (TSA), and tubular adenomas (TA), and compared the consistency of standard histologic diagnosis of SSLs by experienced gastrointestinal pathologists with that of AGRN IHC.
RESULTS
Differential gene expression analysis and IHC identified AGRN, serine peptidase inhibitor (SERPINE2), and TIMP metallopeptidase inhibitor 1 (TIMP1) elevated in SSLs and HPs but decreased in TAs and absent in normal colon. AGRN-positive basal laminae were noted in all TA, TSA, HP, and SSL in distinguishable patterns, whereas other polyps and normal mucosa were negative. SSL with or without dysplasia consistently showed IHC staining for AGRN in the muscularis mucosae, which was absent in HP, TSA, TA, and other polyps. In contrast, histologic evaluation showed only weak interobserver agreement (kappa value = 0.493) in distinguishing SSLs.
CONCLUSIONS
Muscularis mucosae-based AGRN immunostaining is a novel biomarker to distinguish SSL from HP, TSA, and TA, with a specificity of 97.1% and sensitivity of 98.9% and can assist in diagnosis of morphologically challenging colonic polyps.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Agrin; Biomarkers, Tumor; Child; Child, Preschool; Colonic Polyps; Colorectal Neoplasms; Diagnosis, Differential; Gene Expression Regulation, Neoplastic; Humans; Hyperplasia; Middle Aged; Mucous Membrane; Young Adult
PubMed: 31852835
DOI: 10.1158/1078-0432.CCR-19-2898 -
The Journal of Neuroscience : the... Nov 2010The elusiveness of neuropathic pain mechanisms is a major impediment in developing effective clinical treatments. Here we show that peripheral nerve injury decreased...
The elusiveness of neuropathic pain mechanisms is a major impediment in developing effective clinical treatments. Here we show that peripheral nerve injury decreased agrin expression in the ipsilateral spinal dorsal horn of rats displaying tactile allodynia. SCP1, an acetaminophen analog, suppressed allodynia and promoted agrin upregulation. Preemptive treatment with SCP1 also upregulated agrin, thereby preventing neuropathic pain development. Expression of 50 kDa agrin delivered by adeno-associated virus into the dorsal horn also suppressed allodynia and hyperalgesia. Allodynia suppression was a consequence of serine residue 896/897 phosphorylation of NMDA receptor NR1 subunits in the GABA interneurons of the dorsal horn. Agrin silencing by small interference RNA, administered with either AAV-Ag50 vector or SCP1, blocked allodynia suppression, agrin upregulation, and NR1 phosphorylation. In conclusion, 50 kDa agrin modulates neuropathic pain through NR1 phosphorylation in GABA neurons. This mechanism may open new approaches for treating not only neuropathic pain, but also epilepsy, tremors, and spasticity.
Topics: Agrin; Analysis of Variance; Animals; Blotting, Western; Down-Regulation; Immunohistochemistry; Male; Neuralgia; Neurons; Phosphorylation; RNA Interference; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Reverse Transcriptase Polymerase Chain Reaction; Sciatic Nerve; gamma-Aminobutyric Acid
PubMed: 21068333
DOI: 10.1523/JNEUROSCI.4418-10.2010 -
Blood Jun 2012Agrin, an extracellular matrix protein belonging to the heterogeneous family of heparan sulfate proteoglycans (HSPGs), is expressed by cells of the hematopoietic system...
Agrin, an extracellular matrix protein belonging to the heterogeneous family of heparan sulfate proteoglycans (HSPGs), is expressed by cells of the hematopoietic system but its role in leukocyte biology is not yet clear. Here we demonstrate that agrin has a crucial, nonredundant role in myeloid cell development and functions. We have identified lineage-specific alterations that affect maturation, survival and properties of agrin-deficient monocytic cells, and occur at stages later than stem cell precursors. Our data indicate that the cell-autonomous signals delivered by agrin are sensed by macrophages through the α-DC (DG) receptor and lead to the activation of signaling pathways resulting in rearrangements of the actin cytoskeleton during the phagocytic synapse formation and phosphorylation of extracellular signal-regulated kinases (Erk 1/2). Altogether, these data identify agrin as a novel player of innate immunity.
Topics: Agrin; Animals; Cell Survival; Dystroglycans; Extracellular Signal-Regulated MAP Kinases; Gene Deletion; Gene Expression Regulation, Developmental; Macrophages; Mice; Mice, Inbred C57BL; Monocytes; Myeloid Cells; Myelopoiesis; Phagocytosis; Phosphorylation
PubMed: 22517892
DOI: 10.1182/blood-2011-09-382812 -
The Journal of Biological Chemistry Aug 2023Collagen Q (ColQ) is a nonfibrillar collagen that plays a crucial role at the vertebrate neuromuscular junction (NMJ) by anchoring acetylcholinesterase to the synapse....
Collagen Q (ColQ) is a nonfibrillar collagen that plays a crucial role at the vertebrate neuromuscular junction (NMJ) by anchoring acetylcholinesterase to the synapse. ColQ also functions in signaling, as it regulates acetylcholine receptor clustering and synaptic gene expression, in a manner dependent on muscle-specific kinase (MuSK), a key protein in NMJ formation and maintenance. MuSK forms a complex with low-density lipoprotein receptor-related protein 4 (LRP4), its coreceptor for the proteoglycan agrin at the NMJ. Previous studies suggested that ColQ also interacts with MuSK. However, the molecular mechanisms underlying ColQ functions and ColQ-MuSK interaction have not been fully elucidated. Here, we investigated whether ColQ binds directly to MuSK and/or LRP4 and whether it modulates agrin-mediated MuSK-LRP4 activation. Using coimmunoprecipitation, pull-down, plate-binding assays, and surface plasmon resonance, we show that ColQ binds directly to LRP4 but not to MuSK and that ColQ interacts indirectly with MuSK through LRP4. In addition, we show that the LRP4 N-terminal region, which contains the agrin-binding sites, is also crucial for ColQ binding to LRP4. Moreover, ColQ-LRP4 interaction was reduced in the presence of agrin, suggesting that agrin and ColQ compete for binding to LRP4. Strikingly, we reveal ColQ has two opposing effects on agrin-induced MuSK-LRP4 signaling: it constitutively reduces MuSK phosphorylation levels in agrin-stimulated myotubes but concomitantly increases MuSK accumulation at the muscle cell surface. Our results identify LRP4 as a major receptor of ColQ and provide new insights into mechanisms of ColQ signaling and acetylcholinesterase anchoring at the NMJ.
Topics: Humans; Acetylcholinesterase; Agrin; Collagen; LDL-Receptor Related Proteins; Muscle Fibers, Skeletal; Neuromuscular Junction; Receptor Protein-Tyrosine Kinases
PubMed: 37356721
DOI: 10.1016/j.jbc.2023.104962 -
Glycobiology Dec 2005Recent studies have begun to investigate the role of agrin in brain and suggest that agrin's function likely extends beyond that of a synaptogenic protein. Particularly,...
Recent studies have begun to investigate the role of agrin in brain and suggest that agrin's function likely extends beyond that of a synaptogenic protein. Particularly, it has been shown that agrin is associated with the pathological lesions of Alzheimer's disease (AD) and may contribute to the formation of beta-amyloid (Abeta) plaques in AD. We have extended the analysis of agrin's function in neurodegenerative diseases to investigate its role in Parkinson's disease (PD). Alpha-synuclein is a critical molecular determinant in familial and sporadic PD, with the formation of alpha-synuclein fibrils being enhanced by sulfated macromolecules. In the studies reported here, we show that agrin binds to alpha-synuclein in a heparan sulfate-dependent (HS-dependent) manner, induces conformational changes in this protein characterized by beta-sheet structure, and enhances insolubility of alpha-synuclein. We also show that agrin accelerates the formation of protofibrils by alpha-synuclein and decreases the half-time of fibril formation. The association of agrin with PD lesions was also explored in PD human brain, and these studies shown that agrin colocalizes with alpha-synuclein in neuronal Lewy bodies in the substantia nigra of PD brain. These studies indicate that agrin is capable of accelerating the formation of insoluble protein fibrils in a second common neurodegenerative disease. These findings may indicate shared molecular mechanisms leading to the pathophysiology in these two neurodegenerative disorders.
Topics: Agrin; Alzheimer Disease; Animals; Antibodies, Monoclonal; Brain; Cell Death; Chickens; Circular Dichroism; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Heparitin Sulfate; Humans; Immunoblotting; Immunohistochemistry; Lewy Bodies; Microscopy, Electron, Transmission; Neurodegenerative Diseases; Neurons; Parkinson Disease; Prions; Protein Binding; Protein Conformation; Recombinant Proteins; Solubility; Substantia Nigra; Synucleins; Time Factors; alpha-Synuclein
PubMed: 16037493
DOI: 10.1093/glycob/cwj014 -
Nature Jun 1996
Topics: Agrin; Animals; Cytoskeletal Proteins; Dystroglycans; Membrane Glycoproteins; Mice; Mice, Knockout; Neuromuscular Junction; Receptor Aggregation; Receptor Protein-Tyrosine Kinases; Receptors, Cholinergic; Synaptic Transmission
PubMed: 8632818
DOI: 10.1038/381478a0 -
Molecular and Cellular Neurosciences Jan 2002Agrin mediates motor neuron-induced differentiation of the postsynaptic apparatus of the neuromuscular junction but its function in brain remains unknown. Here we report...
Agrin mediates motor neuron-induced differentiation of the postsynaptic apparatus of the neuromuscular junction but its function in brain remains unknown. Here we report that expression of c-fos, induced by activation of nicotinic or glutamatergic receptors, was significantly lower in cortical neurons cultured from agrin-deficient mutant mouse embryos compared to wildtype. Agrin-deficient neurons also exhibited increased resistance to excitotoxic injury. Treatment with recombinant agrin restored glutamate-induced c-fos expression and excitotoxicity of the agrin-deficient neurons to near wild-type levels, confirming the agrin dependence of the phenotype. The observation that c-fos induction by activation of voltage-gated Ca2+ channels is also reduced in agrin-deficient neurons raises the possibility that agrin may play a wider role by regulating responses to Ca(2+)-mediated signals. Consistent with the decline in response of cultured mutant neurons to glutamate, decreases in kainic acid-induced seizure and mortality were observed in adult agrin heterozygous mice. Together, these data demonstrate that agrin plays an important role in defining neuronal responses to excitatory neurotransmitters both in vitro and in vivo.
Topics: Agrin; Animals; Calcium Channels; Calcium Signaling; Cell Communication; Cells, Cultured; Cerebral Cortex; Electrophysiology; Epilepsy; Excitatory Amino Acid Agonists; Genotype; Glutamic Acid; Heterozygote; Homozygote; In Vitro Techniques; Kainic Acid; Mice; Neurons; Neurotoxins; Nicotine; Nicotinic Agonists; Phenotype; Proto-Oncogene Proteins c-fos; Receptors, Glutamate
PubMed: 11817901
DOI: 10.1006/mcne.2001.1056 -
Histochemistry and Cell Biology Apr 2007Agrin is a heparan sulfate proteoglycan that is best known for its crucial involvement in the organization and maintenance of postsynaptic structures at the...
Agrin is a heparan sulfate proteoglycan that is best known for its crucial involvement in the organization and maintenance of postsynaptic structures at the neuromuscular junction. Consistent with this role, mice deficient of agrin die at birth due to respiratory failure. Here we examined the early postnatal development of agrin-deficient mice in which perinatal death was prevented by transgenic expression of neural agrin in motor neurons. Such transgenic, agrin-deficient mice were born at Mendelian ratio but exhibited severe postnatal growth retardation. Growth plate morpholgy was markedly altered in these mice, with changes being most prominent in the hypertrophic zone. Compression of this zone was not caused by reduced viability of hypertrophic chondrocytes, as no differences in the apoptosis rates could be observed. Furthermore, deposition of the major cartilage matrix components collagen type II and aggrecan was slightly reduced in these mice. Consistent with a role for agrin in skeletal development, we show for the first time that agrin is highly expressed by chondrocytes and localizes to the growth plate in wild-type mice. Our data show that agrin is expressed in cartilage and that it plays a critical role in normal skeletal growth.
Topics: Aggrecans; Agrin; Animals; Apoptosis; Cartilage; Cell Proliferation; Chickens; Chondrocytes; Collagen Type II; Female; Gene Expression; Growth Disorders; Growth Plate; Immunohistochemistry; Male; Mice; Mice, Knockout; Mice, Transgenic; Receptor Protein-Tyrosine Kinases; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 17186266
DOI: 10.1007/s00418-006-0258-2 -
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