Collagen XIII secures pre- and postsynaptic integrity of the neuromuscular synapse

© The Author 2017. Published by Oxford University Press. All rights reserved. Both transmembrane and extracellular cues, one of which is collagen XIII, regulate the formation and function of the neuromuscular synapse, and their absence results in myasthenia. We show that the phenotypical changes in collagen XIII knock-out mice are milder than symptoms in human patients, but the Col13a1 -/- mice recapitulate major muscle findings of congenital myasthenic syndrome type 19 and serve as a disease model. In the lack of collagen XIII neuromuscular synapses do not reach full size, alignment, complexity and function resulting in reduced muscle strength. Collagen XIII is particularly important for the preterminal integrity, and when absent, destabilization of the motor nerves results in muscle regeneration and in atrophy especially in the case of slow muscle fibers. Collagen XIII was found to affect synaptic integrity through binding the ColQ tail of acetylcholine esterase. Although collagen XIII is a muscle-bound transmembrane molecule, it also undergoes ectodomain shedding to become a synaptic basal lamina component. We investigated the two forms' roles by novel Col13a1 tm/tm mice in which ectodomain shedding is impaired. While postsynaptic maturation, terminal branching and neurotransmission was exaggerated in the Col13a1 tm/tm mice, the transmembrane form's presence sufficed to prevent defects in transsynaptic adhesion, Schwann cell invagination/retraction, vesicle accumulation and acetylcholine receptor clustering and acetylcholinesterase dispersion seen in the Col13a1 -/- mice, pointing to the transmembrane form as the major conductor of collagen XIII effects. Altogether, collagen XIII secures postsynaptic, synaptic and presynaptic integrity, and it is required for gaining and maintaining normal size, complexity and functional capacity of the neuromuscular synapse

Collagen XIII as a neuromuscular synapse organizer:roles of collagen XIII and its transmembrane form, and effects of shedding and overexpression in the neuromuscular system in mouse models

Abstract Collagen XIII is a transmembrane protein consisting of intracellular, transmembrane and extracellular domains. The latter can be cleaved by proteases of the furin family at the plasma membrane and in the trans-Golgi network. Both the transmembrane and shed collagen XIII are expressed at the neuromuscular junctions of mice and humans. Such motor synapse passes the contraction signal from the central nervous system to the muscles and brings about all voluntary movements. Loss of both forms of collagen XIII in mice and loss-of-function mutations in the COL13A1 gene in humans leads to congenital myasthenic syndrome characterized by decreased neuromuscular transmission and muscle weakness. To study the roles of the two collagen XIII forms, a novel mouse line was engineered to harbor only the transmembrane collagen XIII by mutating the furin cleavage site. Transmembrane collagen XIII was discovered to be sufficient to prevent adhesion defects, Schwann cell invagination, the ineffective vesicle accumulation and dispersion of both acetylcholinesterase and acetylcholine receptors, phenotypes seen in the complete lack of collagen XIII. On the other hand, lack of shedding led to acetylcholine receptor fragmentation, aberrantly increased neurotransmission and presynaptic complexity. Remarkably, in vivo and in vitro interaction of collagen XIII and acetylcholinesterase-anchoring ColQ was detected. Furthermore, muscle and neuromuscular junction phenotype in the lack of both forms of collagen XIII closely resembled those in the human patients harboring mutations in the COL13A1 gene and these mice were validated as a good model for studying the human disease. Misexpression of collagen XIII was studied with mice exhibiting transgenic overexpression of the protein. Overexpression of collagen XIII was detected to be mostly extrasynaptic in the muscles of such mice. Exogenous collagen XIII was found at the myotendinous junctions, tenocytes and fibroblast-like cells, in addition to some localization in the near vicinity of the neuromuscular junctions. Collagen XIII expression was found, for the most part, to be normal at the neuromuscular junctions, although some were devoid of collagen XIII. The neuromuscular junction phenotype resembled in many ways the findings made in the lack of collagen XIII. Furthermore, acetylcholine receptor and nerve pattern was discovered to be widened.Tiivistelmä Kollageeni XIII on solukalvoproteiini, jonka rakenne koostuu solunsisäisestä, solukalvon läpäisevästä ja solun ulkoisesta osasta, joka pystytään entsymaattisesti irrottamaan solukalvoilta. Täten se esiintyy kahdessa eri muodossaan; solukalvomuotoisena ja soluvälitilan lihasperäisenä proteiinina hiirten ja ihmisten hermolihasliitoksessa. Tässä motorisessa synapsissa keskushermostosta peräisin oleva lihaksen supistumiskäsky välittyy lihakseen ja aikaan saa tahdonalaiset liikkeet. Molempien kollageeni XIII:n muotojen puute hiirillä ja COL13A1 geenin mutaatiot ihmisillä johtavat synnynnäiseen myasteeniseen oireyhtymään, jossa heikentynyt hermolihasliitoksen toiminta johtaa lihasheikkouteen. Kollageeni XIII:n eri muotojen hermolihasliitosvaikutusten selvittämiseksi luotiin hiirilinja, jossa kollageeni XIII ilmenee geneettisen manipulaation seurauksena ainoastaan solukalvomuodossaan. Tutkimukset osoittivat solukalvomuotoisen kollageeni XIII:n tarvittavan hermon ja lihaksen kiinnittymiseen toisiinsa, hermovälittäjäainerakkuloiden ankkuroimiseen hermopäätteeseen, estämään Schwannin solujen tunkeutuminen synapsirakoon, asetyylikoliiniesteraasin sitomiseen ja asetyylikoliinireseptorien vakaantumiseen. Soluvälitilan kollageeni XIII:n puutos puolestaan johti lihaksen puolen liitoksen pirstaloitumiseen sekä hermopäätteiden liialliseen kasvuun ja aktiivisuuteen. Kollageeni XIII todettiin sitoutuvan asetyylikoliiniesteraasia hermolihasliitokseen ankkuroivan kollageeni Q:n kanssa. Lisäksi molempien kollageeni XIII:n muotojen suhteen poistogeenisten hiirten hermolihas- ja lihaslöydökset todettiin muistuttavan COL13A1 geenin mutaatioista kärsivien ihmisten vastaavia löydöksiä todistaen nämä hiiret hyväksi tautimalliksi tulevaisuuden hoitomuotojen suunnitteluun. Kollageeni XIII:n ylimäärän vaikutusta hermolihasliitokseen ja lihaskudokseen tutkittiin kollageeni XIII:a ylenmäärin ilmentävillä hiirillä. Kollageeni XIII todettiin ilmentyvän ylenmäärin lihaksessa fibroblastinkaltaisissa soluissa, lihasjänneliitoksessa ja hermolihasliitoksen lähettyvillä, mutta ei hermolihasliitoksessa. Osa hermolihasliitoksista näissä hiirissä ilmensi jopa vähemmän kollageeni XIII:a kuin normaalisti. Asetyylikoliinireseptorien ja hermojen valtaama alue todettiin leventyneeksi ja hermolihasliitoslöydökset muistuttivat molempien kollageeni XIII:n muotojen suhteen poistogeenisien hiirten löydöksiä

Kipupumpun turvallinen käyttäminen - tarkistuslista opetukseen

Opinnäytetyö toteutettiin kehittämistyönä, jossa tuotettiin tarkistuslista kipupumpun ohjelmoinnista Savonia-ammattikorkeakoululle käytettäväksi sairaanhoitajaopiskelijoiden opetuksessa. Opiskelijat voivat toteuttaa kipupumpun ohjelmoinnin tarkistuslistan mukaan. Tavoitteena oli lisätä opiskelijoiden tietämystä kipupumpuista ja niiden avulla toteutettavan kivunhoidon toteuttamisesta. Tavoite oli myös parantaa potilasturvallisuutta lääkehoidossa. Tietoa kivusta ja kipupumpun käytöstä etsittiin eri kirjallisuuslähteistä. Valittu näyttöön perustuva tieto kerättiin teoriaosioon, jossa käytiin läpi kipua ja sen hoitoa, lääkehoidon potilasturvallisuutta sekä itse kipupumppua. Tätä teoriaa käytettiin pohjana tuotokselle eli CADD-Legacy PCA -kipupumpun tarkistuslistalle. Työn tuloksena oli tarkistuslista, jossa käydään läpi kipupumpun CADD-Legacy PCA -kipupumpun käyttö aina paristojen asettamisesta ohjelmointiin ja infuusion aloitukseen ja lopetukseen. Lisäksi tarkistuslistassa neuvotaan muun muassa boluksen eli kerta-annoksen antaminen. Työn teoriaosio tarjoaa ajankohtaista tietoa kivusta ja kivunhoidosta, jota opiskelijat voivat hyödyntää opinnoissaan. Koska tarkistuslista tehtiin koulussa tapahtuvaan opetuskäyttöön, se eroaa ohjeistukseltaan hieman varsinaisessa työympäristössä tapahtuvasta kipupumpun käytöstä. Tämän takia yksi mielenkiintoinen kehittämisidea olisi vastaavanlaisen tarkistuslistan kehittäminen potilastyöhön laillistetuille hoitoalan ammattilaisille

Collagen XIII and other ECM components in the assembly and disease of the neuromuscular junction

Abstract Alongside playing structural roles, the extracellular matrix (ECM) acts as an interaction platform for cellular homeostasis, organ development, and maintenance. The necessity of the ECM is highlighted by the diverse, sometimes very serious diseases that stem from defects in its components. The neuromuscular junction (NMJ) is a large peripheral motor synapse differing from its central counterparts through the ECM included at the synaptic cleft. Such synaptic basal lamina (BL) is specialized to support NMJ establishment, differentiation, maturation, stabilization, and function and diverges in molecular composition from the extrasynaptic ECM. Mutations, toxins, and autoantibodies may compromise NMJ integrity and function, thereby leading to congenital myasthenic syndromes (CMSs), poisoning, and autoimmune diseases, respectively, and all these conditions may involve synaptic ECM molecules. With neurotransmission degraded or blocked, muscle function is impaired or even prevented. At worst, this can be fatal. The article reviews the synaptic BL composition required for assembly and function of the NMJ molecular machinery through the lens of studies primarily with mouse models but also with human patients. In‐depth focus is given to collagen XIII, a postsynaptic‐membrane‐spanning but also shed ECM protein that in recent years has been revealed to be a significant component for the NMJ. Its deficiency in humans causes CMS, and autoantibodies against it have been recognized in autoimmune myasthenia gravis. Mouse models have exposed numerous details that appear to recapitulate human NMJ phenotypes relatively faithfully and thereby can be readily used to generate information necessary for understanding and ultimately treating human diseases

Correct expression and localization of collagen XIII are crucial for the normal formation and function of the neuromuscular system

© 2019 Federation of European Neuroscience Societies and John Wiley & Sons Ltd Transmembrane collagen XIII has been linked to maturation of the musculoskeletal system. Its absence in mice (Col13a1−/−) results in impaired neuromuscular junction (NMJ) differentiation and function, while transgenic overexpression (Col13a1oe) leads to abnormally high bone mass. Similarly, loss-of-function mutations in COL13A1 in humans produce muscle weakness, decreased motor synapse function and mild dysmorphic skeletal features. Here, analysis of the exogenous overexpression of collagen XIII in various muscles revealed highly increased transcript and protein levels, especially in the diaphragm. Unexpectedly, the main location of exogenous collagen XIII in the muscle was extrasynaptic, in fibroblast-like cells, while some motor synapses were devoid of collagen XIII, possibly due to a dominant negative effect. Concomitantly, phenotypical changes in the NMJs of the Col13a1oe mice partly resembled those previously observed in Col13a1−/− mice. Namely, the overall increase in collagen XIII expression in the muscle produced both pre- and postsynaptic abnormalities at the NMJ, especially in the diaphragm. We discovered delayed and compromised acetylcholine receptor (AChR) clustering, axonal neurofilament aggregation, patchy acetylcholine vesicle (AChV) accumulation, disrupted adhesion of the nerve and muscle, Schwann cell invagination and altered evoked synaptic function. Furthermore, the patterns of the nerve trunks and AChR clusters in the diaphragm were broader in the adult muscles, and already prenatally in the Col13a1oe mice, suggesting collagen XIII involvement in the development of the neuromuscular system. Overall, these results confirm the role of collagen XIII at the neuromuscular synapses and highlight the importance of its correct expression and localization for motor synapse formation and function

Correct expression and localization of collagen XIII are crucial for the normal formation and function of the neuromuscular system

© 2019 Federation of European Neuroscience Societies and John Wiley & Sons Ltd Transmembrane collagen XIII has been linked to maturation of the musculoskeletal system. Its absence in mice (Col13a1−/−) results in impaired neuromuscular junction (NMJ) differentiation and function, while transgenic overexpression (Col13a1oe) leads to abnormally high bone mass. Similarly, loss-of-function mutations in COL13A1 in humans produce muscle weakness, decreased motor synapse function and mild dysmorphic skeletal features. Here, analysis of the exogenous overexpression of collagen XIII in various muscles revealed highly increased transcript and protein levels, especially in the diaphragm. Unexpectedly, the main location of exogenous collagen XIII in the muscle was extrasynaptic, in fibroblast-like cells, while some motor synapses were devoid of collagen XIII, possibly due to a dominant negative effect. Concomitantly, phenotypical changes in the NMJs of the Col13a1oe mice partly resembled those previously observed in Col13a1−/− mice. Namely, the overall increase in collagen XIII expression in the muscle produced both pre- and postsynaptic abnormalities at the NMJ, especially in the diaphragm. We discovered delayed and compromised acetylcholine receptor (AChR) clustering, axonal neurofilament aggregation, patchy acetylcholine vesicle (AChV) accumulation, disrupted adhesion of the nerve and muscle, Schwann cell invagination and altered evoked synaptic function. Furthermore, the patterns of the nerve trunks and AChR clusters in the diaphragm were broader in the adult muscles, and already prenatally in the Col13a1oe mice, suggesting collagen XIII involvement in the development of the neuromuscular system. Overall, these results confirm the role of collagen XIII at the neuromuscular synapses and highlight the importance of its correct expression and localization for motor synapse formation and function

Correct expression and localization of collagen XIII are crucial for the normal formation and function of the neuromuscular system

© 2019 Federation of European Neuroscience Societies and John Wiley & Sons Ltd Transmembrane collagen XIII has been linked to maturation of the musculoskeletal system. Its absence in mice (Col13a1−/−) results in impaired neuromuscular junction (NMJ) differentiation and function, while transgenic overexpression (Col13a1oe) leads to abnormally high bone mass. Similarly, loss-of-function mutations in COL13A1 in humans produce muscle weakness, decreased motor synapse function and mild dysmorphic skeletal features. Here, analysis of the exogenous overexpression of collagen XIII in various muscles revealed highly increased transcript and protein levels, especially in the diaphragm. Unexpectedly, the main location of exogenous collagen XIII in the muscle was extrasynaptic, in fibroblast-like cells, while some motor synapses were devoid of collagen XIII, possibly due to a dominant negative effect. Concomitantly, phenotypical changes in the NMJs of the Col13a1oe mice partly resembled those previously observed in Col13a1−/− mice. Namely, the overall increase in collagen XIII expression in the muscle produced both pre- and postsynaptic abnormalities at the NMJ, especially in the diaphragm. We discovered delayed and compromised acetylcholine receptor (AChR) clustering, axonal neurofilament aggregation, patchy acetylcholine vesicle (AChV) accumulation, disrupted adhesion of the nerve and muscle, Schwann cell invagination and altered evoked synaptic function. Furthermore, the patterns of the nerve trunks and AChR clusters in the diaphragm were broader in the adult muscles, and already prenatally in the Col13a1oe mice, suggesting collagen XIII involvement in the development of the neuromuscular system. Overall, these results confirm the role of collagen XIII at the neuromuscular synapses and highlight the importance of its correct expression and localization for motor synapse formation and function