Distinct phenotypes in zebrafish models of human startle disease
Startle disease is an inherited neurological disorder that causes affected individuals to suffer noise- or touch-induced non-epileptic seizures, excessive muscle stiffness and neonatal apnea episodes. Mutations known to cause startle disease have been identified in glycine receptor subunit (GLRA1 an...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2013-12-01
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| Series: | Neurobiology of Disease |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0969996113002386 |
| _version_ | 1818576192855343104 |
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| author | Lisa R. Ganser Qing Yan Victoria M. James Robert Kozol Maya Topf Robert J. Harvey Julia E. Dallman |
| author_facet | Lisa R. Ganser Qing Yan Victoria M. James Robert Kozol Maya Topf Robert J. Harvey Julia E. Dallman |
| author_sort | Lisa R. Ganser |
| collection | DOAJ |
| description | Startle disease is an inherited neurological disorder that causes affected individuals to suffer noise- or touch-induced non-epileptic seizures, excessive muscle stiffness and neonatal apnea episodes. Mutations known to cause startle disease have been identified in glycine receptor subunit (GLRA1 and GLRB) and glycine transporter (SLC6A5) genes, which serve essential functions at glycinergic synapses. Despite the significant successes in identifying startle disease mutations, many idiopathic cases remain unresolved. Exome sequencing in these individuals will identify new candidate genes. To validate these candidate disease genes, zebrafish is an ideal choice due to rapid knockdown strategies, accessible embryonic stages, and stereotyped behaviors. The only existing zebrafish model of startle disease, bandoneon (beo), harbors point mutations in glrbb (one of two zebrafish orthologs of human GLRB) that cause compromised glycinergic transmission and touch-induced bilateral muscle contractions. In order to further develop zebrafish as a model for startle disease, we sought to identify common phenotypic outcomes of knocking down zebrafish orthologs of two known startle disease genes, GLRA1 and GLRB, using splice site-targeted morpholinos. Although both morphants were expected to result in phenotypes similar to the zebrafish beo mutant, our direct comparison demonstrated that while both glra1 and glrbb morphants exhibited embryonic spasticity, only glrbb morphants exhibited bilateral contractions characteristic of beo mutants. Likewise, zebrafish over-expressing a dominant startle disease mutation (GlyR α1R271Q) exhibited spasticity but not bilateral contractions. Since GlyR βb can interact with GlyR α subunits 2–4 in addition to GlyR α1, loss of the GlyR βb subunit may produce more severe phenotypes by affecting multiple GlyR subtypes. Indeed, immunohistochemistry of glra1 morphants suggests that in zebrafish, alternate GlyR α subunits can compensate for the loss of the GlyR α1 subunit. To address the potential for interplay among GlyR subunits during development, we quantified the expression time-course for genes known to be critical to glycinergic synapse function. We found that GlyR α2, α3 and α4a are expressed in the correct temporal pattern and could compensate for the loss of the GlyR α1 subunit. Based on our findings, future studies that aim to model candidate startle disease genes in zebrafish should include measures of spasticity and synaptic development. |
| first_indexed | 2024-12-16T06:10:07Z |
| format | Article |
| id | doaj.art-7db6659dfcec49578528ce7f85a8e256 |
| institution | Directory Open Access Journal |
| issn | 1095-953X |
| language | English |
| last_indexed | 2024-12-16T06:10:07Z |
| publishDate | 2013-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Neurobiology of Disease |
| spelling | doaj.art-7db6659dfcec49578528ce7f85a8e2562022-12-21T22:41:25ZengElsevierNeurobiology of Disease1095-953X2013-12-0160139151Distinct phenotypes in zebrafish models of human startle diseaseLisa R. Ganser0Qing Yan1Victoria M. James2Robert Kozol3Maya Topf4Robert J. Harvey5Julia E. Dallman6Department of Biology and Physics, 1000 Chastain Rd, #1202, Kennesaw State University, Kennesaw, GA 30144 USADepartment of Biology, Cox Science Center, 1301 Memorial Drive, University of Miami, Coral Gables, FL 33124-0421, USADepartment of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK; Institute for Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London WC1E 7HX, UKDepartment of Biology, Cox Science Center, 1301 Memorial Drive, University of Miami, Coral Gables, FL 33124-0421, USAInstitute for Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London WC1E 7HX, UKDepartment of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UKDepartment of Biology, Cox Science Center, 1301 Memorial Drive, University of Miami, Coral Gables, FL 33124-0421, USA; Corresponding author.Startle disease is an inherited neurological disorder that causes affected individuals to suffer noise- or touch-induced non-epileptic seizures, excessive muscle stiffness and neonatal apnea episodes. Mutations known to cause startle disease have been identified in glycine receptor subunit (GLRA1 and GLRB) and glycine transporter (SLC6A5) genes, which serve essential functions at glycinergic synapses. Despite the significant successes in identifying startle disease mutations, many idiopathic cases remain unresolved. Exome sequencing in these individuals will identify new candidate genes. To validate these candidate disease genes, zebrafish is an ideal choice due to rapid knockdown strategies, accessible embryonic stages, and stereotyped behaviors. The only existing zebrafish model of startle disease, bandoneon (beo), harbors point mutations in glrbb (one of two zebrafish orthologs of human GLRB) that cause compromised glycinergic transmission and touch-induced bilateral muscle contractions. In order to further develop zebrafish as a model for startle disease, we sought to identify common phenotypic outcomes of knocking down zebrafish orthologs of two known startle disease genes, GLRA1 and GLRB, using splice site-targeted morpholinos. Although both morphants were expected to result in phenotypes similar to the zebrafish beo mutant, our direct comparison demonstrated that while both glra1 and glrbb morphants exhibited embryonic spasticity, only glrbb morphants exhibited bilateral contractions characteristic of beo mutants. Likewise, zebrafish over-expressing a dominant startle disease mutation (GlyR α1R271Q) exhibited spasticity but not bilateral contractions. Since GlyR βb can interact with GlyR α subunits 2–4 in addition to GlyR α1, loss of the GlyR βb subunit may produce more severe phenotypes by affecting multiple GlyR subtypes. Indeed, immunohistochemistry of glra1 morphants suggests that in zebrafish, alternate GlyR α subunits can compensate for the loss of the GlyR α1 subunit. To address the potential for interplay among GlyR subunits during development, we quantified the expression time-course for genes known to be critical to glycinergic synapse function. We found that GlyR α2, α3 and α4a are expressed in the correct temporal pattern and could compensate for the loss of the GlyR α1 subunit. Based on our findings, future studies that aim to model candidate startle disease genes in zebrafish should include measures of spasticity and synaptic development.http://www.sciencedirect.com/science/article/pii/S0969996113002386glra1glrbGlycine receptorStartle diseaseHyperekplexiaZebrafish |
| spellingShingle | Lisa R. Ganser Qing Yan Victoria M. James Robert Kozol Maya Topf Robert J. Harvey Julia E. Dallman Distinct phenotypes in zebrafish models of human startle disease Neurobiology of Disease glra1 glrb Glycine receptor Startle disease Hyperekplexia Zebrafish |
| title | Distinct phenotypes in zebrafish models of human startle disease |
| title_full | Distinct phenotypes in zebrafish models of human startle disease |
| title_fullStr | Distinct phenotypes in zebrafish models of human startle disease |
| title_full_unstemmed | Distinct phenotypes in zebrafish models of human startle disease |
| title_short | Distinct phenotypes in zebrafish models of human startle disease |
| title_sort | distinct phenotypes in zebrafish models of human startle disease |
| topic | glra1 glrb Glycine receptor Startle disease Hyperekplexia Zebrafish |
| url | http://www.sciencedirect.com/science/article/pii/S0969996113002386 |
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