Umeå University's logo

umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Obscurin maintains myofiber identity in extraocular muscles
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.ORCID iD: 0000-0003-0885-6586
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).ORCID iD: 0000-0003-2508-9921
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
Show others and affiliations
2024 (English)In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 65, no 2, article id 19Article in journal (Refereed) Published
Abstract [en]

Purpose: The cytoskeleton of the extraocular muscles (EOMs) is significantly different from that of other muscles. We aimed to investigate the role of obscurin, a fundamental cytoskeletal protein, in the EOMs.

Methods: The distribution of obscurin in human and zebrafish EOMs was compared using immunohistochemistry. The two obscurin genes in zebrafish, obscna and obscnb, were knocked out using CRISPR/Cas9, and the EOMs were investigated using immunohistochemistry, qPCR, and in situ hybridization. The optokinetic reflex (OKR) in five-day-old larvae and adult obscna−/−;obscnb−/− and sibling control zebrafish was analyzed. Swimming distance was recorded at the same age.

Results: The obscurin distribution pattern was similar in human and zebrafish EOMs. The proportion of slow and fast myofibers was reduced in obscna−/−;obscnb−/− zebrafish EOMs but not in trunk muscle, whereas the number of myofibers containing cardiac myosin myh7 was significantly increased in EOMs of obscurin double mutants. Loss of obscurin resulted in less OKRs in zebrafish larvae but not in adult zebrafish.

Conclusions: Obscurin expression is conserved in normal human and zebrafish EOMs. Loss of obscurin induces a myofiber type shift in the EOMs, with upregulation of cardiac myosin heavy chain, myh7, showing an adaptation strategy in EOMs. Our model will facilitate further studies in conditions related to obscurin.

Place, publisher, year, edition, pages
Association for Research in Vision and Ophthalmology , 2024. Vol. 65, no 2, article id 19
Keywords [en]
extraocular muscles, myofiber, myosin heavy chain 7, obscurin, zebrafish
National Category
Ophthalmology
Identifiers
URN: urn:nbn:se:umu:diva-218165DOI: 10.1167/iovs.65.2.19PubMedID: 38334702Scopus ID: 2-s2.0-85184789466OAI: oai:DiVA.org:umu-218165DiVA, id: diva2:1820290
Funder
Swedish Research Council, 2018-02401Umeå UniversityRegion VästerbottenUmeå University, FS 2.1.6-1911-22Stiftelsen Kronprinsessan Margaretas arbetsnämnd för synskadade
Note

Originally included in thesis in manuscript form. 

Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-03-05Bibliographically approved
In thesis
1. Genetic studies of zebrafish muscles: clues to protection in muscle disease
Open this publication in new window or tab >>Genetic studies of zebrafish muscles: clues to protection in muscle disease
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Genetiska studier av zebrafiskarnas muskler : ledtrådar om skydd mot muskeldystrofier
Abstract [en]

Muscular dystrophies (MDs) are caused by dysregulation of over 40 proteins but commonly share features of muscle weakness, myofiber death and regeneration, loss of ambulation and premature death. A MD involves a broken link anywhere in the connection from extracellular matrix through the sarcolemma to the sarcomere. Thus, any protein which is a part of this link causes MD if misfolded, dysregulated or absent. In MD, the most common causes of death are cardiac or respiratory failure, when the muscles involved in these processes fail. Although MDs affect 1:3500-5000 births worldwide there are currently no cures available. Extraocular muscles (EOMs) are strikingly not affected by MDs, however, the mechanisms behind this native resistance remain elusive. We have recently shown that the EOMs cytoskeleton differs significantly from that of other muscles and hypothesized that investigation of their cytoskeleton in MD models would provide important clues. Furthermore, we hypothesized that application of the EOMs strategies to trunk muscle tissue would decrease the detrimental impact of MD overall.

The zebrafish model system has recently increased vastly in popularity, and has quickly become a MD model. Due to its compatibility with the CRISPR/Cas9 method, genetic knockout studies can be utilized to generate novel mutant lines tailored to fit various aspects in studies of the zebrafish skeletal muscle. In this thesis I present nine new zebrafish lines which I used to study muscle biology processes, including muscle regeneration and the EOM cytoskeleton. 

Our results clearly demonstrate the need for understanding compensatory mechanisms in biology. Interestingly, pax3 and pax7 were shown to functionally compensate for each other both in appendicular muscle formation and in muscle regeneration, respectively, two processes where these individual genes have great impact in other organisms. This finding would also prove to be important in aiding our understanding of the EOM biology in adaptive strategies towards MDs. Furthermore, our results show that zebrafish EOMs are a good model to study cytoskeletal composition, as they share important features with human EOMs. Utilizing the CRISPR/Cas9 genome editing technique, I developed several knockout models of cytoskeletal proteins (desmin, obscurin, plectin) and studied their importance for the function of the EOMs.  In studies of zebrafish EOMs lacking obscurin, we found that EOMs functionally adapt their myosin composition over time via upregulation of myh7, a cardiac specific myosin. Furthermore, an RNA-sequencing screen on a CRISPR/Cas9 induced desminopathy model (desma; desmb double mutant) identified several protective genes of interest. We show that a four and a half LIM-domain protein (Fhl2) is upregulated in EOMs in several muscular dystrophy models and that fhl2b protects EOMs from excessive myonuclei turnover and hypertrophy. Furthermore, its ectopic expression in trunk muscle can also protect an additional muscle dystrophy model (dmd) from acute early death, improve myofiber function and stabilize neuromuscular junctions. Importantly, this protein was also detected in both human and mouse EOMs, indicating a potentially conserved role in the EOMs across species.

In summary, we identified several novel strategies of adaptation to disease progression in the EOMs. Together, these findings have contributed significantly to a better understanding of the EOMs and suggest new treatment strategies for MD that may have important future clinical applications.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2023. p. 75
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2275
Keywords
zebrafish, muscle, extraocular muscles, intermediate filaments, bioinformatics, genetics, CRISPR/Cas9
National Category
Ophthalmology Cell and Molecular Biology
Research subject
ophthalmology; cell research
Identifiers
urn:nbn:se:umu:diva-218166 (URN)9789180702362 (ISBN)9789180702379 (ISBN)
Public defence
2024-01-26, Aula Biologica - BIO.E.203, Biologihuset, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2023-12-21 Created: 2023-12-18 Last updated: 2023-12-19Bibliographically approved

Open Access in DiVA

fulltext(12024 kB)12 downloads
File information
File name FULLTEXT01.pdfFile size 12024 kBChecksum SHA-512
8c3bac96af7b9d52d0c5c7a1d0229f20ad8e16968e4966437271d7248a14a04b140fca9b311b5f4a4e2bf2fa5175523391b206121daa2436e9bb3962fa359641
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMedScopus

Authority records

Kahsay, AbrahaDennhag, NilsLiu, Jing-XiaNord, Hannavon Hofsten, JonasDomellöf, Fatima Pedrosa

Search in DiVA

By author/editor
Kahsay, AbrahaDennhag, NilsLiu, Jing-XiaNord, Hannavon Hofsten, JonasDomellöf, Fatima Pedrosa
By organisation
Department of Integrative Medical Biology (IMB)Ophthalmology
In the same journal
Investigative Ophthalmology and Visual Science
Ophthalmology

Search outside of DiVA

GoogleGoogle Scholar
Total: 12 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 132 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf