Linked Life Data

12878677

Source:http://linkedlifedata.com/resource/pubmed/id/12878677

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 17
pubmed:dateCreated
2003-7-24
pubmed:abstractText
The M-line and its associated creatine kinase (CK) M-isoform (CK-M) are ubiquitous features of skeletal and cardiac muscle. The M-line maintains myosin myofilaments in register, links the contractile apparatus to the cytoskeleton for external force transfer and localizes CK-based energy storage and transfer to the site of highest ATP demand. We establish here that the muscle group responsible for movements of the eye, extraocular muscle (EOM), is divergent from other striated muscles in lacking both an M-line and its associated CK-M. Although an M-line forms during myogenesis, both in vivo and in vitro, it is actively repressed after birth. Transcripts of the major M-line structural proteins, myomesin 1 and myomesin 2, follow the same pattern of postnatal downregulation, while the embryonic heart-specific EH-myomesin 1 transcript is expressed early and retained in adult eye muscle. By immunocytochemistry, myomesin protein is absent from adult EOM sarcomeres. M-line suppression does not occur in organotypic co-culture with oculomotor motoneurons, suggesting that the mechanism for suppression may lie in muscle group-specific activation or workload patterns experienced only in vivo. The M-line is, however, still lost in dark-reared rats, despite the developmental delay this paradigm produces in the visuomotor system and EOMs. EOM was low in all CK isoform transcripts except for the sarcomeric mitochondrial (Ckmt2) isoform. Total CK enzyme activity of EOM was one-third that of hindlimb muscle. These findings are singularly unique among fast-twitch skeletal muscles. Since EOM exhibits isoform diversity for other sarcomeric proteins, the M-line/CK-M divergence probably represents a key physiological adaptation for the unique energetics and functional demands placed on this muscle group in voluntary and reflexive eye movements.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-0949
pubmed:author
pubmed:issnType
Print
pubmed:volume
206
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3101-12
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:12878677-Adaptation, Physiological, pubmed-meshheading:12878677-Amino Acid Sequence, pubmed-meshheading:12878677-Animals, pubmed-meshheading:12878677-Creatine Kinase, pubmed-meshheading:12878677-Creatine Kinase, MM Form, pubmed-meshheading:12878677-DNA Primers, pubmed-meshheading:12878677-Immunohistochemistry, pubmed-meshheading:12878677-Isoenzymes, pubmed-meshheading:12878677-Molecular Sequence Data, pubmed-meshheading:12878677-Muscle Proteins, pubmed-meshheading:12878677-Oculomotor Muscles, pubmed-meshheading:12878677-Protein Structure, Secondary, pubmed-meshheading:12878677-Rats, pubmed-meshheading:12878677-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:12878677-Sarcomeres, pubmed-meshheading:12878677-Sequence Alignment, pubmed-meshheading:12878677-Sequence Analysis, DNA
pubmed:year
2003
pubmed:articleTitle
Postnatal suppression of myomesin, muscle creatine kinase and the M-line in rat extraocular muscle.
pubmed:affiliation
Department of Ophthalmology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, OH 44106, USA. jdp7@po.cwru.edu
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't