Evidence that nebulin is a protein‐ruler in muscle thin filaments

Labeit, Siegfried; Gibson, Toby J.; Lakey, Anne F.; Leonard, Kevin; Zeviani, Massimo; Knight, Peter J.; Wardale, John; Trinick, John

doi:10.1016/0014-5793(91)80503-u

Cited by 196 publications

(207 citation statements)

References 21 publications

Supporting

Mentioning

195

Contrasting

Unclassified

Order By: Relevance

“…4). This repeating pattern is consistent with the human nebulin sequence previously reported [ 13,141. We find that 69% of the amino acid residues are identical in 80% of the super repeats encoded by the mouse nebulin contiguous sequences (Fig.…”

Section: Resultssupporting

confidence: 92%

cDNA Cloning of Mouse Nebulin Evidence that the Nebulin‐Coding Sequence is Highly Conserved Among Vertebrates

Zhang

Luo

Herrera

et al. 1996

European Journal of Biochemistry

View full text Add to dashboard Cite

Nebulin is a family of giant myofibrillar proteins with molecular masses ranging over 700-900 kDa. Using a human nebulin cDNA probe, we isolated three nebulin cDNA clones from a mouse skeletal muscle cDNA library. These three clones, labeled 8c, 7a and 4b, carry inserts of 2.0, 3.0 and 3.5 kb, respectively. In Northern blots, each insert detected the same =2S kb message from skeletal muscle as the human nebulin probe, while detecting no messages from cardiac muscle. Sequence data in combination with reverse-transcriptase PCR indicates that clones 7a and 8c overlap to form 4076 bp contiguous sequence. Alignment with the published full-length human nebulin sequence indicates that clone 4b overlaps with clone 7a over 1596 bp. However, after the first 798-bp overlap, the sequence of these two mouse nebulin clones diverge, suggesting that they derive from distinct transcripts encoding isoforms of mouse nebulin. The mouse nebulin clones encode a series of =24S-residue super repeats, each of which can be subdivided into seven =3S-residue, weakly repeating modules centered around a conserved tyrosine residue, consistent with the human nebulin sequence. The mouse nebulin clones align along the central third of the full-length human sequence, corresponding to super repeats 8-16 of the 22 super repeats found in human nebulin. The translated sequence is greater than 90 % identical to the human sequence, with the exception of a 200-amino-acid region at the C-terminus of clone 4b, which is less than 60% identical. In genomic Southern blots, a mouse nebulin probe detected a homologous sequence in a wide variety of vertebrate species under stringent conditions. However, no significant hybridization was observed to genomic DNA from invertebrates and microorganisms, even under very low stringency. The sequence and Southern-blot data suggest that the nebulin sequence is highly conserved among vertebrate species.

show abstract

Section: Resultssupporting

confidence: 92%

cDNA Cloning of Mouse Nebulin Evidence that the Nebulin‐Coding Sequence is Highly Conserved Among Vertebrates

Zhang

Luo

Herrera

et al. 1996

European Journal of Biochemistry

View full text Add to dashboard Cite

show abstract

“…The giant protein nebulin is a skeletal muscle-specific binding partner of Tmod1 and has been proposed to act together with Tmods to regulate skeletal muscle thin filament lengths (Kruger et al, 1991;Labeit et al, 1991;McElhinny et al, 2001). Although loss of Tmod1 did not affect myofibril assembly, we reasoned that nebulin localization might be perturbed in Tmod1 /Tg+ embryonic muscle.…”

Section: Tmod1 Is Dispensable For Skeletal Muscle Development Myofibmentioning

confidence: 95%

“…Mammalian skeletal muscle contains nebulin, a giant rodlike protein that coextends with actin along thin filaments (McElhinny et al, 2003). Nebulin has been proposed to be a molecular ruler that determines the position of Tmod relative to the Z-line, thereby specifying thin filament length (Kruger et al, 1991;Labeit et al, 1991;McElhinny et al, 2001; for review see Littlefield and Fowler, 2008). However, recent evidence challenges this model because nebulin does not coextend with actin along the entire thin filament (Castillo et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Tropomodulin isoforms regulate thin filament pointed-end capping and skeletal muscle physiology

Gokhin¹,

Lewis²,

McKeown³

et al. 2010

J Gen Physiol

View full text Add to dashboard Cite

“…In addition to Tn and Tm, thin filaments of vertebrate skeletal muscle also contain nebulin (3). Nebulin is a giant filamentous protein that spans the entire thin filament, with its C terminus anchored in the Z-disk and its N-terminal region located near the thin filament pointed end (4,5). The majority of the nebulin sequence is composed of ϳ35-amino acid modules, with the central module 9 (M9) and module 162 (M162) modules arranged into seven-module super-repeats (6 -8).…”

mentioning

confidence: 99%

Nebulin Alters Cross-bridge Cycling Kinetics and Increases Thin Filament Activation

Chandra

Mamidi

Ford

et al. 2009

Journal of Biological Chemistry

129

View full text Add to dashboard Cite

Nebulin is a giant filamentous F-actin-binding protein (ϳ800 kDa) that binds along the thin filament of the skeletal muscle sarcomere. Nebulin is one of the least well understood major muscle proteins. Although nebulin is usually viewed as a structural protein, here we investigated whether nebulin plays a role in muscle contraction by using skinned muscle fiber bundles from a nebulin knock-out (NEB KO) mouse model. We measured force-pCa (؊log[Ca 2؉ ]) and force-ATPase relations, as well as the rate of tension re-development (k tr ) in tibialis cranialis muscle fibers. To rule out any alterations in troponin (Tn) isoform expression and/or status of Tn phosphorylation, we studied fiber bundles that had been reconstituted with bacterially expressed fast skeletal muscle recombinant Tn. We also performed a detailed analysis of myosin heavy chain, myosin light chain, and myosin light chain 2 phosphorylation, which showed no significant differences between wild type and NEB KO. Our mechanical studies revealed that NEB KO fibers had increased tension cost (5.9 versus 4.4 pmol millinewtons ؊1 mm ؊1 s ؊1 ) and reductions in k tr (4.7 versus 7.3 s ؊1 ), calcium sensitivity (pCa 50 5.74 versus 5.90), and cooperativity of activation (n H 3.64 versus 4.38). Our findings indicate the following: 1) in skeletal muscle nebulin increases thin filament activation, and 2) through altering cross-bridge cycling kinetics, nebulin increases force and efficiency of contraction. These novel properties of nebulin add a new level of understanding of skeletal muscle function and provide a mechanism for the severe muscle weakness in patients with nebulin-based nemaline myopathy.Muscle contraction is based on cyclic interactions between the myosin cross-bridges that are part of the thick filaments and actin, the major protein of the thin filament (1). The thin filament contains troponin C (TnC), 2 troponin I (TnI), and troponin T (TnT), which together make up the troponin (Tn) complex. The Tn complex and tropomyosin (Tm) together participate in the calcium-dependent regulation of thin filament activation (2). In addition to Tn and Tm, thin filaments of vertebrate skeletal muscle also contain nebulin (3). Nebulin is a giant filamentous protein that spans the entire thin filament, with its C terminus anchored in the Z-disk and its N-terminal region located near the thin filament pointed end (4, 5). The majority of the nebulin sequence is composed of ϳ35-amino acid modules, with the central module 9 (M9) and module 162 (M162) modules arranged into seven-module super-repeats (6 -8). This arrangement enables a single nebulin module to interact with a single actin monomer, and each nebulin super-repeat to associate with a single Tm⅐Tn complex (8 -10). Previous work has shown that nebulin plays structural roles (11,12), and this work is focused on the role of nebulin in regulating muscle contraction.Evidence for the role of nebulin in regulating thin filament activation has been obtained in the following: 1) in in vitro studies that showed that nebul...

show abstract

Evidence that nebulin is a protein‐ruler in muscle thin filaments

Cited by 196 publications

References 21 publications

cDNA Cloning of Mouse Nebulin Evidence that the Nebulin‐Coding Sequence is Highly Conserved Among Vertebrates

cDNA Cloning of Mouse Nebulin Evidence that the Nebulin‐Coding Sequence is Highly Conserved Among Vertebrates

Tropomodulin isoforms regulate thin filament pointed-end capping and skeletal muscle physiology

Nebulin Alters Cross-bridge Cycling Kinetics and Increases Thin Filament Activation

Contact Info

Product

Resources

About