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(Investigative Ophthalmology and Visual Science. 2004;45:4233-4239.)
© 2004 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.04-0456
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Laminin Isoforms in Human Extraocular Muscles

Daniel Kjellgren,1 Lars-Eric Thornell,2,3 Ismo Virtanen,4 and Fatima Pedrosa-Domellöf1,2,3

1From the Departments of Clinical Science, Section of Ophthalmology and 2Integrative Medical Biology, Section of Anatomy, University of Umeå, Umeå, Sweden; the 3Center for Musculoskeletal Research, University of Gävle, Umeå, Sweden; and the 4Department of Anatomy, Institute of Biomedicine, University of Helsinki, Helsinki, Finland.


   Abstract
Top
 Abstract
Materials and Methods
 Results
 Discussion
 References
 
PURPOSE. To determine the laminin isoform composition of the basement membranes (BMs) in the human extraocular muscles (EOMs) and relate it to the fact that EOMs are spared in laminin {alpha}2-chain–deficient congenital muscular dystrophy.

METHODS. Samples from adult human EOMs and limb muscle were processed for immunocytochemistry, with monoclonal antibodies against laminin chains (Ln) {alpha}1 to -5, ß1 and -2, and {gamma}1. Neuromuscular junctions (NMJs) were identified with acetylcholinesterase reaction. The capillary density was measured in sections stained with anti-Ln{alpha}5.

RESULTS. The extrasynaptic BM of the EOM muscle fibers contained Ln{alpha}2, -ß1, -ß2, and -{gamma}1, and, in contrast to limb muscle, it also contained Ln{alpha}4 and -{alpha}5, to some extent. The distinct laminin composition of the EOMs was confirmed by the presence of Lutheran protein, an {alpha}5-chain–specific receptor not found in limb muscle. At the NMJs, there was increased expression of Ln{alpha}4 and expression of Ln{alpha}2, -{alpha}5, -ß1, -ß2, and -{gamma}1 was also maintained. The capillary density was very high (1050 ± 190 capillaries/mm2) in the EOMs and significantly (P < 0.05) higher in the orbital (1170 ± 180 capillaries/mm2) than in the global (930 ± 110 capillaries/mm2) layer.

CONCLUSIONS. The human EOMs showed important differences in laminin isoform composition and capillary density when compared with human limb muscle and muscles of other species. The presence of additional laminin isoforms other than laminin-2 in the BM of the extrasynaptic sarcolemma could partly explain the sparing of the EOMs in Ln{alpha}2-deficient congenital muscular dystrophy.

The extraocular muscles (EOMs) are structurally and functionally highly specialized1 2 3 4 5 6 7 8 9 and have therefore been considered a separate skeletal muscle class or allotype.10 Microscopically, the EOMs are characterized by small muscle fibers of several types that are loosely arranged in a bed of abundant connective tissue with a rich supply of nerves and vessels. Another particular feature is the presence of multiple innervation in some fiber groups. The most striking feature of the EOMs, however, is their distinct behavior in disease. They are selectively spared in congenital myopathies such as Duchenne muscle dystrophy and dystrophinopathies and are selectively involved in other neuromuscular disorders, such as oculopharyngeal muscular dystrophy, Miller-Fischer syndrome, and Grave’s ophthalmopathy.

The uniqueness of the EOM allotype has been elucidated recently at the whole-muscle RNA level in rodent9 11 12 13 14 and monkey.15 However, further characterization of the molecular basis of the EOM allotype at the cellular level is needed before we can fully understand the structural organization that makes these muscles so unique, in particular with respect to their selective sparing/involvement in neuromuscular diseases. Substantial data16 17 suggest that the selective sparing of the EOMs in dystrophic mdx mice relies on constitutive properties (most likely involving the ECM and the cytoskeleton), rather than on molecular adaptations to the absence of dystrophin, and thereby emphasize the need of a thorough characterization of the EOM allotype at the structural level. The purpose of the present study was to characterize the composition of the basement membranes in the EOMs with respect to content of laminin chains, important components of the extracellular matrix (ECM) that play both structural and signaling roles.18 19 20 21

Skeletal muscle fibers are surrounded by a continuous basement membrane (BM) that includes the folds of the neuromuscular junction (NMJ) and the myotendinous junction (MTJ). The major noncollagenous components of the BM are the laminins.

Laminins are glycoprotein trimers composed of an {alpha}-, a ß-, and a {gamma}-chain. There are five different laminin (Ln){alpha}-chains ({alpha}1-5), 3 Ln ß-chains (ß1-3) and 3 Ln {gamma}-chains ({gamma}1-3) known at present. Different combinations of the chains can form >14 laminin isoforms.22 The different laminin chains have complex patterns of expression that in some cases are tissue specific and developmentally regulated. The laminins interact with the underlying cells via cell surface receptors, such as integrins and dystroglycan complex, and thereby influence cell fate and gene expression and participate in cell–ECM communication. An intact link between the ECM and the cytoskeleton is necessary for the structural integrity of muscle fibers. Defects in any of the elements of this link (e.g., collagen, laminin, sarcoglycans, integrin, dystrophin, desmin) are known to cause muscle dystrophy.23 24 25 26 27 28

The predominant laminin in the BM of muscle and peripheral nerve is Ln-2 ({alpha}2ß1{gamma}1).29 30 Mutations in the Ln{alpha}2-chain in humans lead to congenital muscular dystrophy, characteristically affecting the limb and trunk muscles, but sparing the EOMs.24 31

The {alpha}3-chain of laminin is characteristically present in the epithelial BMs, and in muscle it is found only in the blood vessels.21 32 Ln{alpha}4 is present in capillaries, in muscle blood vessels and, during fetal development, it also surrounds myotubes.33 In contrast, Lnß1 and Ln{gamma}1 are rather ubiquitous.19

Data on the composition of the BMs and on the distribution of laminin chains on the human EOMs are lacking, to the best of our knowledge. However, such data may be relevant to elucidate further the selective sparing of the EOMs in muscular dystrophies involving elements of the ECM-dystroglycan complex34 35 as well as to characterize some of the special features of the EOM allotype (e.g., multiple endplates on a single muscle fiber and rich vascularization).


   Materials and Methods
Top
 Abstract
 Materials and Methods
Results
 Discussion
 References
 
Sixteen EOM samples were obtained either at autopsy or after enucleation, from seven male donors (ages 17, 27, 34, 54, 82, 86, and 87 years) and one female donor (age 26 years) with no previously known neuromuscular disease. Six samples were taken from the rectus superior muscle, five from the rectus lateralis muscle, two from the rectus inferior, two from the rectus medialis, and one from the obliquus superior muscle. Samples from the biceps brachi and the first lumbrical and quadriceps muscles were also obtained at autopsy and used for comparison. All samples were obtained according to the ethical recommendations of the Swedish Transplantation Law, with the approval of the Medical Ethics Committee, Umeå University, and in compliance with the Declaration of Helsinki.

The samples were mounted on cardboard and rapidly frozen in propane chilled with liquid nitrogen and stored at –80°C until used. Series of 80 cross sections, 5 µm thick, were cut from each muscle sample on a cryostat (Reichert-Jung, Vienna, Austria).

Histochemistry
NMJs were detected histochemically using the acetylcholinesterase reaction.36

Immunocytochemistry
The sections were processed for immunocytochemistry with previously characterized monoclonal antibodies (mAbs), each recognizing a different laminin chain (Table 1) . An mAb against tenascin was used to confirm the location of the MTJs.44 The tissue sections were air dried for 15 to 30 minutes, rehydrated in PBS for 5 minutes, and incubated with 5% normal rabbit serum (DakoCytomation, Glostrup, Denmark) for 15 minutes, to inhibit unspecific staining. The sections were then incubated overnight with the appropriate primary antibody at 4°C. The primary antibodies were diluted in PBS with 0.1% bovine serum albumin. Thereafter, the sections were washed in 0.01 M PBS and again incubated with normal rabbit serum for 15 minutes, followed by incubation with rabbit anti-mouse IgG (DakoCytomation) for 30 minutes at room temperature. After they were washed in PBS for 15 minutes, the sections were incubated with peroxidase mouse antiperoxidase complex (DakoCytomation) for 30 minutes and then washed in PBS for 15 minutes. Development of peroxidase was obtained by applying a solution containing 1 mg/mL of diaminobenzidine and H2O2 for 5 to 10 minutes, followed by rinsing in running water for 5 minutes. Finally, the sections were dehydrated in graded concentrations of ethanol and mounted (Pertex; Histolab Products AB, Gothenburg, Sweden). Control sections were processed as just described, except that the primary antibody was omitted. No staining was observed in the control sections. The sections were photographed under a microscope equipped with a charge-coupled device (CCD) camera (Nikon, Tokyo, Japan).


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  		TABLE 1. Data on the Antibodies Used for Immunocytochemistry

 
Capillaries
The number of capillaries was determined in representative areas of the orbital and global layer in sections from 5 EOM samples, stained with the antibody recognizing Ln{alpha}5-chain. The size of the areas chosen was 500 x 500 µm, except where muscle fascicles were too thin, and 200 x 200-µm areas were chosen instead. Altogether, 11 areas from the global layer and 14 areas from the orbital layer were chosen. All vessels with an outer diameter <15 µm were assumed to be capillaries according to the definition put forward by Jerusalem.46 The mean capillary density was calculated for both the global and the orbital layer in all five muscles. The significance of the mean difference between the two layers was then analyzed, using a two-sample t-test (two-tailed). A total of 4861 capillaries (1977 in the global layer and 2884 in the orbital layer) were counted.


   Results
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 Abstract
 Materials and Methods
 Results
Discussion
 References
 
Extraocular Muscles
The staining patterns observed were identical in the orbital and global layers. No evidence of variation in the staining patterns was noted between the middle and the distal portions of the EOMs.

Anti-Ln{alpha}1 did not show immunoreactivity in any tissue structure in the sampled sections (Fig. 1A) .



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  		FIGURE 1. Photomicrographs of six cross sections from the global layer of a rectus superior muscle immunolabeled with (A) anti-Ln{alpha}1, (B) anti-Ln{alpha}2, (C) anti-Ln{alpha}3, (D) anti-Ln{alpha}4, (E) anti-Ln{alpha}5, and (F) anti-Lnß2. A nerve (N) and an arteriole (A) are indicated. Anti-Ln{alpha}1 did not label any structure, anti-Ln{alpha}2 labeled fiber contours and nerves, and anti-Ln{alpha}3 labeled the arteriole only. Anti-Ln{alpha}4 labeled fiber contours weakly and capillaries and the nerve strongly. Anti-Ln{alpha}5 labeled fiber contours weakly and the capillaries, arterioles, and the perineurium more intensely, whereas anti-Lnß2 labeled all the structures.

 
Anti-Ln{alpha}2 immunoreactivity was present in the fiber contours in the extrasynaptic and synaptic regions (Figs. 1B 2B) , and the MTJs (Fig. 3B) . Anti-Ln{alpha}2 also stained the perineurium and endoneurium, but not the blood vessels (Figs. 1B 2B) . Anti-Ln{alpha}3 immunostained the blood vessels but not the capillaries, the muscle fibers, or the nerves in the EOMs (Fig. 1C) . Anti-Ln{alpha}4 labeled the muscle fiber contours weakly extrasynaptically in most samples (Figs. 1D 2C 4) , moderately at the NMJs (Fig. 2C) and MTJs. This mAb also stained the capillaries strongly (Figs. 1D 2C 4) . Both the perineurium and the endoneurium were strongly labeled by anti-Ln{alpha}4 (Figs. 1D 2C 4) .



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  		FIGURE 2. Photomicrographs of five cross sections (A, B, D–F) from a rectus superior and one from a rectus lateralis (C) muscle treated to show (A) acetylcholinesterase (AchE) activity or immunostained with (B) anti-Ln{alpha}2, (C) anti-Ln{alpha}4, (D) anti-Ln{alpha}5, (E) anti-Lnß1, and (F) anti-Lnß2. Arrows: NMJs detected by their AChE activity. N, nerves. The staining intensity was higher with anti-Ln{alpha}4 at the NMJs (arrows) than in the extrasynaptic portion of the fibers (C).

 


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  		FIGURE 3. Transverse sections from the MTJ area of a rectus superior (A–D, F) and a rectus lateralis (E) muscle immunostained with (A) anti-tenascin, (B) anti-Ln{alpha}2, (C) anti-Ln{alpha}5, (D) anti-Lnß1, (E) anti-Lnß2, and (F) anti-Ln{gamma}1. Arrows: some of the MTJs.

 


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  		FIGURE 4. Photomicrographs of a rectus lateralis muscle and a lumbricalis muscle from the same subject mounted and sectioned together and immunostained with anti-Ln{alpha}4. The muscle fiber contours were labeled in the EOM, but not in the lumbrical muscle.

 
Anti-Ln{alpha}5 immunoreactivity was moderate in the extrasynaptic fiber contours (Fig. 1E) and was slightly increased at the MTJs (Fig. 3C) but not at the NMJs (Fig. 2D) . The capillaries and other blood vessels were strongly labeled with anti-Ln{alpha}5 (Figs. 1E 2D 5) . The perineurium was clearly more strongly stained than the endoneurium (Figs. 1E 2D) .



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  		FIGURE 5. Photomicrographs of sections from a biceps brachi muscle (A, C) and a rectus medialis muscle (B, D) immunostained with anti-Lnß2 (A, B) or anti-Ln{alpha}5 (C, D). All the fiber contours in both muscles were immunostained with anti-Lnß2, whereas this isoform is absent from extrasynaptic BM of rodent skeletal muscle.20 Only the BM of the fibers in the rectus medialis muscle was labeled with anti-Ln{alpha}5. A much higher capillary density in the rectus medialis was demonstrated by staining with anti-Ln{alpha}5.

 
Anti-Lnß1 (Figs. 2E 3D) , anti-Lnß2 (Figs. 1F 2F 3E 5B) and anti-Ln{gamma}1 (Fig. 3F) immunostained muscle fiber contours, capillaries, other blood vessels, perineurium, and endoneurium strongly. Anti-Lnß2 labeled all fiber contours even at a very low concentration (mAb diluted 1:40,000) in the EOMs and in the limb muscle samples (Figs. 5A 5B) . The staining intensity appeared higher at the MTJs with anti-Lnß2 (Fig. 3E) and anti-Ln{gamma}1 (Fig. 3F) and, to a lesser degree, with anti-Lnß1 (Fig. 3D) . The BM was as strongly labeled at the NMJs as it was extrasynaptically with anti-Lnß1, anti-Lnß2, and anti-Ln{gamma}1 (Fig. 2) .

Limb Muscle
The BM of the limb muscle fibers was either unlabeled (Fig. 5C) or weakly labeled with anti-Ln{alpha}5. We have observed variation in the amount of staining seen around muscle fibers of different skeletal muscles (Thornell L-E, unpublished observation, 1999) indicating intermuscle and interindividual variation in the amounts of the Ln{alpha}5 present. We tested the hypothesis that the EOMs differ from limb muscles in {alpha}5 chain composition by using an antibody against Lutheran protein. Lutheran blood group glycoprotein is a transmembrane receptor for the {alpha}5-chain,47 48 present on the surface of cells and epithelia in various tissues that also contain {alpha}5-chain.

Anti-Lutheran immunostained the contours of the fibers in the EOMs only, whereas it labeled capillaries, blood vessels and perineurium in both the EOMs and limb muscle (Fig. 6) .



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  		FIGURE 6. Photomicrographs of a rectus lateralis muscle and a lumbricalis muscle from the same subject mounted and sectioned together and immunostained with anti-Lu. The mAb reacted with the blood vessels of both muscles but only with the BM of the muscle fibers in the EOM.

 
The laminin chain composition of human MTJs37 and NMJs30 have been determined previously. In addition, we observed staining of the NMJs with anti-LN{alpha}4 in adult limb muscle (Fig. 7) .



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  		FIGURE 7. Photomicrographs of NMJs (arrows) in limb muscle identified by the localized acetylcholinesterase activity (A) and immunostained with anti-Ln{alpha}4 (B).

 
Capillary Density
The capillary density in the EOMs, determined in sections processed with anti-Ln{alpha}5, was 1050 ± 190 capillaries/mm2. The capillary density was significantly (P < 0.05) higher in the orbital layer (1170 ± 180 capillaries/mm2) than in the global layer (930 ± 110 capillaries/mm2).


   Discussion
Top
 Abstract
 Materials and Methods
 Results
 Discussion
References
 
The present study showed important differences in BM laminin isoform composition and capillary density between the human EOMs, human limb muscle, and muscles of other species. The presence of additional laminin isoforms other than laminin-2 in the BM of the extrasynaptic sarcolemma could partly explain the sparing of the EOMs in Ln{alpha}2-deficient congenital muscular dystrophy.

Extrasynaptic BM
The present immunohistochemical data indicate that the extrasynaptic BM of adult human EOM muscle fibers contained Ln{alpha}2, -ß1, -ß2, and -{gamma}1, and, to some extent, Ln{alpha}4 and -{alpha}5. Lnß2 has traditionally been regarded as being absent from the extrasynaptic BM.20 In the present study, Lnß2 was detected with mAb C4, an mAb that has been suggested to cross-react with Lnß1 at high concentrations.49 The mAb C4 was diluted up to 1:40,000 in the present work, and the staining delineating EOM and limb muscle fibers remained remarkably stable, refuting a possible cross-reaction. Furthermore, Lnß2 was also detected in the extrasynaptic BM of human limb muscle fibers, in a previous study.50 Therefore, there is an important interspecies difference between human and rodent muscle with respect to the presence of Lnß2 in the extrasynaptic BM.

In adult human skeletal and cardiac muscle the main isoform of the extrasynaptic BM is laminin-2 ({alpha}2ß1{gamma}1) formerly known as merosin.19 20 29 33 37 Ln{alpha}140 and -{alpha}3 chains41 have not been detected in the BM of human muscle fibers. Ln{alpha}4 chain is found in adult human smooth and cardiac muscle, but not in mature skeletal muscle fibers.33 Ln{alpha}5 chain is present in epithelial BM and in endothelial tissues including capillaries but only at the NMJs of muscle fibers. Thus, the Ln{alpha}2 chain is the only {alpha}-chain normally found extrasynaptically in human limb muscle. Ln{alpha}2 is a chain of laminin-2 ({alpha}2ß1{gamma}1), -4 ({alpha}2ß2{gamma}1), and -12 ({alpha}2ß1{gamma}3). However, Ln{gamma}3 is only present in epithelia and peripheral nerves,52 which implies that laminin-2 and -4 are the only laminin isoforms of extrajunctional BM in skeletal muscle. The expression of Ln{alpha}4 and -{alpha}5 in the extrasynaptic BM of human EOM fibers described herein suggests the presence of additional laminin isoforms in the BM of these fibers. Ln{alpha}4 and -{alpha}5 are chains of laminin-8 ({alpha}4ß1{gamma}1), -9 ({alpha}4ß2{gamma}1), -10 ({alpha}5ß1{gamma}1), and -11 ({alpha}5ß2{gamma}1), and since LNß1, -ß2 and -{gamma}1 were detected, theoretically all these laminins could be present in the BM of EOM fibers. The presence of Ln{alpha}5 chain receptor Lutheran on the surface of the muscle fibers of the human EOMs and its absence in limb muscle strongly confirms the distinct structural composition of the BMs of the human eye muscles.

This complex laminin isoform composition is a possible explanation for the sparing of EOMs in merosin-deficient congenital muscular dystrophy (CMD). CMDs are characterized by postnatal hypotonia, contractures, muscle weakness, and brain involvement.52 Approximately 50% of the CMD cases are caused by mutations in LAMA2, the gene encoding the Ln{alpha}2 chain, resulting in complete or partial Ln{alpha}2 (merosin) deficiency.24 31 Loss of BM stability and degradation of the extracellular framework has been demonstrated in Ln{alpha}2-deficient mice.53 The EOMs are spared in this disease, but the exact mechanism for this is not completely known.16 The presence of additional laminin isoforms, such as laminin-8, -9, -10, and -11 in the BM of the EOMs may be crucial for the maintenance of muscle fiber integrity in the absence of Ln{alpha}2 chain.

The presence of Ln{alpha}4, an isoform typical of developing myotubes,33 in adult EOMs adds to the list of developmental protein isoforms (e.g., embryonic and fetal myosin heavy chains)7 54 that these muscles retain and that are likely to be of major importance for their unique properties.

Neuromuscular Junction
At the NMJs we found increased expression of Ln{alpha}4 and also that expression of Ln{alpha}2, -{alpha}5, -ß1, -ß2, and -{gamma}1 was maintained. In mice, laminin-4 ({alpha}2ß2{gamma}1), -9 ({alpha}4ß2{gamma}1), and -11 ({alpha}5ß2{gamma}1) are present in the synaptic BM, and laminin-2 ({alpha}2ß1{gamma}1) and -8 ({alpha}4ß1{gamma}1) are found in the BM of the adjoining Schwann cells.20 Ln{alpha}4 has not been detected in adult human limb muscle BM, although it is present during development,33 but Ln{alpha}5 is expressed at the NMJs. Herein, we report the novel presence of Ln{alpha}4, even in the NMJ of human limb muscle. Ln{alpha}4 is crucial for proper synaptic localization.55

Myotendinous Junctions
The MTJs contained Ln{alpha}2, -{alpha}5, -ß1, -ß2, and -{gamma}1 as described for skeletal muscle.37 50 56 Ln{alpha}1 is found in developing MTJs but not for sure in adult human MTJs, which makes Ln{alpha}1 also a developmental isoform.37 We could not detect Ln{alpha}1 in MTJs of the adult human EOMs. Thus, the EOMs show an independent regulation of the developmental laminin chains {alpha}1 and {alpha}4, given that Ln{alpha}1 was absent in the adult EOM, but Ln{alpha}4 was found in the extrasynaptic BM, as in developing muscle.33

Nerves and Blood Vessels
The perineurium was labeled by mAb against Ln{alpha}2, -{alpha}4, -{alpha}5, -ß1, -ß2, and -{gamma}1. The endoneurium stained strongly with all these antibodies except anti-Ln{alpha}5, which only stained the endoneurium moderately. In mice, the endoneurium contains laminin-2 ({alpha}2ß1{gamma}1) and the perineurium laminin-9 ({alpha}4ß2{gamma}1) and -10 ({alpha}5ß1{gamma}1).20 In a large human peripheral nerve it has recently been demonstrated that the endoneurium contains Ln{alpha}2, -{alpha}4, -ß1, and -{gamma}1, whereas the perineurium displays Ln{alpha}3, -{alpha}4, -{alpha}5, -ß1, -ß2, and -{gamma}1.32 Our findings differ from those of Wallquist et al.32 in that we found Lnß2 in the endoneurium and no trace of Ln{alpha}3 in the perineurium in the EOMs. Therefore, there seems to be a difference between the laminin composition of large peripheral nerves (in this case the sural nerve) and small nerves close to their endpoints in the EOMs.

The capillaries were stained by mAbs against Ln{alpha}4, -{alpha}5, -ß1, and -ß2. Larger blood vessels were in addition also stained with the mAb against Ln{alpha}3, in accordance with previous results.32

The capillary were was higher in the EOMs than in any other previously reported human muscle—for example biceps brachi (440 ± 118 capillaries/µm2) and first dorsal interosseus (375 ± 86 capillaries/µm2), including the richly vascularized jaw muscles—for example, the masseter (813 ± 81 capillaries/µm2).57 The significantly higher capillary density of the orbital layer is in line with the higher oxidative enzyme activity58 and higher overall vascular density of the orbital layer.59


   Acknowledgements
 
The authors thank Margaretha Enerstedt for excellent technical assistance, Mona Lindström and Lena Carlsson for help in preparing the figures, and Per Stål for expertise in the capillary field.


   Footnotes
 
Supported by grants from Stiftelsen KMA, the Swedish Society for Medical Research, the Swedish Research Council, and the Medical Faculty of Umeå University.

Submitted for publication April 20, 2004; revised May 18, 2004; accepted June 9, 2004.

Disclosure: D. Kjellgren, None; L.-E. Thornell, None; I. Virtanen, None; F. Pedrosa-Domellöf, None

The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Corresponding author: Fatima Pedrosa-Domellöf, Department of Integrative Medical Biology, Section of Anatomy, Umeå University, S-901 87 Umeå, Sweden; fatima.pedrosa-domellof{at}anatomy.umu.se.


   References
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 Abstract
 Materials and Methods
 Results
 Discussion
 References
 

  1. Chiarandini DJ, Davidowitz J. Structure and function of extraocular muscle fibers. Curr Top Eye Res. 1979;1:91–142.[Medline][Order article via Infotrieve]
  2. Hoh JF. Muscle fiber types and function. Curr Opin Rheumatol. 1992;4:801–808.[Medline][Order article via Infotrieve]
  3. Pachter BR. Rat extraocular muscle. 3. Histochemical variability along the length of multiply-innervated fibers of the orbital surface layer. Histochemistry. 1984;80:535–538.[ISI][Medline][Order article via Infotrieve]
  4. Porter JD, Baker RS. Muscles of a different "color": the unusual properties of the extraocular muscles may predispose or protect them in neurogenic and myogenic disease. Neurology. 1996;46:30–37.[Free Full Text]
  5. Li ZB, Rossmanith GH, Hoh JF. Cross-bridge kinetics of rabbit single extraocular and limb muscle fibers. Invest Ophthalmol Vis Sci. 2000;41:3770–3774.[Abstract/Free Full Text]
  6. Porter JD. Extraocular muscle: cellular adaptations for a diverse functional repertoire. Ann NY Acad Sci. 2002;956:7–16.[Abstract/Free Full Text]
  7. Kjellgren D, Thornell LE, Andersen J, Pedrosa-Domellof F. Myosin heavy chain isoforms in human extraocular muscles. Invest Ophthalmol Vis Sci. 2003;44:1419–1425.[Abstract/Free Full Text]
  8. Kjellgren D, Ryan M, Ohlendieck K, Thornell L E, Pedrosa-Domellof F. Sarco(endo)plasmic reticulum Ca2+ ATPases (SERCA1 and -2) in human extraocular muscles. Invest Ophthalmol Vis Sci. 2003;44:5057–5062.[Abstract/Free Full Text]
  9. Cheng G, Porter JD. Transcriptional profile of rat extraocular muscle by serial analysis of gene expression. Invest Ophthalmol Vis Sci. 2002;43:1048–1058.[Abstract/Free Full Text]
  10. Hoh JF, Hughes S, Hoy JF. Myogenic and neurogenic regulation of myosin gene expression in cat jaw-closing muscles regenerating in fast and slow limb muscle beds (published correction appears in J Muscle Res Cell Motil. 1988;9:567 and 1992;13:126). J Muscle Res Cell Motil. 1988;9:59–72.[CrossRef][ISI][Medline][Order article via Infotrieve]
  11. Porter JD, Khanna S, Kaminski HJ, et al. Extraocular muscle is defined by a fundamentally distinct gene expression profile. Proc Natl Acad Sci USA. 2001;98:12062–12067.[Abstract/Free Full Text]
  12. Porter JD, Merriam AP, Leahy P, et al. Temporal gene expression profiling of dystrophin-deficient (mdx) mouse diaphragm identifies conserved and muscle group-specific mechanisms in the pathogenesis of muscular dystrophy. Hum Mol Genet. 2004;13:257–269.[Abstract/Free Full Text]
  13. Khanna S, Merriam AP, Gong B, Leahy P, Porter JD. Comprehensive expression profiling by muscle tissue class and identification of the molecular niche of extraocular muscle. FASEB J. 2003;17:1370–1372.[Abstract/Free Full Text]
  14. Fischer MD, Gorospe JR, Felder E, et al. Expression profiling reveals metabolic and structural components of extraocular muscles. Physiol Genom. 2002;9:71–84.[Abstract/Free Full Text]
  15. Cheng G, Mustari MJ, Khanna S, Porter JD. Comprehensive evaluation of the extraocular muscle critical period by expression profiling in the dark-reared rat and monocularly deprived monkey. Invest Ophthalmol Vis Sci. 2003;44:3842–3855.[Abstract/Free Full Text]
  16. Porter JD, Karathanasis P. Extraocular muscle in merosin-deficient muscular dystrophy: cation homeostasis is maintained but is not mechanistic in muscle sparing. Cell Tissue Res. 1998;292:495–501.[CrossRef][ISI][Medline][Order article via Infotrieve]
  17. Porter JD, Merriam AP, Khanna S, et al. Constitutive properties, not molecular adaptations, mediate extraocular muscle sparing in dystrophic mdx mice. FASEB J. 2003;17:893–895.[Abstract/Free Full Text]
  18. Patton BL, Miner JH, Chiu AY, Sanes JR. Distribution and function of laminins in the neuromuscular system of developing, adult, and mutant mice. J Cell Biol. 1997;139:1507–1521.[Abstract/Free Full Text]
  19. Colognato H, Yurchenco PD. Form and function: the laminin family of heterotrimers. Dev Dyn. 2000;218:213–234.[CrossRef][ISI][Medline][Order article via Infotrieve]
  20. Patton BL. Laminins of the neuromuscular system. Microsc Res Tech. 2000;51:247–261.[CrossRef][ISI][Medline][Order article via Infotrieve]
  21. Patarroyo M, Tryggvason K, Virtanen I. Laminin isoforms in tumor invasion, angiogenesis and metastasis. Semin Cancer Biol. 2002;12:197–207.[CrossRef][ISI][Medline][Order article via Infotrieve]
  22. Libby RT, Champliaud MF, Claudepierre T, et al. Laminin expression in adult and developing retinae: evidence of two novel CNS laminins. J Neurosci. 2000;20:6517–6528.[Abstract/Free Full Text]
  23. Bertini E, Pepe G. Collagen type VI and related disorders: Bethlem myopathy and Ullrich scleroatonic muscular dystrophy. Eur J Paediatr Neurol. 2002;6:193–198.[CrossRef][Medline][Order article via Infotrieve]
  24. Tome FM, Evangelista T, Leclerc A, et al. Congenital muscular dystrophy with merosin deficiency. Comptes Rendus de l’Academie des Sciences, Serie III. 1994;317:351–357.
  25. Mayer U, Saher G, Fassler R, et al. Absence of integrin alpha 7 causes a novel form of muscular dystrophy. Nat Genet. 1997;17:318–323.[ISI][Medline][Order article via Infotrieve]
  26. O’Brien KF, Kunkel LM. Dystrophin and muscular dystrophy: past, present, and future. Mol Genet Metab. 2001;74:75–88.[CrossRef][ISI][Medline][Order article via Infotrieve]
  27. Carlsson L, Fischer C, Sjoberg G, Robson RM, Sejersen T, Thornell LE. Cytoskeletal derangements in hereditary myopathy with a desmin L345P mutation. Acta Neuropathol (Berl). 2002;104:493–504.[Medline][Order article via Infotrieve]
  28. Emery AEH. The Muscular Dystrophies. 2001; Oxford University Press Oxford, UK.
  29. Leivo I, Engvall E. Merosin, a protein specific for basement membranes of Schwann cells, striated muscle, and trophoblast, is expressed late in nerve and muscle development. Proc Natl Acad Sci USA. 1988;85:1544–1548.[Abstract/Free Full Text]
  30. Gullberg D, Tiger CF, Velling T. Laminins during muscle development and in muscular dystrophies. Cell Mol Life Sci. 1999;56:442–460.[CrossRef][ISI][Medline][Order article via Infotrieve]
  31. Helbling-Leclerc A, Zhang X, Topaloglu H, et al. Mutations in the laminin alpha 2-chain gene (LAMA2) cause merosin-deficient congenital muscular dystrophy. Nat Genet. 1995;11:216–218.[CrossRef][ISI][Medline][Order article via Infotrieve]
  32. Wallquist W, Patarroyo M, Thams S, et al. Laminin chains in rat and human peripheral nerve: distribution and regulation during development and after axonal injury. J Comp Neurol. 2002;454:284–293.[CrossRef][ISI][Medline][Order article via Infotrieve]
  33. Petajaniemi N, Korhonen M, Kortesmaa J, et al. Localization of laminin alpha4-chain in developing and adult human tissues. J Histochem Cytochem. 2002;50:1113–1130.[Abstract/Free Full Text]
  34. Porter JD, Merriam AP, Hack AA, Andrade FH, McNally EM. Extraocular muscle is spared despite the absence of an intact sarcoglycan complex in gamma- or delta-sarcoglycan-deficient mice. Neuromuscul Disord. 2001;11:197–207.[CrossRef][ISI][Medline][Order article via Infotrieve]
  35. Kaminski HJ, al-Hakim M, Leigh RJ, Katirji MB, Ruff RL. Extraocular muscles are spared in advanced Duchenne dystrophy. Ann Neurol. 1992;32:586–568.[CrossRef][ISI][Medline][Order article via Infotrieve]
  36. Dubowitz V. Muscle Biopsy: A Practical Approach. 1985;39–40. Ballière Tindall Eastbourne, UK.
  37. Pedrosa-Domellof F, Tiger CF, Virtanen I, Thornell LE, Gullberg D. Laminin chains in developing and adult human myotendinous junctions. J Histochem Cytochem. 2000;48:201–210.[Abstract/Free Full Text]
  38. Sewry CA, Uziyel Y, Torelli S, et al. Differential labelling of laminin alpha 2 in muscle and neural tissue of dy/dy mice: are there isoforms of the laminin alpha 2 chain?. Neuropathol Appl Neurobiol. 1998;24:66–72.[ISI][Medline][Order article via Infotrieve]
  39. Rousselle P, Lunstrum GP, Keene DR, Burgeson RE. Kalinin: an epithelium-specific basement membrane adhesion molecule that is a component of anchoring filaments. J Cell Biol. 1991;114:567–576.[Abstract/Free Full Text]
  40. Tiger CF, Champliaud F, Pedrosa-Domellof F, Thornell E, Ekblom P, Gullberg D. Presence of laminin alpha5 chain and lack of laminin alpha1 chain during human muscle development and in muscular dystrophies. J Biol Chem. 1997;272:28590–28595.[Abstract/Free Full Text]
  41. Howeedy AA, Virtanen I, Laitinen L, Gould NS, Koukoulis GK, Gould VE. Differential distribution of tenascin in the normal, hyperplastic, and neoplastic breast. Lab Invest. 1990;63:798–806.[ISI][Medline][Order article via Infotrieve]
  42. Hunter DD, Shah V, Merlie JP, Sanes JR. A laminin-like adhesive protein concentrated in the synaptic cleft of the neuromuscular junction. Nature. 1989;338:229–234.[CrossRef][Medline][Order article via Infotrieve]
  43. Geberhiwot T, Wondimu Z, Salo S, et al. Chain specificity assignment of monoclonal antibodies to human laminins by using recombinant laminin beta1 and gamma1 chains. Matrix Biol. 2000;19:163–167.[CrossRef][ISI][Medline][Order article via Infotrieve]
  44. Gullberg D, Velling T, Sjoberg G, et al. Tenascin-C expression correlates with macrophage invasion in Duchenne muscular dystrophy and in myositis. Neuromuscul Disord. 1997;7:39–54.[CrossRef][ISI][Medline][Order article via Infotrieve]
  45. Parsons SF, Mallinson G, Daniels GL, Green CA, Smythe JS, Anstee DJ. Use of domain-deletion mutants to locate Lutheran blood group antigens to each of the five immunoglobulin superfamily domains of the Lutheran glycoprotein: elucidation of the molecular basis of the Lu(a)/Lu(b) and the Au(a)/Au(b) polymorphisms. Blood. 1997;89:4219–4225.[Abstract/Free Full Text]
  46. Jerusalem F. The microcirculation of muscle. Engel BB eds. Myology. 1986;343–358. McGraw Hill New York.
  47. Parsons SF, Lee G, Spring FA, et al. Lutheran blood group glycoprotein and its newly characterized mouse homologue specifically bind alpha5 chain-containing human laminin with high affinity. Blood. 2001;97:312–320.[Abstract/Free Full Text]
  48. Kikkawa Y, Moulson CL, Virtanen I, Miner JH. Identification of the binding site for the Lutheran blood group glycoprotein on laminin alpha 5 through expression of chimeric laminin chains in vivo. J Biol Chem. 2002;277:44864–44869.[Abstract/Free Full Text]
  49. Cho SI, Ko J, Patton BL, Sanes JR, Chiu AY. Motor neurons and Schwann cells distinguish between synaptic and extrasynaptic isoforms of laminin. J Neurobiol. 1998;37:339–358.[CrossRef][ISI][Medline][Order article via Infotrieve]
  50. Wewer UM, Thornell LE, Loechel F, et al. Extrasynaptic location of laminin beta 2 chain in developing and adult human skeletal muscle. Am J Pathol. 1997;151:621–631.[Abstract]
  51. Koch M, Olson P F, Albus A, et al. Characterization and expression of the laminin gamma3 chain: a novel, non-basement membrane-associated, laminin chain. J Cell Biol. 1999;145:605–618.[Abstract/Free Full Text]
  52. Voit T. Congenital muscular dystrophies: 1997 update. Brain Dev. 1998;20:65–74.[CrossRef][ISI][Medline][Order article via Infotrieve]
  53. Yurchenco PD, Cheng YS, Campbell K, Li S. Loss of basement membrane, receptor and cytoskeletal lattices in a laminin-deficient muscular dystrophy. J Cell Sci. 2004;117:735–742.[Abstract/Free Full Text]
  54. Wieczorek DF, Periasamy M, Butler-Browne GS, Whalen RG, Nadal-Ginard B. Co-expression of multiple myosin heavy chain genes, in addition to a tissue-specific one, in extraocular musculature. J Cell Biol. 1985;101:618–629.[Abstract/Free Full Text]
  55. Patton BL, Cunningham JM, Thyboll J, et al. Properly formed but improperly localized synaptic specializations in the absence of laminin alpha4. Nat Neurosci. 2001;4:597–604.[CrossRef][ISI][Medline][Order article via Infotrieve]
  56. Engvall E, Earwicker D, Haaparanta T, Ruoslahti E, Sanes JR. Distribution and isolation of four laminin variants; tissue restricted distribution of heterotrimers assembled from five different subunits. Cell Regul. 1990;1:731–740.[ISI][Medline][Order article via Infotrieve]
  57. Stal P, Eriksson PO, Thornell LE. Differences in capillary supply between human oro-facial, masticatory and limb muscles. J Muscle Res Cell Motil. 1996;17:183–197.[CrossRef][ISI][Medline][Order article via Infotrieve]
  58. Wasicky R, Ziya-Ghazvini F, Blumer R, Lukas JR, Mayr R. Muscle fiber types of human extraocular muscles: a histochemical and immunohistochemical study. Invest Ophthalmol Vis Sci. 2000;41:980–990.[Abstract/Free Full Text]
  59. Oh SY, Poukens V, Cohen MS, Demer JL. Structure-function correlation of laminar vascularity in human rectus extraocular muscles. Invest Ophthalmol Vis Sci. 2001;42:17–22.[Abstract/Free Full Text]



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