Neuromuscular Diseases

The Laing Laboratory is one of the world's foremost laboratories in the investigation of the genetic causes of muscle diseases in newborn children. The Laboratory was the first in the world to identify a gene for one sub-group of these disorders and later showed that many of the children affected with these diseases have mutations in one of the two most important proteins in muscle contraction. These results have helped families all round the world know the cause of their children's muscle problems. We are now researching possible treatments for diseases where we have identified the genes, while at the same time continuing work to find other genes for muscle diseases. The Laboratory's reputation means that we receive samples for analysis from all round the world. The Laboratory is thus playing a leading role in a consortium of groups working towards defeating these diseases.

In 2008, Professor Laing, edited the first ever book on the human muscle diseases caused by mutations in the proteins of the sarcomere, the functional unit of muscle contraction. This reinforces the standing of the Laing Laboratory in researching and pioneering this group of diseases.

Senior Research Staff

Professor Nigel Laing Head, Neuromuscular Diseases Research: genetic muscular disorders

Dr Kristen Nowak Fellow Research: neuromuscular disease genetics; actin proteins; recombinant protein production

Research Details

The Laing Laboratory has been hunting human disease genes for nearly twenty years. We started analysing large Australian families with dominantly inherited neurological and neuromuscular disorders, making world first discoveries. These discoveries led to DNA samples being sent to us from around the world for the diseases that we had identified genes for and this continuing influx of samples in turn has led to further breakthroughs.

The fact is that in Australasia there are many large families with dominant diseases because of founder effects, where one person carrying a dominant mutation has emigrated to Australia, stayed in this wonderful country and had large families, with many descendents that we can trace. In order to find the genes for dominant human diseases, you have to study large families, so it follows that in many ways Australia is an ideal country in which to study dominant diseases. It also means that we are able to carry out studies that other groups around the world cannot. This has allowed us over the years to break new ground. As an example, Western Australia has one of the largest inherited familial amyotrophic lateral sclerosis (FALS) (otherwise known as motor neurone disease) families in the world. This family helped identify what is still the major gene identified for FALS, the superoxide dismutase gene (SOD1) in 1993.

We simultaneously were working on the largest known family with dominantly inherited nemaline myopathy, one of the better known congenital myopathies, diseases which generally affect newborn babies and at there most severe lead to complete paralysis at birth. We obtained the first linkage of a gene for nemaline myopathy to a region of chromosome 1 in this family in 1992 and three years later in 1995 identified the first gene found for nemaline myopathy as mutated slow alpha-tropomyosin (TPM3), one of the muscle thin filament proteins. This discovery created a paradigm shift in our understanding of this group of diseases.

In 1995 we also obtained the first ever linkage for any distal myopathy, this time in a large Western Australian family. This family has an unusual form of distal myopathy in that it has childhood onset, whereas most dominant distal myopathies have adult onset. In 2004 we finally published that the gene was mutated slow-skeletal/beta-cardiac myosin (MYH7), which was a huge surprise to the muscle research community since mutations in this gene had already been associated with cardiomyopathy. However, it is now perfectly clear that particular mutations in a particular region of that myosin cause this relatively skeletal-muscle specific disease, yet other mutations in the gene cause the skeletal muscle disease myosin storage myopathy, while most mutations in the gene cause cardiomyopathy. This work adds to the growing understanding that different mutations in one gene can cause different diseases.

In 1999 the Laing Laboratory identified, for the first time, mutations in the skeletal muscle alpha-actin gene (ACTA1) as a cause of congenital myopathies. This initial publication described 15 different mutations in ACTA1 causing nemaline myopathy, intranuclear rods and accumulation of actin in muscle fibres. We now know that mutations in ACTA1 may also cause congenital fibre type disproportion and core-like phenotypes and so far we, and others, have found over 130 different mutations in ACTA1.

The Laing laboratory has thus coincidentally identified human muscle diseases of the two most fundamental proteins in muscle contraction - actin and myosin. Our most recent finding is recessive ACTA1 disease causing complete absence of skeletal muscle actin. Interestingly, most of the affected children have some movement at birth and our studies show that the level of function in the children likely correlates with how much alpha-cardiac actin the children are expressing in their muscles. Cardiac alpha-actin is the fetal isoform of actin, normally present in developing muscle, but switched off around birth. The children with no alpha-skeletal actin have maintained variable levels of this fetal actin.

One of the puzzles with children severely affected by mutations in the skeletal muscle alpha actin gene ACTA1 is that eye movements remain unaffected even when other skeletal muscles are barely functional. In 2008 we showed that the extraocular muscles, the muscles that move the eyes, have high levels of cardiac actin, similar levels in fact to those in the heart. We postulated that it is this high level of cardiac actin that maintains function in the eye muscles.

Way back when we first found skeletal muscle actin disease in 1998, we wondered whether it would be possible to use cardiac actin, the actin isoform present in fetal muscle, to treat skeletal muscle actin disease. We set out to see how well cardiac actin might function in skeletal muscle. In collaboration with Professor Dame Kay Davies in Oxford, Dr Kristen Nowak made the transgenic mice that express high levels of cardiac actin in skeletal muscle necessary to test this. We imported those mice back to Australia and also mice from the laboratory of Professor Jim Lessard in the USA in which he had knocked out the skeletal muscle actin gene. Homozygous skeletal muscle actin knockout mice, mice with both copies of their skeletal actin gene knocked out died by nine days after birth. If cardiac actin could replace skeletal muscle actin in muscles after birth, if we bred the cardiac actin mice from Oxford with the skeletal actin knockout mice from the USA, then the resulting mice would survive. This is exactly what happened. The offspring mice were very similar to normal mice and have managed to live past two years of age, which is old age for mice. This work was published online in the Journal of Cell Biology May 25th 2009 (http://jcb.rupress.org/pap.shtml).

Having identified a number of disease genes, our aims now are to continue finding other human disease genes, decipher the mechanisms of pathobiology caused by the mutant proteins, while at the same time working towards developing treatments for some of these diseases.

Group Highlights

The Laing Laboratory's main funding is from the Australian National Health and Medical Research Council (NH&MRC). The Laboratory also regularly receives funding from the US Muscular Dystrophy Association (USMDA) and the Association Francaise contre les Myopathies (AFM) the French Muscular Dystrophy Association and is supported by the Western Australian Government's Medical and Health Research Infrastructure Fund.

Professor Laing is an NHMRC Principal Research Fellow.

2007 Publications

1. Agrawal PB, Greenleaf RS, Tomczak KK, Lehtokari VL, Wallgren-Pettersson C, Wallefeld W, Laing NG, Darras BT, Maciver SK, Dormitzer PR, Beggs AH. 2007. Nemaline myopathy with minicores caused by mutation of the CFL2 gene encoding the skeletal muscle actin-binding protein, cofilin-2. American Journal of Human Genetics 80(1):162-7. [NCBI PubMed Entry]
2. Bouldin AA, Parisi MA, Laing N, Patterson K, Gospe SM, Jr. 2007. Variable presentation of nemaline myopathy: novel mutation of alpha actin gene. Muscle & Nerve 35(2):254-8. [NCBI PubMed Entry]
3. Nowak KJ, Sewry CA, Navarro C, Squier W, Reina C, Ricoy JR, Jayawant SS, Childs AM, Dobbie JA, Appleton, RE, Mountford RC, Walker KR, Clement S, Barois A, Muntoni F, Romero NB, Laing NG. 2007. Nemaline myopathy caused by absence of alpha-skeletal muscle actin. Annals of Neurology 61(2):175-84. [NCBI PubMed Entry] [IF 7.6]
4. Penisson-Besnier I, Monnier N, Toutain A, Dubas F, Laing N. 2007. A second pedigree with autosomal dominant nemaline myopathy caused by TPM3 mutation: A clinical and pathological study. Neuromuscular Disorders 17(4):330-7. [NCBI PubMed Entry]
5. Laing N. 2007. More surprises in sarcomeric protein diseases. Brain 130(Pt 6):1453-5. [NCBI PubMed Entry]
6. Lehtokari VL, Ceuterick-de Groote C, de Jonghe P, Marttila M, Laing NG, Pelin K, Wallgren-Pettersson C. 2007. Cap disease caused by heterozygous deletion of the beta-tropomyosin gene TPM2. Neuromuscular Disorders 17(6):433-42. [NCBI PubMed Entry]
7. Ravenscroft G, Nowak KJ, Jackaman C, Clément S, Lyons MA, Gallagher S, Bakker AJ, Laing NG. 2007. Dissociated flexor digitorum brevis myofiber culture system-A more mature muscle culture system. Cell Motility and the Cytoskeleton 64(10):727-38. [NCBI PubMed Entry]
8. Laing NG. 2007. Congenital myopathies. Current Opinion in Neurology 20(5):583-9. [NCBI PubMed Entry]
9. Jackaman C, Nowak KJ, Ravenscroft G, Lim EM, Clément S, Laing NG. 2007. Novel application of flow cytometry: Determination of muscle fiber types and protein levels in whole murine skeletal muscles and heart. Cell Motility and the Cytoskeleton 64(12):914-25. [NCBI PubMed Entry]
10. Koy A, Ilkovski B, Laing N, North K, Weis J, Neuen-Jacob E, Mayatepek E, Voit T. 2007. Nemaline myopathy with exclusively intranuclear rods and a novel mutation in ACTA1 (Q139H). Neuropediatrics 38(6):282-6. [NCBI PubMed Entry]

2008 Publications

1. Tsaousidou MK, Ouahchi K, Warner TT, Yang Y, Simpson MA, Laing NG, Wilkinson PA, Madrid RE, Patel H, Hentati F, Patton MA, Hentati A, Lamont PJ, Siddique T, Crosby AH. 2008. Sequence Alterations within CYP7B1 Implicate Defective Cholesterol Homeostasis in Motor-Neuron Degeneration. American Journal of Human Genetics 82(2):510-5. [NCBI PubMed Entry]
2. Clarke NF, Kolski H, Dye DE, Lim E, Smith RL, Patel R, Fahey MC, Bellance R, Romero NB, Johnson ES, Labarre-Vila A, Monnier N, Laing NG, North KN. 2008. Mutations in TPM3 are a common cause of congenital fiber type disproportion. Annals of Neurology 63(3):329-37. [NCBI PubMed Entry]
3. Howell JM, Walker KR, Davies L, Dunton E, Everaardt A, Laing N, Karpati G. 2008. Adenovirus and adeno-associated virus-mediated delivery of human myophosphorylase cDNA and LacZ cDNA to muscle in the ovine model of McArdle's disease: Expression and re-expression of glycogen phosphorylase. Neuromuscular Disorders 18(3):248-58. [NCBI PubMed Entry]
4. Ilkovski B, Mokbel N, Lewis RA, Walker K, Nowak KJ, Domazetovska A, Laing NG, Fowler VM, North KN, Cooper ST. 2008. Disease severity and thin filament regulation in M9R TPM3 nemaline myopathy. Journal of Neuropathology and Experimental Neurology 67(9):867-77. [NCBI PubMed Entry]
5. Lehtokari VL, Pelin K, Donner K, Voit T, Rudnik-Schoneborn S, Stoetter M, Talim B, Topaloglu H, Laing NG, Wallgren-Pettersson C. 2008. Identification of a founder mutation in TPM3 in nemaline myopathy patients of Turkish origin. European Journal of Human Genetics 16(9):1055-61. [NCBI PubMed Entry]
6. Ravenscroft G, Colley SM, Walker KR, Clement S, Bringans S, Lipscombe R, Fabian VA, Laing NG, Nowak KJ. 2008. Expression of cardiac alpha-actin spares extraocular muscles in skeletal muscle alpha-actin diseases - Quantification of striated alpha-actins by MRM-mass spectrometry. Neuromuscular Disorders 18(12):953-958. [NCBI PubMed Entry]
7. North KN, Laing NG. 2008. Skeletal muscle alpha-actin diseases. Advances in experimental medicine and biology 642:15-27. [NCBI PubMed Entry]
8. Nowak KJ. 2008. Therapeutic approaches for the sarcomeric protein diseases. Advances in experimental medicine and biology 642:207-223. [NCBI PubMed Entry]
9. Laing NG. 2008. Multiplicity of experimental approaches to therapy for genetic muscle diseases and necessity for population screening. Journal of muscle research and cell motility 29(6-8):247-52. [NCBI PubMed Entry]
10. Laing NG (ed). 2008. The Sarcomere and Skeletal Muscle Disease. Landes Bioscience, Springer, New York. Available at www.landesbioscience.com.

2009 Publications

1. Lehtokari VL, Greenleaf RS, Dechene ET, Kellinsalmi M, Pelin K, Laing NG, Beggs AH, Wallgren-Pettersson C. 2009. The exon 55 deletion in the nebulin gene - One single founder mutation with world-wide occurrence. Neuromuscular disorders 19:179-181. [NCBI PubMed Entry]
2. Laing NG, Wallgren-Pettersson C. 2009. 161st ENMC International Workshop on nemaline myopathy and related disorders, Newcastle upon Tyne, 2008. Neuromuscular disorders 19:300-305. [NCBI PubMed Entry]
3. Feng JJ, Ushakov DS, Ferenczi MA, Laing NG, Nowak KJ, Marston SB. 2009. Direct visualisation and kinetic analysis of normal and nemaline myopathy actin polymerisation using total internal reflection microscopy. Journal of muscle research and cell motility 30:85-92. [NCBI PubMed Entry]
4. Nowak KJ, Ravenscroft G, Jackaman C, Filipovska A, Davies SM, Lim EM, Squire SE, Potter AC, Baker E, Clement S, Sewry CA, Fabian V, Crawford K, Lessard JL, Griffiths LM, Papadimitriou JM, Shen Y, Morahan G, Bakker AJ, Davies KE, Laing NG. 2009. Rescue of skeletal muscle {alpha}-actin-null mice by cardiac (fetal) {alpha}-actin. The Journal of cell biology 185:903-915. [NCBI PubMed Entry]
5. Goebel HH, Laing NG. 2009. Actinopathies and myosinopathies. Brain Pathology 19:516-22. [NCBI PubMed Entry]
6. Laing NG, Dye DE, Wallgren-Pettersson C, Richard G, Monnier N, Lillis S, Winder TL, Lochmuller H, Graziano C, Mitrani-Rosenbaum S, Twomey D, Sparrow JC, Beggs AH, Nowak KJ. 2009. Mutations and polymorphisms of the skeletal muscle alpha-actin gene (ACTA1). Human mutation 30:1267-1277. [NCBI PubMed Entry]
7. Bojdo A, Obersztyn E, Wallgren-Pettersson C, Lehtokari V, Laing N, Davis M, Kulakowska Z. 2009. [Nemaline myopathy as a cause of neonatal hypotonia - with emphasis on personal experiences. Report of a family with two brothers affected]. Medycyna wieku rozwojowego 13:5-10. [NCBI PubMed Entry]
8. Romero NB, Lehtokari VL, Quijano-Roy S, Monnier N, Claeys KG, Carlier RY, Pellegrini N, Orlikowski D, Barois A, Laing NG, Lunardi J, Fardeau M, Pelin K, Wallgren-Pettersson C. 2009. Core-rod myopathy caused by mutations in the nebulin gene. Neurology 73:1159-1161. [NCBI PubMed Entry]
9. Mastaglia FL, Needham M, Scott A, James I, Zilko P, Day T, Kiers L, Corbett A, Witt CS, Allcock R, Laing N, Garlepp M, Christiansen FT. 2009. Sporadic inclusion body myositis: HLA-DRB1 allele interactions influence disease risk and clinical phenotype. Neuromuscular disorders 19:763-765. [NCBI PubMed Entry]
10. Laing NG, Lamont PJ. 2009. Distal myopathies. In: Lisak RP, Truong DD, Carroll WM, Bhidayasiri R (eds) International Neurology: A clinical approach. Blackwell, Oxford, pp235-237.