The long-term goals of this project are to understand the role of Cofilin-2 (CFL2) in skeletal muscle and its mutation in congenital myopathies (CMs). CMs are characterized by relatively non-progressive skeletal muscle weakness, hypotonia presenting in early life. Nemaline Myopathy (NM), the most common type, is a genetic disorder with nemaline bodies present in the muscle and mutations identified in five different genes that constitute the thin filament. In a recent breakthrough, I have identified a sixth gene, CFL2, mutated in NM. Two siblings with clinical diagnosis of typical NM and non-specific congenital myopathy born to consanguineous parents carry a homozygous missense mutation c.103G>A (A35T), and exhibit drastically reduced levels of cofilin-2 protein in their muscles. In contrast, the amount of CFL2 mRNA is increased about 8 fold compared to normal controls. Cofilin-2 belongs to AC group of proteins that include cofilin-1, cofilin-2 and actin depolymerization factor. These proteins function by causing actin severance and depolymerization, and are essential in a wide range of cellular functions including locomotion, cytokinesis, endocytosis, and muscle development. This is the first identified case of a human mutation in the AC group of genes. The molecular mechanism of NM/congenital myopathy caused by this mutation needs to be understood. In addition, cofilin-2 function in skeletal muscle needs to be elucidated.
In Aim 1, we will screen all NM/other CM cases for CFL2 mutations and characterize the transcriptional profile associated with these mutations to understand downstream effects.
In Aim 2, we will evaluate the biochemical and functional consequences of the identified mutation.
In Aim 3, CFL2 expression in C2C12 cells will be knocked down using shRNA techniques and functional consequences will be evaluated.
In Aim 4, conventional Cfl2 knockout and c.103G>A mutation knockin mouse models will be generated. This project will introduce me to a variety of techniques including microarray analysis, gene-silencing and creating knockout/knockin mouse models. It willl give me the opportunity to work in an intellectually stimulating environment, where I will approach scientific questions in novel ways fostering my transition to independence. My sponsor Dr Beggs, collaborators/advisors Dr Darras, Dr Dormitzer, Dr Kohane, Dr Kunkel and Dr Maciver, and my Neonatology Division Chief Dr Kourembanas will help me in this process.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08AR055072-05
Application #
8101006
Study Section
Arthritis and Musculoskeletal and Skin Diseases Special Grants Review Committee (AMS)
Program Officer
Boyce, Amanda T
Project Start
2007-07-01
Project End
2012-06-30
Budget Start
2011-07-01
Budget End
2012-06-30
Support Year
5
Fiscal Year
2011
Total Cost
$126,500
Indirect Cost
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
Brownstein, Catherine A; Beggs, Alan H; Rodan, Lance et al. (2016) Clinical heterogeneity associated with KCNA1 mutations include cataplexy and nonataxic presentations. Neurogenetics 17:11-6
Subramanian, Khaushik; Gianni, Davide; Balla, Cristina et al. (2015) Cofilin-2 phosphorylation and sequestration in myocardial aggregates: novel pathogenetic mechanisms for idiopathic dilated cardiomyopathy. J Am Coll Cardiol 65:1199-1214
Thaker, Vidhu V; Esteves, Kristyn M; Towne, Meghan C et al. (2015) Whole exome sequencing identifies RAI1 mutation in a morbidly obese child diagnosed with ROHHAD syndrome. J Clin Endocrinol Metab 100:1723-30
Morton, Sarah U; Joshi, Mugdha; Savic, Talia et al. (2015) Skeletal muscle microRNA and messenger RNA profiling in cofilin-2 deficient mice reveals cell cycle dysregulation hindering muscle regeneration. PLoS One 10:e0123829
Joshi, Mugdha; Eagan, Jacqueline; Desai, Nirav K et al. (2014) A compound heterozygous mutation in GPD1 causes hepatomegaly, steatohepatitis, and hypertriglyceridemia. Eur J Hum Genet 22:1229-32
Agrawal, Pankaj B; Pierson, Christopher R; Joshi, Mugdha et al. (2014) SPEG interacts with myotubularin, and its deficiency causes centronuclear myopathy with dilated cardiomyopathy. Am J Hum Genet 95:218-26
Agrawal, Pankaj B; Joshi, Mugdha; Marinakis, Nicholas S et al. (2014) Expanding the phenotype associated with the NEFL mutation: neuromuscular disease in a family with overlapping myopathic and neurogenic findings. JAMA Neurol 71:1413-20
Touma, Marlin; Joshi, Mugdha; Connolly, Meghan C et al. (2013) Whole genome sequencing identifies SCN2A mutation in monozygotic twins with Ohtahara syndrome and unique neuropathologic findings. Epilepsia 54:e81-5
Agrawal, Pankaj B; Joshi, Mugdha; Savic, Talia et al. (2012) Normal myofibrillar development followed by progressive sarcomeric disruption with actin accumulations in a mouse Cfl2 knockout demonstrates requirement of cofilin-2 for muscle maintenance. Hum Mol Genet 21:2341-56
Ockeloen, C W; Gilhuis, H J; Pfundt, R et al. (2012) Congenital myopathy caused by a novel missense mutation in the CFL2 gene. Neuromuscul Disord 22:632-9

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