Proteomic identification of FHL1 as the protein mutated in human reducing body myopathy.
Reducing body myopathy (RBM) is a rare disorder causing progressive muscular weakness characterized by aggresome-like inclusions in the myofibrils. Identification of genes responsible for RBM by traditional genetic approaches has been impossible due to the frequently sporadic occurrence in affected patients and small family sizes. As an alternative approach to gene identification, we used laser microdissection of intracytoplasmic inclusions identified in patient muscle biopsies, followed by nanoflow liquid chromatography-tandem mass spectrometry and proteomic analysis. The most prominent component of the inclusions was the Xq26.3-encoded four and a half LIM domain 1 (FHL1) protein, expressed predominantly in skeletal but also in cardiac muscle. Mutational analysis identified 4 FHL1 mutations in 2 sporadic unrelated females and in 2 families with severely affected boys and less-affected mothers. Transfection of kidney COS-7 and skeletal muscle C2C12 cells with mutant FHL1 induced the formation of aggresome-like inclusions that incorporated both mutant and wild-type FHL1 and trapped other proteins in a dominant-negative manner. Thus, a novel laser microdissection/proteomics approach has helped identify both inherited and de novo mutations in FHL1, thereby defining a new X-linked protein aggregation disorder of muscle.
Schessl
Joachim
J
Division of Neurology, The Children's Hospital of Philadelphia, Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Zou
Yaqun
Y
McGrath
Meagan J
MJ
Cowling
Belinda S
BS
Maiti
Baijayanta
B
Chin
Steven S
SS
Sewry
Caroline
C
Battini
Roberta
R
Hu
Ying
Y
Cottle
Denny L
DL
Rosenblatt
Michael
M
Spruce
Lynn
L
Ganguly
Arupa
A
Kirschner
Janbernd
J
Judkins
Alexander R
AR
Golden
Jeffrey A
JA
Goebel
Hans-Hilmar
HH
Muntoni
Francesco
F
Flanigan
Kevin M
KM
Mitchell
Christina A
CA
Bönnemann
Carsten G
CG
D000595:Amino Acid Sequence; D040181:Genetic Diseases, X-Linked / Q000235:genetics; D002479:Inclusion Bodies / Q000737:chemistry*; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D060588:LIM Domain Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D009135:Muscular Diseases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D040901:Proteomics / Q000379:methods*; D014162:Transfection
C101149:FHL1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D009124:Muscle Proteins