Nuclear envelope dystrophies show a transcriptional fingerprint suggesting disruption of Rb-MyoD pathways in muscle regeneration.
Mutations of lamin A/C (LMNA) cause a wide range of human disorders, including progeria, lipodystrophy, neuropathies and autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD). EDMD is also caused by X-linked recessive loss-of-function mutations of emerin, another component of the inner nuclear lamina that directly interacts with LMNA. One model for disease pathogenesis of LMNA and emerin mutations is cell-specific perturbations of the mRNA transcriptome in terminally differentiated cells. To test this model, we studied 125 human muscle biopsies from 13 diagnostic groups (125 U133A, 125 U133B microarrays), including EDMD patients with LMNA and emerin mutations. A Visual and Statistical Data Analyzer (VISDA) algorithm was used to statistically model cluster hierarchy, resulting in a tree of phenotypic classifications. Validations of the diagnostic tree included permutations of U133A and U133B arrays, and use of two probe set algorithms (MAS5.0 and MBEI). This showed that the two nuclear envelope defects (EDMD LMNA, EDMD emerin) were highly related disorders and were also related to fascioscapulohumeral muscular dystrophy (FSHD). FSHD has recently been hypothesized to involve abnormal interactions of chromatin with the nuclear envelope. To identify disease-specific transcripts for EDMD, we applied a leave-one-out (LOO) cross-validation approach using LMNA patient muscle as a test data set, with reverse transcription-polymerase chain reaction (RT-PCR) validations in both LMNA and emerin patient muscle. A high proportion of top-ranked and validated transcripts were components of the same transcriptional regulatory pathway involving Rb1 and MyoD during muscle regeneration (CRI-1, CREBBP, Nap1L1, ECREBBP/p300), where each was specifically upregulated in EDMD. Using a muscle regeneration time series (27 time points) we develop a transcriptional model for downstream consequences of LMNA and emerin mutations. We propose that key interactions between the nuclear envelope and Rb and MyoD fail in EDMD at the point of myoblast exit from the cell cycle, leading to poorly coordinated phosphorylation and acetylation steps. Our data is consistent with mutations of nuclear lamina components leading to destabilization of the transcriptome in differentiated cells.
Research Center for Genetic Medicine, Children's National Medical Center, Washington DC 20010, USA.
Marina
M
Bakay
Zuyi
Z
Wang
Gisela
G
Melcon
Louis
L
Schiltz
Jianhua
J
Xuan
Po
P
Zhao
Vittorio
V
Sartorelli
Jinwook
J
Seo
Elena
E
Pegoraro
Corrado
C
Angelini
Ben
B
Shneiderman
Diana
D
Escolar
Yi-Wen
YW
Chen
Sara T
ST
Winokur
Lauren M
LM
Pachman
Chenguang
C
Fan
Raul
R
Mandler
Yoram
Y
Nevo
Erynn
E
Gordon
Yitan
Y
Zhu
Yibin
Y
Dong
Yue
Y
Wang
Eric P
EP
Hoffman
D001706:Biopsy; D002648:Child; D016172:DNA Fingerprinting; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D034904:Lamin Type A / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics; D015233:Models, Statistical; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology*; D009136:Muscular Dystrophies / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020389:Muscular Dystrophy, Emery-Dreifuss / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D017570:MyoD Protein / Q000378:metabolism; D009685:Nuclear Envelope / Q000473:pathology*; D009687:Nuclear Proteins; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D012038:Regeneration / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013946:Thymopoietins / Q000235:genetics; D014158:Transcription, Genetic
C494847:LMNA protein, human; D034904:Lamin Type A; D008565:Membrane Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D009687:Nuclear Proteins; D012333:RNA, Messenger; D013946:Thymopoietins; C092710:emerin