Dysregulation of the Tweak/Fn14 pathway in skeletal muscle of spinal muscular atrophy mice
biorxiv(2021)
摘要
Spinal muscular atrophy (SMA) is a childhood neuromuscular disorder caused by depletion of the survival motor neuron (SMN) protein. SMA is characterized by the selective death of spinal cord motor neurons, leading to progressive muscle wasting. Loss of skeletal muscle in SMA is a combination of denervation-induced muscle atrophy and intrinsic muscle pathologies. Elucidation of the pathways involved is essential to identify the key molecules that contribute to and sustain muscle pathology. The tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/TNF receptor superfamily member fibroblast growth factor inducible 14 (Fn14) pathway has been shown to play a critical role in the regulation of denervation-induced muscle atrophy as well as muscle proliferation, differentiation and metabolism in adults. However, it is not clear whether this pathway would be important in highly dynamic and developing muscle. We thus investigated the potential role of the TWEAK/Fn14 pathway in SMA muscle pathology, using the severe Taiwanese Smn-/-;SMN2 and the less severe Smn2B/- SMA mice, which undergo a progressive neuromuscular decline in the first three post-natal weeks. Here, we report significantly dysregulated expression of the TWEAK/Fn14 pathway during disease progression in skeletal muscle of the two SMA mouse models. In addition, siRNA-mediated Smn knockdown in C2C12 myoblasts suggests a genetic interaction between Smn and the TWEAK/Fn14 pathway. Further analyses of SMA, Tweak-/- and Fn14-/- mice revealed dysregulated myopathy, myogenesis and glucose metabolism pathways as a common skeletal muscle feature, and providing further evidence in support of a relationship between the TWEAK/Fn14 pathway and Smn. Finally, a pharmacological intervention (Fc-TWEAK) to upregulate the activity of the TWEAK/Fn14 pathway improved disease phenotypes in the two SMA mouse models. Our study provides novel mechanistic insights into the molecular players that contribute to muscle pathology in SMA and into the role of the TWEAK/Fn14 pathway in developing muscle.
### Competing Interest Statement
The authors have declared no competing interest.
* ALS
: amyotrophic lateral sclerosis
ANOVA
: analysis of variance
cDNA
: complementary deoxyribonucleic acid
DEG
: differently expressed genes
DMEM
: Dulbecco’s Modified Eagle’s Media
FBS
: fetal bovine serum
FDR
: false discovery rate
GO
: gene ontology
H&E
: hematoxylin-and-eosin
KEGG
: Kyoto Encyclopedia of Genes and Genomes
mRNA
: messenger RNA
NF-κB
: nuclear factor kappa-light-chain-enhancer of activated B cells
NMJ
: neuromuscular junctions
P
: postnatal day
p
: probability value
PBS
: phosphate buffered saline
PCR
: polymerase chain reaction
PFA
: paraformaldehyde
qPCR
: quantitative polymerase chain reaction
RIPA
: radioimmunoprecipitation
RNA
: ribonucleic acid
RNAi
: RNA interference
RT-qPCR
: reverse transcriptase-quantitative
PCR SEM
: standard error of the mean
siRNA
: small interfering RNA
SMA
: spinal muscular atrophy
STRING
: Search Tool for the Retrieval of Interacting Genes/Proteins
TA
: tibialis anterior
WT
: wild type
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关键词
tweak/fn14 pathway,atrophy,skeletal muscle,mice,dysregulation
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