TY - JOUR
T1 - Developmental arrest of Drosophila survival motor neuron (Smn) mutants accounts for differences in expression of minor intron-containing genes
AU - Garcia, Eric L.
AU - Lu, Zhipeng
AU - Meers, Michael P.
AU - Praveen, Kavita
AU - Matera, A. Gregory
PY - 2013/11
Y1 - 2013/11
N2 - Reduced levels of survival motor neuron (SMN) protein lead to a neuromuscular disease called spinal muscular atrophy (SMA). Animal models of SMA recapitulate many aspects of the human disease, including locomotion and viability defects, but have thus far failed to uncover the causative link between a lack of SMN protein and neuromuscular dysfunction. While SMN is known to assemble small nuclear ribonucleoproteins (snRNPs) that catalyze pre-mRNA splicing, it remains unclear whether disruptions in splicing are etiologic for SMA. To investigate this issue, we carried out RNA deep-sequencing (RNA-seq) on agematched Drosophila Smn-null and wild-type larvae. Comparison of genome-wide mRNA expression profiles with publicly available data sets revealed the timing of a developmental arrest in the Smn mutants. Furthermore, genome-wide differences in splicing between wild-type and Smn animals did not correlate with changes in mRNA levels. Specifically, we found that mRNA levels of genes that contain minor introns vary more over developmental time than they do between wild-type and Smn mutants. An analysis of reads mapping to minor-class intron-exon junctions revealed only small changes in the splicing of minor introns in Smn larvae, within the normal fluctuations that occur throughout development. In contrast, Smn mutants displayed a prominent increase in levels of stress-responsive transcripts, indicating a systemic response to the developmental arrest induced by loss of SMN protein. These findings not only provide important mechanistic insight into the developmental arrest displayed by Smn mutants, but also argue against a minor-intron-dependent etiology for SMA.
AB - Reduced levels of survival motor neuron (SMN) protein lead to a neuromuscular disease called spinal muscular atrophy (SMA). Animal models of SMA recapitulate many aspects of the human disease, including locomotion and viability defects, but have thus far failed to uncover the causative link between a lack of SMN protein and neuromuscular dysfunction. While SMN is known to assemble small nuclear ribonucleoproteins (snRNPs) that catalyze pre-mRNA splicing, it remains unclear whether disruptions in splicing are etiologic for SMA. To investigate this issue, we carried out RNA deep-sequencing (RNA-seq) on agematched Drosophila Smn-null and wild-type larvae. Comparison of genome-wide mRNA expression profiles with publicly available data sets revealed the timing of a developmental arrest in the Smn mutants. Furthermore, genome-wide differences in splicing between wild-type and Smn animals did not correlate with changes in mRNA levels. Specifically, we found that mRNA levels of genes that contain minor introns vary more over developmental time than they do between wild-type and Smn mutants. An analysis of reads mapping to minor-class intron-exon junctions revealed only small changes in the splicing of minor introns in Smn larvae, within the normal fluctuations that occur throughout development. In contrast, Smn mutants displayed a prominent increase in levels of stress-responsive transcripts, indicating a systemic response to the developmental arrest induced by loss of SMN protein. These findings not only provide important mechanistic insight into the developmental arrest displayed by Smn mutants, but also argue against a minor-intron-dependent etiology for SMA.
KW - DILP8
KW - Drosophila insulin-like peptide 8
KW - Minor intron
KW - RNA-sequencing
KW - SnRNP
KW - Spinal muscular atrophy
KW - Splicing
KW - Stress signaling pathways
KW - Survival motor neuron
KW - Transcriptome
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U2 - 10.1261/rna.038919.113
DO - 10.1261/rna.038919.113
M3 - Article
C2 - 24006466
AN - SCOPUS:84886048721
SN - 1355-8382
VL - 19
SP - 1510
EP - 1516
JO - RNA
JF - RNA
IS - 11
ER -