Transcriptome correlation analysis identifies two unique craniosynostosis subtypes associated with IRS1 activation.
The discovery of causal mechanisms associated with nonsyndromic craniosynostosis has proven to be a difficult task due to the complex nature of the disease. In this study, differential transcriptome correlation analysis was used to identify two molecularly distinct subtypes of nonsyndromic craniosynostosis, termed subtype A and subtype B. In addition to unique correlation structure, subtype A was also associated with high IGF pathway expression, whereas subtype B was associated with high integrin expression. To identify a pathologic link between altered gene correlation/expression and the disease state, phosphorylation assays were performed on primary osteoblast cell lines derived from cases within subtype A or subtype B, as well as on primary osteoblast cell lines with novel IGF1R variants previously reported by our lab (Cunningham ML, Horst JA, Rieder MJ, Hing AV, Stanaway IB, Park SS, Samudrala R, Speltz ML. Am J Med Genet A 155A: 91-97, 2011). Elevated IRS1 (pan-tyr) and GSK3β (ser-9) phosphorylation were observed in two novel IGF1R variants with receptor L domain mutations. In subtype A, a hypomineralization phenotype coupled with decreased phosphorylation of IRS1 (ser-312), p38 (thr-180/tyr-182), and p70S6K (thr-412) was observed. In subtype B, decreased phosphorylation of IRS1 (ser-312) as well as increased phosphorylation of Akt (ser-473), GSK3β (ser-9), IGF1R (tyr-1135/tyr-1136), JNK (thr-183/tyr-187), p70S6K (thr-412), and pRPS6 (ser-235/ser-236) was observed, thus implicating the activation of IRS1-mediated Akt signaling in potentiating craniosynostosis in this subtype. Taken together, these results suggest that despite the stimulation of different pathways, activating phosphorylation patterns for IRS1 were consistent in cell lines from both subtypes and the IGF1R variants, thus implicating a key role for IRS1 in the pathogenesis of nonsyndromic craniosynostosis.
Center for Tissue and Cell Sciences, Seattle Children's Research Institute, Seattle, Washington 98101, USA. stamperb@pacificu.edu
B D
BD
Stamper
B
B
Mecham
S S
SS
Park
H
H
Wilkerson
F M
FM
Farin
R P
RP
Beyer
T K
TK
Bammler
L M
LM
Mangravite
M L
ML
Cunningham
D002460:Cell Line; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003398:Craniosynostoses / Q000145:classification / Q000235:genetics* / Q000473:pathology; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007223:Infant; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000235:genetics / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D015533:Transcriptional Activation; D059467:Transcriptome / Q000235:genetics*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; D038601:Ribosomal Protein S6; D017526:Receptor, IGF Type 1; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3