Apoptosis in a rodent model of cranial suture fusion: in situ imaging and gene expression analysis.
Craniosynostosis, the premature fusion of cranial sutures, is one of the most common craniofacial anomalies, with a reported incidence of up to one in 2500 live births. Despite its prevalence, the cause of craniosynostosis remains unknown. Previously, apoptosis has been postulated to be a contributing factor in the pathogenesis of craniosynostosis, although the role of programmed cell death in cranial sutures is poorly understood. To address this problem, the authors used an established rodent model of posterior-frontal suture fusion and sagittal suture patency to globally examine apoptosis in cranial sutures. Apoptosis was evaluated by systemically coinjecting Sprague-Dawley rats with both fluorescent and technetium-99m-labeled annexin V at time points before, during, and after the period of predicted posterior-frontal suture fusion to determine the magnitude and time course of overall apoptotic activity in both fusing and patent sutures. Using these novel in situ imaging techniques, the authors observed a significant increase in the overall levels of apoptosis in both the posterior-frontal and sagittal suture complexes during the period of predicted posterior-frontal suture fusion. To further explore this increase in apoptotic activity, they used microarray technology to study apoptosis-related genes within the suture complex. Interestingly, there was activation of distinct apoptotic pathways in the posterior-frontal and sagittal sutures during the period of predicted posterior-frontal suture fusion. Whereas increased transcription of genes associated with the mitochondria-mediated apoptotic pathway occurred in the posterior-frontal suture during fusion, activation of genes associated with the death receptor-mediated apoptotic pathway predominated in the patent sagittal suture during the same time period. These data suggest that although overall apoptotic activity in rat patent and fusing sutures is similar, the pathways mediating apoptosis within each suture are distinct.
Fong
Kenton D
KD
Department of Surgery, Division of Plastic and Reconstructive Surgery, Stanford University, Calif. 94305-5148, USA.
Song
HanJoon M
HM
Nacamuli
Randall P
RP
Franc
Benjamin L
BL
Mari
Carina
C
Fang
Tony D
TD
Warren
Stephen M
SM
Contag
Christopher H
CH
Blankenberg
Francis G
FG
Longaker
Michael T
MT
D000818:Animals; D017304:Annexin A5; D017209:Apoptosis / Q000235:genetics; D001345:Autoradiography; D003393:Cranial Sutures / Q000473:pathology* / Q000502:physiology / Q000503:physiopathology; D003398:Craniosynostoses / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D053222:Fas Ligand Protein; D005456:Fluorescent Dyes; D015870:Gene Expression; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism
D017304:Annexin A5; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D005456:Fluorescent Dyes; D008562:Membrane Glycoproteins; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C417036:technetium Tc 99m annexin V