The functional genomic response of developing embryonic submandibular glands to NF-kappa B inhibition.
BACKGROUND
The proper balance between epithelial cell proliferation, quiescence, and apoptosis during development is mediated by the specific temporal and spatial appearance of transcription factors, growth factors, cytokines, caspases, etc. Since our prior studies suggest the importance of transcription factor NF-kappaB during embryonic submandibular salivary gland (SMG) development, we attempted to delineate the emergent dynamics of a cognate signaling network by studying the molecular patterns and phenotypic outcomes of interrupted NF-kappaB signaling in embryonic SMG explants.


RESULTS
SN50-mediated inhibition of NF-kappaB nuclear translocation in E15 SMG explants cultured for 2 days results in a highly significant increase in apoptosis and decrease in cell proliferation. Probabilistic Neural Network (PNN) analyses of transcriptomic and proteomic assays identify specific transcripts and proteins with altered expression that best discriminate control from SN50-treated SMGs. These include PCNA, GR, BMP1, BMP3b, Chk1, Caspase 6, E2F1, c-Raf, ERK1/2 and JNK-1, as well as several others of lesser importance. Increased expression of signaling pathway components is not necessarily probative of pathway activity; however, as confirmation we found a significant increase in activated (phosphorylated/cleaved) ERK 1/2, Caspase 3, and PARP in SN50-treated explants. This increased activity of proapoptotic (caspase3/PARP) and compensatory antiapoptotic (ERK1/2) pathways is consistent with the dramatic cell death seen in SN50-treated SMGs.


CONCLUSIONS
Our morphological and functional genomic analyses indicate that the primary and secondary effects of NF-kappaB-mediated transcription are critical to embryonic SMG developmental homeostasis. Relative to understanding complex genetic networks and organogenesis, our results illustrate the importance of evaluating the gene, protein, and activated protein expression of multiple components from multiple pathways within broad functional categories.
Melnick
M
M
Laboratory for Developmental Genetics, University of Southern California Los Angeles, CA, USA. mmelnick@hsc.usc.edu
Chen
H
H
Min Zhou
Y
Y
Jaskoll
T
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D046508:Culture Techniques; D005314:Embryonic and Fetal Development / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D016678:Genome; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000502:physiology*; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D010455:Peptides / Q000494:pharmacology*; D010641:Phenotype; D020543:Proteome / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D013363:Submandibular Gland / Q000187:drug effects* / Q000196:embryology* / Q000294:innervation; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology
D016328:NF-kappa B; D010455:Peptides; D020543:Proteome; C118258:SN50 peptide