Mutations in each of the transcriptional co-activator genes - CBP, p300, Cited2, 
Cart1 and Carm1 - result in neural tube defects in mice. The present study thus 
furnishes a complete and comparative temporal and spatial expression map of 
CBP/p300 and associated transcriptional co-activators, Cited2, Cart1 and Carm1 
during the period of murine neural tube development (embryonic days 8.5 to 
10.5). Each co-activator except Cart1 was expressed in the dorsal neural folds 
on E8.5. Although CBP and p300 are functionally interchangeable in vitro, their 
respective expression patterns diverge during embryogenesis before neural fold 
fusion is complete. CBP gene expression was lost from the neural folds by E8.75 
and was thereafter weakly expressed in the maxillary region and limb buds, while 
p300 exhibited strong expression in the first branchial arch, limb bud and 
telencephalic regions on E9.5. Cart1 exhibited strong expression in the 
forebrain mesenchyme from E9.0 through E10.5. Although CBP, p300, Carm1 and 
Cited2 share temporal expression on E8.5, these co-activators have different 
spatial expression in mesenchyme and/or the neuroepithelium. Nevertheless, 
co-localization to the dorsal neural folds on E8.5 suggests a functional role in 
elevation and/or fusion of the neural folds. Target genes, and pathways that 
promote cranial neural tube fusion that are activated by 
CBP/p300/Carm1/Cited2/Cart1-containing transcriptional complexes await 
elucidation.