Generation of a conditional allele of the CBP gene in mouse

Abstract

CREB-binding protein (CBP) is an important transcriptional cofactor for various intracellular signaling pathways, including Ca(2+)- and cAMP-mediated gene activation. The loss of one CBP allele causes the human Rubinstein-Taybi syndrome, which is characterized by mental retardation and other severe developmental defects. Deletion of both CBP alleles in the mouse leads to early embryonic lethality. To address the function of CBP in late embryogenesis and in adult physiology, a floxed CBP allele (CBP(fl)) was generated. Using the Cre/loxP recombination system, CBP function was disrupted in principal forebrain neurons by breeding with a transgenic CaMKIIalpha-Cre mouse line to obtain CBP(fl/fl;CaMKIIalphaCre) mice. These mice contain CBP(stop523) alleles specifically in principal forebrain neurons, presumably resulting in the production of a truncated CBP protein unable to interact with a number of transcription factors, including phosphorylated CREB.

Ablation of CBP in Forebrain Principal Neurons Causes Modest Memory and Transcriptional Defects and a Dramatic Reduction of Histone Acetylation But Does Not Affect Cell Viability

“…The generation of both CBP f/f (Zhang et al, 2004) and CaMKII␣-cre (CKIIcre) (Tsien et al, 1996) mice has been described previously. Mice were maintained and bred under standard conditions, consistent with Spanish and European regulations and approved by the Institutional Animal Care and Use Committee.…”

“…PCR was performed for 30 cycles (1 min at 95°C, 1 min at 54°C, 1 min at 72°C). The sequences of the primers Z38 and Z40 were as described previously (Zhang et al, 2004).…”

“…Previous work has demonstrated that both CBP f/f mice (Zhang et al, 2004) and CaMKII␣-cre transgenic mice (Tsien et al, 1996) are indistinguishable from wild-type mice. CaMKII␣-cre/CBP f/f mice, from now on referred as CKIIcre/CBP f/f , have a normal lifespan and show no overt anatomical or behavioral abnormality (Table 1).…”

“…To explore the consequences of the neuronal elimination of CBP in adult brain function bypassing the embryonic lethality caused by CBP depletion, we produced mice bearing both a floxed crebbp allele (CBP f ) in homozygosity (Zhang et al, 2004) and the transgene CaMKII␣-cre, which drives the expression of cre recombinase in postmitotic principal neurons of the forebrain (Tsien et al, 1996). This genetic manipulation results in mice that express a truncated CBP protein (CBP stop523 ) that lacks KAT activity (amino acids 1300 -1700) and is also unable to interact with a number of transcription factors involved in neuronal function, such as CREB, c-fos, jun, nuclear factor-B, and others, because critical domains (KIX, CH3) involved in these interactions are encoded by exons downstream of the deletion (Chan and La Thangue, 2001).…”

“…1 E), but layers 2 and 3 seemed more severely affected (ϳ70% of the cells; data not shown) than the other layers. The loss of CBP also affected most principal neurons in the amygdala formation, whereas immunostaining in the cerebellum was sim- (Zhang et al, 2004)] and transcript levels (named 5ЈCBD and E8rev) are also depicted. B, The recombination of genomic DNA (band marked as "recomb") was detected only in genomic DNA from cre-expressing tissues (Ctx, cortex; Hpc, hippocampus; Str, striatum) but not in the cerebellum (Cb) or the tail.…”