Figure 7.

CAR expression and alternative splicing of exon 9 during enterocytic differentiation of Caco-2 TC7 cells. (A) Northern Blot analysis with polyadenylated RNA of the indicated cell lines. Caco-2 TC7 cells were analyzed from subconfluent (sub), confluent (confl) and 15 days post-confluent (15d pc) cultures. The blot was sequentially hybridized with probes for the genes indicated. The arrow marks the major CAR mRNA species of 1.4 to 1.7 kb. (B) Analysis of the expression of transcripts with alternatively spliced exon 9 by qualitative RT-PCR with random hexamer primed cDNA of polyadenylated RNA of Caco-2 TC7 cells cultured until confluence (confl) and for 15 days post-confluent (15d pc). PCR was performed with primers F2/R2 (Table 1). SV1 and SV5 denote control reactions performed with DNA of the corresponding CAR isoform expression plasmids. The lane on the left shows a 50 bp ladder size marker. By mixing DNA of SV1 and SV5 CAR isoform expression plasmids in different molar ratios, we confirmed that both fragments were amplified with equal efficiency (data not shown).