Abstract
Histone acetyltransferases (HATs), p300 and cAMP response element binding protein (CREB)-binding protein (CBP) are two structurally related transcriptional co-activators that activate expression of many eukaryotic genes involved in cellular growth and signaling, muscle differentiation and embryogenesis. However, whether these proteins play important and different roles in mouse cardiogenesis is not clear. Here, we investigate the protein distributions and mRNA expression of the two HATs in embryonic and adult mouse heart during normal heart development by using immunohistochemical and RT-PCR techniques. The data from immunohistochemical experiments revealed that p300 was extensively present in nearly every region of the hearts from embryonic stages to the adulthood. However, no CBP expression was detected in embryonic hearts at day E7.5. CBP expression appeared at the later stages, and the distribution of CBP was less than that of p300. In the developmental hearts after E10.5, both for p300 and CBP, the mRNA expression levels reached a peak on day E10.5, and then were gradually decreased afterwards. These results reveal that both p300 and CBP are related to embryonic heart development. The dynamic expression patterns of these two enzymes during mouse heart development indicate that they may play an important role on heart development. However, there is a difference in spatiotemporal expression patterns between these two enzymes during heart development. The expression of p300 is earlier and more predominate, suggesting that p300 may play a more important role in embryonic heart development especially during cardiac precursor cell induction and interventricular septum formation.
Highlights
The heart is the first functional organ during embryogenesis and its formation is initiated in a region of anterior mesoderm known as the cardiac crescent at about embryonic day 7.5 (E 7.5) in mice
All amplification products were resolved in a 1.5% agarose gel and sequencing confirmed the identity of each PCR amplified product and electrophoresis and the bands were analyzed with a Gelatin image formation meter (Bio-Rad) and Quantity One Version 4.4
We showed that during the early embryonic heart development stages (E7.5-E9.5), p300 was highly expressed in crescent-shaped cardiogenic plate at E7.5 (Figure 2A), while no CBP expression was detected in this region at the same stage (Figure 2D)
Summary
The heart is the first functional organ during embryogenesis and its formation is initiated in a region of anterior mesoderm known as the cardiac crescent at about embryonic day 7.5 (E 7.5) in mice. Soon after their specification, the cardiac crescent from cardiac precursor cells converges along the ventral midline of the embryos to form the linear heart tube at around day E 8.5, which undergoes looping, chamber growth, specification and fourchamber formation [1,2]. The transcriptional co-activator p300 and CBP are HATs that regulate gene expression by acetylating histones and play central roles in a wide range of cellular processes during heart development [5-7]. The reports from recent studies indicate that the two proteins may have different distribution patterns and functions in embryogenesis [9-14]
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