PDK1 plays a critical role in regulating cardiac function in mice and human / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>PDK1 is an essential protein kinase that plays a critical role in mammalian development. Mouse lacking PDK1 leads to multiple abnormalities and embryonic lethality at E9.5. To elucidate the role of PDK1 in the heart, we investigated the cardiac phenotype of mice that lack PDK1 in the heart in different growth periods and the alteration of PDK1 signaling in human failing heart.</p><p><b>METHODS</b>We employed Cre/loxP system to generate PDK1(flox/flox): α-MHC-Cre mice, which specifically deleted PDK1 in cardiac muscle at birth, and tamoxifen-inducible heart-specific PDK1 knockout mice (PDK1(flox/flox):MerCreMer mice), in which PDK1 was deleted in myocardium in response to the treatment with tamoxifen. Transmural myocardial tissues from human failing hearts and normal hearts were sampled from the left ventricular apex to analyze the activity of PDK1/Akt signaling pathways by Western blotting.</p><p><b>RESULTS</b>PDK1(flox/flox): α-MHC-Cre mice died of heart failure at 5 and 10 weeks old. PDK1(flox/flox) -MerCreMer mice died of heart failure from 5 to 21 weeks after the initiation of tamoxifen treatment at 8 weeks old. We found that expression levels of PDK1 in human failing heart tissues were significantly decreased compared with control hearts.</p><p><b>CONCLUSION</b>Our results suggest that PDK1 signaling network takes part in regulating cardiac viability and function in mice, and may be also involved in human heart failure disease.</p>

Changes of MAPK and Akt signaling pathways in hearts and placentas of aborted fetuses with congenital heart disease / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study the changes of MAPK and Akt signaling pathways in hearts and placentas of aborted fetuses with congenital heart disease (CHD), and investigate their roles in the pathogenesis of CHD.</p><p><b>METHODS</b>Ten aborted fetuses with severe CHD (CHD group) and 7 gestational age-matched non-cardiac malformation aborted fetuses (control group) were enrolled. Western blot analysis was undertaken to assess the expression of p38, p38alpha, p-p38, MEF2, ERK, p-ERK, Akt, p-Akt(Ser473) and p-Akt(Thr308) in left ventricles and placentas of the fetuses, while semi-quantitative reverse transcription polymerase chain reaction analysis was used to detect the expression of p38alpha isoforms mRNA in hearts.</p><p><b>RESULTS</b>Compared with the heart samples of the control group, the protein expression levels of p38 and its alpha isoform in 4 cases, p-p38 in 6 cases, MEF2 in 2 cases, p-ERK in 8 cases, Akt in 4 cases, p-Akt(Ser473) and p-Akt(Thr308) in 8 cases decreased, while the protein expression levels of p-p38 in 2 cases and p-Akt(Thr308) in 1 case increased. P-p38 protein level in 3 cases and p-ERK protein level in 2 cases decreased in placentas compared with the control group. The changes of protein expression of MAPK and Akt signaling pathway in hearts were not consistent with those in placentas in the CHD group. The expression of p38alpha isoform2 mRNA showed descent tendency in 4 heart samples with CHD, while the expression of other three p38alpha isoforms mRNA was reduced in only 1 sample compared with the control group.</p><p><b>CONCLUSIONS</b>Dysfunction of MAPK and Akt signaling pathways is tissue-specific in aborted fetuses with CHD. The perturbed two signaling pathways in hearts may contribute to the pathogenesis of human CHD.</p>