Histone deacetylase 3 suppresses the expression of SHP-1 via deacetylation of DNMT1 to promote heart failure.

AIMS: Heart failure (HF) is a progressive disease with recurrent hospitalizations and high mortality. However, the mechanisms underlying HF remain unclear. The present study aimed to explore the regulatory mechanism of histone deacetylase 3 (HDAC3) and DNA methyltransferase 1 (DNMT1)/Src homology domain 2-containing tyrosine phosphatase-1 (SHP-1) axis in HF. METHODS: The HF rat models and hypertrophy cell models were established. The characteristic parameters of the heart were detected by echocardiography. A multichannel physiological signal acquisition system was used to detect the hemodynamic parameters. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of HDAC3, DNMT1, and SHP-1 mRNAs, while Western blot was applied to analyze the expression of proteins. Masson staining was used to analyze the degree of collagen fiber infiltration. TdT-mediated DUTP nick end labeling (TUNEL) staining was performed to analyze the apoptosis of myocardial tissue cells. Co-immunoprecipitation (co-IP) was conducted to study the interaction between HDAC3 and DNMT1. Flow cytometry was used to analyze the apoptosis. KEY FINDINGS: HDAC3 and DNMT1 were highly expressed in HF rat and hypertrophy cell models. HDAC3 modified DNMT1 through deacetylation to inhibit ubiquitination-mediated degradation, which promoted the expression of DNMT1. DNMT1 inhibited SHP-1 expression via methylation in the promoter region. In summary, HDAC3 modified DNMT1 by deacetylation to suppress SHP-1 expression, which in turn led to the development of cardiomyocyte hypertrophy-induced HF. SIGNIFICANCE: This study provided potential therapeutic targets for HF treatment.

[CO2 fluxes in mire and grassland on Ruoergai plateau].

With closed chamber and GC technique, a comparative study was conducted on the CO2 fluxes in mire and grassland on Ruoergai plateau during the plant growth period in 2003-2005. The results showed that the mean value of the CO2 fluxes in the three years was 203.22 mg x m(-2) x h(-1) in mire and 323.03 mg x m(-2) x h(-1) in grassland, with the former being only about 60% of the latter. The perennially water-logging of mire limited the decomposition of plant residues, roots and organic substances, resulting in a lower CO2 flux in mire than in grassland. The seasonal changes of CO2 fluxes in mire and grassland were positively correlated with air temperature, the peak value being usually appeared in July or August, and the diurnal changes of the CO2 fluxes were also positively correlated with air temperature, the peak value being usually appeared between 11:00 and 17:00. The CO2 fluxes had a higher correlation with the soil temperature at the depth of 5 cm than at the depths of 10 cm and 15 cm.

[Characteristics of nitrous oxide flux in spring wheat field ecosystem in Sanjiang Plain of Northeast China].

With static-closed-chamber and GC (Agilent 4890), the nitrous oxide (N2O) flux in spring wheat field ecosystem in the Sanjiang Plain of Northeast China was continuously observed in situ from May 2004 to October 2006. The results showed that the N2O flux presented obvious seasonal and inter-annual variation, which was mainly related with precipitation and field water management. The diurnal variation of N2O flux had correlations with the air temperature and the temperature at 5 cm underground. Wheat field ecosystem was the strong sources of atmosphere N2O during plant growth season. The N2O flux decreased obviously in fallowing period, was weaker in freezing period, and increased slowly when soil thawing. The average N2O flux in wheat growth season was 0.190 mg x m(-2) x h(-1), the flux was 0.077 mg x m(-2) x h(-1) from after-reaping to before-freezing period, and 0.017 mg x m(-2) x h(-1) in freezing and thawing period.

[Annual dynamics of CO2, CH4, N2O emissions from freshwater marshes and affected by nitrogen fertilization].

Annual dynamics of CO2, CH4, N2O emissions from freshwater marshes and affected by nitrogen fertilization were studied in situ in Sanjiang Plain of Northeast China from June 2002 to December 2004, using the static opaque chamber-GC techniques. The results showed that there was significant seasonal and annual variation in the CO2, CH4 and N2O emissions. The ecosystem emission of CO2 reached a maximum of 779.33- 965.40 mg x (mxh)(-1) in July and August, CH4 reached a maximum of 19.19-30.52 mg x (mxh)(-1) in August, N2O reached a maximum of 0.072-0.15 mgx (mxh)(-1) in May and September, respectively. While the minimum of the CO2, CH4, N2O emission was 2.36-18.73 mg x (mxh)(-1), - 0.35 - 0.59 mg x (mxh)(-1), - 0.032- 0.009 mg (mxh)(-1), respectively, which occurs in winter. The freshwater marsh was the sink of N2O in winter. Temperature was a primary factor, controlling greenhouse gas seasonal emissions in freshwater marshes; while the precipitation and floodwater depth were the dominating influencing factors, affecting the greenhouse gas annual variations. Especially, the influence of precipitation on CH4 emissions was more obvious, comparing with the CO2 and N20 emissions. And the summer higher CH4 emission was mainly induced by the ice and snow thawing water in winter. Respiration of the ecosystem and CH4 emission were exponentially dependent on soil temperature of 5cm depth, while the N2O emission was not related to the soil temperature and water depth. The greenhouse gas (CO2, CH4, N2O) emissions were significantly influenced by nitrogen fertilization in Sanjiang Plain. The CO2, CH4, N2O flux of fertilization increased 34% , 145% , 110% , respectively, comparing to the control treatment.

[Dynamics of CO2, CH4 and N2O emission fluxes from mires during freezing and thawing season].

In the Sanjiang Plain, the freezing and thawing phase have 7 - 8 months and play important role in the greenhouse gases emission. The characters of the greenhouse gases emission during freezing and thawing season in the Sanjiang Plain were studied, using the static chamber and gas chromatogram method. The results observed show that there were obvious CH4 and CO2 emissions in winter and the CH4 emission made a relatively large contribution to the total CH4 flux from the different type mires during the winter in the Sanjiang Plain. And there were significantly CH4 and CO2 emission peak values during thawing time. The CH4 and CO2 emissions fluxes from seasonal flooded mire were larger than that from continuously flooded mire during thawing time. On the contrary, the CH4 and CO2 emissions from continuously flooded mire were larger than that from seasonal flooded mire in winter. During thawing, there was exponential relationship between CO2 fluxes and the soil temperature (5cm) (R2 = 0.912, p< 0.001). Meanwhile, CO2 fluxes was obviously correlated with the CH4 emission fluxes (R2 = 0.751, p < 0.001). The mires are N2O sink in winter and gradually become N2O source, with increasing temperature during thawing time. The characters of the greenhouse gases emission, during freezing and thawing in the Sanjiang Plain respond to the microbial activity in winter and the effects of thawing on soil carbon mineralization, nitrification and denitrification.

[The changes of the soil hydrothermal condition and the dynamics of C, N after the mire tillage].

The wetlands gain increasing attention to its crucial ecological and environmental function. The tillage of the mires in the Sanjiang Plain has played the important role in regulation of the region ecological balance and climate. Prior to tillage, the mean soil temperature of the topsoil (10 cm) in mire from June to September was 12.72 degrees C +/- 4.12 degrees C, distinctly lower than that of the tilled soil, which was 16.71 degrees C +/- 3.81 degrees C. However, the daily mean evaporation of 4.87 mm +/- 3.78 mm in the mire was larger than that of the tilled soil with mean soil temperature of 2.66 mm +/- 3.78 mm from May to September. The alteration of the oxidization-reduction condition and the augment of the soil temperature led to the increases of soil organic matter (SOM) decomposition ratio and the soil respiration flux, the mean soil respiration (CO2) flux [(946.36 +/- 195.78) mg x (m2 x h)(-1)] was 6 times larger than that of the mire [(153.75 +/- 82.59) mg x (m2 x h)(-1)] from August to September. At the initial stage (5-7a) of the mire tillage, the SOM and the nutrients levels change significantly, but after the 15-20a of continuous cultivation, the SOM loss curve came to a relative stable value. The lessen of the input and strength of the decomposition rate of SOM resulted in the accretion of soil bulk capacity and specific gravity, its changing trend was similar to the changing of the soil organic carbon (SOC) loss.