Time series RNA-seq analysis identifies MAPK10 as a critical gene in diabetes mellitus-induced atrial fibrillation in mice.

Atrial fibrillation (AF) is a major complication of type 2 diabetes mellitus (T2DM) and plays critical roles in the pathogenesis of atrial remodeling. However, the differentially expressed genes in atria during the development of AF induced by hyperglycemia have rarely been reported. Here, we showed time-dependent increased AF incidence and duration, atrial enlargement, inflammation, fibrosis, conduction time and action potential duration in db/db mice, a model of T2DM. RNA sequencing analysis showed that 2256 genes were differentially expressed in the atria at 12, 14 and 16 weeks. Gene Ontology analysis showed that these genes participate primarily in cell adhesion, cellular response to interferon-beta, immune system process, positive regulation of cell migration, ion transport and cellular response to interferon-gamma. Analysis of significant pathways revealed the IL-17 signaling pathway, TNF signaling pathway, MAPK signaling pathway, chemokine signaling pathway, and cAMP receptor signaling. Additionally, these differentially expressed genes were classified into 50 profiles by hierarchical clustering analysis. Twelve of these profiles were significant and comprised 1115 genes. Gene coexpression network analysis identified that mitogen-activated protein kinase 10 (MAPK10) was localized in the core of the gene network and was the most highly expressed gene at different time points. Knockdown of MAPK10 markedly attenuated DM-induced AF incidence, atrial inflammation, fibrosis, electrical disorder and apoptosis in db/db mice. In summary, the present findings revealed that many genes are involved in DM-induced AF and that MAPK10 plays a central role in this disease, indicating that strategies targeting MAPK10 may represent a potential therapeutic approach to treat DM-induced AF.

Time Series Transcriptomic Analysis by RNA Sequencing Reveals a Key Role of PI3K in Sepsis-Induced Myocardial Injury in Mice.

Septic cardiomyopathy is the main complication and cause of death of severe sepsis with limited therapeutic strategy. However, the molecular mechanism of sepsis-induced cardiac injury remains unclear. The present study was designed to investigate differentially expressed genes (DEGs) involved in the pathogenesis of septic cardiomyopathy induced by cecal ligation and puncture (CLP) in mice. Male C57BL/6J mice (8-10 weeks old) were subjected to CLP with 21-gauge needles for 24, 48, and 72 h. Myocardial function was assessed by echocardiography. The pathological changes of the heart were evaluated by hematoxylin and eosin as well as immunohistochemical staining. Time series RNA sequencing was utilized to investigate the gene expression profiles. CLP surgery resulted in a significant decrease of animal survival rate and left ventricle contractile function, and an increase in cardiac dilation and infiltration of proinflammatory cells including Mac-2+ macrophages in a time-dependent manner. RNA sequencing identified 5,607 DEGs in septic myocardium at 24, 48, and 72 h after CLP operation. Moreover, gene ontology analysis revealed that these DEGs were mainly associated with the biological processes, including cell adhesion, immune system process, inflammatory response, and positive regulation of cell migration. KEGG pathway enrichment analysis indicated that Staphylococcus aureus infection, osteoclast differentiation, leishmaniasis, and ECM-receptor interaction were significantly altered in septic hearts. Notably, Pik3r1 and Pik3r5 were localized in the center of the gene co-expression network, and were markedly upregulated in CLP-induced septic myocardium. Further, blocking PI3Kγ by the specific inhibitor CZC24832 significantly protected against sepsis-induced cardiac impairment. The present study uncovers the gene expression signatures of CLP-induced myocardial injury and sheds light on the role of Pik3r5 in septic cardiomyopathy.

Angiotensin II Stimulates the Proliferation and Migration of Lymphatic Endothelial Cells Through Angiotensin Type 1 Receptors.

BACKGROUND/AIM: The proliferation and migration of lymphatic endothelial cells (LECs) is essential for lymphatic vessel growth (also known as lymphangiogenesis), which plays a crucial role in regulating the tissue fluid balance and immune cell trafficking under physiological and pathological conditions. Several growth factors, such as VEGF-C, can stimulate lymphangiogenesis. However, the effects of angiotensin II (Ang II) on the proliferation and migration of mouse LECs and the underlying potential mechanisms remain unknown. METHODS: Wild-type mice were infused with Ang II (1,000 ng/kg/min) for 1-2 weeks. Murine LECs were stimulated with Ang II (500 nM) or saline for 12-48 h. Cell proliferation was determined with 5-bromo-2-deoxyuridine (BrdU) incorporation assays, while cell migration was assessed by scratch wound healing and transwell chamber assays. The gene expression profiles were obtained by time series microarray and real-time PCR analyses. RESULTS: Ang II treatment significantly induced lymphangiogenesis in the hearts of mice and the proliferation and migration of cultured LECs in a time-dependent manner. This effect was completely blocked by losartan, an angiotensin II type 1 receptor (AT1R) antagonist. The microarray results identified 1,385 differentially expressed genes (DEGs) at one or more time points in the Ang II-treated cells compared with the control saline-treated cells. These DEGs were primarily involved in biological processes and pathways, including sensory perception of smell, the G protein coupled receptor signaling pathway, cell adhesion, olfactory transduction, Jak-STAT, alcoholism, RIG-I-like receptor and ECM-receptor interaction. Furthermore, these DEGs were classified into 16 clusters, 7 of which (Nos. 13, 2, 8, 15, 7, 3, and 12, containing 586 genes) were statistically significant. Importantly, the Ang II-induced alterations the expression of lymphangiogenesis-related genes were reversed by losartan. CONCLUSION: The results of the present indicate that Ang II can directly regulate the proliferation and migration of LECs through AT1R in vivo and in vitro, which may provide new potential treatments for Ang II-induced hypertension and cardiac remodeling.

Time Series Gene Expression Profiling and Temporal Regulatory Pathway Analysis of Angiotensin II Induced Atrial Fibrillation in Mice.

Background/Aim: Angiotensin II (Ang II) and hypertension play critical roles in the pathogenesis of the atrial remodeling that contributes to atrial fibrillation (AF). However, the gene expression profiles and signaling pathways in atria during the development of AF induced by Ang II remain unknown. Methods: Wild-type male mice (C57BL/6 background, 10 weeks old) were administered an infusion of Ang II (2000 ng/kg/min) using an osmotic pump for 1, 2, and 3 weeks. Blood pressure (BP) was measured by the tail-cuff method. AF was induced and recorded. Atrial enlargement and remodeling were examined by echocardiography and Masson's trichrome staining. Time-series microarray analyses were conducted to examine gene expression profiles and pathways. Results: Ang II infusion resulted in marked elevation of systolic BP, increased AF incidence and duration, atrial enlargement, fibrosis, and atrial infiltration of myofibroblasts and F4/80-positive macrophages in a time-dependent manner. Microarray results showed that 1,719 genes were differentially expressed in the atrium at weeks 1, 2, and 3 after Ang II infusion. Gene ontology showed that these genes participate mainly in immune system processes, and regulation of cell migration, cell adhesion, complement activation, and the inflammatory response. Significant pathways included lysosomal and phagosomal pathways, which are involved in antigen processing and presentation, as well as chemokine signaling, and extracellular matrix-receptor interaction, which are known to play important roles in Ang II-induced AF. Moreover, these differentially expressed genes were classified into 50 profiles by hierarchical cluster analysis. Of these, eight profiles were significant and contained a total of 1,157 genes. Gene co-expression network analysis identified that Pik3cg (also known as phosphoinositide-3-kinase regulatory subunit 3) was localized in the core of the gene network, and was the most highly expressed among the Pik3 isoforms at different time points. Conclusion: The present findings revealed that many genes are involved in Ang II-induced AF, and highlighted that Pik3cg may play a central role in this disease.