The hemangioblast hypothesis has been hotly debated for over a century. Hemangioblasts are defined as multipotent cells that can give rise to both hematopoietic cells and endothelial cells. The existence of hemangioblasts has now been confirmed and many important molecules and several signaling pathways are involved in their generation and differentiation. Fibroblast growth factor, renin-angiotensin system and runt-related transcription factor 1 (Runx1) direct the formation of hemangioblasts through highly selective gene expression patterns. On the other hand, the hemogenic endothelium theory and a newly discovered pattern of hematopoietic/endothelial differentiation make the genesis of hemangioblasts more complicated. But how hemangioblasts are formed and how hematopoietic cells or endothelial cells are derived from remains largely unknown. Here we summarize the current knowledge of the signaling pathways and molecules involved in hemangioblast development and suggest some future clinical applications. Anat Rec, 294:580-588, 2011. V V C 2011 Wiley-Liss, Inc.

Myelination by oligodendrocytes facilitates rapid nerve conduction. Loss of oligodendrocytes and failure of myelination lead to nerve degeneration and numerous demyelinating white matter diseases. N-methyl-D-aspartate (NMDA) receptors, which are key regulators on neuron survival and functions, have been recently identified to express in oligodendrocytes, especially in the myelin sheath. NMDA receptor signaling in oligodendrocytes plays crucial roles in energy metabolism and myelination. In the present review, we highlight the subcellular location-specific impairment of excessive NMDA receptor signaling on oligodendrocyte energy metabolism in soma and myelin, and the mechanisms including Ca(2+) overload, acidotoxicity, mitochondria dysfunction, and impairment of respiratory chains. Conversely, physiological NMDA receptor signaling regulates differentiation and migration of oligodendrocytes. How can we use above knowledge to treat excitotoxic oligodendrocyte loss, congenital myelination deficiency, or postnatal demyelination? A thorough understanding of NMDA receptor signaling-mediated cellular events in oligodendrocytes at the pathophysiological level will no doubt aid in exploring effective therapeutic strategies for demyelinating white matter diseases.

Aims: Cardiac hypertrophy, in the long-term, is a maladaptive response to the change in hemodynamics needed to maintain cardiac output that leads to heart failure and sudden death. However, the underlying regulatory mechanisms causing cardiac hypertrophy remain to be elucidated. Recent studies have highlighted the importance of long non-coding RNAs (lncRNAs) in many biological processes and diseases. However, knowledge of the role of lncRNAs in cardiac diseases is still limited. Methods and Results：We identified the role of NPPA-AS1 in cardiac hypertrophy and remodeling. NPPA-AS1 is a heart-enriched and -conserved lncRNA, located in the antisense strand of the atrial natriuretic peptide (NPPA) gene. The cardiac expression of NPPA-AS1 was markedly upregulated early and sustained, in response to stress caused by transverse aortic constriction (TAC) in mice. NPPA-AS1 levels were also increased in failing human hearts. To determine the functional role of NPPA-AS1 in the heart in vivo, we inactivated NPPA-AS1 in mice using CRISPR-Cas9. Under basal conditions, there was no body or cardiac morphological or functional phenotype in NPPA-AS1-inactivated mice. However, in vivo germline inactivation of NPPA-AS1 minimized the TAC-induced cardiac hypertrophy and fibrosis and normalized the cardiac size, weight, and function. GapmeR-mediated or AAV9-shRNA-mediated silencing of NPPA-AS1 could also block and attenuate TAC-induced pathological cardiac remodeling, which reveals its clinical translation potential. The beneficial cardiac effects of inhibition of NPPA-AS1 were related to the recruitment of transcriptional coactivator EP300 to bind with transcription factor GATA4 to promote GATA4 acetylation and inhibition of hypertrophic gene expression. Conclusions: Our studies show that NPPA-AS1 recruits the transcriptional factor GATA4, increasing EP300/GATA4 binding and subsequent GATA4 acetylation to promote pathological cardiac hypertrophy. Inhibition of NPPA-AS1 could serve as a potential therapeutic strategy in the treatment of maladaptive cardiac hypertrophy and remodeling.