C1q-TNF-Related Protein-9 Promotes Cardiac Hypertrophy and Failure.

RATIONALE: Myocardial endothelial cells promote cardiomyocyte hypertrophy, possibly through the release of growth factors. The identity of these factors, however, remains largely unknown, and we hypothesized here that the secreted CTRP9 (C1q-tumor necrosis factor-related protein-9) might act as endothelial-derived protein to modulate heart remodeling in response to pressure overload. OBJECTIVE: To examine the source of cardiac CTRP9 and its function during pressure overload. METHODS AND RESULTS: CTRP9 was mainly derived from myocardial capillary endothelial cells. CTRP9 mRNA expression was enhanced in hypertrophic human hearts and in mouse hearts after transverse aortic constriction (TAC). CTRP9 protein was more abundant in the serum of patients with severe aortic stenosis and in murine hearts after TAC. Interestingly, heterozygous and especially homozygous knock-out C1qtnf9 (CTRP9) gene-deleted mice were protected from the development of cardiac hypertrophy, left ventricular dilatation, and dysfunction during TAC. CTRP9 overexpression, in turn, promoted hypertrophic cardiac remodeling and dysfunction after TAC in mice and induced hypertrophy in isolated adult cardiomyocytes. Mechanistically, CTRP9 knock-out mice showed strongly reduced levels of activated prohypertrophic ERK5 (extracellular signal-regulated kinase 5) during TAC compared with wild-type mice, while CTRP9 overexpression entailed increased ERK5 activation in response to pressure overload. Inhibition of ERK5 by a dominant negative MEK5 mutant or by the ERK5/MEK5 inhibitor BIX02189 blunted CTRP9 triggered hypertrophy in isolated adult cardiomyocytes in vitro and attenuated mouse cardiomyocyte hypertrophy and cardiac dysfunction in vivo, respectively. Downstream of ERK5, we identified the prohypertrophic transcription factor GATA4, which was directly activated through ERK5-dependent phosphorylation. CONCLUSIONS: The upregulation of CTRP9 during hypertrophic heart disease facilitates maladaptive cardiac remodeling and left ventricular dysfunction and might constitute a therapeutic target in the future.

Lamin A/C-dependent chromatin architecture safeguards naïve pluripotency to prevent aberrant cardiovascular cell fate and function.

Tight control of cell fate choices is crucial for normal development. Here we show that lamin A/C plays a key role in chromatin organization in embryonic stem cells (ESCs), which safeguards naïve pluripotency and ensures proper cell fate choices during cardiogenesis. We report changes in chromatin compaction and localization of cardiac genes in Lmna-/- ESCs resulting in precocious activation of a transcriptional program promoting cardiomyocyte versus endothelial cell fate. This is accompanied by premature cardiomyocyte differentiation, cell cycle withdrawal and abnormal contractility. Gata4 is activated by lamin A/C loss and Gata4 silencing or haploinsufficiency rescues the aberrant cardiovascular cell fate choices induced by lamin A/C deficiency. We uncover divergent functions of lamin A/C in naïve pluripotent stem cells and cardiomyocytes, which have distinct contributions to the transcriptional alterations of patients with LMNA-associated cardiomyopathy. We conclude that disruption of lamin A/C-dependent chromatin architecture in ESCs is a primary event in LMNA loss-of-function cardiomyopathy.

Hepatic Endothelial Notch Activation Protects against Liver Metastasis by Regulating Endothelial-Tumor Cell Adhesion Independent of Angiocrine Signaling.

The interaction of tumor cells with organ-specific endothelial cells (EC) is an important step during metastatic progression. Notch signaling in organ-specific niches has been implicated in mediating opposing effects on organotropic metastasis to the lungs and the liver, respectively. In this study, we scrutinized the role of endothelial Notch activation during liver metastasis. To target hepatic EC (HEC), a novel EC subtype-specific Cre driver mouse was generated. Clec4g-Cretg/wt mice were crossed to Rosa26N1ICD-IRES-GFP to enhance Notch signaling in HEC (NICDOE-HEC). In NICDOE-HEC mice, hepatic metastasis of malignant melanoma and colorectal carcinoma was significantly reduced. These mice revealed reduced liver growth and impaired metabolic zonation due to suppression of hepatic angiocrine Wnt signaling. Hepatic metastasis, however, was not controlled by angiocrine Wnt signaling, as deficiency of the Wnt cargo receptor Wls in HEC of WlsHEC-KO mice did not affect hepatic metastasis. In contrast, the hepatic microvasculature in NICDOE-HEC mice revealed a special form of sinusoidal capillarization, with effacement of endothelial zonation functionally paralleled by reduced tumor cell adhesion in vivo. Notably, expression of endothelial adhesion molecule ICAM1 by HEC was significantly reduced. Treatment with an anti-ICAM1 antibody significantly inhibited tumor cell adhesion to HEC in wild-type mice confirming that Notch controls hepatic metastasis via modulation of HEC adhesion molecules. As endothelial Notch activation in the lung has been shown to promote lung metastasis, tumor therapy will require approaches that target Notch in an organ-, cell type-, and context-specific manner. SIGNIFICANCE: Manipulation of Notch signaling in the endothelium has opposing, organ-specific effects on metastasis to the lung and the liver, demonstrating that this pathway should be targeted in a cell- and context-specific fashion.

Mutations in the gene encoding paired box domain (PAX8) are not a frequent cause of congenital hypothyroidism (CH) in Iranian patients with thyroid dysgenesis.

OBJECTIVE: Congenital hypothyroidism (CH) may be caused by defects in the thyroid or in one of the stages in the synthesis of thyroid hormones. Thyroid dysgenesis may be associated with mutation in the paired box transcription factor 8 (PAX8) gene. We attempted to screen PAX8 gene mutation in 50 CH patients with thyroid dysgenesis. SUBJECTS AND METHODS: The patients were classified in two groups as agenesis and ectopic based on biochemical and para clinical tests. By employing PCR, Single Strand Conformation Polymorphism (SSCP) and sequencing, exons 3 to 12 of PAX8 gene with their exon-intron boundaries were studied. RESULTS: No mutation was found in these patients in any of the exons. CONCLUSION: Our results, once again, indicate that the PAX8 mutation rate is very low and can only explain a minority of the cases. Therefore, it is highly needed to further investigate the genes controlling development and function of thyroid.

Mutations in the gene encoding paired box domain (PAX8) are not a frequent cause of congenital hypothyroidism (CH) in Iranian patients with thyroid dysgenesis / As mutações no gene PAX8 não constituem uma causa frequente de hipotireoidismo congênito em pacientes iranianos com disgenesia tiroidiana

OBJECTIVE: Congenital hypothyroidism (CH) may be caused by defects in the thyroid or in one of the stages in the synthesis of thyroid hormones. Thyroid dysgenesis may be associated with mutation in the paired box transcription factor 8 (PAX8) gene. We attempted to screen PAX8 gene mutation in 50 CH patients with thyroid dysgenesis. SUBJECTS AND METHODS: The patients were classified in two groups as agenesis and ectopic based on biochemical and para clinical tests. By employing PCR, Single Strand Conformation Polymorphism (SSCP) and sequencing, exons 3 to 12 of PAX8 gene with their exon-intron boundaries were studied. RESULTS: No mutation was found in these patients in any of the exons. CONCLUSION: Our results, once again, indicate that the PAX8 mutation rate is very low and can only explain a minority of the cases. Therefore, it is highly needed to further investigate the genes controlling development and function of thyroid.

OBJETIVO: O hipotireoidismo congênito (HC) pode ser causado por defeitos na formação da tireoide ou em uma das etapas da síntese dos hormônios tireoidianos. A disgenesia da tireoide pode ser associada a mutações no fator de transcrição PAX8. Neste estudo, foram rastreadas mutações no gene PAX8 em 50 pacientes com CH com disgenesia da tireoide. SUJEITOS E MÉTODOS: Os pacientes foram classificados em dois grupos, com agenesia ou com ectopia, segundo os testes bioquímicos e paraclínicos. Foram empregadas as técnicas de SSCP (Single Strand Conformation Polymorphism) e sequenciamento para analisar os éxons 3 a 12 do gene PAX8 e suas bordas éxon-intron. RESULTADOS: Nenhuma mutação foi encontrada nesses pacientes, em qualquer um dos éxons. CONCLUSÃO: Nossos resultados, mais uma vez, indicam que a taxa de mutação PAX8 é muito baixa e só pode explicar a minoria dos casos. Portanto, é altamente necessário investigar outros genes que controlam o desenvolvimento e as funções tireoideanas.