Blood vessels deliver oxygen and nutrients to every part of the body, but also nourish diseases such as cancer. Over the past decade, our understanding of the molecular mechanisms of angiogenesis (blood vessel growth) has increased at an explosive rate and has led to the approval of anti-angiogenic drugs for cancer and eye diseases. So far, hundreds of thousands of patients have benefited from blockers of the angiogenic protein vascular endothelial growth factor, but limited efficacy and resistance remain outstanding problems. Recent preclinical and clinical studies have shown new molecular targets and principles, which may provide avenues for improving the therapeutic benefit from anti-angiogenic strategies.

/pdf/molecular-mechanisms-and-clinical-applications-of-2j04l9iq9q.pdf

Molecular mechanisms and clinical applications of angiogenesis

Mitochondria: In Sickness and in Health

Hypoxia inducible factors and the response to hypoxic stress

Macrophages have an important role in the maintenance of tissue homeostasis. To perform this function, macrophages must have the capacity to monitor the functional states of their 'client cells': namely, the parenchymal cells in the various tissues in which macrophages reside. Tumours exhibit many features of abnormally developed organs, including tissue architecture and cellular composition. Similarly to macrophages in normal tissues and organs, macrophages in tumours (tumour-associated macrophages) perform some key homeostatic functions that allow tumour maintenance and growth. However, the signals involved in communication between tumours and macrophages are poorly defined. Here we show that lactic acid produced by tumour cells, as a by-product of aerobic or anaerobic glycolysis, has a critical function in signalling, through inducing the expression of vascular endothelial growth factor and the M2-like polarization of tumour-associated macrophages. Furthermore, we demonstrate that this effect of lactic acid is mediated by hypoxia-inducible factor 1α (HIF1α). Finally, we show that the lactate-induced expression of arginase 1 by macrophages has an important role in tumour growth. Collectively, these findings identify a mechanism of communication between macrophages and their client cells, including tumour cells. This communication most probably evolved to promote homeostasis in normal tissues but can also be engaged in tumours to promote their growth.

/pdf/functional-polarization-of-tumour-associated-macrophages-by-56kr8jsez3.pdf

Functional polarization of tumour-associated macrophages by tumour-derived lactic acid

MicroRNAs (miRNAs) are a class of posttranscriptional regulators that have recently introduced an additional level of intricacy to our understanding of gene regulation. There are currently over 10,000 miRNAs that have been identified in a range of species including metazoa, mycetozoa, viridiplantae, and viruses, of which 940, to date, are found in humans. It is estimated that more than 60% of human protein-coding genes harbor miRNA target sites in their 3′ untranslated region and, thus, are potentially regulated by these molecules in health and disease. This review will first briefly describe the discovery, structure, and mode of function of miRNAs in mammalian cells, before elaborating on their roles and significance during development and pathogenesis in the various mammalian organs, while attempting to reconcile their functions with our existing knowledge of their targets. Finally, we will summarize some of the advances made in utilizing miRNAs in therapeutics.

/pdf/micrornas-in-development-and-disease-472gt45lvo.pdf

MicroRNAs in development and disease.

Ischaemia of the heart, brain and limbs is a leading cause of morbidity and mortality worldwide. Hypoxia stimulates the secretion of vascular endothelial growth factor (VEGF) and other angiogenic factors, leading to neovascularization and protection against ischaemic injury. Here we show that the transcriptional coactivator PGC-1alpha (peroxisome-proliferator-activated receptor-gamma coactivator-1alpha), a potent metabolic sensor and regulator, is induced by a lack of nutrients and oxygen, and PGC-1alpha powerfully regulates VEGF expression and angiogenesis in cultured muscle cells and skeletal muscle in vivo. PGC-1alpha-/- mice show a striking failure to reconstitute blood flow in a normal manner to the limb after an ischaemic insult, whereas transgenic expression of PGC-1alpha in skeletal muscle is protective. Surprisingly, the induction of VEGF by PGC-1alpha does not involve the canonical hypoxia response pathway and hypoxia inducible factor (HIF). Instead, PGC-1alpha coactivates the orphan nuclear receptor ERR-alpha (oestrogen-related receptor-alpha) on conserved binding sites found in the promoter and in a cluster within the first intron of the VEGF gene. Thus, PGC-1alpha and ERR-alpha, major regulators of mitochondrial function in response to exercise and other stimuli, also control a novel angiogenic pathway that delivers needed oxygen and substrates. PGC-1alpha may provide a novel therapeutic target for treating ischaemic diseases.

/pdf/hif-independent-regulation-of-vegf-and-angiogenesis-by-the-4qxt70kiu5.pdf

HIF-independent regulation of VEGF and angiogenesis by the transcriptional coactivator PGC-1α

Myostatin is a highly conserved, potent negative regulator of skeletal muscle hypertrophy in many species, from rodents to humans, although its mechanisms of action are incompletely understood. Transcript profiling of hearts from a genetic model of cardiac hypertrophy revealed dramatic upregulation of myostatin, not previously recognized to play a role in the heart. Here we show that myostatin abrogates the cardiomyocyte growth response to phenylephrine in vitro through inhibition of p38 and the serine-threonine kinase Akt, a critical determinant of cell size in many species from drosophila to mammals. Evaluation of male myostatin-null mice revealed that their cardiomyocytes and hearts overall were slightly smaller at baseline than littermate controls but exhibited more exuberant growth in response to chronic phenylephrine infusion. The increased cardiac growth in myostatin-null mice corresponded with increased p38 phosphorylation and Akt activation in vivo after phenylephrine treatment. Together, these data demonstrate that myostatin is dynamically regulated in the heart and acts more broadly than previously appreciated to regulate growth of multiple types of striated muscle.

Myostatin Regulates Cardiomyocyte Growth Through Modulation of Akt Signaling

Background— Response gene to complement 32 (RGC-32) is induced by activation of complement and regulates cell proliferation. To determine the mechanism of RGC-32 in angiogenesis, we examined the ro...

Shi-Yin Foo

Papers

HIF-independent regulation of VEGF and angiogenesis by the transcriptional coactivator PGC-1α

Myostatin Regulates Cardiomyocyte Growth Through Modulation of Akt Signaling

Response Gene to Complement 32, a Novel Hypoxia-Regulated Angiogenic Inhibitor

RTEF-1, an upstream gene of hypoxia-inducible factor-1α, accelerates recovery from ischemia.