Lactate dehydrogenase a expression is necessary to sustain rapid angiogenesis of pulmonary microvascular endothelium.

Angiogenesis is a fundamental property of endothelium, yet not all endothelial cells display equivalent angiogenic responses; pulmonary microvascular endothelial cells undergo rapid angiogenesis when compared to endothelial cells isolated from conduit vessels. At present it is not clear how pulmonary microvascular endothelial cells fulfill the bioenergetic demands that are necessary to sustain such rapid blood vessel formation. We have previously established that pulmonary microvascular endothelial cells utilize aerobic glycolysis to generate ATP during growth, a process that requires the expression of lactate dehydrogenase A to convert pyruvate to lactate. Here, we test the hypothesis that lactate dehydrogenase A is required for pulmonary microvascular endothelial cells to sustain rapid angiogenesis. To test this hypothesis, Tet-On and Tet-Off conditional expression systems were developed in pulmonary microvascular endothelial cells, where doxycycline is utilized to induce lactate dehydrogenase A shRNA expression. Expression of LDH-A shRNA induced a time-dependent decrease in LDH-A protein, which corresponded with a decrease in glucose consumption from the media, lactate production and cell growth; re-expression of LDH-A rescued each of these parameters. LDH-A silencing greatly reduced network formation on Matrigel in vitro, and decreased blood vessel formation in Matrigel in vivo. These findings demonstrate that LDH-A is critically important for sustaining the rapid angiogenesis of pulmonary microvascular endothelial cells.

Critical role for lactate dehydrogenase A in aerobic glycolysis that sustains pulmonary microvascular endothelial cell proliferation.

Pulmonary microvascular endothelial cells possess both highly proliferative and angiogenic capacities, yet it is unclear how these cells sustain the metabolic requirements essential for such growth. Rapidly proliferating cells rely on aerobic glycolysis to sustain growth, which is characterized by glucose consumption, glucose fermentation to lactate, and lactic acidosis, all in the presence of sufficient oxygen concentrations. Lactate dehydrogenase A converts pyruvate to lactate necessary to sustain rapid flux through glycolysis. We therefore tested the hypothesis that pulmonary microvascular endothelial cells express lactate dehydrogenase A necessary to utilize aerobic glycolysis and support their growth. Pulmonary microvascular endothelial cell (PMVEC) growth curves were conducted over a 7-day period. PMVECs consumed glucose, converted glucose into lactate, and acidified the media. Restricting extracellular glucose abolished the lactic acidosis and reduced PMVEC growth, as did replacing glucose with galactose. In contrast, slow-growing pulmonary artery endothelial cells (PAECs) minimally consumed glucose and did not develop a lactic acidosis throughout the growth curve. Oxygen consumption was twofold higher in PAECs than in PMVECs, yet total cellular ATP concentrations were twofold higher in PMVECs. Glucose transporter 1, hexokinase-2, and lactate dehydrogenase A were all upregulated in PMVECs compared with their macrovascular counterparts. Inhibiting lactate dehydrogenase A activity and expression prevented lactic acidosis and reduced PMVEC growth. Thus PMVECs utilize aerobic glycolysis to sustain their rapid growth rates, which is dependent on lactate dehydrogenase A.

Haplogroup analysis of the risk associated with APOE promoter polymorphisms (-219T/G, -491A/T and -427T/C) in Colombian Alzheimer's disease patients.

Results analyzing the association between polymorphisms in the promoter region of the apolipoprotein E (APOE) gene and Alzheimer's disease (AD) are contradictory. We studied the association of three polymorphisms in the APOE promoter (-219T/G, -491A/T and -427T/C) with AD in a sample of the Colombian population. The polymorphism -491A/T confers increased risk for AD associated with AA genotype independent of APOEe4 allele (odds ratio (OR): 2.64) and more pronounced in men (OR: 6.07). Genotypes TT and TG of -219T/G showed a significant association with AD, but this was lost in an adjusted model. We did not find any association with -427T/C polymorphism. Using a haplogroup analysis of the promoter polymorphisms, we further confirmed their independent contribution as genetic risk factors for AD.