Hyperhomocysteinemia is an independent risk factor for cardiovascular disease and accelerates atherosclerosis in apoE ؊/؊ mice. Despite the observations that homocysteine causes endoplasmic reticulum (ER) stress and programmed cell death (PCD) in cultured human vascular endothelial cells, the cellular factors responsible for this effect and their relevance to atherogenesis have not been completely elucidated. We report here that homocysteine induces the expression of T-cell death-associated gene 51 (TDAG51), a member of the pleckstrin homology-related domain family, in cultured human vascular endothelial cells. This effect was observed for other ER stress-inducing agents, including dithiothreitol and tunicamycin. TDAG51 expression was attenuated in homozygous A/A mutant eukaryotic translation initiation factor 2␣ mouse embryonic fibroblasts treated with homocysteine or tunicamycin, suggesting that ER stress-induced phosphorylation of eukaryotic translation initiation factor 2␣ is required for TDAG51 transcriptional activation. Transient overexpression of TDAG51 elicited significant changes in cell morphology, decreased cell adhesion, and promoted detachmentmediated PCD. In support of these in vitro findings, TDAG51 expression was increased and correlated with PCD in the atherosclerotic lesions from apoE ؊/؊ mice fed hyperhomocysteinemic diets, compared with mice fed a control diet. Collectively, these findings provide evidence that TDAG51 is induced by homocysteine, promotes detachment-mediated PCD, and contributes to the development of atherosclerosis observed in hyperhomocysteinemia.

Background-A causal relation between hyperhomocysteinemia (HHcy) and accelerated atherosclerosis has been established in apolipoprotein E-deficient (apoE Ϫ/Ϫ ) mice. Although several cellular stress mechanisms have been proposed to explain the atherogenic effects of HHcy, including oxidative stress, endoplasmic reticulum (ER) stress, and inflammation, their association with atherogenesis has not been completely elucidated. Methods and Results-ApoEϪ/Ϫ mice were fed a control or a high-methionine (HM) diet for 4 (early lesion group) or 18 (advanced lesion group) weeks to induce HHcy. Total plasma homocysteine levels and atherosclerotic lesion size were significantly increased in early and advanced lesion groups fed the HM diet compared with control groups. Markers of ER stress (GRP78/94, phospho-PERK), oxidative stress (HSP70), and inflammation (phospho-IB-␣) were assessed by immunohistochemical staining of these atherosclerotic lesions. GRP78/94, HSP70, and phospho-IB-␣ immunostaining were significantly increased in the advanced lesion group fed the HM diet compared with the control group. HSP47, an ER-resident molecular chaperone involved in collagen folding and secretion, was also increased in advanced lesions of mice fed the HM diet. GRP78/94 and HSP47 were predominantly localized to the smooth muscle cell-rich fibrous cap, whereas HSP70 and phospho-IB-␣ were observed in the lipid-rich necrotic core. Increased HSP70 and phospho-IB-␣ immunostaining in advanced lesions of mice fed the HM diet are consistent with enhanced carotid artery dihydroethidium staining. Interestingly, GRP78/94 and phospho-PERK were markedly increased in macrophage foam cells from early lesions of mice fed the control or the HM diet.

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Exposure to excess glucocorticoids programs susceptibility to cardiovascular and renal dysfunction in later life although the mechanisms have not been clearly elucidated. We administered corticosterone (CORT; 33 μg·kg(-1)·h(-1)) to pregnant mice for 60 h from embryonic day (E) 12.5. Prenatal CORT resulted in postnatal growth restriction and reduced nephron endowment at postnatal day 30 in both male and female offspring. The reduction in nephron number was associated with increased expression of apoptotic markers in the kidney at E14.5. In offspring of both sexes at 12 mo of age, there were no differences in kidney weights, urine output, or urinary sodium excretion; however, prenatal CORT exposure increased the urinary albumin/creatinine ratio and 24-h urinary albumin excretion. Surprisingly, at 12 mo male but not female offspring exposed to prenatal CORT were hypotensive, with mean arterial blood pressures ∼10 mmHg lower than untreated controls (P < 0.001). Finally, we examined how offspring responded to a renal or cardiovascular challenge (saline load or restraint stress). When given 0.9% NaCl as drinking water for 7 days, there were no differences in blood pressures or urinary parameters between groups. Restraint stress (15 min) caused a tachycardic response in all animals; however the increase in heart rate was not sustained in male offspring exposed to CORT (P < 0.01), suggesting that autonomic control of cardiovascular function may be altered. These data demonstrate that excess prenatal CORT impairs kidney development and increases the risk of cardiovascular dysfunction especially in males.