Histone H3 E50K mutation confers oncogenic activity and supports an EMT phenotype.

Sequencing of human patient tumors has identified recurrent missense mutations in genes encoding core histones. We report that mutations that convert histone H3 amino acid 50 from a glutamate to a lysine (H3E50K) support an oncogenic phenotype in human cells. Expression of H3E50K is sufficient to transform human cells as evidenced by a dramatic increase in cell migration and invasion, and a statistically significant increase in proliferation and clonogenicity. H3E50K also increases the invasive phenotype in the context of co-occurring BRAF mutations, which are present in patient tumors characterized by H3E50K. H3E50 lies on the globular domain surface in a region that contacts H4 within the nucleosome. We find that H3E50K perturbs proximal H3 post-translational modifications globally and dysregulates gene expression, activating the epithelial to mesenchymal transition. Functional studies using S. cerevisiae reveal that, while yeast cells that express H3E50K as the sole copy of histone H3 show sensitivity to cellular stressors, including caffeine, H3E50K cells display some genetic interactions that are distinct from the characterized H3K36M oncohistone yeast model. Taken together, these data suggest that additional histone H3 mutations have the potential to be oncogenic drivers and function through distinct mechanisms that dysregulate gene expression.

Long-term angiotensin-converting enzyme inhibitor treatment attenuates adrenergic responsiveness without altering hemodynamic control in patients undergoing cardiac surgery.

BACKGROUND: The sympathoadrenal and the renin-angiotensin systems are involved in blood pressure regulation and are known to be markedly activated during cardiac surgery. Because unexpected hypotensive events have been reported repeatedly during anesthesia in patients chronically treated with angiotensin-converting enzyme (ACE) inhibitors, the authors questioned whether renin-angiotensin system blockade would alter the hemodynamic control through attenuation of the endocrine response to surgery and/or through attenuation of the pressor effects of exogenous catecholamines. METHODS: Patients with preserved left ventricular function undergoing mitral valve replacement or coronary revascularization were divided into two groups according to preoperative drug therapy: patients receiving ACE inhibitors for at least 3 months (ACEI) group, n = 22) and those receiving other cardiovascular drug therapy (control group, n = 19). Anesthesia was induced using fentanyl and midazolam. Systemic hemodynamic variables were recorded before surgery, after anesthesia induction, during sternotomy, after aortic cross-clamping, after aortic unclamping, as well as after separation from cardiopulmonary bypass (CPB) and during skin closure. Blood was sampled repeatedly up to 24 h after surgery for hormone analysis. To test adrenergic responsiveness, incremental doses of norepinephrine were infused intravenously during hypothermic CPB and after separation from CPB. From the dose-response curves, pressor (defined as mean arterial pressure changes), and vasoconstrictor (defined as systemic vascular resistance changes) effects were analyzed, and the slopes and the dose of norepinephrine required to increase mean arterial pressure by 20% were calculated (PD(20)). RESULTS: At no time did the systemic hemodynamics and the need for vasopressor support differ between the two treatment groups. However, for anesthesia induction, significantly less fentanyl and midazolam were given in the ACEI group. Although plasma renin activity was significantly greater in the ACEI group throughout the whole 24-h study period, plasma concentrations of angiotensin II did not differ between the two groups. Similar changes in catecholamines angiotensin II, and plasma renin activity were found in the two groups in response to surgery and CPB. The pressor and constrictor effects of norepinephrine infusion were attenuated markedly in the ACEI group: the dose-response curves were shifted to the right and the slopes were decreased at the two study periods; PD(20) was significantly greater during hypothermic CPB (0.08 micro/kg in the ACEI group vs. 0.03 micro/kg in the control group; P < 0.05) and after separation from CPB (0.52 micro/kg in the ACEI group vs. 0.1 micro/kg in the control group; P < 0.05). In both groups, PD(20) was significantly less during hypothermic CPB than in the period immediately after CPB. CONCLUSIONS: Long-term ACE inhibitor treatment in patients with preserved left ventricular function alters neither the endocrine response nor the hemodynamic stability during cardiac surgery. However, a significantly attenuated adrenergic responsiveness associated with incomplete blockade of the plasma renin-angiotensin system supports the hypothesis that inhibition of angiotensin II generation and of bradykinin degradation within the vascular wall mediates some of the vasodilatory effects of ACE inhibitors.

Plasma concentration of nine hormones and neurotransmitters during usual activities or constant bed rest for 34 H.

Thyroid-stimulating hormone (TSH), cortisol, melatonin, prolactin, luteinizing hormone (LH), delta-sleep-inducing peptide (DSIP), its phosphorylated form (P-DSIP), heart rate, and body temperature were measured every half hour during two 24-h periods in five normal men. tau-Amino-butyric acid (GABA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured less frequently. The first period, the "activity" condition, included usual daily activities. The second period, or "rest" condition, consisted of fasting, constant bed rest during 34 h, and partial light deprivation. Compared with the "rest" condition, the "activity" condition increased heart rate, temperature, LH, and TSH in most subjects, and cortisol in two of five subjects. It retarded the onset of nocturnal cortisol and melatonin secretion. The temporal pattern and the absolute values of the concentrations of DSIP, P-DSIP, MHPG, GABA, and prolactin showed no or minimal changes during the two conditions. In spite of the influence of the "activity" versus "rest" condition on several hormones, the mean concentrations as well as the temporal organization of their secretion into plasma were quite stable within each subject, whereas they varied much more between individuals. TSH, cortisol, and melatonin values were also stable within an 8-month period in one subject who was studied on four occasions. The results illustrate that the patterns of hormones rhythms and their reactivity to changes in the environment are, to a large extent, specific to each subject.

Differences between circadian and ultradian organization of cortisol and melatonin rhythms during activity and rest.

We compared the cortisol and melatonin circadian and ultradian rhythms in normal men using two approaches: 1) the men were exposed successively to two conditions, one normal and a second chosen to alter differently each of the hormones, i.e. complete bedrest for 34 h (supine, fasting, and under dim light), and 2) analyses of the rhythms using a combination of curve smoothing for the description of the 24-h rhythm, and peak detection and spectral analysis for the measurement of periodic phenomena. Blood was sampled every 30 min from 0700-0700 h. A diurnal rhythm was detected for both hormones, with different underlying frequencies. Plasma cortisol had an ultradian rhythm of 8 h. From 0000-0800 h (night) and 0830-1600 h (early day), the pulsatile activity and baseline values of cortisol were high, while from 1630-2400 h (late day), these variables were low. During complete bedrest, pulsatile activity and baseline values were even higher during the night period, and the nocturnal peak of cortisol, usually present between 0300-1000 h, was split in two, with an early peak at 0000-0400 h. There were two specific events during the day associated with synchronous, high amplitude pulses: awakening and eating at noon. No such pulses occurred at suppertime or when the men fasted. Melatonin secretion was organized around a 5.5-h period. In the rest condition, plasma melatonin values were higher during the night. The 24-h rhythms of cortisol and melatonin were temporally related. Plasma melatonin began to rise when plasma cortisol was at its lowest, it peaked when cortisol began to rise, and it began to decrease when cortisol reached its peak, with a 5-h phase delay between plasma cortisol and melatonin rise at night. In summary, melatonin and cortisol rhythms have different ultradian frequencies, suggesting an intrinsic difference in the mechanisms controlling their secretion. In addition, their responses to restricted physical activity in an environment with dim light were completely different; for plasma melatonin, the change was primarily quantitative, with an increase in total production especially at night, while for plasma cortisol, there was more of a qualitative change, with different patterns of pulsatile activity and possible splitting of the nocturnal peak. The differences in the ultradian organization of these two hormones imply that the correlation between their peaks must depend on a third factor, which is likely to be the 24-h organization of the day.