Neutrophil depletion after subarachnoid hemorrhage improves memory via NMDA receptors.

Cognitive deficits after aneurysmal subarachnoid hemorrhage (SAH) are common and disabling. Patients who experience delayed deterioration associated with vasospasm are likely to have cognitive deficits, particularly problems with executive function, verbal and spatial memory. Here, we report neurophysiological and pathological mechanisms underlying behavioral deficits in a murine model of SAH.

Metabolic clock generates nutrient anticipation rhythms in mTOR signaling.

The mTOR signaling pathway modulates metabolic processes with respect to nutrient availability and other growth-related cues. According to the existing paradigm, mTOR complex 1 (mTORC1) activityin vivo is induced by food and gradually decreases during fasting. We found that mTORC1 activity is controlled by an internal clock mechanism different from the known light-entrainable circadian clock.

BMAL1-dependent regulation of the mTOR signaling pathway delays aging.

The circadian clock, an internal time-keeping system, has been linked with control of aging, but molecular mechanisms of regulation are not known. BMAL1 is a transcriptional factor and core component of the circadian clock; BMAL1 deficiency is associated with premature aging and reduced lifespan. Here we report that activity of mammalian Target of Rapamycin Complex 1 (mTORC1) is increased upon BMAL1 deficiency both in vivo and in cell culture.

Circadian clock protein BMAL1 regulates cellular senescence in vivo.

Deficiency of the circadian clock transcriptional factor BMAL1 results in the development of premature aging in mice. In agreement with the accelerated aging phenotype, we observed an increase in the number of senescent cells in different tissues (lungs, liver and spleen) of Bmal1(-/-) mice, which suggests the important role of BMAL1 in the control of senescence in vivo. However, no difference in the rate of proliferation and senescence between primary fibroblasts isolated from wild-type and Bmal1(-/-) mice has been detected, suggesting that BMAL1 does not play a significant role in replicative senescence in vitro.

Circadian regulation of cell cycle: Molecular connections between aging and the circadian clock.

The circadian clock generates oscillations in physiology and behavior, known as circadian rhythms. Links between the circadian clock genes Periods, Bmal1, and Cryptochromes and aging and cancer are emerging. Circadian clock gene expression is changed in human pathologies, and transgenic mice with mutations in clock genes develop cancer and premature aging.