Circadian rhythmicity is a fundamental aspect of human physiology. Proper circadian rhythms in cardiovascular output, metabolism, and sleep, for example, are essential to physical and psychiatric health, and the incidence of stroke, asthma, heart attack, and sleep disturbances all correlate strongly with time of day. However, understanding how circadian modulation of the body's physiology contributes to human health and disease will require a basic understanding of how circadian rhythms are generated and expressed. The goal of this proposal is to identify the basic mechanisms that drive circadian output from the suprachiasmatic nucleus (SCN), the brain's clock. SCN neurons demonstrate circadian rhythms in spontaneous action potential firing, and this rhythmic output is essential for timing circadian behaviors and physiology. Therefore, daily modulation of excitability is a critical basis for generating the circadian rhythm in neuronal activity in the SCN. The large conductance Ca2+-activated K+ channel (BK), encoded by the Kcnma1 gene, is an essential regulator of circadian physiological and behavioral rhythms in mouse and fly. In the SCN, BK currents shape circadian rhythms in neuronal firing by regulating the day-night difference in firing frequency, but the basic mechanisms underlying BK's actions are unknown. In the proposed research, we test the central hypothesis that the daily modulation of BK current properties drives the circadian rhythm in SCN neuronal firing. This hypothesis will be investigated using electrophysiology and molecular biology through the following specific aims: 1. To determine whether the constituents of the BK channel complex vary over the circadian cycle, 2. To determine how the properties of native BK currents vary with circadian phase in the SCN, 3. To test whether daily modulation of BK currents drives circadian rhythms in neuronal firing in the SCN. The significance of this research is that it provides a unique approach to directly link changes in the biophysical properties of an ionic current to changes in neural coding. The outcome of these studies is an understanding of the detailed mechanisms that govern circadian output. Understanding output from the brain's master clock is a critical step toward the development of novel ways to manipulate the circadian aspects of human physiology and pathophysiology.

Public Health Relevance

There is strong evidence that proper circadian rhythms in cardiovascular output, metabolism, and sleep, for example, are essential to physical and psychiatric health. The incidence of stroke, asthma, heart attack, and sleep disturbances all correlate strongly with time of day. Understanding how circadian modulation of the body's physiology contributes to human health and disease requires a basic understanding of how circadian rhythms are generated and expressed.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL102758-01
Application #
7879056
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Laposky, Aaron D
Project Start
2010-04-01
Project End
2015-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
1
Fiscal Year
2010
Total Cost
$375,000
Indirect Cost
Name
University of Maryland Baltimore
Department
Physiology
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Zhang, Jiyuan; Guan, Xin; Li, Qin et al. (2018) Glutamate-activated BK channel complexes formed with NMDA receptors. Proc Natl Acad Sci U S A 115:E9006-E9014
Whitt, Joshua P; McNally, Beth A; Meredith, Andrea L (2018) Differential contribution of Ca2+ sources to day and night BK current activation in the circadian clock. J Gen Physiol 150:259-275
Alshahrani, Saeed; Rapoport, Robert M; Zahedi, Kamyar et al. (2017) The non-diuretic hypotensive effects of thiazides are enhanced during volume depletion states. PLoS One 12:e0181376
Wang, Wuyang; Zhang, Xiaoli; Gao, Qiong et al. (2017) A voltage-dependent K+ channel in the lysosome is required for refilling lysosomal Ca2+ stores. J Cell Biol 216:1715-1730
Nelson, Alexandra B; Faulstich, Michael; Moghadam, Setareh et al. (2017) BK Channels Are Required for Multisensory Plasticity in the Oculomotor System. Neuron 93:211-220
(2016) ABSTRACTS OF PAPERS AT THE SEVENTIETH ANNUAL MEETING OF THE SOCIETY OF GENERAL PHYSIOLOGISTS: Genetic and Animal Models for Ion Channel Function in Physiology and Disease. J Gen Physiol 148:183
Nagaraj, Chandran; Tang, Bi; Nagy, Bence M et al. (2016) Docosahexaenoic acid causes rapid pulmonary arterial relaxation via KCa channel-mediated hyperpolarisation in pulmonary hypertension. Eur Respir J 48:1127-1136
Hayashi, Yoshinori; Morinaga, Saori; Zhang, Jing et al. (2016) BK channels in microglia are required for morphine-induced hyperalgesia. Nat Commun 7:11697
Singh, H; Li, M; Hall, L et al. (2016) MaxiK channel interactome reveals its interaction with GABA transporter 3 and heat shock protein 60 in the mammalian brain. Neuroscience 317:76-107
Whitt, Joshua P; Montgomery, Jenna R; Meredith, Andrea L (2016) BK channel inactivation gates daytime excitability in the circadian clock. Nat Commun 7:10837

Showing the most recent 10 out of 21 publications