Obstructive sleep apnea is associated with neural injury, including motoneuronal dysfunction. The overall goal of the proposed studies is to advance mechanisms by which intermittent hypoxia (IH) injures motoneurons in an effort to unveil novel directions for development of therapies for sleep apnea. Focusing on cellular mechanisms of IH injury, we have found that IH results in a marked unfolded protein response and apoptosis in hypoglossal and facial motoneurons, while motor trigeminal and occulomotor neurons confer resistance. We have identified several important differences in the IH response between susceptible and resistant motoneurons. In this proposal, we seek to test each difference as a potential avenue for treating motoneuronal injury. First, susceptible motoneurons show activation of an endoplasmic reticulum (ER) sensor, PERK, in response to IH. PERK is activated when BiP, the master regulator chaperone of the ER, is released from PERK to chaperone unfolded proteins.
In Aim 1, we will test the role BiP plays in protecting motoneurons from IH injury. IH susceptible motoneurons accumulate a pro-apoptotic protein CHOP. Thus we suspect impaired degradation of CHOP in susceptible motoneurons contributes to their demise (Aim 2). IH cause significant injury to other organelles and cellular processes. Which of these are secondary to ER injury or which are primary will be explored. SIRT1 may play a more global role in responding to the metabolic challenges of IH (Aim 3). Here again, crosstalk between BiP, CHOP and SIRT1 pathways will be determined. Having identified in mice a differential IH susceptibility across upper airway motoneurons and having identified key mediators in the ER and oxidative stress injury pathways, we will next examine these mechanisms in post-mortem human upper airway motoneurons. This work is designed to advance novel therapeutics for nerve injury in obstructive sleep apnea.

Public Health Relevance

Obstructive sleep apnea is a common disorder in children as well as in adults, and in adults, sleep apnea is associated with peripheral nerve and brain injury. Using a mouse model of the sleep apnea oxygenation patterns we have identified a significant injury to the neurons that innervate the upper airway. The proposed studies are designed to identify novel pathways for therapies to prevent and/or reverse the injuries.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL096037-01A1
Application #
7790100
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Laposky, Aaron D
Project Start
2010-01-01
Project End
2013-12-31
Budget Start
2010-01-01
Budget End
2010-12-31
Support Year
1
Fiscal Year
2010
Total Cost
$454,328
Indirect Cost
Name
University of Pennsylvania
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Zhang, Jing; Zhu, Yan; Zhan, Guanxia et al. (2014) Extended wakefulness: compromised metabolics in and degeneration of locus ceruleus neurons. J Neurosci 34:4418-31
Li, Yanpeng; Panossian, Lori A; Zhang, Jing et al. (2014) Effects of chronic sleep fragmentation on wake-active neurons and the hypercapnic arousal response. Sleep 37:51-64
Chou, Yu-Ting; Zhan, Guanxia; Zhu, Yan et al. (2013) C/EBP homologous binding protein (CHOP) underlies neural injury in sleep apnea model. Sleep 36:481-92
Veasey, Sigrid C; Lear, Jessica; Zhu, Yan et al. (2013) Long-term intermittent hypoxia elevates cobalt levels in the brain and injures white matter in adult mice. Sleep 36:1471-81
Veasey, Sigrid C (2012) Piecing together phenotypes of brain injury and dysfunction in obstructive sleep apnea. Front Neurol 3:139
Zhang, Jing; Veasey, Sigrid (2012) Making sense of oxidative stress in obstructive sleep apnea: mediator or distracter? Front Neurol 3:179
Panossian, Lori A; Veasey, Sigrid C (2012) Daytime sleepiness in obesity: mechanisms beyond obstructive sleep apnea--a review. Sleep 35:605-15
Li, Yanpeng; Veasey, Sigrid C (2012) Neurobiology and neuropathophysiology of obstructive sleep apnea. Neuromolecular Med 14:168-79
Panossian, Lori; Fenik, Polina; Zhu, Yan et al. (2011) SIRT1 regulation of wakefulness and senescence-like phenotype in wake neurons. J Neurosci 31:4025-36