Americans spend at least $100 billion each year on low back pain, a ubiquitous job-related disability and a leading contributor to missed days of work. While the etiology of disc disease is multifactorial, there is general agreement that loss of water and a decrease in osmotic pressure compromises cellular function and exacerbates the disease state. We have recently shown that T1? MRI and Opening Pressure (OP), parameters of disc hydration and osmotic status, provide quantitative measures of both tissue degeneration and back pain. Despite recognition of these facts, molecular mechanisms that control the disc water content and osmotic pressure remain poorly understood. We have shown that TonEBP, the only known osmoresponsive transcription factor is expressed in the nucleus pulposus (NP) and is diminished in the disease state. Based on these findings, we propose to test an innovative overarching hypothesis: TonEBP activity is linked to osmotic status of the NP and correlates with T1? and OP and controls critical NP survival and functional activities; compromised TonEBP function promotes development of disease. To test this central hypothesis, first, we will measure the expression of TonEBP and its target genes in human degenerate discs in relationship to measures of hydration status and pain: T1? and OP. We will then define the importance of TonEBP by suppressing its expression and evaluating its effects on NP cell apoptosis, autophagy and senescence. Second, we will determine the mechanism by which TonEBP controls expression of water transporters (aquaporins) and proteoglycans, molecules required for the maintenance of the osmotic properties of the disc. In addition, we will measure expression of key enzymes required for glycan synthesis and sulfation. We will determine if the disease process has altered the ability of TonEBP to respond to osmotic shifts. We will ascertain if restoration of TonEBP activity in diseased human cells using angiotensin II (ANG II), PDGF-BB or TonEBP expression plasmid stimulates matrix synthesis and aquaporin levels. The third goal of the investigation is to determine if inactivation of TonEBP compromises osmotic and biomechanical properties of the disc in vivo. Using lentiviral-ShTonEBP injection in rat discs and conditional inactivation of TonEBP in TonEBPf/f mice, we will determine if suppression causes alterations in T1? signal, matrix composition and biomechanical properties of the disc. Finally, using a well characterized rat model of disc disease, we will attempt to restore TonEBP expression/activity using either PDGF-BB or ANG II and monitor changes. Outcomes from these studies will provide foundation for innovative strategies aimed at restoring osmotic and water balance mediated through TonEBP, thereby delaying the development or progression of degenerative disc disease in the aging spine.

Public Health Relevance

Lower back pain experienced by millions of aging Americans is closely linked to degenerative disc disease, a condition that afflicts the spine. During degeneration, dehydration causes a decrease in intervertebral disc height. The goal of the proposal is to understand the mechanisms that control the water binding properties of the disc and develop new non-surgical strategies for the prevention and treatment of the disease.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Skeletal Biology Structure and Regeneration Study Section (SBSR)
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Tyree, Bernadette
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Thomas Jefferson University
Schools of Medicine
United States
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Gorth, Deborah J; Shapiro, Irving M; Risbud, Makarand V (2018) Transgenic mice overexpressing human TNF-? experience early onset spontaneous intervertebral disc herniation in the absence of overt degeneration. Cell Death Dis 10:7
Choi, Hyowon; Chaiyamongkol, Weera; Doolittle, Alexandra C et al. (2018) COX-2 expression mediated by calcium-TonEBP signaling axis under hyperosmotic conditions serves osmoprotective function in nucleus pulposus cells. J Biol Chem 293:8969-8981
Silagi, Elizabeth S; Schoepflin, Zachary R; Seifert, Erin L et al. (2018) Bicarbonate Recycling by HIF-1-Dependent Carbonic Anhydrase Isoforms 9 and 12 Is Critical in Maintaining Intracellular pH and Viability of Nucleus Pulposus Cells. J Bone Miner Res 33:338-355
Pan, Hehai; Strickland, Adam; Madhu, Vedavathi et al. (2018) RNA binding protein HuR regulates extracellular matrix gene expression and pH homeostasis independent of controlling HIF-1? signaling in nucleus pulposus cells. Matrix Biol :
Silagi, Elizabeth S; Shapiro, Irving M; Risbud, Makarand V (2018) Glycosaminoglycan synthesis in the nucleus pulposus: Dysregulation and the pathogenesis of disc degeneration. Matrix Biol 71-72:368-379
Choi, Hyowon; Tessier, Steven; Silagi, Elizabeth S et al. (2018) A novel mouse model of intervertebral disc degeneration shows altered cell fate and matrix homeostasis. Matrix Biol 70:102-122
Johnson, Zariel I; Doolittle, Alexandra C; Snuggs, Joseph W et al. (2017) TNF-? promotes nuclear enrichment of the transcription factor TonEBP/NFAT5 to selectively control inflammatory but not osmoregulatory responses in nucleus pulposus cells. J Biol Chem 292:17561-17575
Liu, Chao; Choi, Hyowon; Johnson, Zariel I et al. (2017) Lack of evidence for involvement of TonEBP and hyperosmotic stimulus in induction of autophagy in the nucleus pulposus. Sci Rep 7:4543
Schoepflin, Zachary R; Silagi, Elizabeth S; Shapiro, Irving M et al. (2017) PHD3 is a transcriptional coactivator of HIF-1? in nucleus pulposus cells independent of the PKM2-JMJD5 axis. FASEB J 31:3831-3847
Binch, Abbie L A; Shapiro, Irving M; Risbud, Makarand V (2016) Syndecan-4 in intervertebral disc and cartilage: Saint or synner? Matrix Biol 52-54:355-362

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