Makarand V Risbud

Thomas Jefferson University, Philadelphia, Pennsylvania, United States

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Publications (104)401.59 Total impact

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    ABSTRACT: Matrix metalloproteinase-3 (MMP-3) plays an important role in intervertebral disc degeneration, a ubiquitous condition closely linked to low back pain and disability. Elevated expression of syndecan 4, a cell surface heparan sulfate proteoglycan, actively controls disc matrix catabolism. However, the relationship between MMP-3 expression and syndecan 4 in the context of inflammatory disc disease has not been clearly defined. We investigated the mechanisms by which cytokines control MMP-3 expression in rat and human nucleus pulposus cells. Cytokine treatment increased MMP-3 expression and promoter activity. Stable silencing of syndecan 4 blocked cytokine-mediated MMP-3 expression; more important, syndecan 4 did not mediate its effects through NF-κB or mitogen-activated protein kinase (MAPK) pathways. However, treatment with MAPK and NF-κB inhibitors resulted in partial blocking of the inductive effect of cytokines on MMP-3 expression. Loss-of-function studies confirmed that NF-κB, p38α/β2/γ/δ, and extracellular signal-regulated kinase (ERK) 2, but not ERK1, contributed to cytokine-dependent induction of MMP3 promoter activity. Similarly, inhibitor treatments, lentiviral short hairpin-p65, and short hairpin-I κ B kinase β significantly decreased cytokine-dependent up-regulation in MMP-3 expression. Finally, we show that transforming growth factor-β can block the up-regulation of MMP-3 induced by tumor necrosis factor (TNF)-α by counteracting the NF-κB pathway and syndecan 4 expression. Taken together, our results suggest that cooperative signaling through syndecan 4 and the TNF receptor 1-MAPK-NF-κB axis is required for TNF-α-dependent expression of MMP-3 in nucleus pulposus cells. Controlling these pathways may slow the progression of intervertebral disc degeneration and matrix catabolism.
    The American journal of pathology. 07/2014;
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    ABSTRACT: The objective of this study was to determine the role of FIH-1 in regulating HIF-1 activity in the nucleus pulposus (NP) cells, and the control of this regulation by binding and sequestration of FIH-1 by Mint3. FIH-1 and Mint3 were both expressed in the NP, and were shown to strongly co-localize within the cell nucleus. While both mRNA and protein expression of FIH-1 decreased in hypoxia, only Mint3 protein levels were hypoxia sensitive. Overexpression of FIH-1 was able to reduce HIF-1 function as seen by changes in activities of HRE-luciferase reporter and HIF-1α-CTAD and HIF-2α-TAD. Moreover, co-transfection of either full-length Mint3 or the N-terminus of Mint3 abrogated FIH-1-dependent reduction in HIF-1 activity under both normoxia and hypoxia. Nuclear levels of FIH-1 and Mint3 decreased in hypoxia, and use of specific nuclear import and export inhibitors clearly showed that cellular compartmentalization of overexpressed FIH-1 was critical for its regulation of HIF-1 activity in NP cells. Interestingly, microarray results after stable silencing of FIH-1 showed no significant changes in transcripts of classical HIF-1 target genes. However, expression of several other transcripts, including those of Notch pathway changed in FIH-1 silenced cells. Moreover, co-transfection of Notch-ICD could restore suppression of HIF1-TAD activity by exogenous FIH-1. Taken together, these results suggest that possibly due to low endogenous levels and/or preferential association with substrates such as Notch, FIH-1 activity does not represent a major mechanism by which NP cells control HIF-1-dependent transcription, a testament to their adaptation to a unique hypoxic niche.
    The Journal of biological chemistry. 05/2014;
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    ABSTRACT: Intervertebral disc degeneration is the leading cause of chronic back pain. Recent studies show that raised level of SDC4, a cell-surface heparan sulfate (HS) proteoglycan, plays a role in pathogenesis of disc degeneration. However, in nucleus pulposus (NP) cells of the healthy intervertebral disc, the mechanisms that control expression of SDC4 and its physiological function are unknown. Hypoxia induced SDC4 mRNA and protein expression by ∼2.4- and 4.4-fold (P<0.05), respectively, in NP cells. While the activity of the SDC4 promoter containing hypoxia response element (HRE) was induced 2-fold (P<0.05), the HRE mutation decreased the activity by 40% in hypoxia. Transfections with plasmids coding prolyl-4-hydroxylase domain protein 2 (PHD2) and ShPHD2 show that hypoxic expression of SDC4 mRNA and protein is regulated by PHD2 through controlling hypoxia-inducible factor 1α (HIF-1α) levels. Although overexpression of HIF-1α significantly increased SDC4 protein levels, stable suppression of HIF-1α and HIF-1β decreased SDC4 expression by 50% in human NP cells. Finally, suppression of SDC4 expression, as well as HS function, resulted in an ∼2-fold increase in sex-determining region Y (SRY)-box 9 (Sox9) mRNA, and protein (P<0.05) and simultaneous increase in Sox9 transcriptional activity and target gene expression. Taken together, our findings suggest that in healthy discs, SDC4, through its HS side chains, contributes to maintenance of the hypoxic tissue niche by controlling baseline expression of Sox9.-Fujita, N., Hirose, Y., Tran, C. M., Chiba, K., Miyamoto, T., Toyama, Y., Shapiro, I. M., Risbud, M. V. HIF-1-PHD2 axis controls expression of syndecan 4 in nucleus pulposus cells.
    The FASEB Journal 02/2014; · 5.70 Impact Factor
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    ABSTRACT: The objective of the study was to examine the regulation of CCN2 by inflammatory cytokines, IL-1β and TNF-α and to determine if CCN2 modulates IL-1β-dependent catabolic gene expression in nucleus pulposus (NP) cells. IL-1β and TNF-α suppress CCN2 mRNA and protein expression in an NF-κB dependent but MAPK independent manner. The conserved κB sites located at -93/-86 and -546/-537 bp in the CCN2 promoter mediated this suppression. On the other hand, treatment of NP cells with IL-1β in combination with CCN2 suppressed the inductive effect of IL-1β on catabolic genes, including MMP-3, ADAMTS-5, syndecan 4 (SDC4) and prolyl hydroxylase 3 (PHD3). Likewise, silencing of CCN2 in human NP cells resulted in elevated basal expression of several catabolic genes and inflammatory cytokines like IL-6, IL-4 and IL-12 as measured by gene expression and cytokine protein array respectively. Interestingly, the suppressive effect of CCN2 on IL-1β was independent of modulation of NF-κB signaling. Using disintegrins, echistatin (ECH) and VLO4, peptide inhibitors to αvβ3 and α5β1 integrins, we showed that CCN2 binding to both integrins was required for the inhibition of IL-1β-induced catabolic gene expression. Noteworthy, analysis of human tissues showed a trend of altered expression of these integrins during degeneration. Taken together, these results suggest that CCN2 and inflammatory cytokines form a functional negative feedback loop in NP cells that may be important in the pathogenesis of disc disease.
    Journal of Biological Chemistry 01/2014; · 4.65 Impact Factor
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    Zariel I. Johnson, Irving M. Shapiro, Makarand V. Risbud
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    ABSTRACT: Degeneration of the intervertebral disc is characterized by changes in proteoglycan status, loss of bound water molecules, decreased tissue osmotic pressure and a resulting mechanical failure of the disc. A similar spectrum of changes is evident in osteoarthritic articular cartilage. When healthy, resident cells in these skeletal tissues respond to applied mechanical loads by regulating their own osmotic state and the hydration of the extracellular matrix. The transcription factor Tonicity-Responsive Enhancer Binding Protein (TonEBP or NFAT5) is known to mediate the osmoadaptive response in these and other tissues. While the molecular basis of how osmotic loading controls matrix homeostasis is not completely understood, TonEBP regulates the expression of aggrecan and β1,3-glucoronosyltransferase in nucleus pulposus cells, in addition to targets that allow for survival under hypertonic stress. Moreover, in chondrocytes, TonEBP controls expression of several collagen subtypes and Sox9, a master regulator of aggrecan and collagen II expression. Thus, TonEBP-mediated regulation of the matrix composition allows disc cells and chondrocytes to modify the extracellular osmotic state itself. On the other hand, TonEBP in immune cells induces expression of TNF-α, ΙL-6 and MCP-1, pro-inflammatory molecules closely linked to matrix catabolism and pathogenesis of both disc degeneration and osteoarthritis, warranting investigations of this aspect of TonEBP function in skeletal cells. In summary, the TonEBP system, through its effects on extracellular matrix and osmoregulatory genes can be viewed primarily as a protective or homeostatic response to physiological loading.
    Matrix Biology. 01/2014;
  • Makarand V Risbud, Irving M Shapiro
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    ABSTRACT: Degeneration of the intervertebral discs (IVDs) is a major contributor to back, neck and radicular pain. IVD degeneration is characterized by increases in levels of the proinflammatory cytokines TNF, IL-1α, IL-1β, IL-6 and IL-17 secreted by the IVD cells; these cytokines promote extracellular matrix degradation, chemokine production and changes in IVD cell phenotype. The resulting imbalance in catabolic and anabolic responses leads to the degeneration of IVD tissues, as well as disc herniation and radicular pain. The release of chemokines from degenerating discs promotes the infiltration and activation of immune cells, further amplifying the inflammatory cascade. Leukocyte migration into the IVD is accompanied by the appearance of microvasculature tissue and nerve fibres. Furthermore, neurogenic factors, generated by both disc and immune cells, induce expression of pain-associated cation channels in the dorsal root ganglion. Depolarization of these ion channels is likely to promote discogenic and radicular pain, and reinforce the cytokine-mediated degenerative cascade. Taken together, an enhanced understanding of the contribution of cytokines and immune cells to these catabolic, angiogenic and nociceptive processes could provide new targets for the treatment of symptomatic disc disease. In this Review, the role of key inflammatory cytokines during each of the individual phases of degenerative disc disease, as well as the outcomes of major clinical studies aimed at blocking cytokine function, are discussed.
    Nature Reviews Rheumatology 10/2013; · 9.75 Impact Factor
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    ABSTRACT: Despite many advances in our understanding of the molecular basis of disc degeneration, there remains a paucity of preclinical models which can be used to study the biochemical and molecular events that drive disc degeneration, and the effects of potential therapeutic interventions. The goal of this study is to characterize global gene expression changes in a disc organ culture system that mimics early nontraumatic disc degeneration. To mimic a degenerative insult, rat intervertebral discs were cultured in the presence of TNF-a, IL-1ß and serum-limiting conditions. Gene expression analysis was performed using a microarray to identify differential gene expression between experimental and control groups. Differential pattern of gene expression was confirmed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) or Western blot. Treatment resulted in significant changes in expression of more than 1,000 genes affecting many aspects of cell function including cellular movement, the cell cycle, cellular development, and cell death and proliferation. Many of the most highly upregulated and downregulated genes have known functions in disc degeneration and extracellular matrix hemostasis. Construction of gene networks based on known cellular pathways and expression data from our analysis demonstrated that the network associated with cell death, cell cycle regulation and DNA replication and repair was most heavily affected in this model of disc degeneration. This rat organ culture model uses cytokine exposure to induce wide gene expression changes with the most affected genes having known reported functions in disc degeneration. We propose that this model is a valuable tool to study the etiology of disc degeneration and evaluate potential therapeutic treatments.
    Arthritis research & therapy 09/2013; 15(5):R121. · 4.27 Impact Factor
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    ABSTRACT: Study Design: Laboratory study.Objective: The aims of this study were 1) To confirm that Substance P (SP) is expressed by nucleus pulposus (NP) and annulus fibrosus (AF) cells; 2) To determine the effect of SP on expression of inflammatory mediators in human disc cells and the effect of inflammatory mediators on expression of SP; and 3) To characterize the relative expression of SP receptor isoforms in disc tissue and describe whether exposure to SP changes receptor expression.Summary of Background Data: Substance P, classically described as a neurotransmitter, acts as an inflammatory regulator in other tissue types but its role within the intervertebral disc has not been characterized.Methods: Human AF and NP cells from 7 individuals were expanded in monolayer and maintained in alginate bead culture. Cells were treated with SP or IL-1β/TNF-α. After treatment, the cells were recovered, RNA was isolated and transcribed into cDNA. Quantitative RT-PCR was performed to evaluate expression of inflammatory mediators, SP and its receptors.Results: Disc cells treated with SP demonstrated significant upregulation of IL-1β, IL-6 and IL-8 in NP and AF cells while significant upregulation of RANTES and TNF occurred only in the AF. SP was expressed by AF and NP cells at low levels; expression did not change significantly with SP treatment but was significantly upregulated after treatment with IL-1β/TNF-α. Both SP receptor isoforms were expressed by NP and AF cells.Conclusion: SP upregulates inflammatory mediators in disc cells. SP and SP receptors were expressed in both NP and AF and expression did not change after treatment with SP but increased after treatment with IL-1β/TNF-α. SP likely acts in an autocrine or paracrine manner in IVD cells and may be involved in "crosstalk" between disc cells and neurons, providing a potential mechanism for transmission of painful discogenic stimuli.
    Spine 07/2013; · 2.16 Impact Factor
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    ABSTRACT: STUDY DESIGN.: Laboratory study. OBJECTIVE.: To evaluate expression of chemokine regulated and normal T cell expressed and secreted (RANTES)/C-C motif ligand 5 (CCL5) and interleukins in intervertebral discs (IVDs) specimens from patients with discogram-proven painful degeneration. SUMMARY OF BACKGROUND DATA.: Discogenic back pain results in tremendous costs related to treatment and lost productivity. The relationship between inflammation, degeneration (IVD), and cytokine upregulation is well established, but other mediators of the inflammatory cascade are not well characterized. METHODS.: Painful IVDs were taken from 18 patients undergoing surgery for discogenic pain with positive preoperative discogram. Painless control tissue was taken at autopsy from patients without back pain/spinal pathology or spinal levels with negative discograms resected for deformity.Quantitative real time polymerase chain reaction (qRT-PCR) was performed to evaluate RANTES, IL-1β, IL-6, and IL-8 expression in painful and control discs. RANTES and interleukin expression were analyzed on the basis of Pfirrmann grade.Disc cells were cultured in alginate beads using 2 groups: an untreated group and a group treated with 10 ng/mL IL-1β, 10 ng/mL TNF-α, and 1% fetal bovine serum to induce a degenerative phenotype. RESULTS.: Nine painless IVD specimens and 7 painful IVD specimens were collected. RANTES expression demonstrated a 3.60-fold increase in painful discs versus painless discs, a significant difference (P = 0.049). IL-1β expression demonstrated significantly higher expression in painful discs (P = 0.03). RANTES expression data demonstrated significant upregulation with increasing Pfirrmann grade (P = 0.045). RANTES expression correlated significantly with IL-1β expression (ρ = 0.67, P < 0.0001). RANTES expression increased more than 200-fold in the alginate culture model in cells treated with IL-1β/TNF-α, 1% fetal bovine serum (P < 0.001). CONCLUSION.: RANTES and IL-1β expression was significantly elevated in painful IVDs after careful selection of painless versus painful IVD tissue. RANTES expression was found to correlate significantly with expression of IL-1β. RANTES was upregulated by IL-1β/TNF-α/1% fetal bovine serum an in vitro treatment to induce a degenerative phenotype.
    Spine 05/2013; 38(11):873-80. · 2.16 Impact Factor
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    ABSTRACT: We investigated TNF-α and IL-1β regulation of ADAMTS-4 expression in nucleus pulposus (NP) cells and its role in aggrecan degradation. Real-time quantitative RT-PCR, Western blotting, and transient transfections with rat NP cells and lentiviral silencing with human NP cells were performed to determine the roles of MAPK and NF-κB in cytokine-mediated ADAMTS-4 expression and function. ADAMTS4 expression and promoter activity increased in NP cells after TNF-α and IL-1β treatment. Treatment of cells with MAPK and NF-κB inhibitors abolished the inductive effect of the cytokines on ADAMTS4 mRNA and protein expression. Although ERK1, p38α, p38β2, and p38γ were involved in induction, ERK2 and p38δ played no role in TNF-α-dependent promoter activity. The inductive effect of p65 on ADAMTS4 promoter was confirmed through gain and loss-of-function studies. Cotransfection of p50 completely blocked p65-mediated induction. Lentiviral transduction with shRNA plasmids shp65, shp52, shIKK-α, and shIKK-β significantly decreased TNF-α-dependent increase in ADAMTS-4 and -5 levels and aggrecan degradation. Silencing of either ADAMTS-4 or -5 resulted in reduction in TNF-α-dependent aggrecan degradation in NP cells. By controlling activation of MAPK and NF-κB signaling, TNF-α and IL-1β modulate expression of ADAMTS-4 in NP cells. To our knowledge, this is the first study to show nonredundant contribution of both ADAMTS-4 and ADAMTS-5 to aggrecan degradation in human NP cells in vitro.
    American Journal Of Pathology 04/2013; · 4.60 Impact Factor
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    ABSTRACT: The objective of the study was to investigate how inflammatory cytokines, IL-1β and TNF-α control Notch signaling activity in nucleus pulposus (NP) cells. An increase in expression of selective Notch receptors (Notch1, 2), ligand (Jagged 2) and target genes (Hes1, Hey1 and Hey2) was observed in NP cells following cytokine treatment. A concomitant increase in Notch signaling as evidenced by induction in activity of target gene Hes1 and Hey1 promoters and reporter 12xCSL was seen. Moreover, treatment increased activity of a 2 kb Notch2 promoter. Treatment of cells with NF-κB and MAPK inhibitors abolished the inductive effect of cytokines on Notch2 promoter and its expression. Gain and loss-of-function studies confirmed the inductive effect of p65 on Notch2 promoter activity. In contrast, p50 blocked the cytokine induction of promoter activity. Supporting the promoter studies, lentiviral delivery of sh-p65, and sh-IKKβ significantly decreased cytokine dependent change in Notch2 expression. Interestingly, MAPK signaling showed an isoform specific control of Notch2 promoter, p38α/β2/δ, ERK1 and ERK2 contributed to cytokine dependent induction while p38γ played no role. Analysis of human NP tissues showed that Notch 1, 2 and Hey2 expression correlated with each other. Moreover, expression of Notch2 and IL-1β as well as the number of cells immunopositive for Notch2 significantly increased in histologically degenerate discs compared to non-degenerate discs. Taken together these results explain the observed dysregulated expression of Notch genes in degenerative disc disease. Thus controlling IL-1β and TNF-αactivities during disc disease may restore Notch signaling and nucleus pulposus cell function.
    Journal of Biological Chemistry 04/2013; · 4.65 Impact Factor
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    Cassie M Tran, Irving M Shapiro, Makarand V Risbud
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    ABSTRACT: Connective tissue growth factor (CCN2/CTGF) plays an important role in extracellular matrix synthesis, especially in skeletal tissues such as cartilage, bone, and the intervertebral disc. As a result there is a growing interest in examining the function and regulation of this important molecule in the disc. This review discusses the regulation of CCN2 by TGF-β and hypoxia, two critical determinants that characterize the disc microenvironment, and discusses known functions of CCN2 in the disc. The almost ubiquitous regulation of CCN2 by TGF-β, including that seen in the disc, emphasizes the importance of the TGF-β-CCN2 relationship, especially in terms of extracellular matrix synthesis. Likewise, the unique cross-talk between CCN2 and HIF-1 in the disc highlights the tissue and niche specific mode of regulation. Taken together the current literature supports an anabolic role for CCN2 in the disc and its involvement in the maintenance of tissue homeostasis during both health and disease. Further studies of CCN2 in this tissue may reveal valuable targets for the biological therapy of disc degeneration.
    Matrix biology: journal of the International Society for Matrix Biology 04/2013; · 3.56 Impact Factor
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    ABSTRACT: The objective of the study was to investigate if HIF-1α and CCN2 form a regulatory network in hypoxic nucleus pulposus (NP) cells. A decrease in CCN2 expression and proximal promoter activity was observed in NP cells after hypoxic culture. Analysis of both human and mouse CCN2 promoters using the JASPAR core database revealed the presence of putative hypoxia response elements (HREs). Transfection experiments showed that both promoter activities and CCN2 expression decreases in hypoxia in a HIF-1α-dependent fashion. Interestingly, deletion analysis and mutation of the HREs individually or in combination resulted in no change in promoter activity in response to hypoxia or in response to HIF-1α, suggesting an indirect mode of regulation. Notably, silencing of endogenous CCN2 increased HIF-1α levels and its target gene expression, suggesting a role for CCN2 in controlling basal HIF-1α levels. On the other hand, treatment of cells with rCCN2 resulted in a decrease in the ability of HIF-1α transactivating domain to recruit co-activators and diminished target gene expression. Lastly, knockdown of CCN2 in NP cells results in a significant decrease in GAG synthesis and expression of aggrecan and collagen II. Immunohistochemical staining of intervertebral discs of CCN2 null embryos shows a decrease in aggrecan. These findings reveal a negative feedback loop between CCN2 and HIF-1α in NP cells and demonstrate a role for CCN2 in maintaining matrix homeostasis in this tissue.
    Journal of Biological Chemistry 03/2013; · 4.65 Impact Factor
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    ABSTRACT: Objective To investigate tumor necrosis factor α (TNFα) and interleukin-1β (IL-1β) regulation of CCL3 expression in nucleus pulposus (NP) cells and in macrophage migration. Methods Quantitative reverse transcription–polymerase chain reaction and immunohistochemistry were used to measure CCL3 expression in NP cells. Transfections were used to determine the role of NF-κB, CCAAT/enhancer binding protein (C/EBPβ), and MAPK on cytokine-mediated CCL3 promoter activity. The effect of NP-conditioned medium on macrophage migration was measured using a Transwell system. ResultsAn increase in CCL3 expression and promoter activity was observed in NP cells after TNFα or IL-1β treatment. Treatment of cells with NF-κB and MAPK inhibitors abolished the effect of the cytokines on CCL3 expression. The inductive effect of p65 and C/EBPβ on the CCL3 promoter was confirmed through gain-of-function and loss-of-function studies. Notably, cotransfection with p50 completely blocked cytokine- and p65-dependent induction. In contrast, c-Rel and RelB had little effect on promoter activity. Lentiviral transduction with short hairpin RNA for p65 (shp65) and shIKKβ significantly decreased the TNFα-dependent increase in CCL3 expression. Analysis of degenerated human NP tissue samples showed that CCL3, but not CCL4, expression correlated positively with the grade of tissue degeneration. Importantly, treatment of macrophages with conditioned medium of NP cells treated with TNFα or IL-1β promoted their migration. Pretreatment of macrophages with an antagonist of CCR1, the primary receptor for CCL3 and CCL4, blocked cytokine-mediated migration. Conclusion Our findings indicate that TNFα and IL-1β modulate the expression of CCL3 in NP cells by controlling the activation of MAPK, NF-κB, and C/EBPβ signaling. The CCL3–CCR1 axis may play an important role in promoting macrophage infiltration in degenerated, herniated discs.
    Arthritis & Rheumatology 03/2013; 65(3). · 7.48 Impact Factor
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    ABSTRACT: Despite the high prevalence of intervertebral disc disease, little is known about changes in intervertebral disc cells and their regenerative potential with ageing and intervertebral disc degeneration. Here we identify populations of progenitor cells that are Tie2 positive (Tie2(+)) and disialoganglioside 2 positive (GD2(+)), in the nucleus pulposus from mice and humans. These cells form spheroid colonies that express type II collagen and aggrecan. They are clonally multipotent and differentiated into mesenchymal lineages and induced reorganization of nucleus pulposus tissue when transplanted into non-obese diabetic/severe combined immunodeficient mice. The frequency of Tie2(+) cells in tissues from patients decreases markedly with age and degeneration of the intervertebral disc, suggesting exhaustion of their capacity for regeneration. However, progenitor cells (Tie2(+)GD2(+)) can be induced from their precursor cells (Tie2(+)GD2(-)) under simple culture conditions. Moreover, angiopoietin-1, a ligand of Tie2, is crucial for the survival of nucleus pulposus cells. Our results offer insights for regenerative therapy and a new diagnostic standard.
    Nature Communications 12/2012; 3:1264. · 10.74 Impact Factor
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    ABSTRACT: Recent studies suggest a differential role of PHD isoforms in controlling hypoxia inducible factor (HIF)-α degradation and activity in nucleus pulposus (NP) cells. However, the regulation and function of PHDs under inflammatory conditions that characterize disc disease is not yet known. Here, we show that in NP cells, TNF-α and IL-1β induce PHD3 expression through NF-κB. Lentiviral delivery of Sh-P65 and Sh-IKKβ confirms that cytokine-mediated PHD3 expression is NF-κB dependent. Noteworthy, although both cytokines induce HIF activity, use of Sh-HIF-1α and PHD3 promoter/enhancer constructs harboring well characterized hypoxia response element (HRE) show lack of HIF involvement in cytokine mediated PHD3 expression. Loss of function studies clearly indicate that PHD3 serves as a co-activator of NF-κB signaling activity in NP cells; PHD3 interacts with, and co-localizes with, p65. We observed that when PHD3 is silenced there is a significant decrease in TNF-α-induced expression of catabolic markers that include ADAMTS5, syndecan4, MMP13 and COX2, at the same time there is restoration of aggrecan and collagen type II expression. Noteworthy, hydroxylase function of PHDs is not required for mediating cytokine-dependent gene expression. These findings show that by enhancing the activity of inflammatory cytokines PHD3 may serve a critical role in degenerative disc disease.
    Journal of Biological Chemistry 09/2012; · 4.65 Impact Factor

Publication Stats

3k Citations
401.59 Total Impact Points


  • 2002–2014
    • Thomas Jefferson University
      • Department of Orthopaedic Surgery
      Philadelphia, Pennsylvania, United States
    • Sree Chitra Tirunal Institute for Medical Sciences and Technology
      Tiruvananantapuram, Kerala, India
  • 2012
    • Thomas Jefferson University Hospitals
      Philadelphia, Pennsylvania, United States
    • Tokai University
      Hiratuka, Kanagawa, Japan
  • 2004
    • Charité Universitätsmedizin Berlin
      Berlín, Berlin, Germany
    • National University of Singapore
      Tumasik, Singapore
  • 1999–2003
    • National Centre For Cell Science, Pune
      Poona, Mahārāshtra, India
  • 2001
    • Humboldt-Universität zu Berlin
      • Department of Psychology
      Berlín, Berlin, Germany
  • 2000
    • Indian Institute of Technology Bombay
      Mumbai, Mahārāshtra, India