Vascular endothelial growth factor-A is a survival factor for nucleus pulposus cells in the intervertebral disc

Fujita, Nobuyuki; Imai, Jun; Suzuki, T.; Yamada, Masayuki; Ninomiya, Ken; Miyamoto, Kana; Iwasaki, Ryuichiro; Morioka, Hideo; Matsumoto, Morio; Chiba, Kazuhiro; Watanabe, Shinya; Suda, Toshio; Toyama, Yoshiaki; Miyamoto, Takeshi

doi:10.1016/j.bbrc.2008.05.044

Cited by 72 publications

(67 citation statements)

References 23 publications

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“…1B), further suggesting that estrogen depletion stabilizes HIF1α protein rather than inducing Hif1α mRNA in osteoclasts. Assessment of hypoxia using pimonidazole (Pimo) (18), which detects low oxygen tension areas, showed that the hypoxic state was comparable in the endosteal zone of Sham and Ovx mouse bones (Fig. 1C).…”

Section: Resultsmentioning

confidence: 98%

HIF1α is required for osteoclast activation by estrogen deficiency in postmenopausal osteoporosis

Miyauchi

Sato²,

Kobayashi³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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In women, estrogen deficiency after menopause frequently accelerates osteoclastic bone resorption, leading to osteoporosis, the most common skeletal disorder. However, mechanisms underlying osteoporosis resulting from estrogen deficiency remain largely unknown. Here we show that in bone-resorbing osteoclasts, estrogendependent destabilization of hypoxia-inducible factor 1 alpha (HIF1α), which is unstable in the presence of oxygen, plays a pivotal role in promoting bone loss in estrogen-deficient conditions. In vitro, HIF1α was destabilized by estrogen treatment even in hypoxic conditions, and estrogen loss in ovariectomized (Ovx) mice stabilized HIF1α in osteoclasts and promoted their activation and subsequent bone loss in vivo. Osteoclast-specific HIF1α inactivation antagonized bone loss in Ovx mice and osteoclast-specific estrogen receptor alpha deficient mice, both models of estrogen-deficient osteoporosis. Oral administration of a HIF1α inhibitor protected Ovx mice from osteoclast activation and bone loss. Thus, HIF1α represents a promising therapeutic target in osteoporosis.B one mass is tightly regulated by a delicate balance between osteoblastic bone formation and osteoclastic bone resorption. Estrogen loss in women after menopause frequently promotes activation of osteoclastic bone resorption, causing osteoporosis. Osteoporotic bone phenotypes are seen in ovariectomized female mice, and estrogen deficiency-induced bone loss in both mouse models and women is ameliorated by estrogen treatment (1, 2). However, estrogen administration reportedly increases risk of cardiovascular events and carcinogenesis of the mammary gland and uterus (3). Bioavailable estrogens including selective estrogen receptor modulators (SERMs) also protect bone from estrogen deficiency-induced osteoporosis (4), and estrogen and SERMs primarily act via estrogen receptors (ER), ERα and ERβ (5, 6). However, how SERMs act on bone remains largely unknown. Thus, understanding of osteoclast activation following estrogen loss is crucial for development of safe therapeutic reagents.Both the endosteal zone of bone marrow cavities and epiphyseal growth plates are hypoxic areas, and the hypoxia-inducible factor (HIF) signaling pathway governs chondrocyte and osteoblast function in these respective areas (7,8). The HIF1 transcription factor consists of an oxygen-regulated alpha subunit, HIF1α, and a constitutively expressed beta subunit, HIF1β. Under normoxia, HIF1α is posttranslationally modified by prolyl hydroxylases, which catalyze hydroxylation of proline residues in the presence of O 2 and Fe 2+ . Recognition of hydroxylated HIF1α by the von Hippel-Lindau tumor suppressor protein recruits an E3 ubiquitin ligase complex targeting HIF1α for proteasomal degradation. Conversely, under hypoxia, proline hydroxylation is inhibited by substrate (O 2 ) deprivation, allowing HIF1α accumulation and formation of an active transcriptional complex with HIF1β (9). Recently, regulation of HIF1α protein levels by factors other than O 2 , including reactive ...

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Section: Resultsmentioning

confidence: 98%

HIF1α is required for osteoclast activation by estrogen deficiency in postmenopausal osteoporosis

Miyauchi

Sato²,

Kobayashi³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

164

160

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“…VEGF, a principal regulator of blood vessel formation and hematopoiesis, has been reported to improve cell survival of hematopoietic stem cells [Gerber et al, 2002] and ADMSCs [Stubbs et al, 2012]. Recent studies suggested that VEGF may serve as a survival factor for NP cells in the normal IVD [Agrawal et al, 2008;Fujita et al, 2008].…”

Section: Discussionmentioning

confidence: 99%

Influence of Hypoxia in the Intervertebral Disc on the Biological Behaviors of Rat Adipose- and Nucleus Pulposus-Derived Mesenchymal Stem Cells

Tao

Liang

et al. 2013

Cells Tissues Organs

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Adipose-derived mesenchymal stem cells (ADMSCs) and nucleus pulposus-derived mesenchymal stem cells (NPMSCs) are two cell candidates for cell-based therapies for intervertebral disc (IVD) regeneration. However, little work has been done to determine the influence of hypoxia in the IVD on the biological behaviors of ADMSCs and NPMSCs. This study aimed to investigate the viability, proliferation and differentiation of rat ADMSCs and NPMSCs in the hypoxic environment of IVD in vitro. ADMSCs and NPMSCs isolated from 6 SD rats were cultured under normoxia (20% O₂) and hypoxia (2% O₂) mimicking the standard condition and hypoxic environment of the IVD for 14 days. Cell viability was determined by the annexin-V-FITC/propidium iodide double-staining assay and cell proliferation was measured by MTT assay. The expression of hypoxia-inducible factor-1α, glucose transporter (GLUT)-1, GLUT-3 and vascular endothelial growth factor-A at the mRNA level was examined by RT-PCR. In cells cultured in three-dimensional micromass and differentiation medium, aggrecan, collagen-II and Sox-9 expression at mRNA and protein levels were examined by RT-PCR and Western blot. Hypoxia inhibited the viability and proliferation of both ADMSCs and NPMSCs, but promoted the chondrocytic differentiation of ADMSCs and NPMSCs. Compared to ADMSCs, NPMSCs showed greater viability, proliferation and chondrocytic differentiation under hypoxia. In conclusion, hypoxia in the IVD had a significant impact on the viability, proliferation and chondrocytic differentiation of ADMSCs and NPMSCs. NPMSCs exhibited more potent biological activity than ADMSCs in the hypoxic environment of the IVD and may represent another candidate for cell-based therapy for IVD regeneration.

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“…Finally, because the disc is avascular, nutrient supply-particularly, oxygen-has been thought to be a strong determinant of IVD form and function during growth (Urban et al, 2004;Grunhagen et al, 2006). Aside from MAPK signaling and VEGF expression changes in rat NP cells (Risbud et al, 2005a,b;Agrawal et al, 2008;Fujita et al, 2008), hypoxia does not appear to generate oxaemic distress (Rajpurohit et al, 2002;Risbud et al, 2006;Lee et al, 2007). However, it is not clear how hypoxia might regulate other genes associated with the immature NP such as CD24, type IIA collagen, a 6 integrin subunit, and galectin-3 (Zhu et al, 2001;Hunter et al, 2003;Fujita et al, 2005;Chen et al, 2006;Gilchrist et al, 2007;Zeng et al, 2007).…”

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confidence: 99%

Environmental regulation of notochordal gene expression in nucleus pulposus cells

Rastogi

Thakore

Leung

et al. 2009

Journal Cellular Physiology

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Cells of the nucleus pulposus (NP) in the intervertebral disc are derived directly from the embryonic notochord. In humans, a shift in NP cell population coincides with the beginning of age-related changes in the extracellular matrix that can lead to spinal disorders. To begin identifying the bases of these changes, the manner by which relevant environmental factors impact cell function must be understood. This study investigated the roles of biochemical, nutritional, and physical factors in regulating immature NP cells. Specifically, we examined cell morphology, attachment, proliferation, and expression of genes associated with the notochord and immature NP (Sox9, CD24, and type IIA procollagen). Primary cells isolated from rat caudal discs were exposed to different media formulations and physical culture configurations either in 21% (ambient) or 2% (hypoxic) O2. As expected, cells in alginate beads retained a vacuolated morphology similar to chordocytes, with little change in gene expression. Interestingly, NP tissues not enzymatically digested were more profoundly influenced by oxygen. In monolayer, alpha-MEM preserved vacuolated morphology, produced the highest efficiency of attachment, and best maintained gene expression. DMEM and Opti-MEM cultures resulted in high levels of proliferation, but these appeared to involve small non-vacuolated cells. Gene expression patterns for cells in DMEM monolayer cultures were consistent with chondrocyte de-differentiation, with the response being delayed by hypoxia. Overall, results indicate that certain environmental conditions induce cellular changes that compromise the notochordal phenotype in immature NP. These results form the foundation on which the mechanisms of such changes can be elucidated.

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Vascular endothelial growth factor-A is a survival factor for nucleus pulposus cells in the intervertebral disc

Cited by 72 publications

References 23 publications

HIF1α is required for osteoclast activation by estrogen deficiency in postmenopausal osteoporosis

HIF1α is required for osteoclast activation by estrogen deficiency in postmenopausal osteoporosis

Influence of Hypoxia in the Intervertebral Disc on the Biological Behaviors of Rat Adipose- and Nucleus Pulposus-Derived Mesenchymal Stem Cells

Environmental regulation of notochordal gene expression in nucleus pulposus cells

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