Abstract
Although cervical ossification of the posterior longitudinal ligament (OPLL) is one of the most common spinal diseases, the pathogenic mechanism is still not fully understood. Abnormal mechanical stress distribution is believed to be one of the main causes of OPLL. We have previously found that mechanical stress can up-regulate connexin 43 (Cx43) expression in ligament fibroblasts; this transduces mechanical signals to promote osteoblastic differentiation. In the present study, in order to explore further the intracellular mechanisms of Cx43-induced osteoblast differentiation of ligament fibroblasts, we investigate the potential roles of the osteogenic signaling pathway components ERK1/2, p38 MAPK and JNK in Cx43-mediated mechanical signal transduction. We first confirm higher Cx43 levels in both in vivo ligament tissue from OPLL patients and in vitro cultured OPLL cells. We find that ERK1/2, p38 MAPK and the JNK pathway are all activated both in vivo and in vitro. The activation of these signals was dependent upon Cx43, as its knock-down resulted in diminished mechanical effects and reduced signaling. Moreover, its knock-down almost reversed the osteogenic effect of mechanical stress on ligament fibroblasts and the blocking of the ERK1/2 and p38 MAPK pathways but not the JNK pathway, partly diminished this effect. Therefore, Cx43, which is up-regulated by mechanical stress, seems to function partly via the activation of ERK1/2 and p38 MAPK signals to promote the osteoblastic differentiation of ligament fibroblasts.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Batra N, Burra S, Siller-Jackson AJ, Gu S, Xia X, Weber GF, DeSimone D, Bonewald LF, Lafer EM, Spraque E, Schwartz MA, Jiang JX (2012) Mechanical stress-activated integrin α5β1 induces opening of connexin 43 hemichannels. Proc Natl Acad Sci U S A 109:3359–3364
Batra N, Riquelme MA, Burra S, Kar R, Gu S, Jiang JX (2014) Direct regulation of osteocytic connexin 43 hemichannels through AKT kinase activated by mechanical stimulation. J Biol Chem 289:10582–10591
Chung DJ, Castro CH, Watkins M, Stains JP, Chung MY, Szejnfeld VL, Willecke K, Theis M, Civitelli R (2006) Low peak bone mass and attenuated anabolic response to parathyroid hormone in mice with an osteoblast-specific deletion of connexin43. J Cell Sci 119:4187–4198
Epstein N (2002) Ossification of the cervical posterior longitudinal ligament: a review. Neurosurg Focus 13:ECP1
Furlan F, Lecanda F, Screen J, Civitelli R (2001) Proliferation, differentiation and apoptosis in connexin43- null osteoblasts. Cell Commun Adhes 8:367–371
Inamasu J, Guiot BH, Sachs DC (2006) Ossification of the posterior longitudinal ligament: an update on its biology, epidemiology, and natural history. Neurosurgery 58:1027–1039
Iwasaki K, Furukawa KI, Tanno M, Kusumi T, Ueyama K, Tanaka M, Kudo H, Toh S, Harata S, Motomura S (2004) Uniaxial cyclic stretch induces Cbfa1 expression in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament. Calcif Tissue Int 74:448–457
Iwasawa T, Iwasaki K, Sawada T, Okada A, Ueyama K, Motomura S, Harata S, Inoue I, Toh S, Furukawa KI (2006) Pathophysiological role of endothelin in ectopic ossification of human spinal ligaments induced by mechanical stress. Calcif Tissue Int 79:422–430
Kapur S, Baylink DJ, Lau KH (2003) Fluid flow shear stimulates human osteoblast proliferation and differentiation through multiple interacting and competing signal transduction pathways. Bone 32:241–251
Kato Y, Kanchiku T, Imajo Y, Kimura K, Ichihara K, Kawano S, Hamanaka D, Yaji K, Taquchi T (2010) Biomechanical study of the effect of degree of static comparession of the spinal cord in ossification of the posterior longitudinal ligament. J Neurosurg Spine 12:301–305
Liu J, Zhao Z, Li J, Zou L, Shuler C, Zou Y, Huang X, Li M, Wang J (2009) Hydrostatic pressures promote initial osteodifferentiation with ERK1/2 not p38 MAPK signaling involved. J Cell Biochem 107:224–232
Mu C, Lv T, Wang Z, Ma S, Ma J, Liu J, Yu J, Mu J (2014) Mechanical stress stimulates the osteo/odontoblastic differentiation of human stem cells from apical papilla via Erk 1/2 and JNK MAPK pathways. Biomed Res Int 2014:494378
Nishida N, Kanchiku T, Kato Y, Imajo Y, Yoshida Y, Kawano S, Taquchi T (2014) Cervical ossification of the posterior longitudinal ligment: biomechanical analysis of the influence of static and dynamic factors. J Spinal Cord Med 38:593–598
Ohishi H, Furukawa KI, Iwasaki K, Ueyama K, Okada A, Motomura S, Harata S, Toh S (2003) Role of prostaglandin I2 in the gene expression induced by mechanical stress in spinal ligament cells derived from patients with ossification of the posterior longitudinal ligament. J Pharmacol Exp Ther 305:818–824
Plotkin LI, Speacht TL, Donahue HJ (2015) Cx43 and mechanotransduction in bone. Curr Osteoporos Rep 13:67–72
Roberto C (2008) Cell-cell communication in the osteoblast/osteocyte lineage. Arch Biochem Biophys 473:188–192
Stains JP, Watkins MP, Grimston SK, Hebert C, Civitelli R (2014) Molecular mechanisms of osteoblast/osteocyte regulation by connexin43. Calcif Tissue Int 94:55–67
Tanno M, Furukawa KI, Ueyama K, Harata S, Motomura S (2003) Uniaxial cyclic stretch induces osteogenic differentiation and synthesis of bone morphogenetic proteins of spinal ligament cells derived from patients with ossification of the posterior longitudinal ligaments. Bone 33:475–484
Tsukamoto N, Maeda T, Miura H, Jingushi S, Hosokawa A, Harimaya K, Higaki H, Kurata K, Iwamoto Y (2006) Repetitive tensile stress to rat caudal vertebrae inducing cartilage formation in the spinal ligaments: a possible role of mechanical stress in the development of ossification of the spinal ligaments. J Neurosurg Spine 5:234–242
Weyts FA, Li YS, Leeuwen J van, Weinans H, Chien S (2002) ERK activation and alpha v beta 3 integrin signaling through Shc recuitment in response to mechanical stimulation in human osteoblasts. J Cell Biochem 87:85–92
Yan Q, Wang B, Sui W, Zou G, Chen H, Xie S, Zou H (2012) Expression of GSK-3β in renal allograft tissue and its significance in pathogenesis of chronic allograft dysfunction. Diagn Pathol 7:5
Yang HS, Lu XH, Chen DY, Yuan W, Yang LL, He HL, Chen Y (2011a) Upregulated expression of connexin43 in spinal ligament fibroblasts derived from patients presenting ossification of the posterior longitudinal ligament. Spine 36:2267–2274
Yang HS, Lu XH, Chen DY, Yuan W, Yang LL, Chen Y, He HL (2011b) Mechanical strain induces Cx43 expression in spinal ligament fibroblasts derived from patients presenting ossification of the posterior longitudinal ligament. Eur Spine J 20:1459–1465
Yellowley CE, Li Z, Zhou Z, Jacobs CR, Donahue HJ (2000) Functional gap junctions between osteocytic and osteoblastic cells. J Bone Miner Res 15:209–217
Zhang P, Wu Y, Jiang Z, Jiang L, Fang B (2012) Osteogenic response of mesenchymal stem cells to continuous mechanical strain is dependent on ERK1/2-Runx2 signaling. Int J Mol Med 29:1083–1089
Author information
Authors and Affiliations
Corresponding authors
Additional information
Dechun Chen and Yang Liu contributed equally to this work and should be considered as co-first authors.
This study was supported by grants from the National Natural Science Foundation of China (nos. 81201427 and 81371916) and grants from the Science and Technology Commission of Shanghai Municipality (nos. 13430710700 and 14431900900).
Rights and permissions
About this article
Cite this article
Chen, D., Liu, Y., Yang, H. et al. Connexin 43 promotes ossification of the posterior longitudinal ligament through activation of the ERK1/2 and p38 MAPK pathways. Cell Tissue Res 363, 765–773 (2016). https://doi.org/10.1007/s00441-015-2277-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00441-015-2277-6