Estrogen Enhances Matrix Synthesis in Nucleus Pulposus Cell through the Estrogen Receptor β-p38 MAPK Pathway.
OBJECTIVE
Matrix homeostasis within the disc nucleus pulposus (NP) tissue is important for disc function. Increasing evidence indicates that sex hormone can influence the severity of disc degeneration. This study was aimed to study the role of 17β-estradiol (E2) in NP matrix synthesis and its underlying mechanism.


METHODS
Rat NP cells were cultured with (10-5, 10-7 and 10-9 M) or without (control) E2 for48 hours. The estrogen receptor (ER)-β antagonist PHTPP and ERβ agonist ERB 041 were used to investigate the role mediated by ERβ. The p38 MAPK inhibitor SB203580 was used to investigate the role of p38 MAPK signaling pathway. Gene and protein expression of SOX9, aggrecan and collagen II, glycosaminoglycan (GAG) content, and immunostaining assay for aggrecan and collagen II were analyzed to evaluate matrix production in rat NP cells.


RESULTS
E2 enhanced NP matrix synthesis in a concentration-dependent manner regarding gene and proetin expression of SOX9, aggrecan and collagen II, protein deposition of aggrecan and collagen II, and GAG content. Moreover, activation of p38 MAPK signaling pathway was increased with elevating E2 concentration. Further analysis indicated that ERB 041 and PHTPP could respectively enhance and suppress effects of E2 on matrix synthesis in NP cells, as well as activation of p38 MAPK pathway. Additionally, inhibition of p38 MAPK signaling pathway significantly abolished the effects of E2 on matrix synthesis.


CONCLUSIONS
E2 can enhance matrix synthesis of NP cells and the ERβ/p38 MAPK pathway is involved in this regulatory process.
Department of Orthopedic Surgery, Southwest Hospital, Third Military Medical University, Chongqing, China.
Pei
P
Li
Yuan
Y
Xu
Yibo
Y
Gan
Liyuan
L
Wang
Bin
B
Ouyang
Chengmin
C
Zhang
Lei
L
Luo
Chen
C
Zhao
Qiang
Q
Zhou
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D047629:Estrogen Receptor beta / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D000070614:Nucleus Pulposus / Q000187:drug effects / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D047629:Estrogen Receptor beta; D004967:Estrogens; D006025:Glycosaminoglycans; D048051:p38 Mitogen-Activated Protein Kinases