Dongping Ye

Overexpression of hTERT extends replicative capacity of human nucleus pulposus cells, and protects against serum starvation‐induced apoptosis and cell cycle arrest

The nucleus pulposus (NP) cells are chondrocyte‐like cells that are required for the resistance of compressive loads through the synthesis of collagen fibrils and proteoglycan aggrecans, and the generation of a hydrostatic swelling pressure, and thus play an important role in the intervertebral disc. Here, we report the production and characterization of an immortalized human NP cell line from normal NP cells using stable transfection of recombinant human telomerase reverse transcriptase (hTERT) gene. The hTERT‐transfected NP cells exhibited morphological characteristics typical of native cells. When compared with the first generation of normal NP cells, the hTERT‐transfected NP cells grew faster and had an increased level of IGF‐1 and TGF‐β gene expression. They were successfully passaged over 20 generations without significant change in the levels of type II collagen and proteoglycan aggrecan expression. In addition, they showed resistance to serum starvation‐induced apoptosis, G1 cell cycle arrest, and gene expression of p53, CCNE1, Fas, and Caspase 3. Moreover, histology revealed that no tumorigenicity of NP cells over expressing hTERT was observed after they were implanted in nude mice. Taken together, an immortalized human NP cell line was established, which has an extended lifespan, retains phenotypic features similar to primary parent NP cells, and should provide a suitable model for studying the biology of NP cells. J. Cell. Biochem. 113: 2112–2121, 2012.

Comparative and quantitative proteomic analysis of normal and degenerated human annulus fibrosus cells

Degeneration of the intervertebral disc (IVD) is a major chronic medical condition associated with back pain. To better understand the pathogenesis of IVD degeneration, we performed comparative and quantitative proteomic analyses of normal and degenerated human annulus fibrosus (AF) cells and identified proteins that are differentially expressed between them. Annulus fibrosus cells were isolated and cultured from patients with lumbar disc herniation (the experimental group, degenerated AF cells) and scoliosis patients who underwent orthopaedic surgery (the control group, normal AF cells). Comparative proteomic analyses of normal and degenerated cultured AF cells were carried out using 2‐D electrophoresis, mass spectrometric analyses, and database searching. Quantitative analyses of silver‐stained 2‐D electrophoresis gels of normal and degenerated cultured AF cells identified 10 protein spots that showed the most altered differential expression levels between the two groups. Among these, three proteins were decreased, including heat shock cognate 71‐kDa protein, glucose‐6‐phosphate 1‐dehydrogenase, and protocadherin‐23, whereas seven proteins were increased, including guanine nucleotide‐binding protein G(i) subunit α‐2, superoxide dismutase, transmembrane protein 51, adenosine receptor A3, 26S protease regulatory subunit 8, lipid phosphate phosphatase‐related protein, and fatty acyl‐crotonic acid reductase 1. These differentially expressed proteins might be involved in the pathophysiological process of IVD degeneration and have potential values as biomarkers of the degeneration of IVD.

miR-155 Inhibits Nucleus Pulposus Cells' Degeneration through Targeting ERK 1/2.

We first investigated the difference in microRNA expression between normal NP cells and degenerative NP cells using gene chip. We have found that the expression of ERK1/2 was decreased with overexpression of miR-155 in normal nucleus pulposus cell. Expression of ERK1/2 was increased with inhibition of miR-155. Overexpression or inhibition of miR-155 had no effects on the expression level of mRNA ERK1/2 in nucleus pulposus cell, which showed that miR-155 affected the expression of pERK1/2 after transcription of ERK1/2 mRNA indicating that ERK1/2 was a new target protein regulated by miR-155. In the degeneration of intervertebral disc, inhibited miR-155 decreased the expressions of extracellular main matrix collagen II and glycosaminoglycan and increased expression of ERK1/2. Taken together, our data suggested that miR-155 was the identified miRNA which regulated NP cells degenerated through directly targeting ERK1/2.

Natural Germacrane Sesquiterpenes Inhibit Osteoclast Formation, Bone Resorption, RANKL-Induced NF-κB Activation, and IκBα Degradation

Osteolytic bone diseases are commonly presented with enhanced osteoclast formation and bone resorption. Sesquiterpene lactone natural compounds have been found to possess anti-inflammatory and immune-modulation effects. Here, we identified three germacrane sesquiterpenes using computer-based virtual screening for the structural similarity with sesquiterpene lactone, parthenolide. We showed that natural germacrane sesquiterpene compounds A, B, and C inhibit osteoclast formation and bone resorption in a dose-dependent manner, with relative potency compound A > compound C > compound B based on their equimolar concentrations. Mechanistic studies by Luciferase reporter gene assay and Western blot analysis showed that germacrane sesquiterpene compound A inhibits RANKL-induced activation of NF-κB and IκBα degradation. This study reveals that natural germacrane sesquiterpene compounds are inhibitors for osteoclast formation and bone resorption, and provides evidence that naturally-occurring compounds might be beneficial as alternative medicine for the prevention and treatment of osteolysis.

Differential expression of extracellular-signal-regulated kinase 5 (ERK5) in normal and degenerated human nucleus pulposus tissues and cells

Extracellular-signal-regulated kinase 5 (ERK5) is a member of the mitogen-activated protein kinase (MAPK) family and regulates a wide variety of cellular processes such as proliferation, differentiation, necrosis, apoptosis and degeneration. However, the expression of ERK5 and its role in degenerated human nucleus pulposus (NP) is hitherto unknown. In this study, we observed the differential expression of ERK5 in normal and degenerated human nucleus pulposus tissues by using immunohistochemical staining and Western blot. Treatment of NP cells with Pro-inflammatory cytokine, TNF-α decreased ERK5 gene expression as well as NP marker gene expression; including the type II collagen and aggrecan. Suppression of ERK5 gene expression in NP cells by ERK5 siRNA resulted in decreased gene expression of type II collagen and aggrecan. Furthermore, inhibition of ERK5 activation by BIX02188 (5μM) decreased the gene expression of type II collagen and aggrecan in NP cells. Our results document the expression of ERK5 in degenerated nucleus pulposus tissues, and suggest a potential involvement of ERK5 in human degenerated nucleus pulposus.

Corrigendum to “Moderate Fluid Shear Stress Could Regulate the Cytoskeleton of Nucleus Pulposus and Surrounding Inflammatory Mediators by Activating the FAK-MEK5-ERK5-cFos-AP1 Signaling Pathway”

[This corrects the article DOI: 10.1155/2018/9405738.].

Protective effect of p53 on the viability of intervertebral disc nucleus pulposus cells under low glucose condition

P53 is a famous cancer suppressor and plays key roles in metabolism. Intervertebral disc (IVD) is the largest avascular cartilaginous structure in humans and its degeneration is a common cause of spine diseases initiated from damaged nucleus pulposus (NP) cells. The potential cause of disc degeneration has been attributed to aging, genetic factors, mechanical factors and nutrition. In this study, we found that p53 decreased and leaked to the cytoplasm in NP cells as the glucose level decreases, in contrast to cancer cells in which p53 increases and concentrates to the nuclei. Comparing with in p53 knockdown NP cells, relative high p53 expression in normal control NP cells inhibited autophagy and the pentose phosphate pathway. Furthermore, the expression of Sox 9 and type II collagen were higher in p53 normal control than p53 knockdown NP cells. Based on these results, we believe that relative high p53 facilitates NP cell viability and integrity.