ER stress activating ATF4/CHOP-TNF-α signaling pathway contributes to alcohol-induced disruption of osteogenic lineage of multipotential mesenchymal stem cell

Yueping Chen, Hui Gao, Qingshui Yin, Liang Chen, Panfeng Dong, Xiaoyun Zhang, Jie Kang
Cellular Physiology and Biochemistry 2013, 32 (3): 743-54

BACKGROUND/AIMS: Studies have provided substantial evidence that osteoblasts and adipocytes share common progenitor‒multipotential mesenchymal stem cells in bone marrow (BMSCs), and excessive alcohol consumption shifts away from osteogenic to adipogenic lineage. However, how exactly alcohol impairs osteogenesis is still incompletely understood. This study was designed to shed light on this issue.

METHODS: We treated primary BMSCs from human subjects with alcohol for 24 days. We measured changes of genes related to endoplasmic reticulum (ER) stress, adipogenic markers and osteogenic markers using quantitative real-time RT-PCR and Western blot analysis. We performed Oil red O staining and quantification of adipogenesis. We also conducted caspase 3 activity assay to assess BMSC apoptosis.

RESULTS: We showed here that chronic exposure of BMSCs to alcohol induced adipogenesis and disrupted osteogenesis as indicated by upregulation of adipogenic markers (PPARγ2 and aP2), downregulation of osteogenic markers (Osf2/Cbfa1), and accumulation of lipid droplets. Alcohol induced ER stress, as reflected by increased expression of glucose-regulated proteins GRP78 and GRP94, and by increased expression of transcription factors activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP), and enhanced caspase 3 activity. Additionally, ER stress also upregulated tumor necrosis factor-alpha (TNF-α). Simultaneous silencing of ATF4 and CHOP prevented upregulation of TNF-α. Knockdown of either ATF4 and CHOP or TNF-α by their siRNAs was able to reverse the ethanol-induced adipogenesis.

CONCLUSION: Our data therefore revealed a role of ER stress and ATF4/CHOP in the ethanol-induced inhibition of osteogenesis, and activation of TNF-α signaling by ATF4/CHOP linking ER stress to adipogenic lineage in response to alcohol stimulation. This work should establish a new signaling pathway linking alcohol, ER stress, and TNF-α to loss of bone formation: Ethanol → ER stress↑↑↑ → ATF4 & CHOP↑↑↑ → TNF-α↑↑↑ → Osteoblasts↓↓↓.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"