Ze Li,1,* Jing Peng Liu,2,* Feng Hua Yao,3,* Yang Cao,1 Shou Chun Li,1 Yuan Yang Liu,1 Su Xin Wen,1 Yu Xiao Liu,1 Ai Jun Liu1 

1Department of Neurosurgery, First Medical Center of the Chinese PLA General Hospital, Beijing, 100853, People’s Republic of China; 2Department of Traditional Chinese Medical Science, Sixth Medical Center of the Chinese PLA General Hospital, Beijing, 100037, People’s Republic of China; 3Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Beijing, 100853, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Ai Jun Liu; Yu Xiao Liu, Department of Neurosurgery, First Medical Center of the Chinese PLA General Hospital, 28 Fuxing Road, Haidian District, Beijing, 100853, People’s Republic of China, Tel +86 1066848351 ; +86 1066848354, Email liuaj719@sina.com; wjliu8004@163.com

Background: Cold inducible RNA-binding protein (CIRP) is an important danger-associated molecular pattern involved in tissue-specific and systemic inflammation related to inflammation and Alzheimer’s disease (AD). However, the precise roles and mechanism of CIRP in the functional changes in astrocytes during the development of AD are still unknown. This study aimed to assess gene expression alterations in astrocytes after they overexpress CIRP (oe-CIRP) and to explore the relationship between abnormal CIRP expression and AD.
Methods: We created astrocyte cell lines with a CIRP or control vector expression using three human glioma cell lines U87, U251 and H4, and analyzed the mRNA expression profiles of 3 pairs of cells via microarray. Bioinformatics identified differentially expressed mRNAs between CIRP-overexpressing (ov-CIRP) and control groups, validated by q-PCR and Western blotting (WB). Finally, the effect of CIRP overexpression in astrocytes on neurons was observed in a coculture system.
Results: We identified 119 mRNAs with obvious fold changes between the ov-CIRP and control groups for all 3 pairs of human glioma cell lines. The biological functional analysis indicated that urokinase plasminogen activator (uPA), a gene whose expression significantly decreased after CIRP overexpression, was closely associated with AD. WB and q-PCR confirmed that CIRP overexpression significantly inhibited uPA at both mRNA and protein levels in U87, U251 and H4 cells. Moreover, compared with those cocultured with control astrocytes, SH-SY5Y cells cocultured with CIRP-overexpressing astrocytes exhibited a significant increase in the expression of amyloid-β (Aβ)1– 42 and the hyperphosphorylated microtubule-associated protein tau (Tau).
Conclusion: CIRP overexpression in astrocytes inhibits uPA expression, promoting Aβ 1-42 production and tau phosphorylation in neurons, thereby increasing AD risk. These results suggest that the overexpression of CIRP in astrocytes contributes to the development of AD.

Keywords: cold-inducible RNA-binding protein, Alzheimer disease, astrocyte, neuron