1. Academic Validation
  2. Hypoxia-inducible factor-1α-mediated upregulation of CD99 promotes the proliferation of placental mesenchymal stem cells by regulating ERK1/2

Hypoxia-inducible factor-1α-mediated upregulation of CD99 promotes the proliferation of placental mesenchymal stem cells by regulating ERK1/2

  • World J Stem Cells. 2021 Apr 26;13(4):317-330. doi: 10.4252/wjsc.v13.i4.317.
Xu-Dong Feng 1 Jia-Qi Zhu 1 Jia-Hang Zhou 1 Fei-Yan Lin 1 Bing Feng 1 Xiao-Wei Shi 1 Qiao-Ling Pan 1 Jiong Yu 1 Lan-Juan Li 1 Hong-Cui Cao 2
Affiliations

Affiliations

  • 1 State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China.
  • 2 State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China. hccao@zju.edu.cn.
Abstract

Background: As human placenta-derived mesenchymal stem cells (hP-MSCs) exist in a physiologically hypoxic microenvironment, various studies have focused on the influence of hypoxia. However, the underlying mechanisms remain to be further explored.

Aim: The aim was to reveal the possible mechanisms by which hypoxia enhances the proliferation of hP-MSCs.

Methods: A hypoxic cell incubator (2.5% O2) was used to mimic a hypoxic microenvironment. Cell counting kit-8 and 5-ethynyl-20-deoxyuridine incorporation assays were used to assay the proliferation of hP-MSCs. The cell cycle was profiled by flow cytometry. Transcriptome profiling of hP-MSCs under hypoxia was performed by RNA Sequencing. CD99 mRNA expression was assayed by reverse transcription-polymerase chain reaction. Small interfering RNA-mediated hypoxia-inducible factor 1α (HIF-1α) or CD99 knockdown of hP-MSCs, luciferase reporter assays, and the ERK1/2 signaling inhibitor PD98059 were used in the mechanistic analysis. Protein expression was assayed by western blotting; immunofluorescence assays were conducted to evaluate changes in expression levels.

Results: Hypoxia enhanced hP-MSC proliferation, increased the expression of cyclin E1, cyclin-dependent kinase 2, and cyclin A2, and decreased the expression of p21. Under hypoxia, CD99 expression was increased by HIF-1α. CD99-specific small interfering RNA or the ERK1/2 signaling inhibitor PD98059 abrogated the hypoxia-induced increase in cell proliferation.

Conclusion: Hypoxia promoted hP-MSCs proliferation in a manner dependent on CD99 regulation of the MAPK/ERK signaling pathway in vitro.

Keywords

CD99; Hypoxia; Hypoxia-inducible factor 1α; MAPK/ERK signaling pathway; Mesenchymal stem cells; Proliferation; RNA sequencing assay.

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