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The potential function of miR-135b-mediated JAK2/STAT3 signaling pathway during osteoblast differentiation

Xiang-Tao Zhang1, Min Sun2, Li Zhang3

  • 1Department of Orthopedics, The No.1 Hospital of Shijiazhuang, Shijiazhuang, Hebei, China.

The Kaohsiung Journal of Medical Sciences
|April 23, 2020
PubMed

Insights

MicroRNA-135b (miR-135b) inhibition promotes osteoblast differentiation by activating the JAK2/STAT3 pathway. Conversely, miR-135b mimics or JAK2 inhibition impede this process in MC3T3-E1 cells.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • Osteoblast differentiation is crucial for bone formation and is regulated by complex molecular mechanisms.
  • MicroRNAs (miRNAs) play significant roles in cellular processes, including osteogenesis.
  • The JAK2/STAT3 signaling pathway is implicated in various cellular functions, potentially including bone metabolism.

Purpose of the Study:

  • To investigate the role of miR-135b in osteoblast differentiation of MC3T3-E1 cells.
  • To elucidate the relationship between miR-135b and the JAK2/STAT3 signaling pathway in this context.
  • To determine the therapeutic potential of modulating miR-135b for bone regeneration.

Main Methods:

  • MC3T3-E1 cells were treated with miR-135b mimics, inhibitors, AG490 (a JAK2 inhibitor), or combinations.
  • Cell viability was assessed using MTT assay.
  • Alkaline phosphatase (ALP) activity and mineralization were quantified.
  • Gene and protein expression (miR-135b, osteoblast markers, JAK2, p-JAK2, STAT3, p-STAT3) were analyzed via qRT-PCR and Western blotting.
  • JAK2 as a direct target of miR-135b was validated using a dual-luciferase reporter assay.

Main Results:

  • MiR-135b downregulation correlated with increased JAK2 expression during osteoblast differentiation.
  • MiR-135b mimics or AG490 treatment reduced cell viability, ALP activity, and mineralization, while increasing apoptosis.
  • MiR-135b inhibition enhanced cell viability, ALP activity, and mineralization, with decreased apoptosis.
  • JAK2 was confirmed as a direct target of miR-135b.
  • AG490 reversed the pro-osteogenic effects of miR-135b inhibition.
  • Inhibition of miR-135b activated the JAK2/STAT3 pathway, promoting osteoblast differentiation.

Conclusions:

  • MiR-135b acts as a negative regulator of osteoblast differentiation in MC3T3-E1 cells.
  • The JAK2/STAT3 signaling pathway is a key mediator of miR-135b's effects on osteogenesis.
  • Modulating miR-135b levels presents a potential therapeutic strategy for enhancing bone formation.
Keywords:
JAK2/STAT3MC3T3-E1 cellsmiR-135bosteoblast differentiation

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