MicroRNA Networks Driving Skeletal Aging and WNT Pathway Modulation

Area of Science:

• Biogerontology
• Skeletal Biology
• Molecular Biology

Background:

• Cellular senescence is a significant factor in skeletal aging, observed in both normal aging and accelerated conditions like radiotherapy.
• Osteocytes, crucial bone cells, play a role in skeletal aging due to their longevity and abundance.

Purpose of the Study:

• To identify common differentially regulated microRNAs (miRs) associated with skeletal aging across physiological and radiation-induced contexts.
• To investigate the role of specific miRs, including miR-183-5p (WNT pathway) and miR-155-5p (SASP), in skeletal aging.
• To explore the effects of a Sclerostin antibody (Scl-Ab) on miR regulation and WNT pathway activity in aging bone.

Main Methods:

• MicroRNA (miR) sequencing was performed on young vs. old mouse femurs, focally radiated vs. non-radiated femurs, and young vs. old osteocytes.
• A neutralizing antibody to Sclerostin (Scl-Ab) was used to assess WNT pathway and senescence-related gene expression.
• miR sequencing was conducted on radiated bones from Scl-Ab treated mice.

Main Results:

• miR-135a-5p and miR-671-5p were commonly downregulated in aging bone models.
• miR-183-5p was the sole commonly upregulated miR, regulating the WNT pathway.
• miR-155-5p, linked to the Senescence-Associated Secretory Phenotype (SASP), was elevated in two conditions.
• Scl-Ab treatment downregulated miR-133a-3p, which is upregulated in radiation-induced skeletal aging.

Conclusions:

• Specific miRs, such as miR-183-5p and miR-155-5p, are key regulators of skeletal aging.
• Modulation of the WNT pathway using Scl-Ab influences miR expression and may impact skeletal aging.
• The study identifies potential therapeutic targets for mitigating skeletal aging and its associated pathologies.