Chromatin changes trigger laminin genes dysregulation in aging kidneys

Area of Science:

• Epigenetics
• Molecular Biology
• Gerontology

Background:

• Gene expression dysregulation is a key feature of aging.
• Laminin genes play crucial roles in kidney structure and function.
• Aberrant gene expression in aging kidneys contributes to functional decline.

Purpose of the Study:

• To investigate epigenetic mechanisms behind altered laminin gene expression in aging rat kidneys.
• To identify specific laminin genes and epigenetic marks involved in age-related kidney changes.
• To elucidate the role of histone modifications and DNA methylation in laminin gene dysregulation during aging.

Main Methods:

• Quantitative real-time PCR to measure mRNA levels of laminin genes.
• Western blot analysis to assess protein expression and epigenetic mark abundance.
• Chromatin immunoprecipitation to evaluate RNA polymerase II density and histone modification levels (H3K27me3).
• In vitro studies using Ezh2 and DNA methylation inhibitors (2'-deoxy-5-azacytidine) in kidney cells.

Main Results:

• Laminin alpha 3 (Lama3), beta 3 (Lama3), and gamma 2 (Lamc2) mRNA levels were elevated in old rat kidneys.
• Lamc2 exhibited the most significant upregulation at both mRNA and protein levels.
• Increased RNA polymerase II density at the Lamc2 gene indicated transcriptional upregulation.
• Aging kidneys showed reduced H3K27me3 and 5-methylcytosine (5mC) marks at the Lamc2 gene.
• Ezh2 inhibitor treatment did not affect Lamc2 expression, while DNA methylation inhibition upregulated Lamc2.
• No changes in total cellular H3K27me3 or Ezh2 levels were observed in aged kidneys.

Conclusions:

• The loss of DNA methylation (5mC) at silenced laminin genes, particularly Lamc2, is a primary driver of their de-repression in aging kidneys.
• Epigenetic alterations, specifically demethylation, contribute to age-related changes in kidney gene expression.
• These findings suggest that aberrant laminin gene expression due to epigenetic changes may contribute to the decline in renal function during aging.