# Female Aging Affects Coilin Pattern in Mouse Cumulus Cells

## TL;DR

This study shows that aging in female mice affects the structure of cumulus cells surrounding eggs, potentially offering a new biomarker for ovarian aging.

## Contribution

The study identifies age-related changes in coilin-positive nuclear bodies in cumulus cells unrelated to gene expression.

## Key findings

- Older mice had fewer coilin-positive bodies in cumulus cells.
- Gene expression of Coil and Smn1 remained unchanged with age.
- Age-related changes in coilin bodies may reflect metabolic shifts in cumulus cells.

## Abstract

Cumulus cells (CCs) are a distinct population of granulosa cells (GCs) that surround the developing and ovulated mammalian oocyte. The features of their structural organization and the expression pattern of key genes significantly affect oocyte viability. Changes in the functional activity of the nucleus are often expressed in changes in the structure of nuclear bodies (NBs), including Cajal bodies (CBs). The diagnostic protein of CBs is coilin, which maintains their structural integrity. Using fluorescent and electron microscopy, we examined maternal aging-associated changes in coilin pattern in mouse CCs. We found that older mice had a decrease in the number of coilin-positive bodies, while external transcriptome data analysis revealed no significant changes in Coil and Smn1 gene expression. We hypothesized that the age-related dynamics of coilin-containing bodies are determined not by changes in the expression level of key components of these bodies, but by age-related changes in CC metabolism. Considering that CCs are a by-product of IVF protocols, making them available for analysis in sufficient quantities, age-related changes in the number and size of coilin-positive NBs in CCs may serve as a promising biomarker for assessing ovarian functional aging.