Regulation of a structure that ensures eggs receive the correct number of chromosomes

What is it about?

For healthy offspring eggs and sperm must receive one and only one copy of each pair of chromosomes. In most organisms, including humans, a large protein structure called the synaptonemal complex (SC) is required for the process of ensuring the correct number of chromosomes by holding pairs of chromosomes together early in the process of egg and sperm production. The mechanisms that control where and when to build the SC are poorly understood but the identification of mutations in fruit fly females that cause SC proteins to form large repeated structures instead of building properly between pairs of chromosomes provides new insights into this regulation. The mutations affect a protein called Seven in absentia (Sina) which is required for the degradation of proteins. This work suggests a protein must be destroyed to direct SC proteins to build properly between pairs of chromosomes to orchestrate the events required to direct one of each chromosome into the egg.

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Photo by Navid saberi on Unsplash

Photo by Navid saberi on Unsplash

Why is it important?

Defects early in the process of making eggs and sperm lead to infertility, miscarriage and birth defects and affect a significant number of individuals. Yet we are only beginning to understand the causes of these defects. The identification of Sina, a protein involved in degrading proteins, as a crucial regulator of where and how to build the synaptonemal complex indicates making sure proteins are destroyed at the correct time is important for fertility. Sina is part of a family of proteins that are also present in mammals. Regulating protein degradation may be a future avenue to explore for understanding and treating infertility.

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