Loss of Calponin 2 causes premature ovarian insufficiency in mice

TL;DR

Removing Calponin 2 in mice leads to early ovarian failure, showing its role in maintaining ovarian health and fertility.

Contribution

This study identifies Calponin 2 as a key regulator of ovarian follicle development and function.

Findings

Cnn2-KO mice had smaller litter sizes and fewer ovarian follicles compared to wild type mice.

Loss of Calponin 2 caused age-progressive depletion of ovarian follicles.

Calponin 2 localizes with actin stress fibers in cumulus cells, suggesting a functional role in folliculogenesis.

Abstract

Premature ovarian insufficiency (POI) is a condition defined as women developing menopause before 40 years old. These patients display low ovarian reserve at young age and difficulties to conceive even with assisted reproductive technology. The pathogenesis of ovarian insufficiency is not fully understood. Genetic factors may underlie most of the cases. Actin cytoskeleton plays a pivotal role in ovarian folliculogenesis. Calponin 2 encoded by the Cnn2 gene is an actin associated protein that regulates motility and mechanical signaling related cellular functions.

The present study compared breeding of age-matched calponin 2 knockout (Cnn2-KO) and wild type (WT) mice and found that Cnn2-KO mothers had significantly smaller litter sizes. Ovaries from 4 weeks old Cnn2-KO mice showed significantly lower numbers of total ovarian follicles than WT control with the presence of multi-oocyte follicles. Cnn2-KO mice also showed age-progressive earlier depletion of ovarian follicles. Cnn2 expression is detected in the cumulus cells of the ovarian follicles of WT mice and colocalizes with actin stress fiber, tropomyosin and myosin II in primary cultures of cumulus cells.

The findings demonstrate that the loss of calponin 2 impairs ovarian folliculogenesis with premature depletion of ovarian follicles. The role of calponin 2 in ovarian granulosa cells suggests a molecular target for further investigations on the pathogenesis of POI and for therapeutic development.

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