Ca2+ oscillatory pattern in fertilized mouse eggs affects gene expression and development to term

Area of Science:

• Reproductive Biology
• Developmental Biology
• Molecular Biology

Background:

• Sperm-induced calcium (Ca2+) oscillations regulate egg activation events in a temporal sequence.
• The impact of these Ca2+ signaling patterns on long-term development, including development to term, remains largely unknown.

Purpose of the Study:

• To investigate the long-term consequences of altered Ca2+ signaling patterns on embryonic development and gene expression.
• To determine if manipulating Ca2+ oscillations affects implantation, post-implantation development, and offspring viability.

Main Methods:

• Developed experimental procedures to inhibit or stimulate the natural Ca2+ oscillation pattern in fertilized eggs.
• Utilized embryo transfer to assess developmental competence, implantation rates, and offspring development.
• Performed microarray analysis to examine global gene expression patterns in response to altered Ca2+ signaling.

Main Results:

• Altered Ca2+ oscillations did not affect blastocyst development but reduced offspring birth rates, indicating compromised developmental competence.
• Premature interruption of Ca2+ signaling impaired implantation, while hyper-stimulation compromised post-implantation development.
• Gene expression analysis revealed significant mis-regulation of transcripts involved in RNA processing, transcription, and cell adhesion following reduced oscillations, and metabolism following hyper-stimulation.

Conclusions:

• Precise regulation of Ca2+ signaling during early embryonic development is critical for successful implantation and development to term.
• Both insufficient and excessive Ca2+ signaling can lead to long-term adverse effects on gene expression and developmental outcomes.
• These findings underscore the sensitivity of early developmental processes to the precise dynamics of intracellular calcium signaling.