ZC3H14 phosphorylation is required for nuclear speckle assembly during zygotic splicing activation in mice.

Phosphorylation of ZC3H14 by CDK12/13 is essential for nuclear speckle formation during zygotic splicing activation in mice.

• Why it matters: Understanding how nuclear speckles are assembled during early development is crucial because ZSA is vital for embryo progression, yet its regulatory mechanisms are poorly known.
• What they did: The study used Zc3h14 knockout mice and mutants mimicking phosphorylation states to investigate ZC3H14’s role, revealing its phosphorylation-dependent localization and function in speckle assembly.
• The result: Phosphorylation of ZC3H14 promotes proper splicing and embryo development, with mutants affecting fertility and early embryonic arrest, highlighting its importance in early mouse development.