Characterization of ΔN-Zfp36l2 Mutant Associated with Arrest of Early Embryonic Development and Female Infertility

The zinc finger protein 36-like 2, Zfp36l2, has been implicated in female mouse infertility, because an amino-terminal truncation mutation (Delta N-Zfp36l2) leads to two-cell stage arrest of embryos derived from the homozygous mutant female gamete. Zfp36l2 is a member of the tristetraprolin (TTP) family of CCCH tandem zinc finger proteins that can bind to transcripts containing AU-rich elements ( ARE), resulting in deadenylation and destabilization of these transcripts. I show here that the mouse Zfp36l2 is composed of two exons and a single intron, encoding a polypeptide of 484 amino acids. I observed that Delta N-Zfp36l2 protein is similar to both wild-type Zfp36l2 and TTP (Zfp36) in that it shuttles between the cytoplasm and nucleus, binds to RNAs containing AREs, and promotes deadenylation of a model ARE transcript in a cell-based co-transfection assay. Surprisingly, in contrast to TTP, Zfp36l2 mRNA and protein were rapidly down-regulated upon LPS exposure in bone marrow-derived macrophages. The Delta N-Zfp36l2 protein was substantially more resistant to stimulus-induced down-regulation than the WT. I postulate that the embryonic arrest linked to the Delta N-Zfp36l2 truncation might be related to its resistance to stimulus-induced down-regulation.