Disruption of the mouse protein Ser/Thr phosphatase 2Cβ gene leads to early pre-implantation lethality

Abstract

Protein phosphatase 2Cbeta (PP2Cbeta) is a member of a family of protein Ser/Thr phosphatases (PP2C) that is composed of at least twelve different gene products. Recent studies have revealed that PP2Cbeta mRNA accumulates in mature sperm, unfertilized metaphase II-arrested oocytes and zygotes, but that the mRNA level then decreases sharply between the early two-cell and eight-cell stages, remaining at low levels during the 16-cell to blastocyst stages of mice. These observations raised the possibility that PP2Cbeta plays a crucial role during gametogenesis, fertilization, and/or early stages of embryonic development. In this study, we employed a gene knockout technique in mice to test this possibility. We found that PP2Cbeta(Delta/wt) mice generate normal mature gametes. However, PP2Cbeta(Delta/Delta) embryos die between the two-cell and eight-cell stages. To our interest, PP2Cbeta(Delta/Delta) ES cells which had been generated by transfecting PP2Cbeta(3lox/3lox) ES cells with Cre-expressing plasmid were viable. In addition, knockdown of PP2Cbeta using siRNA did not affect the proliferation of wild-type ES cells. These observations suggest that relatively high PP2Cbeta expression is specifically required during the early stages of pre-implantation development. The possible mechanisms for the early pre-implantation lethality of PP2Cbeta(Delta/Delta) mice are discussed.

Ppm1b negatively regulates necroptosis through dephosphorylating Rip3

“…As Ppm1b KO mouse is pre-implantation lethal 31 , we generated a Ppm1b gene-trap mouse line ( Ppm1b +/d ) using embryonic stem cells containing a retroviral gene trap in the second intron of the Ppm1b locus (Fig. 4f).…”

“…It was shown that gene deletion of Ppm1b led to early pre-implantation lethality in mice 31 . Although Rip3 knockout can rescue spontaneous necroptosis in Ppm1b knockdown cells, Rip3 KO cannot rescue the lethality of Ppm1b gene deletion.…”

De novo synthesis of protein phosphatase 1A, magnesium dependent, alpha isoform (PPM1A) during oocyte maturation

“…Since PPM1A protein levels were suggested to be a key factor for its activation [11,15], we speculate that accumulation of PPM1A has an essential role in regulating post-translation modification processes during oogenesis. Moreover, the fact that PPM1B was found to be elevated during early stages of pre-implantation in embryonic development, and knockout of PPM1B led to embryonic lethality, indicates the important role of the PPM1 family in mouse embryonic development [30]. Though a growing mouse oocyte, arrested at diplotene of the first meiotic prophase, is transcriptionally and translationally active, a large number of synthesized mRNAs are not used for immediate translation but instead are stored to support oocyte maturation and early pre-implantation embryogenesis [31].…”

Deletion of C2orf34, PREPL and SLC3A1 causes atypical hypotonia-cystinuria syndrome

“…It is, however, not clear what the endogenous substrates for PP2Cβ are. In mouse, PP2Cβ has essential functions in early development, as a PPM1B knock-out mouse model shows an early pre-implantation lethality 20. Most likely, redundancy of family members of PPM1B rescues the early lethality in human.…”