Generation of Ppp2Ca and Ppp2Cb conditional null alleles in mouse

Abstract

Protein phosphatase 2A (PP2A) is one of the most abundant serine/threonine phosphatases, with a critical role in embryonic development and human disease. There are two isoforms of the catalytic subunit of PP2A, Ppp2ca and Ppp2cb. Null mutation of Ppp2ca leads to early embryonic lethality at E6.5, hindering functional study of PP2A beyond this stage. We generated conditional null alleles of Ppp2ca and Ppp2cb by flanking with loxP sites exons 3 to 5 of Ppp2ca and exon 3 of Ppp2cb. Ppp2ca(fl/fl) mice did not display any visible phenotype. Homozygous mutants in which Cre-mediated excision resulted in global deletion of Ppp2ca displayed embryonic lethality and developmental defects similar to those previously reported. Ppp2cb(Δ/Δ) mice generated by the same strategy did not display any obvious morphological or physiological defects. These mouse strains can serve as important genetic tools to study the roles of PP2A during development and disease in a spatial- or temporal-specific manner.

PP2A regulates kinetochore-microtubule attachment during meiosis I in oocyte

“…Previous studies have shown that Ppp2ca is expressed at a higher abundance than Ppp2cb in most human tissues 7 and the dominant functions of PP2Aca cannot be compensated by PP2Acb in embryonic development, the liver, or the heart. [8][9][10][11][12] From our data, a single knockout of Ppp2ca or Ppp2cb in oocytes resulted in normal fertility, revealing that each PP2Ac could support oocyte maturation by itself. We suspect that PP2Acb may exist as a backup regulator for PP2Aca to regulate cell division in both meiosis and mitosis, which can only be revealed when PP2Aca and PP2Acb are simultaneously depleted.…”

“…The PP2Aca-null zygote is embryonic lethal, whereas the PP2Acb-null mouse has no obvious abnormality. 10 The function of PP2Acb has never been demonstrated. Previous studies have shown that Ppp2ca is expressed at a higher abundance than Ppp2cb in most human tissues 7 and the dominant functions of PP2Aca cannot be compensated by PP2Acb in embryonic development, the liver, or the heart.…”

“…7 Tissue specific loss of Ppp2ca in the liver and heart causes severe physiological abnormalities, indicating that the functions of PP2Aca cannot be compensated by PP2Acb. [8][9][10][11][12] The PP2Acs are highly expressed in the ovary 7 and whether PP2Aca and PP2Acb are mutual independent in oocyte growth and maturation is unknown.…”

Phosphatase: PP2A structural importance, regulation and its aberrant expression in cancer

“…Thus, the loss of Ppp2ca results in the absence of mesodermal germ layer, indicating defect in embryo differentiation. Interestingly, Ppp2cb knockout mice model showed no abnormal phenotype [93]. Thus, the results from these knock-out mouse models indicated that while Ppp2ca is essential for the developmental process in the mouse, Ppp2cb is not.…”

Circumventing Embryonic Lethality with Lcmt1 Deficiency: Generation of Hypomorphic Lcmt1 Mice with Reduced Protein Phosphatase 2A Methyltransferase Expression and Defects in Insulin Signaling

“…PP2A exists in the cytosol primarily as a heterodimer consisting of a catalytic (C) and a scaffolding (A) subunit, to which a variety of targeting or regulatory (B) subunits associate, altering the specificity of the phosphatase [12], [13]. The complexity of PP2A composition arises from the enormity of distinct PP2A holoenzyme assemblies formed by proteins coded by the two similar yet non-redundant genes responsible for the catalytic subunit [14], [15], the two non-redundant genes coding for the scaffolding subunit [16], [17], and the four unrelated families of regulatory subunits encoded by multiple genes with a variety of splice variants giving rise to at least 23 different B subunits [10], [11], [18], [19], [20]. The vast array of subunits available for integration into PP2A holoenzymes are themselves regulated by spatial and temporal means as well as a strict regimen of posttranslational modifications [10], [21].…”