Cell cycle regulation during mammalian female meiosis: Characterization of the MASTL-ENSA/ARPP19 pathway in mouse oocytes

meiosis;meiotic maturation;oocyte;alpha-endosulfine;ENSA;Greatwall;MASTL;ARPP19;PP2A;not listed

Matthews, Lauren MScott, Alan ;

Johns Hopkins University

关键词: meiosis;    meiotic maturation;    oocyte;    alpha-endosulfine;    ENSA;    Greatwall;    MASTL;    ARPP19;    PP2A;    not listed;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60311/MATTHEWS-DISSERTATION-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Mammalian oocytes undergo two successive rounds of division without an intervening S-phase to form a haploid gamete. Oocytes are arrested in prophase I in the ovary until the time of ovulation when the oocyte exits from this arrest and progresses through meiosis I. The egg then arrests at metaphase of meiosis II until fertilization when the second meiotic division is completed. The progression from prophase I to metaphase II, known as meiotic maturation, must be carefully regulated in order to successfully form a haploid gamete. The MASTL-ENSA/ARPP19 pathway has emerged as an important regulator of M-phase entry and progression. The kinase, MASTL (microtubule- associated serine/threonine kinase-like), phosphorylates its two substrates, ENSA (alpha-endosulfine) and ARPP19 (cAMP-regulated phosphoprotein-19), which can then inhibit the activity of the protein phosphatase PP2A. Inhibition of PP2A maintains the phosphorylated state of CDK1 substrates, thus allowing progression into and/or maintenance of an M-phase state. The work in this thesis characterizes the MASTL- ENSA/ARPP19 pathway during meiotic maturation in mouse oocytes. ENSA is an abundant protein in mouse oocytes and was expressed by prophase I oocytes, metaphase II eggs and early embryos. ARPP19 was not detected in lysates of prophase I oocytes or early embryos, but was detected in lysates of metaphase II eggs. The kinase, MASTL, and its substrate, ENSA, both play a key role in the progression from prophase I arrest into M-phase of meiosis I. The majority of MASTL-deficient and ENSA-deficient oocytes failed to exit from prophase I arrest. This function of ENSA in oocytes is dependent on PP2A, and specifically on the regulatory subunit PPP2R2D (also known as B55δ). Treatment of ENSA-deficient oocytes with okadaic acid to inhibit PP2A or knockdown of the PPP2R2D subunit rescued the meiotic progression defect, with these oocytes being able to exit from prophase I arrest. These data are evidence of a role for MASTL and ENSA in regulating meiotic maturation in mammalian oocytes and have important implications for our understanding of the molecular regulation of mammalian female meiosis.