Fertyrosine kinase is required for germinal vesicle breakdown and meiosis‐I in mouse oocytes

Abstract

The control of microtubule and actin mediated events that direct the physical arrangement and separation of chromosomes during meiosis is critical since failure to maintain chromosome organization can lead to germ cell aneuploidy. Our previous studies demonstrated a role for FYN tyrosine kinase in chromosome and spindle organization and cortical polarity of the mature mammalian oocyte. In addition to Fyn, mammalian oocytes express the protein tyrosine kinase (PTK) Fer at high levels relative to other tissues and the objective of the present study was to determine the function of this kinase in the oocyte. FER kinase protein was uniformly distributed in the ooplasm of small oocytes but became concentrated in the germinal vesicle during oocyte growth. After germinal vesicle breakdown, FER associated with the MI and MII spindles. Suppression of Fer expression by siRNA knockdown in germinal vesicle stage oocytes did not prevent activation of CDK1 activity or chromosome condensation during in vitro maturation, but did arrest oocytes prior to germinal vesicle breakdown or during MI. The resultant phenotype displayed condensed chromosomes trapped in the germinal vesicle, or condensed chromosomes poorly arranged in a metaphase plate but with an underdeveloped spindle microtubule structure or chromosomes compacted into a tight sphere. The results demonstrate that, FER kinase plays a critical role in oocyte meiotic spindle microtubule dynamics and may have an additional function in germinal vesicle breakdown.

Protein tyrosine kinase signaling during oocyte maturation and fertilization

“…Later, analyses were performed on rat and mouse oocytes (Mehlmann et al, 1998; Talmor et al, 1998; Kurokawa et al, 2004; Meng et al, 2006) using both proteomic, and fluorescence microscopy methods based on the use of well‐defined antibodies. In general, the proteomic analyses of most species based on immunoblot techniques has supported the array‐based mRNA expression results presented in Figure 1, indicating that a subset of the SRC‐family, notably fyn and yes (Tsai et al, 2005), fer kinase (McGinnis et al, 2011), and fak kinase (Tsai et al, 2005) are expressed at very high levels in oocytes. These results indicate that the oocyte is highly specialized biochemically with a large commitment to signaling pathways involving the fyn , fer , and fak kinases.…”

“…The ABL family of PTKs shares close homology with the SRC‐family and is also expressed highly in oocytes at both the mRNA and protein level (Iwaoki et al, 1993; Moore and Kinsey, 1994). Other cytosolic PTKs include fer , which is very highly expressed in oocytes while the closely related fes is barely detectable (McGinnis et al, 2011). In addition to the cytosolic PTKs, oocytes are also known to express transcripts for a number of receptor tyrosine kinases such as IGF1r (Okamura et al, 2001) and c‐kit (receptor for steel factor) (Horie et al, 1991; Hutt et al, 2006a).…”

“…Data for the abl, src , yes , fyn , fer , and fak genes obtained from arrays representing oocytes, zygotes, ovary, and several additional tissues is presented. The relative transcript abundance (relative to average transcript abundance in each tissue) is presented along the horizontal axis (top) (relative expression levels calculated as previously reported (McGinnis et al, 2011)).…”

Phospho-Signaling at Oocyte Maturation and Fertilization: Set Up for Embryogenesis and Beyond Part I. Protein Kinases

“…It shows a uniform distribution in the ooplasm of small oocytes, but becomes concentrated in the germinal vesicle (GV) during oocyte growth. Association of FER with spindle bodies is seen after GV breakdown (GVBD), suggesting that it is involved in the control of cell cycle and/or chromosomal dynamics (McGinnis et al 2011b). In support with this, siRNA-mediated knockdown of FER causes the failure of the oocytes to undergo GVBD or during MI (McGinnis et al 2011b).…”

“…Association of FER with spindle bodies is seen after GV breakdown (GVBD), suggesting that it is involved in the control of cell cycle and/or chromosomal dynamics (McGinnis et al 2011b). In support with this, siRNA-mediated knockdown of FER causes the failure of the oocytes to undergo GVBD or during MI (McGinnis et al 2011b). While upstream and downstream mediators of FER regulation and functions have not yet been shown, other cell systems so far analyzed demonstrate that phospholipase D (PLD)-phosphatidic acid (PA) pathway is capable of stimulating FER activity ), and that TATA-element modulatory protein is a substrate of nuclear-localized FER (Schwartz et al 1998).…”