NEGF2/midkine is a member of a highly conserved, developmentally regulated human gene family. The gene product exhibits
neurite outgrowth-promoting activity and may play a role in nervous system development and/or maintenance.
General function
Ligand, Growth factor
Comment
Cellular localization
Secreted
Comment
Ovarian function
Follicle atresia, Oogenesis, Oocyte maturation, Early embryo development
Comment
Midkine and cytoplasmic maturation of mammalian oocytes in the context of ovarian follicle physiology. Ikeda S 2013 et al.
Midkine (MK) was originally characterized as a member of a distinct family of neurotrophic factors functioning in the central nervous system; however, the abundant expression of MK in ovarian follicles was later discovered. Since then, the physiological roles of this molecule in the ovary have been steadily investigated. MK during the in vitro maturation (IVM) of oocytes was shown to promote the cytoplasmic maturation of oocytes, as indicated by post-fertilization development, and the promoting effects of MK were suggested to be mediated via its pro-survival (anti-apoptotic) effects on cumulus-granulosa cells surrounding oocytes. The oocyte competence-promoting effects of MK can be discussed in the context of the recently discovered MK involvement in the full maturation of ovarian follicles. MK was at the vanguard of a new paradigm for neurotrophic factors as oocytetrophic factors. MK may promote the developmental competence of oocytes via common signalling molecules with the other neurotrophic factor(s). Alternatively or concomitantly, MK may also interact with various transmembrane molecules on cumulus-granulosa cells, which are important for ovarian follicle growth, dominance, and differentiation, and act as a unique pro-survival factor in ovarian follicles, such that MK promotes oocyte competence. MK along with other ovarian neurotrophic factors may contribute to optimizing the IVM system.
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Ikeda et al 2000 reported the effects of Midkine During In Vitro Maturation of Bovine Oocytes on Subsequent Developmental Competence.
Midkine (MK) is known to be a member of a new family of heparin-binding growth/differentiation factors, together with
pleiotrophin, and to be quite rich in bovine follicular fluid. To examine whether treatment with MK during in vitro maturation
(IVM) of bovine granulosa-enclosed oocytes affects their nuclear maturation and postfertilization development to the
blastocyst stage, bovine granulosa-enclosed oocytes obtained from slaughterhouse-derived ovaries were cultured for 24 h in
IVM medium without (control) or with various concentrations (1-500 ng/ml) of MK, followed by in vitro fertilization (IVF)
and culturing. The results indicate that the presence of MK during IVM of bovine granulosa-enclosed oocytes can
enhance their developmental competence to the blastocyst stage after IVF and suggest that the enhancing effects might be
mainly mediated by GCs.
Abilities of cumulus and granulosa cells to enhance the developmental competence of bovine oocytes during in vitro maturation period are promoted by midkine; a possible implication of its apoptosis suppressing effects. Ikeda S et al. We previously reported that when midkine (MK), a heparin-binding growth differentiation factor was used in in vitro maturation (IVM) culture of bovine cumulus-enclosed oocytes (CEOs), their developmental competence to the blastocyst stage after in vitro fertilization (IVF) was enhanced and the effect of MK might be mediated by its action upon mural granulosa cells and cumulus cells that closely surround the oocyte. In the present study, when denuded oocytes (DOs) were matured in IVM medium with or without MK (200 ng/ml) in the presence or absence of isolated cumulus cell masses and subjected to IVF, the enhancing effects of MK on the developmental competence of DOs to the blastocyst stage after IVF were exerted only in the presence of cumulus cells. In addition, we prepared the conditioned media of granulosa cells cultured with or without 200 ng MK/ml (CMMK+ or CMMK- respectively) and examined their effects on the IVM of DOs in terms of their developmental competence to the blastocyst stage after IVF. The supplementation of CMMK+ into IVM medium at 40% (v/v) significantly enhanced the blastocyst development compared with the no additive control and the CMMK- supplemented groups. Furthermore, the effects of MK during IVM of bovine CEOs on the cumulus cell apoptosis were investigated. CEOs were cultured up to 24 h in IVM medium without (control) or with 200 ng MK/ml. The genomic DNA was extracted from CEOs at 0, 6, 12, 18 and 24 h of IVM and subjected to ligation-mediated PCR (LM-PCR) to detect the apoptotic internucleosomal DNA fragmentation. DNA fragmentation was scarcely detected at the start of IVM, whereas it increased time-dependently as the IVM culture progressed. The degree of the fragmentation was significantly lower in the MK-treatment group compared with the control group at 18 and 24 h of IVM. The apoptosis-suppressing effect of MK on cumulus cells was further confirmed in situ by using TUNEL on CEOs. In conclusion, data from the present study further confirmed that MK enhances the developmental competence of bovine oocytes via cumulus and granulosa cells. It was also demonstrated that MK suppresses the apoptosis that occurs in cumulus cells during the period of IVM of bovine CEOs. The putative soluble factor(s) from cumulus cells was suggested from the experiment using CMMK+ . MK may promote the production of such factors in part by its anti-apoptotic effects on cumulus cells.
Expression regulated by
Comment
Ovarian localization
Granulosa, Theca, Follicular Fluid
Comment
Ohyama Y, et al 2000 reported the isolation and identification of midkine and pleiotrophin in bovine follicular fluid.
Two distinct
heparin-binding polypeptides were isolated from bovine follicular fluid by successive
chromatographies. N-Terminal and tryptic peptide fragment analysis of these polypeptides revealed
that they are identical to midkine (MK) and pleiotrophin (PTN), respectively, which form a new
family of heparin-binding growth/differentiation factors.
Nakanishi T, et al 1997 reported the expression of midkine gene was observed
in 19 of 23 normal ovary samples and in 51 of 53 ovarian tumors (13 of 15
benign, both of the two borderline tumors, and all 36 malignant tumors).
The presence of midkine and its possible implication in human ovarian follicles. Hirota Y et al. Problem Ovarian follicles undergo a dynamic change to provide a mature ovum, and the process involves angiogenesis, follicular cell proliferation and leukocyte recruitment. Midkine (MK) is a heparin-binding growth factor that has angiogenic, mitogenic, and chemotactic activities. In the present study, we investigated the presence of MK and its possible role in human ovarian follicles. Method of study Follicular fluid (FF) and luteinized granulosa cells (LGC) were collected from women undergoing in vitro fertilization and embryo transfer. Expression of MK protein in FF was examined by Western blotting. Concentrations of MK, estradiol and oxygen in FF were measured. 5-bromo-2'-deoxyuridine (BrdU) incorporation assay was performed in LGC. Normal ovarian tissues were obtained surgically and used in in-situ hybridization of MK mRNA. Results The presence of MK protein was verified in FF. MK mRNA was expressed in both granulosa cells and theca cells of large follicles. There is a significant negative correlation between the concentrations of MK and oxygen in FF, and a significant positive correlation between the concentrations of MK and estradiol. MK promoted BrdU uptake in LGC. Conclusion The present findings imply that hypoxic condition, a characteristic of growing follicles, associates with the production of MK. Given that MK is involved in granulosa cell proliferation and estradiol production in developing follicles, MK may play a role as a local regulator in the human ovary.
Follicle stages
Antral
Comment
Regulation of midkine messenger ribonucleic acid levels in cultured rat granulosa cellsMinegishi T, et al 1996 .
To investigate the regulation of ovarian midkine (MK) production at the mRNA level, we evaluated changes in MK mRNA in cultured granulosa cells. The level of MK mRNA increased in a time-dependent manner in the presence of FSH or retinoic acid (RA). FSH increased MK mRNA levels in a dose-dependent manner to a maximum of about 2-fold increase. The stimulatory effects of FSH were mimicked by 8-Br-cAMP. RA increased MK mRNA levels in a dose dependent manner to a maximum of about 2 fold increase at a concentration of 0.3 microM. These results show that granulosa cells produce MK mRNA under the independent control of FSH and RA. The coexistence of FSH and RA in this culture exerted no additive effect on the induction of MK mRNA. Analysis of FSH receptor mRNA induction by both reagents revealed that FSH stimulated expression of the FSH receptor while RA had an inhibitory effect on FSH receptor induction regardless of the presence of FSH. These data show that RA increases MK mRNA, and decreases FSH receptor expression, by a pathway independent of cAMP.
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: subfertile Comment: Female infertility in mice deficient in midkine and pleiotrophin, which form a distinct family of growth factors. Muramatsu H et al. Midkine and pleiotrophin form a family of growth factors. Mice deficient in one of the genes show few abnormalities on reproduction and development. To understand their roles in these processes, we produced mice deficient in both genes; the double deficient mice were born in only one third the number expected by Mendelian segregation and 4 weeks after birth weighed about half as much as wild-type mice. Most of the female double deficient mice were infertile. In these mice, the numbers of mature follicles and of ova at ovulation were reduced compared to numbers in wild-type mice. Both midkine and pleiotrophin were expressed in the follicular epithelium and granulosa cells of the ovary. The expression of these factors in the uterus was dramatically altered during the estrous cycle. The diestrus and proestrus periods were long and the estrus period was short in the double deficient mice, indicating the role of the factors in the estrous cycle. Furthermore, vaginal abnormality was found in about half of the double deficient mice. These abnormalities in combination resulted in female infertility. Therefore, midkine and pleiotrophin, together with their signaling receptors, play important roles in the female reproductive system.