New member of the Snf1/AMPK kinase family,Melk, is expressed in the mouse egg and preimplantation embryo

Abstract

The initial phase of mammalian preimplantation development is directed by stored maternal mRNAs and their encoded proteins, yet most of the molecules controlling this process have not been described. We have used differential display analysis of cDNA libraries prepared from unfertilized eggs and preimplantation embryos to isolate three maternal cDNAs that represent novel genes exhibiting different patterns of expression during this developmental period. One of these, Melk, encodes a protein with a kinase catalytic domain and a leucine zipper motif, a new member of the Snf1/AMPK family of kinases. This gene product may play a role in the signal transduction events in the egg and early embryo. Mol. Reprod. Dev. 47:148–156, 1997. © 1997 Wiley‐Liss, Inc.

Melk-Like Kinase Plays a Role in Hematopoiesis in the Zebra Fish

“…The full-length DD29 turned out to be identical with the previously reported gene Melk (19), which is a member of the sucrose nonfermenting protein kinase (SNF1)/AMPK serine/threonine kinase family (16). Melk was originally identified by differential display to isolate maternal cDNA from unfertilized eggs and preimplantation embryos (19). The expression pattern of Melk during the maturation of oocytes and preimplantation development was typical of that described for maternally expressed genes, including ␤-actin and E-cadherin (19).…”

“…The clone described in this work, DD29, is unique, since it encodes a protein kinase having a zinc finger domain. The full-length DD29 turned out to be identical with the previously reported gene Melk (19), which is a member of the sucrose nonfermenting protein kinase (SNF1)/AMPK serine/threonine kinase family (16). Melk was originally identified by differential display to isolate maternal cDNA from unfertilized eggs and preimplantation embryos (19).…”

“…By differential display using mouse neural tissues, we cloned a serine/threonine kinase, Melk, as a gene expressed in mouse embryonic neural tissues. mMelk was originally cloned in oocytes as a maternal gene, but whose function was unknown (12,19). To examine its functions using zebra fish (Danio rerio) as a model system, we then searched an adult zebra fish EST database (GenBank, National Center for Biotechnology Information) for sequences homologous with the mMelk sequence.…”

“…The catalytic domain consisted of 12 subdomains typical of serine/threonine kinase, and this region was highly conserved among mMelk, the zMelk-like gene, Eg3, and hMelk. A leucine zipper motif consisting of a periodic repetition of leucine every seventh residue was found within subdomain VIII of the catalytic domain of mMelk and hMelk, but only an incomplete leucine zipper was found in the zMelklike gene and in Eg3 (19). In the mMelk and zMelk-like kinases, there was a conserved threonine residue (Thr-167 in mMelk and Thr-169 in the zMelk-like gene) within kinase subdomain VIII.…”

The changing AMPK expression profile in differentiating mouse skeletal muscle myoblast cells helps confer increasing resistance to apoptosis

“…However, we only detected the p50 and not the p72 isoform of MELK, which may reflect an alternative MELK translation product as suggested by Gil et al (1997). That MELK is only expressed in the undifferentiated, proliferating C2C12 myoblasts could imply that it has a role in promoting proliferation while inhibiting differentiation programmes, as in other cells (Heyer et al 1997; Gil et al 1998; Davezac et al 2002; Nakano et al 2005). For example, MELK plays an important role in preimplantation embryonic development (Suzuki et al 2003 b ).…”