Crucial Role for Mst1 and Mst2 Kinases in Early Embryonic Development of the Mouse

ABSTRACT Mammalian sterile 20-like kinases 1 and 2 (Mst1 and Mst2, respectively) are potent serine/threonine kinases that are involved in cell proliferation and cell death. To investigate the physiological functions of Mst1 and Mst2, we generated Mst1 and Mst2 mutant mice. Mst1 −/− and Mst2 −/− mice were viable and fertile and developed normally, suggesting possible functional overlaps between the two genes. A characterization of heterozygous and homozygous combinations of Mst1 and Mst2 mutant mice showed that mice containing a single copy of either gene underwent normal organ development; however, Mst1 −/−; Mst2 −/− mice lacking both Mst1 and Mst2 genes started dying in utero at approximately embryonic day 8.5. Mst1 −/−; Mst2 −/− mice exhibited severe growth retardation, failed placental development, impaired yolk sac/embryo vascular patterning and primitive hematopoiesis, increased apoptosis in placentas and embryos, and disorganized proliferating cells in the embryo proper. These findings indicate that both Mst1 and Mst2 kinases play essential roles in early mouse development, regulating placental development, vascular patterning, primitive hematopoiesis, and cell proliferation and survival.

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Molecular characterization of hNRP, a cDNA encoding a human nucleosome-assembly-protein-I-related gene product involved in the induction of cell proliferation

Biochemical Journal ◽

10.1042/bj2970389 ◽

1994 ◽

Vol 297 (2) ◽

pp. 389-397 ◽

Cited By ~ 59

Author(s):

H U Simon ◽

G B Mills ◽

M Kozlowski ◽

D Hogg ◽

D Branch ◽

...

Keyword(s):

Cell Proliferation ◽

Amino Acid ◽

Gene Product ◽

Thymidine Incorporation ◽

Structural Features ◽

Nucleosome Assembly ◽

Proliferating Cells ◽

Amino Acid Similarity ◽

Nucleosome Assembly Protein

We have isolated from a human thymus cDNA library a cDNA clone encoding a potential protein with 54% amino acid similarity to that encoded by a previously identified cDNA for yeast nucleosome assembly protein I (NAP-I). The deduced amino acid sequence for this newly identified cDNA, designated hNRP (human NAP-related protein), contains a potential seven-residue nuclear localization motif, three clusters of highly acidic residues and other structural features found in various proteins implicated in chromatin formation. When expressed as a fusion protein in Escherichia coli, hNRP reacted specifically with a monoclonal antibody raised against human NAP-I. The hNRP transcript was detected in all tissues and cell lines studied, but levels were somewhat increased in rapidly proliferating cells. Moreover, levels of both hNRP mRNA and protein increased rapidly in cultured T-lymphocytes induced to proliferate by incubation with phorbol ester and ionomycin. Phorbol 12-myristate 13-acetate/ionomycin-induced increases in both hNRP mRNA and mitogenesis, as measured by thymidine incorporation, were markedly inhibited, however, in cells treated with an hNRP antisense oligonucleotide. These results demonstrate a correlation between induction of hNRP expression and mitogenesis and taken together with the structural similarities between hNRP and yeast NAP-I suggest that the hNRP gene product participates in DNA replication and thereby plays an important role in the process of cell proliferation.

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Placental development during early pregnancy in sheep: cell proliferation, global methylation, and angiogenesis in the fetal placenta

Reproduction ◽

10.1530/rep-10-0505 ◽

2011 ◽

Vol 141 (4) ◽

pp. 529-540 ◽

Cited By ~ 42

Author(s):

Anna T Grazul-Bilska ◽

Mary Lynn Johnson ◽

Pawel P Borowicz ◽

Megan Minten ◽

Jerzy J Bilski ◽

...

Keyword(s):

Cell Proliferation ◽

Growth Factor ◽

Mrna Expression ◽

Early Pregnancy ◽

Cellular Proliferation ◽

Dna Methyltransferases ◽

Placental Development ◽

Proliferating Cells ◽

Global Methylation ◽

Endothelial Nitric Oxide

To characterize early fetal placental development, gravid uterine tissues were collected from pregnant ewes every other day from day 16 to 30 after mating. Determination of 1) cell proliferation was based on Ki67 protein immunodetection; 2) global methylation was based on 5-methyl-cytosine (5mC) expression and mRNA expression for DNA methyltransferases (DNMTs)1,3a, and3b; and 3) vascular development was based on smooth muscle cell actin immunolocalization and on mRNA expression of several factors involved in the regulation of angiogenesis in fetal membranes (FMs). Throughout early pregnancy, the labeling index (proportion of proliferating cells) was very high (21%) and did not change. Expression of 5mC and mRNA forDNMT3bdecreased, but mRNA forDNMT1and3aincreased. Blood vessels were detected in FM on days 18–30 of pregnancy, and their number per tissue area did not change. The patterns of mRNA expression for placental growth factor, vascular endothelial growth factor, and their receptorsFLT1andKDR; angiopoietins 1 and 2 and their receptorTEK; endothelial nitric oxide synthase and the NO receptorGUCY13B; and hypoxia inducing factor 1 α changed in FM during early pregnancy. These data demonstrate high cellular proliferation rates, and changes in global methylation and mRNA expression of factors involved in the regulation of DNA methylation and angiogenesis in FM during early pregnancy. This description of cellular and molecular changes in FM during early pregnancy will provide the foundation for determining the basis of altered placental development in pregnancies compromised by environmental, genetic, or other factors.

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Characterization of Mouse Rsk4 as an Inhibitor of Fibroblast Growth Factor-RAS-Extracellular Signal-Regulated Kinase Signaling

Molecular and Cellular Biology ◽

10.1128/mcb.24.10.4255-4266.2004 ◽

2004 ◽

Vol 24 (10) ◽

pp. 4255-4266 ◽

Cited By ~ 37

Author(s):

Andrea Pomrehn Myers ◽

Laura B. Corson ◽

Janet Rossant ◽

Julie C. Baker

Keyword(s):

Transcriptional Activation ◽

Signal Transduction Pathway ◽

Mouse Development ◽

S6 Kinase ◽

Extracellular Signal Regulated Kinase ◽

Rtk Signaling ◽

Extracellular Signal ◽

Ribosomal S6 Kinase ◽

Early Mouse

ABSTRACT Receptor tyrosine kinase (RTK) signals regulate the specification of a varied array of tissue types by utilizing distinct modules of proteins to elicit diverse effects. The RSK proteins are part of the RTK signal transduction pathway and are thought to relay these signals by acting downstream of extracellular signal-regulated kinase (ERK). In this study we report the identification of ribosomal S6 kinase 4 (Rsk4) as an inhibitor of RTK signals. Among the RSK proteins, RTK inhibition is specific to RSK4 and, in accordance, is dependent upon a region of the RSK4 protein that is divergent from other RSK family members. We demonstrate that Rsk4 inhibits the transcriptional activation of specific targets of RTK signaling as well as the activation of ERK. Developmentally, Rsk4 is expressed in extraembryonic tissue, where RTK signals are known to have critical roles. Further examination of Rsk4 expression in the extraembryonic tissues demonstrates that its expression is inversely correlated with the presence of activated ERK 1/2. These studies demonstrate a new and divergent function for RSK4 and support a role for RSK proteins in the specification of RTK signals during early mouse development.

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