Regulation of GATA gene expression during vertebrate development

GATA factors regulate critical events in hematopoietic lineages (GATA-1/2/3), the heart and gut (GATA-4/5/6) and various other tissues. Transgenic approaches have revealed that GATA genes are regulated in a modular fashion by sets of enhancers that govern distinct temporal and/or spatial facets of the overall expression patterns. Efforts are underway to resolve how these GATA gene enhancers are themselves regulated in order to elucidate the genetic and molecular hierarchies that govern GATA expression in particular developmental contexts. These enhancers also afford a raft of tools that can be used to selectively perturb and probe various developmental events in transgenic animals.     

FACS-array gene expression analysis during early development of mouse telencephalic interneurons

Cortical interneuron dysfunction has been implicated in multiple human disorders including forms of epilepsy, mental retardation, and autism. Although significant advances have been made, understanding the biologic basis of these disorders will require a level of anatomic, molecular, and genetic detail of interneuron development that currently does not exist. To further delineate the pathways modulating interneuron development we performed fluorescent activated cell sorting (FACs) on genetically engineered mouse embryos that selectively express green fluorescent protein (GFP) in developing interneurons followed by whole genome microarray expression profiling on the isolated cells. Bioinformatics analysis revealed expression of both predicted and unexpected genes in developing cortical interneurons. Two unanticipated pathways discovered to be up regulated prior to interneurons differentiating in the cortex were ion channels/neurotransmitters and synaptic/vesicular related genes. A significant association of neurological disease related genes to the population of developing interneurons was found. These results have defined new and potentially important data on gene expression changes during the development of cortical interneurons. In addition, these data can be mined to uncover numerous novel genes involved in the generation of interneurons and may suggest genes/pathways potentially involved in a number of human neurological disorders.     

N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase expression during early mouse embryonic development

N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) is an enzyme which is known to help build up the GlcAbeta1-3GalNAc(4,6-bisSO4) unit of chondroitin sulfate E (CS-E). This enzymatic activity has been reported in squid cartilage and in human serum, but has never been reported as an enzyme required during early mouse development. On the other hand, CS-E has been shown to bind with strong affinity to Midkine (MK). The latter is a heparin-binding growth factor which has been found to play important regulatory roles in differentiation and morphogenesis during mouse embryonic development. We have analyzed the expression pattern of the GalNAc4S-6ST gene during early mouse embryonic development by whole mount in situ hybridization. The results show that GalNAc4S-6ST is differentially expressed in the anterior visceral ectoderm at stage E5.5 and later becomes restricted to the embryonic endoderm, especially in the prospective midgut region. During the turning process, expression of GalNAc4S-6ST gene is detected in the forebrain, branchial arches, across the gut tube (hindgut, midgut and foregut diverticulum), in the vitelline veins and artery and in the splanchnopleure layer. These results open the possibility of a role for GalNAc4S-6ST during early mouse development.     

Expression of the T-box gene Eomesodermin during early mouse development.

We report the expression pattern of a murine homolog of the Xenopus laevis T-box gene Eomesodermin. mEomes expression is first detected in the extra-embryonic ectoderm prior to gastrulation, and persists there until head-fold stages. In the embryo proper, mEomes is expressed throughout the early primitive streak, nascent mesoderm and in the anterior visceral endoderm. Although mEomes expression disappears from the embryo at late-streak stages, a second domain of mEomes expression is observed in the telencephalon beginning around E10.5.     

Molecular cloning of the mouse CCK gene: expression in different brain regions and during cortical development.

In this paper we describe experiments that address specific issues concerning the regulation of the mouse cholecystokinin gene in brain and intestine. The mouse cholecystokinin gene was cloned and sequenced. Extensive homology among the mouse, man and rat genes was noted particularly in the three exons and the regions upstream of the RNA start site. RNAse protection assays for each of the three exons were used to demonstrate that CCK is expressed in only a subset of tissues and that the same cap site and splice choices are used in brain, intestine as well as in cerebellum, cortex, midbrain, hypothalamus and hippocampus. CCK RNA was also noted to be detectable in kidney. Thus the same gene using the same promoter is expressed in subsets of cells that differ in their biochemical, morphologic and functional characteristics. The level of expression of CCK was also monitored during mouse cortical development and the appearance of CCK RNA was compared to glutamate decarboxylase (GAD), enkephalin and somatostatin. It was noted that each of these cortical markers was first expressed at different times during cortical development. The appearance of CCK RNA during intestinal development was also measured and found to precede appearance in cortex by several days.     

Integrin expression patterns during early limb muscle development in the mouse

Cell-extracellular matrix interactions play crucial roles in limb muscle development but practically nothing is known on what integrins are involved before the differentiation of muscle precursor cells (MPCs) in the limb muscle masses. In this study we determine the expression patterns of integrins during early forelimb muscle development in the mouse. alpha6beta1 integrin is downregulated in the lateral dermomyotome when delamination of MPCs occurs. In late E9.5 embryos, alpha1beta1 and alpha5beta1 are expressed in a pattern very similar to pax3, which marks MPCs migrating to the limb bud. After myf5 upregulation in the limb bud, alpha1beta1 and alpha5beta1 expression is maintained and the alpha4beta1 integrin starts being expressed.     

Integrin expression patterns during early limb muscle development in the mouse

Cell-extracellular matrix interactions play crucial roles in limb muscle development but practically nothing is known on what integrins are involved before the differentiation of muscle precursor cells (MPCs) in the limb muscle masses. In this study we determine the expression patterns of integrins during early forelimb muscle development in the mouse. alpha6beta1 integrin is downregulated in the lateral dermomyotome when delamination of MPCs occurs. In late E9.5 embryos, alpha1beta1 and alpha5beta1 are expressed in a pattern very similar to pax3, which marks MPCs migrating to the limb bud. After myf5 upregulation in the limb bud, alpha1beta1 and alpha5beta1 expression is maintained and the alpha4beta1 integrin starts being expressed.     

Differential gene expression during early murine yolk sac development

The visceral yolk sac (VYS), composed of extraembryonic mesoderm and visceral endoderm, is the initial site of blood cell development and serves important nutritive and absorptive functions. In the mouse, the visceral endoderm becomes a morphologically distinct tissue at the time of implantation (E4.5), while the extraembryonic mesoderm arises during gastrulation (E6.5–8.5). To isolate genes differentially expressed in the developing yolk sac, polymerase chain reaction (PCR) methods were used to construct cDNA from late primitive streak to neural plate stage (E7.5) murine VYS mesoderm and VYS endoderm tissues. Differential screening led to the identification of six VYS mesoderm-enriched clones: ribosomal protein L13a, the heat shock proteins hsc 70 and hsp 86, guanine-nucleotide binding protein-related gene, cellular nucleic acid binding protein, and ã-enolase. One VYS endoderm-specific cDNA was identified as apolipoprotein C2. In situ hybridization studies confirmed the differential expression of these genes in E7.5 yolk sac tissues. These results indicate that representative cDNA populations can be obtained from small numbers of cells and that PCR methodologies permit the study of gene expression during early mammalian postimplantation development. While all of the mesoderm-enriched genes were ubiquitously expressed in the embryo proper, apolipoprotein C2 expression was confined to the visceral endoderm. These results are consistent with the hypothesis that at E7.5, the yolk sac endoderm provides differentiated liver-like functions, while the newly developing extraembryonic mesoderm is still a largely undifferentiated tissue. © 1995 wiley-Liss, Inc.