Sectors expressing the homeobox gene liguleless3 implicate a time-dependent mechanism for cell fate acquisition along the proximal-distal axis of the maize leaf

The longitudinal axis of the maize leaf is composed of, in proximal to distal order, sheath, ligule, auricle and blade. The semidominant Liguleless3-O (Lg3-O) mutation disrupts leaf development at the ligular region of the leaf midrib by transforming blade to sheath. In a previous study, we showed that leaf sectors of Lg3 mutant activity are cell nonautonomous in the transverse dimension and can confer several alternative developmental fates (Fowler, Muehlbauer and Freeling (1996) Genetics 143, 489–503). In our present study we identify five Lg3 sector types in the leaf: sheath-like with displaced ligule (sheath-like), sheath-like with ectopic ligule (ectopic ligule), auricle-like, macro-hairless blade and wild-type blade. The acquisition of a specific sector fate depends on the timing of Lg3 expression. Early Lg3 expression results in adoption of the sheath-like phenotype at the ligule position (a proximal cell fate), whereas later Lg3 expression at the same position results in one of the more distal cell fates. Furthermore, sheath-like Lg3 sectors exhibit a graded continuum of phenotypes in the transformed blade region from the most proximal (sheath) to the most distal (wild-type blade), suggesting that cell fate acquisition is a gradual process. We propose a model for leaf cell fate acquisition based on a timing mechanism whereby cells of the leaf primordium progress through a maturation schedule of competency stages which eventually specify the cell types along the proximal to distal axis of the leaf. In addition, the lateral borders between Lg3 ‘on’ sectors and wild-type leaf sometimes provide evidence of no spreading of the transformed phenotype. In these cases, competency stages are inherited somatically.

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G protein regulation of phospholipase C activity in a membrane-solubilized system occurs through a Mg2(+)- and time-dependent mechanism.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)67715-x ◽

1991 ◽

Vol 266 (8) ◽

pp. 4764-4771

Author(s):

I Litosch

Keyword(s):

Phospholipase C ◽

G Protein ◽

Time Dependent ◽

Protein Regulation ◽

Dependent Mechanism

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Identifying targets of the rough homeobox gene of Drosophila: evidence that rhomboid functions in eye development

Development ◽

10.1242/dev.116.2.335 ◽

1992 ◽

Vol 116 (2) ◽

pp. 335-346 ◽

Cited By ~ 26

Author(s):

M. Freeman ◽

B.E. Kimmel ◽

G.M. Rubin

Keyword(s):

Cell Fate ◽

Target Genes ◽

Eye Development ◽

Expression Patterns ◽

Ectopic Expression ◽

Homeobox Gene ◽

Homeodomain Protein ◽

Dorsoventral Patterning ◽

Altered Expression ◽

Enhancer Trap Lines

In order to identify potential target genes of the rough homeodomain protein, which is known to specify some aspects of the R2/R5 photoreceptor subtype in the Drosophila eye, we have carried out a search for enhancer trap lines whose expression is rough-dependent. We crossed 101 enhancer traps that are expressed in the developing eye into a rough mutant background, and have identified seven lines that have altered expression patterns. One of these putative rough target genes is rhomboid, a gene known to be required for dorsoventral patterning and development of some of the nervous system in the embryo. We have examined the role of rhomboid in eye development and find that, while mutant clones have only a subtle phenotype, ectopic expression of the gene causes the non-neuronal mystery cells to be transformed into photoreceptors. We propose that rhomboid is a part of a partially redundant network of genes that specify photoreceptor cell fate.

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Suppression of GATA factor activity causes axis duplication in Xenopus

Development ◽

10.1242/dev.125.23.4595 ◽

1998 ◽

Vol 125 (23) ◽

pp. 4595-4605 ◽

Cited By ~ 4

Author(s):

T.G. Sykes ◽

A.R. Rodaway ◽

M.E. Walmsley ◽

R.K. Patient

Keyword(s):

Cell Fate ◽

Homeobox Gene ◽

Dominant Negative ◽

Gata Factor ◽

Dorsoventral Axis ◽

Morphogenetic Protein ◽

Head Formation ◽

Bmp Signalling ◽

Bmp Antagonist

In Xenopus, the dorsoventral axis is patterned by the interplay between active signalling in ventral territories, and secreted antagonists from Spemann's organiser. Two signals are important in ventral cells, bone morphogenetic protein-4 (BMP-4) and Wnt-8. BMP-4 plays a conserved role in patterning the vertebrate dorsoventral axis, whilst the precise role of Wnt-8 and its relationship with BMP-4, are still unclear. Here we have investigated the role played by the GATA family of transcription factors, which are expressed in ventral mesendoderm during gastrulation and are required for the differentiation of blood and endodermal tissues. Injection ventrally of a dominant-interfering GATA factor (called G2en) induced the formation of secondary axes that phenocopy those induced by the dominant-negative BMP receptor. However, unlike inhibiting BMP signalling, inhibiting GATA activity in the ectoderm does not lead to neuralisation. In addition, analysis of gene expression in G2en injected embryos reveals that at least one known target gene for BMP-4, the homeobox gene Vent-2, is unaffected. In contrast, the expression of Wnt-8 and the homeobox gene Vent-1 is suppressed by G2en, whilst the organiser-secreted BMP antagonist chordin becomes ectopically expressed. These data therefore suggest that GATA activity is essential for ventral cell fate and that subsets of ventralising and dorsalising genes require GATA activity for their expression and suppression, respectively. Finally, using G2en, we show that suppression of Wnt-8 expression, in conjunction with blocked BMP signalling, does not lead to head formation, suggesting that the head-suppressing Wnt signal may not be Wnt-8.

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Transcriptomic Analysis of Leaf Sheath Maturation in Maize

International Journal of Molecular Sciences ◽

10.3390/ijms20102472 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2472 ◽

Cited By ~ 2

Author(s):

Lei Dong ◽

Lei Qin ◽

Xiuru Dai ◽

Zehong Ding ◽

Ran Bi ◽

...

Keyword(s):

Leaf Blade ◽

Crop Yields ◽

Transcriptional Profiling ◽

Homeobox Gene ◽

Lignin Biosynthesis ◽

Gene Families ◽

Longitudinal Axis ◽

Leaf Sheath ◽

Morphological Development ◽

Maize Leaf

The morphological development of the leaf greatly influences plant architecture and crop yields. The maize leaf is composed of a leaf blade, ligule and sheath. Although extensive transcriptional profiling of the tissues along the longitudinal axis of the developing maize leaf blade has been conducted, little is known about the transcriptional dynamics in sheath tissues, which play important roles in supporting the leaf blade. Using a comprehensive transcriptome dataset, we demonstrated that the leaf sheath transcriptome dynamically changes during maturation, with the construction of basic cellular structures at the earliest stages of sheath maturation with a transition to cell wall biosynthesis and modifications. The transcriptome again changes with photosynthesis and lignin biosynthesis at the last stage of sheath tissue maturation. The different tissues of the maize leaf are highly specialized in their biological functions and we identified 15 genes expressed at significantly higher levels in the leaf sheath compared with their expression in the leaf blade, including the BOP2 homologs GRMZM2G026556 and GRMZM2G022606, DOGT1 (GRMZM2G403740) and transcription factors from the B3 domain, C2H2 zinc finger and homeobox gene families, implicating these genes in sheath maturation and organ specialization.

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The Role of Prep1 in the Regulation of Mesenchymal Stromal Cells

International Journal of Molecular Sciences ◽

10.3390/ijms20153639 ◽

2019 ◽

Vol 20 (15) ◽

pp. 3639 ◽

Cited By ~ 1

Author(s):

Giorgia Maroni ◽

Daniele Panetta ◽

Raffaele Luongo ◽

Indira Krishnan ◽

Federica La Rosa ◽

...

Keyword(s):

Bone Marrow ◽

Cell Fate ◽

Mesenchymal Stromal Cells ◽

Stromal Cells ◽

Molecular Mechanisms ◽

Gene Dosage ◽

Homeobox Gene ◽

Fate Decision

Molecular mechanisms governing cell fate decision events in bone marrow mesenchymal stromal cells (MSC) are still poorly understood. Herein, we investigated the homeobox gene Prep1 as a candidate regulatory molecule, by adopting Prep1 hypomorphic mice as a model to investigate the effects of Prep1 downregulation, using in vitro and in vivo assays, including the innovative single cell RNA sequencing technology. Taken together, our findings indicate that low levels of Prep1 are associated to enhanced adipogenesis and a concomitant reduced osteogenesis in the bone marrow, suggesting Prep1 as a potential regulator of the adipo-osteogenic differentiation of mesenchymal stromal cells. Furthermore, our data suggest that in vivo decreased Prep1 gene dosage favors a pro-adipogenic phenotype and induces a “browning” effect in all fat tissues.

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