Mesenchyme Homeobox Research Articles

PLD.24 Gene expression profiling of human decidua during term labour: inflammation as a key driver of labour

BackgroundThere is accumulating evidence that sterile inflammation is a driver of labour in myometrium and cervix; however the involvement of the decidua is poorly defined. Our previous studies report decidual...

A novel role of Meox1 in regulating TGFβ‐induced smooth muscle cell differentiation (866.3)

Mesenchyme homeobox 1 (MEOX1) is expressed in the early developing somite and derivatives during embryogenesis. Somite has been shown to be one of the origins or progenitors for SMC. Therefore, in this study, we studied the role of MEOX1 in SMC differentiation. Smooth muscle cell (SMC) differentiation is an important process during vasculogenesis and angiogenesis. It is well known that alterations of VSMC phenotype play a role in the progression of several cardiovascular disorders including atherosclerosis, hypertension, and restenosis. However, the molecular mechanisms controlling the differentiation and development of VSMC are largely unknown. We found that transforming growth factor‐β (TGF‐β) induces MEOX1 expression in the initial phase of SMC differentiation of pluripotent mesenchymal C3H10T1/2 cells. MEOX1 expression appears to be mediated by both PI3 kinase and Smad3 signaling pathways because blockade of these two pathways by specific inhibitors leads to a decreased expression of MEOX1 and SMC markers. Importantly, knockdown of MEOX1 by specific shRNA suppresses TGF‐β‐induced expression of SMC early markers including SM22α and calponin. MEOX1 overexpression, on the other hand, increases SMC marker expression. These results indicate that MEOX1 is a novel regulator for TGF‐β‐induced SMC differentiation.

Abstract 544: Meox1, a Novel Regulator in Tgf-ß-induced Smooth Muscle Cell Differentiation

Smooth muscle cell (SMC) differentiation is an important process during vasculogenesis and angiogenesis. It is well known that alterations of VSMC phenotype play a role in the progression of several cardiovascular disorders including atherosclerosis, hypertension, and restenosis. However, the molecular mechanisms controlling the differentiation and development of VSMC are largely unknown. Mesenchyme homeobox 1 (MEOX1) is expressed in the early developing somite and derivatives during embryogenesis. Somite has been shown to be one of the origins or progenitors for SMC. Therefore, in this study, we studied the role of MEOX1 in SMC differentiation. We found that transforming growth factor-β (TGF-β) induces MEOX1 expression in the initial phase of SMC differentiation of pluripotent mesenchymal C3H10T1/2 cells. MEOX1 expression appears to be mediated by both PI3 kinase and Smad3 signaling pathways because blockade of these two pathways by specific inhibitors leads to a decreased expression of MEOX1 and SMC markers. Importantly, knockdown of MEOX1 by specific shRNA suppresses TGF-β-induced expression of SMC early markers including SM22α and calponin. MEOX1 overexpression, on the other hand, increases SMC marker expression. These results indicate that MEOX1 is a novel regulator for TGF-β-induced SMC differentiation.

Multiple Genetic Loci Modulate Lung Adenocarcinoma Clinical Staging

The main prognostic factor of lung cancer patient outcome is clinical stage, a parameter of tumor aggressiveness. Our study was conducted to test whether germ line variations modulate individual differences in clinical stage. We conducted a case-only genome-wide association study (GWAS) using a 620,901 single-nucleotide polymorphism (SNP) array in a first series of 600 lung adenocarcinoma (ADCA) patients and in a replication series of 317 lung ADCA patients. GWAS identified 54 putatively associated SNPs, 3 of which were confirmed in the replication series. Joint analysis of the two series pointed to 22 statistically associated (P < 0.01) genetic variants that together explained about 20% of the phenotypic variation in clinical staging (P < 2 × 10(-16)) and showed a statistically significant difference in overall survival (P = 8.0 × 10(-8)). The strongest statistical association was observed at rs10278557 (P = 1.1 × 10(-5)), located in the mesenchyme homeobox 2 (MEOX2) gene. These data point to the role of germ line variations involving multiple loci in modulating clinical stage and, therefore, prognosis in lung ADCA patients.

Identifications of expressed sequence tags from Pacific threadfin (Polydactylus sexfilis) skeletal muscle cDNA library

Pacific threadfin (Polydactylus sexfilis), locally known as Moi, is a desirable fish for aquaculture and recreational fishing. To understand the basic mechanism of muscle formation and its impacts on flesh quality, we established a cDNA library using mRNA of the skeletal muscle tissue from fingerlings. The library size was 1.1 × 108 plaque forming units mg−1 and the percentage of recombinant clones was >81%. A pilot sequencing project from 181 clones identified 129 useful expressed sequence tags (ESTs), of which 90 ESTs exhibited significant homology to known genes and 39 ESTs have low homologies to unknown genes by blast algorithm. The most abundant EST from the pilot sequence data is nikotinamide riboside kinase 2 (59 times), followed by 60S ribosomal protein L24 (12 times) and ribosomal protein L8 (5 times). Fourteen novel genes were retrieved from the sequenced clones and subjected to gene ontology annotation. Four mRNA sequences were identified as significant regulators of transcription, including Not2p, Tsc22 domain family 2, LIM domain binding factor 3 and mesenchyme homeobox 2. These results suggest that the muscle cDNA library is an useful source for identifying EST sequences of Pacific threadfin.

Role of the Homeodomain Transcription Factor Bapx1 in Mouse Distal Stomach Development

Expansion and patterning of the endoderm generate a highly ordered, multiorgan digestive system in vertebrate animals. Among distal foregut derivatives, the gastric corpus, antrum, pylorus, and duodenum are distinct structures with sharp boundaries. Some homeodomain transcription factors expressed in gut mesenchyme convey positional information required for anterior-posterior patterning of the digestive tract. Barx1, in particular, controls stomach differentiation and morphogenesis. The Nirenberg and Kim homeobox gene Bapx1 (Nkx3-2) has an established role in skeletal development, but its function in the mammalian gut is less clear. We generated a Bapx1(Cre) knock-in allele to fate map Bapx1-expressing cells and evaluate its function in gastrointestinal development. Bapx1-expressing cells populate the gut mesenchyme with a rostral boundary in the hindstomach near the junction of the gastric corpus and antrum. Smooth muscle differentiation and distribution of early regional markers are ostensibly normal in Bapx1(Cre/Cre) gut, but there are distinctive morphologic abnormalities near this rostral Bapx1 domain: the antral segment of the stomach is markedly shortened, and the pyloric constriction is lost. Comparison of expression domains and examination of stomach phenotypes in single and compound Barx1 and Bapx1 mutant mice suggests a hierarchy between these 2 factors; Bapx1 expression is lost in the absence of Barx1. This study reveals the nonredundant requirement for Bapx1 in distal stomach development, places it within a Barx1-dependent pathway, and illustrates the pervasive influence of gut mesenchyme homeobox genes on endoderm differentiation and digestive organogenesis.

Human fetal placental endothelial cells have a mature arterial and a juvenile venous phenotype with adipogenic and osteogenic differentiation potential

Growing interest in the sources of origin of blood vessel related diseases has led to an increasing knowledge about the heterogeneity and plasticity of endothelial cells lining arteries and veins. So far, most of these studies were performed on animal models. Here, we hypothesized that the plasticity of human fetal endothelial cells depends on their vascular bed of origin i.e. vein or artery and further that the differences between arterial and venous endothelial cells would extend to phenotype and genotype. We established a method for the isolation of fetal arterial and venous endothelial cells from the human placenta and studied the characteristics of both cell types. Human placental arterial endothelial cells (HPAEC) and human placental venous endothelial cells (HPVEC) express classical endothelial markers and differ in their phenotypic, genotypic, and functional characteristics: HPAEC are polygonal cells with a smooth surface growing in loose arrangements and forming monolayers with classical endothelial cobblestone morphology. They express artery-related genes (hey-2, connexin 40, depp) and more endothelial-associated genes than HPVEC. Functional testing demonstrated that vascular endothelial growth factors (VEGFs) induce a higher proliferative response on HPAEC, whereas placental growth factors (PlGFs) are only effective on HPVEC. HPVEC are spindle-shaped cells with numerous microvilli at their surface. They grow closely apposed to each other, form fibroblastoid swirling patterns at confluence and have shorter generation and population doubling times than HPAEC. HPVEC overexpress development-associated genes (gremlin, mesenchyme homeobox 2, stem cell protein DSC54) and show an enhanced differentiation potential into adipocytes and osteoblasts in contrast to HPAEC. These data provide collective evidence for a juvenile venous and a more mature arterial phenotype of human fetal endothelial cells. The high plasticity of the fetal venous endothelial cells may reflect their role as tissue-resident endothelial progenitors during embryonic development with a possible benefit for regenerative cell therapy.

Microarray analysis of bladder smooth muscle from patients with myelomeningocele

To examine whether gene profiles can provide a molecular evaluation of the quality and therapeutic potential in patients with myelomeningocele (MM), by comparing genetic profiles of smooth muscle cells (SMCs) from healthy bladders and bladders from patients, to identify genes that are over- and under-expressed in MM bladder SMCs. Bladder SM biopsies were obtained from 'healthy' subjects undergoing bladder surgery for vesico-ureteric reflux and from patients with a neurogenic bladder secondary to MM. Bladder SMCs were expanded in vitro and total RNA was isolated and hybridized to gene chips to evaluate the differential expression levels of 22 283 genes. Differentially expressed genes were identified by two methods. In the first analysis, we directly compared raw data sets of healthy SMCs to those derived from patients with MM. In the second analysis, we indirectly compared healthy SMCs and MM SMCs to a reference file, to create a genetic signature of genes that are over- and under-expressed in MM SMCs. The direct analysis identified 240 genes that were over-expressed and 104 that were under-expressed in MM SMCs. Gene ontology classifications were used to identify biological themes and pathways. Genes that were over-expressed in MM SMCs were involved in development: mesenchyme homeobox 2 (-fold change, 9.3); bone morphogenic protein 6 (4.0); fibroblast growth factor 2 (4.8); inhibin A (4.2), cartilage oliogomeric matrix protein (9.97); collagen 11A (6); collagen 5A2 (3) and collagen 1A1 (2.18). The indirect analysis identified 665 genes that were over-expressed and 1343 that were under-expressed in MM SMCs. Pathway-based analysis of these genetic signatures showed an over-expression of genes involved in muscle development and focal adhesion/extracellular matrix interactions. Genes that were under-expressed in MM SMCs were mapped to muscle contraction, transmission of nerve impulses, and cell-cell adhesion pathways. Our results are consistent with previous studies showing that MM bladders have an excess of extracellular matrix deposition, improper contraction, and are developmentally immature relatively to healthy SMCs. The clinical implication of microarray analysis of MM SMCs is that it provides potential targets that could induce muscle differentiation and inhibit extracellular matrix production.

New Therapeutic Targets in the Neurovascular Pathway in Alzheimer's Disease

Recent findings indicate that neurovascular dysfunction is an integral part of Alzheimer's disease (AD). Changes in the vascular system of the brain may significantly contribute to the onset and progression of dementia and to the development of a chronic neurodegenerative process. In contrast to the neurocentric view, which proposes that changes in chronic neurodegenerative disorders, including AD, can be attributed solely to neuronal disorder and neuronal dysfunction, the neurovascular concept proposes that dysfunction of non-neuronal neighboring cells and disintegration of neurovascular unit function may contribute to the pathogenesis of dementias in the elderly population, and understanding these processes will be crucial for the development of new therapeutic approaches to normalize both vascular and neuronal dysfunction. In this review, I discuss briefly the role of vascular factors and vascular disorder in AD, the link between cerebrovascular disorder and AD, the clearance hypothesis for AD, the role of RAGE (receptor for advanced glycation end products) and LRP (low density lipoprotein receptor related protein 1) in maintaining the levels of amyloid beta-peptide (Abeta) in the brain by controlling its transport across the blood-brain barrier (BBB), and the role of impaired vascular remodeling and cerebral blood flow dysregulation in the disease process. The therapeutic strategies based on new targets in the AD neurovascular pathway, such as RAGE and LRP receptors, and on a few selected genes implicated in AD neurovascular dysfunction (e.g., mesenchyme homeobox gene 2 and myocardin) are also discussed.

Characterization of Mesenchyme Homeobox 2 (MEOX2) transcription factor binding to RING finger protein 10

The molecular mechanisms by which Mesenchyme Homeobox 2 (Meox2) regulates the proliferation, differentiation and migration of vascular smooth muscle cells and cardiomyocytes are not known. The discovery of MEOX2 binding proteins will aid in understanding how MEOX2 functions as a regulator of these key cellular processes. To identify MEOX2 binding proteins, a yeast two-hybrid screen of a human heart cDNA library was performed using a deleted MEOX2 bait protein that does not contain the histidine/glutamine rich region (MEOX2deltaHQ). Eleven putative interacting proteins were identified including RING finger protein 10 (RNF10). In vitro pull-down assays and co-immunoprecipitation studies in mammalian cells further supported the yeast data demonstrating RNF10 bound to MEOX2. The minimal RNF10 binding region of MEOX2 was determined to be a central region between the histidine/glutamine rich domain and the homeodomain (amino acids 101-185). The amino terminal region of RNF10, containing the RING finger domain, was not essential for the binding to MEOX2. Our results also demonstrated that MEOX2 activation of the p21WAF1 promoter was enhanced by RNF10 co-expression.

Gene expression profiling of mesoblastic nephroma and Wilms tumors—comparison and clinical implications

Objectives To better understand the molecular mechanisms in the tumorigenesis and progression of mesoblastic nephroma (MN), we studied its gene expression profiles. MN is the most common tumor of the neonatal kidney. It occurs in a younger age group than the Wilms tumor (WT). To date, very little is known about the etiology and pathogenesis of MN. Methods Using microarrays containing 22,943 cDNA, we analyzed the expression profiles of MN and compared its expression profiles with those of several other types of kidney tumors, including WT. Results MN has a distinct molecular signature that clusters close to the WT, suggesting that both types of tumor share some similarity in gene expression and biology. When comparing the two profiles closely, we identified a number of genes that are commonly upregulated in both tumors, including insulin-like growth factor 2, thrombospondin 4, and mesenchyme homeo box 1. We also identified a set of genes that distinguish MN from WT, some of which may underlie the difference in their behaviors and can be used as diagnostic markers. Among this group of genes, topoisomerase II-alpha, highly expressed in WTs, is not overexpressed in MN. Immunohistochemical staining of topoisomerase II-alpha in additional cases of WTs and MNs confirmed this distinction further. Conclusions The results of our study demonstrated that MN has a distinct gene expression profile and that some of the newly identified genes can be potentially used as novel diagnostic markers.