Osteogenic protein-2. A new member of the transforming growth factor-beta superfamily expressed early in embryogenesis.

Osteogenic protein-2, OP-2, a new member of the transforming growth factor-beta (TGF-beta) superfamily, closely related to the osteogenic/bone morphogenetic proteins, was discovered in mouse embryo and human hippocampus cDNA libraries. The TGF-beta domain of OP-2 shows 74% identity to OP-1, 75% to Vgr-1, and 76% to BMP-5, hence OP-2 may also have bone inductive activity. The genomic locus of OP-2 has seven exons, like OP-1, and spans more than 27 kilobases (kb). In the C-terminal TGF-beta domain, OP-2 has a unique additional cysteine. Mouse embryos express relatively high levels of OP-2 mRNA at 8 days, two species of 3 and 5 kb. A careful study of mRNA expression of the osteogenic proteins in specific organs revealed discrete mRNA species for BMP-3, BMP-4, BMP-5, and BMP-6/Vgr-1 in lung or liver of young and adult mice. OP-1 is expressed in kidney; however, OP-2 and BMP-2 mRNAs were not detected in any organs studied, suggesting an early developmental role.     

OP-1 cDNA encodes an osteogenic protein in the TGF-beta family.

Amino acid sequences of two tryptic peptides derived from enriched bovine osteogenic protein preparations revealed considerable homology to two members of the TGF-beta (transforming growth factor beta) supergene family, DPP (decapentaplegic protein) of Drosophila and Vg-1 (vegetal protein) of Xenopus. Building upon this information we constructed a synthetic consensus gene to use as a probe to screen human genomic libraries. This resulted in the isolation of three interrelated genes. Among these were BMP-2b and BMP-3 which have recently been described by others. The third gene, termed OP-1 (osteogenic protein one), is new and was subsequently shown to encode the human homolog of a major component of bovine osteogenic protein. The genomic clones were used to isolate the corresponding complementary DNA (cDNA) clones. Sequence analysis indicates that OP-1 is a relative of the murine Vgr-1 (Vg-1 related gene). This report describes the cDNA structure and putative amino acid sequence of OP-1.     

Snail family members and cell survival in physiological and pathological cleft palates

Palate fusion is a complex process that involves the coordination of a series of cellular changes including cell death and epithelial to mesenchymal transition (EMT). Since members of the Snail family of zinc-finger regulators are involved in both triggering of the EMT and cell survival, we decided to study their putative role in palatal fusion. Furthermore, Snail genes are induced by transforming growth factor beta gene (TGF-beta) superfamily members, and TGF-beta(3) null mutant mice (TGF-beta(3)-/-) show a cleft palate phenotype. Here we show that in the wild-type mouse at the time of fusion, Snail is expressed in a few cells of the midline epithelial seam (MES), compatible with a role in triggering of the EMT in a small subpopulation of the MES. We also find an intriguing relationship between the expression of Snail family members and cell survival associated to the cleft palate condition. Indeed, Snail is expressed in the medial edge epithelial (MEE) cells in TGF-beta(3)-/-mouse embryo palates, where it is activated by the aberrant expression of its inducer, TGF-beta(1), in the underlying mesenchyme. In contrast to Snail-deficient wild-type pre-adhesion MEE cells, Snail-expressing TGF-beta(3) mutant MEE cells survive as they do their counterparts in the chick embryo. Interestingly, Slug is the Snail family member expressed in the chick MEE, providing another example of interchange of Snail and Slug expression between avian and mammalian embryos. We propose that in the absence of TGF-beta(3), TGF-beta(1) is upregulated in the mesenchyme, and that in both physiological (avian) and pathological (TGF-beta(3)-/-mammalian) cleft palates, it induces the expression of Snail genes promoting the survival of the MEE cells and permitting their subsequent differentiation into keratinized stratified epithelium.     

Protocadherins branch out: Multiple roles in dendrite development

The proper formation of dendritic arbors is a critical step in neural circuit formation, and as such defects in arborization are associated with a variety of neurodevelopmental disorders. Among the best gene candidates are those encoding cell adhesion molecules, including members of the diverse cadherin superfamily characterized by distinctive, repeated adhesive domains in their extracellular regions. Protocadherins (Pcdhs) make up the largest group within this superfamily, encompassing over 80 genes, including the ∼60 genes of the α-, β-, and γ-Pcdh gene clusters and the non-clustered δ-Pcdh genes. An additional group includes the atypical cadherin genes encoding the giant Fat and Dachsous proteins and the 7-transmembrane cadherins. In this review we highlight the many roles that Pcdhs and atypical cadherins have been demonstrated to play in dendritogenesis, dendrite arborization, and dendritic spine regulation. Together, the published studies we discuss implicate these members of the cadherin superfamily as key regulators of dendrite development and function, and as potential therapeutic targets for future interventions in neurodevelopmental disorders.     

Cytokine-specific induction of the TGF-beta inducible early gene (TIEG): regulation by specific members of the TGF-beta family

Select members of the TGF-beta family of cytokines play key regulatory roles in skeletal development, structure, and turnover. This laboratory has previously reported that TGF-beta treatment of immortalized normal human fetal osteoblast (hFOB) cells results in the rapid induction of the mRNA levels of a TGF-beta inducible early gene (TIEG) followed by changes in cell proliferation and bone matrix protein production. Previous studies have also shown that nonmembers of the TGF-beta superfamily showed little or no induction of TIEG mRNA. This article further addresses the cytokine specificity of this TIEG induction by examining whether activin and select bone morphogenetic proteins, (BMP-2, BMP-4, and BMP-6), which are representative of different subfamilies of this superfamily, also induce the expression of TIEG in hFOB cells. However, TGF-beta remained the most potent of these cytokines, inducing TIEG mRNA steady-state levels at 0.1 ng/ml, with a maximum induction of 24-fold at 2.0 ng/ml. The BMP-2 (16-fold), BMP-4 (4-fold), and activin (1-3-fold) also induced TIEG mRNA levels, but at reduced degrees compared to TGF-beta (24-fold), and only at much higher cytokine concentrations, e.g., 50-100 ng/ml, compared to 2 ng/ml for TGF-beta. BMP-6 showed no effect on TIEG mRNA levels. The TIEG protein levels generally correlated with the mRNA steady-state levels. As with TGF-beta, BMP-2 treatment of hFOB cells was shown by confocal microscopy to induce a rapid translocation of the TIEG protein to the nucleus. In summary, the relative potencies of these TGF-beta family members to induce TIEG expression generally follows the general osteoinductive capacity of these cytokines, with TGF-beta > BMP-2 > BMP-4 > activin > BMP-6.     

Altered Cytokine Gene Expression in Peripheral Blood Monocytes across the Menstrual Cycle in Primary Dysmenorrhea: A Case-Control Study

Primary dysmenorrhea is one of the most common gynecological complaints in young women, but potential peripheral immunologic features underlying this condition remain undefined. In this paper, we compared 84 common cytokine gene expression profiles of peripheral blood mononuclear cells (PBMCs) from six primary dysmenorrheic young women and three unaffected controls on the seventh day before (secretory phase), and the first (menstrual phase) and the fifth (regenerative phase) days of menstruation, using a real-time PCR array assay combined with pattern recognition and gene function annotation methods. Comparisons between dysmenorrhea and normal control groups identified 11 (nine increased and two decreased), 14 (five increased and nine decreased), and 15 (seven increased and eight decreased) genes with ≥2-fold difference in expression (P<0.05) in the three phases of menstruation, respectively. In the menstrual phase, genes encoding pro-inflammatory cytokines (IL1B, TNF, IL6, and IL8) were up-regulated, and genes encoding TGF-β superfamily members (BMP4, BMP6, GDF5, GDF11, LEFTY2, NODAL, and MSTN) were down-regulated. Functional annotation revealed an excessive inflammatory response and insufficient TGF-β superfamily member signals with anti-inflammatory consequences, which may directly contribute to menstrual pain. In the secretory and regenerative phases, increased expression of pro-inflammatory cytokines and decreased expression of growth factors were also observed. These factors may be involved in the regulation of decidualization, endometrium breakdown and repair, and indirectly exacerbate primary dysmenorrhea. This first study of cytokine gene expression profiles in PBMCs from young primary dysmenorrheic women demonstrates a shift in the balance between expression patterns of pro-inflammatory cytokines and TGF-β superfamily members across the whole menstrual cycle, underlying the peripheral immunologic features of primary dysmenorrhea.