The Odd-skipped related 1 (Odd 1) gene encodes a zinc finger protein homologous to the Drosophila Odd-skipped class transcription factors that play critical roles in embryonic patterning and tissue morphogenesis. We have generated mice carrying a targeted null mutation in the Odd 1 gene and show that Odd 1 is essential for heart and intermediate mesoderm development. Odd 1(-/-) mutant mouse embryos fail to form atrial septum, display dilated atria with hypoplastic venous valves, and exhibit blood backflow from the heart into systemic veins. In contrast to other transcription factors implicated in atrial septum development, Odd 1 mRNA expression is restricted to the central dorsal domain of the atrial myocardium during normal heart development. Moreover, expression patterns of known key regulatory genes of atrial septum development, including Nkx2.5, Pitx2, and Tbx5, are unaltered in the developing heart in Odd 1(-/-) mutants compared to that of the wild-type littermates. Furthermore, homozygous Odd 1(-/-) mutant embryos exhibit complete agenesis of adrenal glands, metanephric kidneys, gonads, and defects in pericardium formation. Detailed molecular marker analyses show that key regulators of early intermediate mesoderm development, including Lhx1, Pax2, and Wt1, are all down-regulated and nephrogenic mesenchyme undergoes massive apoptosis, resulting in disruption of nephric duct elongation and failure of metanephric induction in the Odd 1(-/-) mutant embryos. These data provide new insights into the molecular mechanisms underlying heart morphogenesis and urogenital development.

Formation of kidney tissue requires the generation of kidney precursor cells and their subsequent differentiation into nephrons, the functional filtration unit of the kidney. Here we report that the gene odd-skipped related 1 (Odd1) plays an important role in both these processes. Odd1 is the earliest known marker of the intermediate mesoderm, the precursor to all kidney tissue. It is localized to mesenchymal precursors within the mesonephric and metanephric kidney and is subsequently downregulated upon tubule differentiation. Mice lacking Odd1 do not form metanephric mesenchyme, and do not express several other factors required for metanephric kidney formation, including Eya1, Six2, Pax2, Sall1 and Gdnf. In transient ectopic expression experiments in the chick embryo, Odd1 can promote expression of the mesonephric precursor markers Pax2 and Lim1. Finally, persistent expression of Odd1 in chick mesonephric precursor cells inhibits differentiation of these precursors into kidney tubules. These data indicate that Odd1 plays an important role in establishing kidney precursor cells, and in regulating their differentiation into kidney tubular tissue.

SummaryOdd-skipped related 2 (Osr2) encodes a key intrinsic regulator of secondary palate growth and morphogenesis

SUMMARYMammalian palate development is a multi-step process, involving initial bilateral downward outgrowth of the palatal shelves from the oral side of the maxillary processes, followed by stagespecific palatal shelf elevation to the horizontal position above the developing tongue and subsequent fusion of the bilateral palatal shelves at the midline to form the intact roof of the oral cavity. Whereas mutations in many genes have been associated with cleft palate pathogenesis, the molecular mechanisms regulating palatal shelf growth, patterning, and elevation are not well understood. Genetic studies of the molecular mechanisms controlling palate development in mutant mouse models are often complicated by early embryonic lethality or gross craniofacial malformation. We report here the development of a mouse strain for tissue-specific analysis of gene function in palate development. We inserted an IresCre bicistronic expression cassette into the 3′ untranslated region of the mouse Osr2 gene through gene targeting. We show, upon crossing to the R26R reporter mice, that Cre expression from the Osr2 IresCre knockin allele activated beta-galactosidase expression specifically throughout the developing palatal mesenchyme from the onset of palatal shelf outgrowth. In addition, the Osr2 IresCre mice display exclusive Cre-mediated recombination in the glomeruli tissues derived from the metanephric mesenchyme and complete absence of Cre activity in other epithelial and mesenchymal tissues in the developing metanephric kidney. These data indicate that the Osr2 IresCre knockin mice provide a unique tool for tissue-specific studies of the molecular mechanisms regulating palate and kidney development.

Background: Bone marrow mesenchymal stem cells (BMSCs) can partially repair chemotherapy-induced ovarian damage. However, low survival rate after transplantation hampers the therapeutic efficiency of BMSCs. Heat shock pretreatment (HSP) effectively improves the cell survival. This study attempted to investigate the mechanisms of HSP on BMSCs survival and the effects of heat shock-pretreated BMSCs (HS-MSCs) on cisplatin-induced granulosa cell (GC) apoptosis. Methods: BMSCs were isolated, cultured, and identified. After receiving HSP for different duration times in a 42°C water bath, the apoptotic rates of BMSCs were detected by Annexin V-FITC/PI to determine the optimal condition of HSP. Cisplatin was added to the medium of HS-MSCs to simulate chemotherapy environment. The proliferative curve, apoptotic rate, and viability of HS-MSCs were determined by CCK-8, Annexin V-FITC/PI, and Hoechst33342/PI respectively to explore the alteration of biological characteristics. The levels of heat shock protein 70 and 90 (HSP70 and HSP90) and the expressions of autophagy-related markers (Beclin1 and LC3B) were detected by Western blot. In addition, the autophagosomes were observed by transmission electronic microscopy to discuss the possible mechanisms. The GCs were isolated, cultured, and identified. The HS-MSCs were co-cultured with GCs before and after the addition of cisplatin. Then, the apoptotic rate and viability of GCs were detected to investigate the therapeutic and preventive effects of HS-MSCs on GC apoptosis. Results: After receiving HSP at 42°C for 1 h, BMSCs represented the lowest apoptotic rate. After the addition of cisplatin, the apoptotic rate of HS-MSCs (11.94% ± 0.63%) was lower than that of BMSCs (14.30% ± 0.80%) and the percentage of HS-MSCs expressing bright blue/dull red fluorescence was lower than that of BMSCs. The expression of HSP70 and HSP90 increased, while the number of autophagosomes, the expression of Beclin1, and the LC3BII/ LC3BI ratio decreased in HS-MSCs. The apoptotic rates of GCs co-cultured with HS-MSCs before and after the addition of cisplatin were 39.88% ± 1.65% and 36.72% ± 0.96%, both lower than those of cisplatin-induced GCs (53.81% ± 1.89%). Conclusion: HSP can alleviate the apoptosis and improve the survival of BMSCs under chemotherapy environment. The mechanism may be associated with the elevated expression of HSP70 and HSP90 and the attenuation of autophagy. Moreover, HS-MSCs have both therapeutic and preventive effects on cisplatin-induced GC apoptosis.