Manipulation of Signal Gradient and Transcription Factors Recapitulates: Multiple Hypothalamic Identities.

During development, the hypothalamus emerges from the ventral diencephalon and is regionalized into several distinct functional domains. Each domain is characterized by a different combination of transcription factors, including Nkx2.1, Nkx2.2, Pax6, and Rx, which are expressed in the presumptive hypothalamus and its surrounding regions, and play critical roles in defining each area. Here, we recapitulated the molecular networks formed by the gradient of Sonic Hedgehog (Shh) and the aforementioned transcription factors. Using combinatorial experimental systems of directed neural differentiation of mouse embryonic stem (ES) cells, as well as a reporter mouse line and gene overexpression in chick embryos, we deciphered the regulation of transcription factors by different Shh signal intensities. We then used CRISPR/Cas9 mutagenesis to demonstrate the mutual repression between Nkx2.1 and Nkx2.2 in a cell-autonomous manner; however, they induce each other in a non-cell-autonomous manner. Moreover, Rx resides upstream of all these transcription factors and determines the location of the hypothalamic region. Our findings suggest that Shh signaling and its downstream transcription network are required for hypothalamic regionalization and establishment.

The Rx transcription factor is required for determination of the retinal lineage and regulates the timing of neuronal differentiation.

Understanding the molecular mechanisms leading to retinal development is of great interest for both basic scientific and clinical applications. Several signaling molecules and transcription factors involved in retinal development have been isolated and analyzed; however, determining the direct impact of the loss of a specific molecule is problematic, due to difficulties in identifying the corresponding cellular lineages in different individuals. Here, we conducted genome-wide expression analysis with embryonic stem (ES) cells devoid of the Rx gene, which encodes one of several homeobox transcription factors essential for retinal development. We performed three-dimensional differentiation of wild-type and mutant cells and compared their gene-expression profiles. The mutant tissue failed to differentiate into the retinal lineage and exhibited precocious expression of genes characteristic of neuronal cells. Together, these results suggest that Rx expression is an important biomarker of the retinal lineage and that it helps regulates appropriate differentiation stages.

A clinical survey of dehydration during winter training in elite fencing athletes.

BACKGROUND: Fencing is suggested as one of the most dangerous sporting events in terms of dehydration because of the uniform and gear covering the entire body. We aimed to elucidate the change in hydration status before and after training in elite fencing athletes in winter along with the assessment of sex and fencing style differences. METHODS: Twenty-seven elite fencing athletes (14 males and 13 females) belonging to the Japanese National Team participated in this clinical survey. Dehydration status before and after winter training was assessed using body mass change, fluid intake, urine osmolarity, urine specific gravity (USG), and sodium, potassium, chlorine, and creatinine levels. RESULTS: More than half of the participants (59.3%) drank water and tea during training. The change rate of body mass (males vs. females, 1.61±0.82% vs. 0.45±0.68%, P<0.01; foil vs. epee, 2.25±0.45% vs. 1.16±0.72%, P<0.05) and sweating rate (males vs. females, 938±251 g/h vs. 506±92 g/h, P<0.01; foil vs. epee, 1136±156 g/h vs. 796±207 g/h, P<0.05) during training showed significant differences between sexes and fencing styles. Of all participants, 66.7% were dehydrated (USG≥1.020), and 37.0% were seriously dehydrated (USG≥1.030) before training. CONCLUSIONS: Fencing athletes may be susceptible to severe dehydration before training, even in winter. Additionally, males and foil fencers appear to be at a greater risk than females and epee fencers of developing dehydration during exercise.

Evolution of Developmental Programs for the Midline Structures in Chordates: Insights From Gene Regulation in the Floor Plate and Hypochord Homologues of Ciona Embryos.

In vertebrate embryos, dorsal midline tissues, including the notochord, the prechordal plate, and the floor plate, play important roles in patterning of the central nervous system, somites, and endodermal tissues by producing extracellular signaling molecules, such as Sonic hedgehog (Shh). In Ciona, hedgehog.b, one of the two hedgehog genes, is expressed in the floor plate of the embryonic neural tube, while none of the hedgehog genes are expressed in the notochord. We have identified a cis-regulatory region of hedgehog.b that was sufficient to drive a reporter gene expression in the floor plate. The hedgehog.b cis-regulatory region also drove ectopic expression of the reporter gene in the endodermal strand, suggesting that the floor plate and the endodermal strand share a part of their gene regulatory programs. The endodermal strand occupies the same topographic position of the embryo as does the vertebrate hypochord, which consists of a row of single cells lined up immediately ventral to the notochord. The hypochord shares expression of several genes with the floor plate, including Shh and FoxA, and play a role in dorsal aorta development. Whole-embryo single-cell transcriptome analysis identified a number of genes specifically expressed in both the floor plate and the endodermal strand in Ciona tailbud embryos. A Ciona FoxA ortholog FoxA.a is shown to be a candidate transcriptional activator for the midline gene battery. The present findings suggest an ancient evolutionary origin of a common developmental program for the midline structures in Olfactores.

Identification and Biochemical Characterization of High Mobility Group Protein 20A as a Novel Ca2+/S100A6 Target.

During screening of protein-protein interactions, using human protein arrays carrying 19,676 recombinant glutathione s-transferase (GST)-fused human proteins, we identified the high-mobility protein group 20A (HMG20A) as a novel S100A6 binding partner. We confirmed the Ca2+-dependent interaction of HMG20A with S100A6 by the protein array method, biotinylated S100A6 overlay, and GST-pulldown assay in vitro and in transfected COS-7 cells. Co-immunoprecipitation of S100A6 with HMG20A from HeLa cells in a Ca2+-dependent manner revealed the physiological relevance of the S100A6/HMG20A interaction. In addition, HMG20A has the ability to interact with S100A1, S100A2, and S100B in a Ca2+-dependent manner, but not with S100A4, A11, A12, and calmodulin. S100A6 binding experiments using various HMG20A mutants revealed that Ca2+/S100A6 interacts with the C-terminal region (residues 311-342) of HMG20A with stoichiometric binding (HMG20A:S100A6 dimer = 1:1). This was confirmed by the fact that a GST-HMG20A mutant lacking the S100A6 binding region (residues 311-347, HMG20A-ΔC) failed to interact with endogenous S100A6 in transfected COS-7 cells, unlike wild-type HMG20A. Taken together, these results identify, for the first time, HMG20A as a target of Ca2+/S100 proteins, and may suggest a novel linkage between Ca2+/S100 protein signaling and HMG20A function, including in the regulation of neural differentiation.

Regulation of the tubulin polymerization-promoting protein by Ca2+/S100 proteins.

To elucidate S100 protein-mediated signaling pathways, we attempted to identify novel binding partners for S100A2 by screening protein arrays carrying 19,676 recombinant glutathione S-transferase (GST)-fused human proteins with biotinylated S100A2. Among newly discovered putative S100A2 interactants, including TMLHE, TRH, RPL36, MRPS34, CDR2L, OIP5, and MED29, we identified and characterized the tubulin polymerization-promoting protein (TPPP) as a novel S100A2-binding protein. We confirmed the interaction of TPPP with Ca2+/S100A2 by multiple independent methods, including the protein array method, S100A2 overlay, and pulldown assay in vitro and in transfected COS-7 cells. Based on the results from the S100A2 overlay assay using various GST-TPPP mutants, the S100A2-binding region was identified in the C-terminal (residues 111-160) of the central core domain of a monomeric form of TPPP that is involved in TPPP dimerization. Chemical cross-linking experiments indicated that S100A2 suppresses dimer formation of His-tagged TPPP in a dose-dependent and a Ca2+-dependent manner. In addition to S100A2, TPPP dimerization is disrupted by other multiple S100 proteins, including S100A6 and S100B, in a Ca2+-dependent manner but not by S100A4. This is consistent with the fact that S100A6 and S100B, but not S100A4, are capable of interacting with GST-TPPP in the presence of Ca2+. Considering these results together, TPPP was identified as a novel target for S100A2, and it is a potential binding target for other multiple S100 proteins, including S100A6 and S100B. Direct binding of the S100 proteins with TPPP may cause disassembly of TPPP dimer formation in response to the increasing concentration of intracellular Ca2+, thus resulting in the regulation of the physiological function of TPPP, such as microtubule organization.

Synergistic antitumor effect of a combination of paclitaxel and carboplatin with nobiletin from Citrus depressa on non-small-cell lung cancer cell lines.

Non-small-cell lung carcinomas do not sufficiently respond to cancer chemotherapeutic drugs. Combination effects of cancer chemotherapy drugs (paclitaxel and carboplatin) with nobiletin or powdered Shiikuwasha extract from Citrus depressa were examined by isobologram and combination index analyses. It was demonstrated that the combination generated a synergistic inhibitory effect against the proliferation of the human non-small-cell lung carcinoma cell lines A549 and H460 and that of the two chemotherapy drugs, paclitaxel was responsible for this synergistic effect. Furthermore, the percentage of apoptotic cells was decreased with increasing rates of nobiletin to paclitaxel and carboplatin. These findings were considered to be attributed to the ability of nobiletin to regulate cells in the G1 phase, which escaped cell death initiated by paclitaxel and carboplatin. An antitumor activity assay showed that this combination significantly suppressed the growth of subcutaneous A549 tumor xenografts in nude mice.