Vestigial-dependent induction contributes to robust patterning but is not essential for wing-fate recruitment in Drosophila.

Cell recruitment is a process by which a differentiated cell induces neighboring cells to adopt its same cell fate. In Drosophila, cells expressing the protein encoded by the wing selector gene, vestigial (vg), drive a feed-forward recruitment signal that expands the Vg pattern as a wave front. However, previous studies on Vg pattern formation do not reveal these dynamics. Here, we use live imaging to show that multiple cells at the periphery of the wing disc simultaneously activate a fluorescent reporter of the recruitment signal, suggesting that cells may be recruited without the need for their contact neighbors be recruited in advance. In support of this observation, when Vg expression is inhibited either at the dorsal-ventral boundary or away from it, the activation of the recruitment signal still occurs at a distance, suggesting that Vg expression is not absolutely required to send or propagate the recruitment signal. However, the strength and extent of the recruitment signal is clearly compromised. We conclude that a feed-forward, contact-dependent cell recruitment process is not essential for Vg patterning, but it is necessary for robustness. Overall, our findings reveal a previously unidentified role of cell recruitment as a robustness-conferring cell differentiation mechanism.

Wnt1 and SFRP1 as potential prognostic factors and therapeutic targets in cutaneous squamous cell carcinoma.

The Wnt signaling pathway plays a key role in insurgence and progression of many different forms of cancer. Some crucial components of the Wnt pathway have been proposed to be novel targets for cancer therapy. To date, the Wnt signaling pathway has not been studied in cutaneous squamous cell carcinoma (CSCC). This study was designed to investigate the expression of Wnt1 and SFRP1 from the Wnt pathway in CSCC. Tissue samples were obtained from 35 patients with CSCC and 30 controls admitted to the Xinjiang Uygur Autonomous Region People's Hospital at Urumchi City, China. Gene and protein expressions of Wnt1 and SFRP1 were quantified by immunohistochemistry and western blotting. Wnt1 expression was significantly higher (P < 0.05) in CSCC samples than in normal skin cells of the control subjects; in contrast, SFRP1 expression was significantly lower in CSCC tissues than that in tissues of control subjects (P < 0.05). Moreover, Wnt1 expression (P < 0.05) was found to be correlated with histopathological differentiation in CSCC, and negatively correlated with SFRP1 expression in CSCC (rs = -0.473, P = 0.015). Therefore, we concluded that Wnt1 and SFRP1 play important roles in the development of CSCC and could be potent markers for diagnosis, prevention, and therapy of CSCC.

Wnt1-induced MAFK expression promotes osteosarcoma cell proliferation.

Osteosarcoma is one of the most common primary bone tumors in children and young adults. In this study, we investigated the role of musculoaponeurotic fibrosarcoma oncogene homolog K (MAFK) in osteosarcoma cell proliferation in vitro and the possible pathways that contributed to MAFK-related osteosarcoma development. We first reported that MAFK was expressed at low levels in an osteosarcoma cell line. Furthermore, a significant correlation between MAFK and the Wnt signaling pathway was observed in osteosarcoma by using a gene microarray assay. We found that expression of MAFK could be induced by Wnt1 in a dose-dependent manner. Furthermore, Wnt1-induced MAFK expression caused a significant increase of cell viability, whereas a Wnt pathway inhibitor, IWR-1-endo, abolished Wnt1-induced effects on MAFK. Finally, cell cycle analysis showed that enhanced cell proliferation might be attributed to re-distribution of the cell cycle. Together, our results suggested that Wnt1-induced MAFK expression promoted cell proliferation in MG63 cells, and that the role of MAFK in osteosarcoma might be closely linked to the Wnt signaling pathway.

Phylogeography of the sand dune ant Mycetophylax simplex along the Brazilian Atlantic Forest coast: remarkably low mtDNA diversity and shallow population structure.

BACKGROUND: During past glacial periods, many species of forest-dwelling animals experienced range contractions. In contrast, species living outside such moist habitats appear to have reacted to Quaternary changes in different ways. The Atlantic Forest represents an excellent opportunity to test phylogeographic hypotheses, because it has a wide range of vegetation types, including unforested habitats covered predominantly by herbaceous and shrubby plants, which are strongly influenced by the harsh environment with strong wind and high insolation. Here, we investigated the distribution of genetic diversity in the endemic sand dune ant Mycetophylax simplex across its known range along the Brazilian coast, with the aim of contributing to the understanding of alternative phylogeographic patterns. We used partial sequences of the mitochondrial gene cytochrome oxidase I and nuclear gene wingless from 108 specimens and 51 specimens, respectively, to assess the phylogeography and demographic history of this species. To achieve this we performed different methods of phylogenetic and standard population genetic analyses. RESULTS: The observed genetic diversity distribution and historical demographic profile suggests that the history of M. simplex does not match the scenario suggested for other Atlantic Forest species. Instead, it underwent demographic changes and range expansions during glacial periods. Our results show that M. simplex presents a shallow phylogeographic structure with isolation by distance among the studied populations, living in an almost panmictic population. Our coalescence approach indicates that the species maintained a stable population size until roughly 75,000 years ago, when it underwent a gradual demographic expansion that were coincident with the low sea-level during the Quaternary. Such demographic events were likely triggered by the expansion of the shorelines during the lowering of the sea level. CONCLUSIONS: Our data suggest that over evolutionary time M. simplex did not undergo dramatic range fragmentation, but rather it likely persisted in largely interconnected populations. Furthermore, we add an important framework about how both glacial and interglacial events could positively affect the distribution and diversification of species. The growing number of contrasting phylogeographic patterns within and among species and regions have shown that Quaternary events influenced the distribution of species in more ways than first supposed.

A broad expression profile of the GMR-GAL4 driver in Drosophila melanogaster.

The GAL4/UAS binary system has been widely used in Drosophila melanogaster for ectopic expression of transgenes in a tissue-specific manner. The GMR-GAL4 driver, which expresses the yeast transcription factor GAL4 under the control of glass multiple reporter (GMR) promoter elements, has been commonly utilized to express target transgenes, specifically in the developing eye. However, we have observed abnormal wing phenotypes; this is a result of the activity of critical wing developing genes, e.g., components of the Notch or Wg pathway, that are up- or down-regulated under the control of the GMR-GAL4 driver. X-gal staining confirmed that UAS-LacZ is expressed in third-instar larva wing imaginal discs, as well as in eye discs, when driven by the GMR-GAL4 driver. Furthermore, we found that GMR-GAL4 also drives UAS-LacZ expression in other tissues, such as brain, trachea, and leg discs. These results indicate that GMR-GAL4 has a broad expression profile, rather than the eye-specific pattern described previously, and that one should be careful when using it as a tool for targeted gene expression.

Effect of different resistance-training regimens on the WNT-signaling pathway.

The purpose of the present study was to evaluate the effects of 8 weeks of strength and power training on the expression of genes related to the canonical WNT pathway and ß-catenin protein levels in physically active men. Twenty-five subjects (27.4 ± 4.6 years) were balanced based on their relative maximum strength in the squat exercise (squat 1RM/body mass) and randomly assigned to strength training (ST) (n = 10), power training (PT) (n = 10), and control (C) (n = 5) groups. The ST and the PT groups performed high and low intensity squats, respectively, thrice a week, for 8 weeks. Muscle biopsies from the vastus lateralis muscle were collected before and after the training period. Relative strength and power increased similarly in both ST and PT groups (P < 0.001). Fiber cross-sectional area also increased similarly in both ST and PT groups. Gene expression and ß-catenin protein expression levels were assessed by real-time PCR and Western blot. Certain genes were up-regulated in the ST group (WNT1: 6.4-fold, P < 0.0001; SFRP1: 3.3-fold, P < 0.0001 and LEF1: 7.3-fold, P < 0.0001) and also in the PT group (WNT1: 24.9-fold, P < 0.0001; SFRP1: 2.7-fold, P < 0.0001; LEF1: 34.1-fold, P < 0.0001 and Cyclin D1: 7.7-fold, P < 0.001). In addition, the expression of key WNT pathway genes was substantially more responsive to PT than to ST (WNT1: P < 0.0001; LEF1: P < 0.0001 and Cyclin D1: P < 0.001). Finally, the total ß-catenin protein content increased only in the PT group (P < 0.05). Our data indicate that a PT regimen triggers greater responses in key elements of the WNT pathway.