Iain D. Keenan

Negative-feedback regulation of FGF signalling by DUSP6/MKP-3 is driven by ERK1/2 and mediated by Ets factor binding to a conserved site within the DUSP6/MKP-3 gene promoter.

DUSP6 (dual-specificity phosphatase 6), also known as MKP-3 [MAPK (mitogen-activated protein kinase) phosphatase-3] specifically inactivates ERK1/2 (extracellular-signal-regulated kinase 1/2) in vitro and in vivo. DUSP6/MKP-3 is inducible by FGF (fibroblast growth factor) signalling and acts as a negative regulator of ERK activity in key and discrete signalling centres that direct outgrowth and patterning in early vertebrate embryos. However, the molecular mechanism by which FGFs induce DUSP6/MKP-3 expression and hence help to set ERK1/2 signalling levels is unknown. In the present study, we demonstrate, using pharmacological inhibitors and analysis of the murine DUSP6/MKP-3 gene promoter, that the ERK pathway is critical for FGF-induced DUSP6/MKP-3 transcription. Furthermore, we show that this response is mediated by a conserved binding site for the Ets (E twenty-six) family of transcriptional regulators and that the Ets2 protein, a known target of ERK signalling, binds to the endogenous DUSP6/MKP-3 promoter. Finally, the murine DUSP6/MKP-3 promoter coupled to EGFP (enhanced green fluorescent protein) recapitulates the specific pattern of endogenous DUSP6/MKP-3 mRNA expression in the chicken neural plate, where its activity depends on FGFR (FGF receptor) and MAPK signalling and an intact Ets-binding site. These findings identify a conserved Ets-factor-dependent mechanism by which ERK signalling activates DUSP6/MKP-3 transcription to deliver ERK1/2-specific negative-feedback control of FGF signalling.

Negative feedback predominates over cross-regulation to control ERK MAPK activity in response to FGF signalling in embryos

Expression of the gene encoding the MKP‐3/Pyst1 protein phosphatase, which inactivates ERK MAPK, is induced by FGF. However, which intracellular signalling pathway mediates this expression is unclear, with essential roles proposed for both ERK and PI(3)K in chick embryonic limb. Here, we report that MKP‐3/Pyst1 expression is sensitive to inhibition of ERK or MAPKK, that endogenous MKP‐3/Pyst1 co‐localizes with activated ERK, and expression of MKP‐3/Pyst1 in mice lacking PDK1, an essential mediator of PI(3)K signalling. We conclude that MKP‐3/Pyst1 expression is mediated by ERK activation and that negative feedback control predominates in limiting the extent of FGF‐induced ERK activity.

Cloning and expression of the Cdx family from the frog Xenopus tropicalis

The caudal‐related (Cdx) homeodomain transcription factors have a conserved role in the development of posterior structures in both vertebrates and invertebrates. A particularly interesting finding is that Cdx proteins have an important function in the regulation of expression from a subset of Hox genes. In this study, we report the cloning of cDNAs from the Cdx genes of the amphibian Xenopus tropicalis. Xenopus tropicalis is a diploid species, related to the commonly used laboratory animal Xenopus laevis, and has attracted attention recently as a potential genetic model for animal development. The Xenopus tropicalis cDNAs, Xtcad1, Xtcad2, and Xtcad3, show between 88 and 94% sequence identity with their Xenopus laevis orthologues. This finding corresponds to between 90 and 95% identity at the level of derived amino acid sequence. We also present a detailed description of Xtcad1, Xtcad2, and Xtcad3 expression during normal development. In common with the Cdx genes of other vertebrates, the Xenopus tropicalis Cdx genes show overlapping and dynamic patterns of expression in posterior regions of the embryo through the early stages of development.

Scrib:Rac1 interactions are required for the morphogenesis of the ventricular myocardium

Aims The organization and maturation of ventricular cardiomyocytes from the embryonic to the adult form is crucial for normal cardiac function. We have shown that a polarity protein, Scrib, may be involved in regulating the early stages of this process. Our goal was to establish whether Scrib plays a cell autonomous role in the ventricular myocardium, and whether this involves well-known polarity pathways. Methods and results Deletion of Scrib in cardiac precursors utilizing Scribflox mice together with the Nkx2.5-Cre driver resulted in disruption of the cytoarchitecture of the forming trabeculae and ventricular septal defects. Although the majority of mice lacking Scrib in the myocardium survived to adulthood, they developed marked cardiac fibrosis. Scrib did not physically interact with the planar cell polarity (PCP) protein, Vangl2, in early cardiomyocytes as it does in other tissues, suggesting that the anomalies did not result from disruption of PCP signalling. However, Scrib interacted with Rac1 physically in embryonic cardiomyocytes and genetically to result in ventricular abnormalities, suggesting that this interaction is crucial for the development of the early myocardium. Conclusions The Scrib–Rac1 interaction plays a crucial role in the organization of developing cardiomyocytes and formation of the ventricular myocardium. Thus, we have identified a novel signalling pathway in the early, functioning, heart muscle. These data also show that the foetus can recover from relatively severe abnormalities in prenatal ventricular development, although cardiac fibrosis can be a long-term consequence.

Improvements in anatomy knowledge when utilizing a novel cyclical “Observe-Reflect-Draw-Edit-Repeat” learning process

Innovative educational strategies can provide variety and enhance student learning while addressing complex logistical and financial issues facing modern anatomy education. Observe‐Reflect‐Draw‐Edit‐Repeat (ORDER), a novel cyclical artistic process, has been designed based on cognitivist and constructivist learning theories, and on processes of critical observation, reflection and drawing in anatomy learning. ORDER was initially investigated in the context of a compulsory first year surface anatomy practical (ORDER‐SAP) at a United Kingdom medical school in which a cross‐over trial with pre‐post anatomy knowledge testing was utilized and student perceptions were identified. Despite positive perceptions of ORDER‐SAP, medical student (n = 154) pre‐post knowledge test scores were significantly greater (P < 0.001) with standard anatomy learning methods (3.26, SD = ±2.25) than with ORDER‐SAP (2.17, ±2.30). Based on these findings, ORDER was modified and evaluated in the context of an optional self‐directed gross anatomy online interactive tutorial (ORDER‐IT) for participating first year medical students (n = 55). Student performance was significantly greater (P < 0.001) with ORDER‐IT (2.71 ± 2.17) when compared to a control tutorial (1.31 ± 2.03). Performances of students with visual and artistic preferences when using ORDER were not significantly different (P > 0.05) to those students without these characteristics. These findings will be of value to anatomy instructors seeking to engage students from diverse learning backgrounds in a research‐led, innovative, time and cost‐effective learning method, in the context of contrasting learning environments. Anat Sci Educ 10: 7–22.

Origin of non-cardiac endothelial cells from an Isl1+ lineage.

The cardiovascular system consists of many cell types with distinct embryonic origins. Cells from an Islet1 (Isl1)‐expressing progenitor population make a substantial contribution to the developing heart. We reasoned that cells derived from Isl1‐expressing progenitors might contribute more widely to the cardiovascular system. We show that cells derived from an Isl1‐expressing progenitor lineage make a wide contribution to the systemic vasculature and that embryos conditionally deficient for Rac1 within this cell population develop defects in the non‐cardiac vasculature. These data define new roles for Isl1 in the developing embryo and demonstrate a contribution of Isl1‐expressing progenitors to vascular endothelium in vivo.

The future of anatomy: a student partner approach to theevaluation and implementation of evidence based artisticlearning techniques

Rationale Since the illustrations of Leonardo da Vinci in the 15-16th Century, artistic portrayals of human anatomy have been used in education. Modern students of anatomy take a variety of approaches to learning including visualisation [1] and while there is limited evidence to support the idea of students as visual learners [2], creating artwork can fulfil components of experiential learning [3] and it is known that visual artistic techniques can improve learning [4].

The future ORDER: a student partner approach forevidence-based evaluation and implementation of an ‘observe–reflect–draw–edit–repeat’ artistic learning process in anatomyeducation

Rationale Since the illustrations of Leonardo da Vinci in the 15-16th Century, artistic portrayals of human anatomy have been used in education. Modern students of anatomy take a variety of approaches to learning including visualisation [1] and while there is limited evidence to support the idea of students as visual learners [2], creating artwork can fulfil components of experiential learning [3] and it is known that visual artistic techniques can improve learning [4].

The future of anatomy education: investigating the impact of student partner approaches for evidence-based evaluation of teaching and learning techniques

Rationale Since the illustrations of Leonardo da Vinci in the 15-16th Century, artistic portrayals of human anatomy have been used in education. Modern students of anatomy take a variety of approaches to learning including visualisation [1] and while there is limited evidence to support the idea of students as visual learners [2], creating artwork can fulfil components of experiential learning [3] and it is known that visual artistic techniques can improve learning [4].

Is dissection of more educational value than other methods of learning and teaching anatomy? A student partner approach for evidence-based investigation of dissection as a teaching and learning method in anatomy

Rationale Since the illustrations of Leonardo da Vinci in the 15-16th Century, artistic portrayals of human anatomy have been used in education. Modern students of anatomy take a variety of approaches to learning including visualisation [1] and while there is limited evidence to support the idea of students as visual learners [2], creating artwork can fulfil components of experiential learning [3] and it is known that visual artistic techniques can improve learning [4].