The Formin proteins are central players in mediating cytoskeletal reorganization and are epistatically positioned in a pathway downstream of Rho activation. These proteins exist in the cytoplasm in an autoinhibited state, which is mediated by intramolecular interactions between the amino-terminal GTPase binding domain (GBD) that encompasses the diaphanous inhibitory domain (DID) and the carboxyl-terminal diaphanous autoregulatory domain (DAD). It Dishevelled ͉ Wnt ͉ Rho D irectional cell migration is required for the development of an organism with proper polarity including dorsoventral, anterior-posterior, and left-right symmetry. Examples of these cell movements include those of gastrulation and neural fold closure. These cell movements are tightly regulated by secreted ligands (1, 2). One of these signaling pathways required for cell movements is the noncanonical Wnt pathway (3-5).Noncanonical Wnt signaling, also termed the planar cell polarity pathway, regulates cell movements through modification of the actin cytoskeleton (1,3,4,6). A number of molecular components for this pathway have been identified including Wnt11, Fz, Dvl, Daam1, Rho, Rac, JNK, Strabismus, and Prickle (reviewed in ref. 5). For noncanonical Wnt signaling, the binding of Wnt to the Frizzled (Fz) receptor stimulates a signal that is transduced to the cytoplasmic phosphoprotein Dishevelled (Dvl). At the level of Dvl, two independent and parallel pathways lead to the activation of the small GTPases Rho and Rac. The first pathway signaling to the small GTPase Rho occurs through the molecule Daam1 (7). This Rho pathway leads to the activation of the Rho-associated kinase Rock and mediates cytoskeletal reorganization (5, 8). The second activates another small GTPase of the Rho-family, Rac, which in turns stimulates JNK activity (9-11). Daam1 is a Formin protein family and has been shown to regulate gastrulation; however, how Daam1 is activated for its function remains unknown.The Formin proteins are central players in regulating cytoskeletal reorganization in mammalian cells (12). The Formin proteins contain three major domains termed the GTPase binding domain (GBD), Formin homology 1 (FH1) domain, and Formin homology 2 (FH2) domain (13). These proteins are proposed to exist in the cytoplasm in an autoinhibited state, which is mediated by a domain termed the diaphanous autoinhibitory domain (DAD) (12). This DAD found in the carboxyl terminus mediates interaction with the amino terminus of the protein and serves to ''lock'' the protein in a folded or closed conformation (12). It is proposed that Rho activation allows for Rho-GTP to bind to the GBD and release this molecule from autoinhibition. The FH1 and FH2 can then bind to effectors to mediate effects on the cytoskeleton. Intriguingly, the FH2 domain has recently been shown to be capable of nucleating actin filaments by itself in vitro, suggesting a complex interplay between the FH1 and FH2 domains along with their effectors for actin polymerization (12). However, it remains unclear how th...

Non-canonical Wnt signaling plays important roles during vertebrate embryogenesis and is required for cell motility during gastrulation. However, the molecular mechanisms of how Wnt signaling regulates modification of the actin cytoskeleton remain incompletely understood. We had previously identified the Formin homology protein Daam1 as an important link between Dishevelled and the Rho GTPase for cytoskeletal modulation. Here, we report that Profilin1 is an effector downstream of Daam1 required for cytoskeletal changes. Profilin1 interacted with the FH1 domain of Daam1 and was localized with Daam1 to actin stress fibers in response to Wnt signaling in mammalian cells. In addition, depletion of Profilin1 inhibited stress fiber formation induced by non-canonical Wnt signaling. Inhibition or depletion of Profilin1 in vivo specifically inhibited blastopore closure in Xenopus but did not affect convergent extension movements, tissue separation or neural fold closure. Our studies define a molecular pathway downstream of Daam1 that controls Wnt-mediated cytoskeletal reorganization for a specific morphogenetic process during vertebrate gastrulation.

During gastrulation, cells in the dorsal marginal zone polarize, elongate, align and intercalate to establish the physical body axis of the developing embryo. Here we demonstrate that the bifunctional channel-kinase TRPM7 is specifically required for vertebrate gastrulation. TRPM7 is temporally expressed maternally and throughout development, and is spatially enriched in tissues undergoing convergent extension during gastrulation. Functional studies reveal that TRPM7’s ion channel, but not its kinase, specifically affects cell polarity and convergent extension movements during gastrulation, independent of mesodermal specification. During gastrulation, the non-canonical Wnt pathway via Dishevelled (Dvl) orchestrates the activities of the GTPases Rho and Rac to control convergent extension movements. We find that TRPM7 functions synergistically with non-canonical Wnt signaling to regulate Rac activity. The phenotype caused by depletion of the Ca2+- and Mg2+-permeant TRPM7 is suppressed by expression of a dominant negative form of Rac, as well as by Mg2+ supplementation or by expression of the Mg2+ transporter SLC41A2. Together, these studies demonstrate an essential role for the ion channel TRPM7 and Mg2+ in Rac-dependent polarized cell movements during vertebrate gastrulation.

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Gastrulation is a critical morphogenetic event during vertebrate embryogenesis, and it is comprised of directional cell movement resulting from the polarization and reorganization of the actin cytoskeleton. The non-canonical Wnt signaling pathway has emerged as a key regulator of gastrulation. However, the molecular mechanisms by which the Wnt pathway mediates changes to the cellular actin cytoskeleton remains poorly defined. We had previously identified the Formin protein Daam1 and an effector molecule XProfilin1 as links for Wnt-mediated cytoskeletal changes during gastrulation. We report here the identification of XProfilin2 as a non-redundant and distinct effector of Daam1 for gastrulation. XProfilin2 interacts with FH1 domain of Daam1 and temporally interacts with Daam1 during gastrulation. In the Xenopus embryo, XProfilin2 is temporally expressed throughout embryogenesis and it is spatially expressed in cells undergoing morphogenetic movement during gastrulation. While we have previously shown XProfilin1 regulates blastopore closure, overexpression or depletion of XProfilin2 specifically affects convergent extension movement independent of mesodermal specification. Specifically, we show that XProfilin2 modulates cell polarization and axial alignment of mesodermal cells undergoing gastrulation independent of XProfilin1. Together, our studies demonstrate XProfilin2 and XProfilin1 are non-redundant effectors for Daam1 for non-canonical Wnt signaling and that they regulate distinct functions during vertebrate gastrulation.

The transcription factor AP2 (TFAP2) has an important role in regulating gene expression in both epidermis and neural crest cells. In order to further characterize these functions we have used a hormone inducible TFAP2α fusion protein in a Xenopus animal cap assay to identify downstream targets of this factor. The most common pattern comprised genes predominantly expressed in the epidermis. A second group was expressed at high levels in the neural crest, but all of these were also expressed in the epidermis as well as in other tissues in which TFAP2α has not been detected, suggesting modular control involving both TFAP2-dependent and TFAP2-independent components. In addition, a few strongly induced genes did not overlap at all in expression pattern with that of TFAP2α in the early embryo, and were also activated precociously in the experimentally manipulated ectoderm, and thus likely represent inappropriate regulatory interactions. A final group was identified that were repressed by TFAP2α and were expressed in the neural plate. These results provide further support for the importance of TFAP2α in ectoderm development, and also highlight the molecular linkage between the epidermis and neural crest in the Xenopus embryo.

Background: Managerial competencies are sets of knowledge, skills, behaviors and attitudes that a person needs to be effective in a diverse managerial job. This study sets out at assessing the level and gap of current actual and ideal required competency, important competency statement, and association between respondents' biographics with a current actual competency level of hospital manager. Methods:A cross-sectional survey used self-administered questionnaire based on Senior Management Service (SMS) competency framework of Department of Public Service and Administration (DPSA) for health manager consists of a set of eleven generic competencies conducted purposively in fifty-one hospital managers working within the Kathmandu Valley. Individual variables were summarized using frequency distribution focused on central tendency and dispersion. Relationships between variables analyzed by using one-way analysis of variance (ANOVA) and significance of difference in the competency profile determined by Wilcoxon signed rank test.Results: Highest self-assessed most developed competencies were honesty and integrity, service delivery innovation, and communication and information. The least developed were program and project management and knowledge management. Most important competencies regarded as strategic capability and leadership; and human resources management and empowerment. Significant gap exists in all generic competencies except communication and information and, honesty and integrity. There was no any significant association between respondents' biographics with current actual competency level. Conclusions:Findings back up the belief of managerial competency lacking and enormous need for development which reflects the local hospital management environment reality. Innovative approaches of management development programs and formal academic programs can improve and link the competency gap among hospital managers of Nepal.