Survey of the Endogonaceae in Minnesota With Synoptic Keys to Genera and Species

Sixteen species in the Endogonaceae (Zygomycotina) were identified from 22 different plant species from a native prairie, an intensively cultivated vegetable field, a reclaimed iron ore tailings basin, an undisturbed site adjacent to the iron ore tailings basin, and from a Pinus resinosa plantation. Seven species of Endogonaceae identified in this study are new records for Minnesota. Synoptic keys to genera and species are presented

Growing Broccoli and Cauliflower in Minnesota

This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Commercial Vegetable Weed, Insect, and Disease Control Guide: Beets, Carrots, Lettuce, Onions, Parsnips, Radishes, Rutabagas, Turnips, Spinach (Revised 1983)

This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Identification of retinoic acid-regulated nuclear matrix-associated protein as a novel regulator of gastric cancer

Background: Retinoic acid-regulated nuclear matrix-associated protein (RAMP) is a WD40 repeat-containing protein that is involved in various biological functions, but little is known about its role in human cancer. This study aims to delineate the oncogenic role of RAMP in gastric carcinogenesis

APCcdh1 Mediates Degradation of the Oncogenic Rho-GEF Ect2 after Mitosis

Background: Besides regulation of actin cytoskeleton-dependent functions, Rho GTPase pathways are essential to cell cycle progression and cell division. Rho, Rac and Cdc42 regulate G1 to S phase progression and are involved in cytokinesis. RhoA GDP/GTP cycling is required for normal cytokinesis and recent reports have shown that the exchange factor Ect2 and the GTPase activating protein MgcRacGAP regulate RhoA activity during mitosis. We previously showed that the transcription factors E2F1 and CUX1 regulate expression of MgcRacGAP and Ect2 as cells enter S-phase. Methodology/Principal Findings: We now report that Ect2 is subject to proteasomal degradation after mitosis, following ubiquitination by the APC/C complex and its co-activator Cdh1. A proper nuclear localization of Ect2 is necessary for its degradation. APC-Cdh1 assembles K11-linked poly-ubiquitin chains on Ect2, depending upon a stretch of,25 amino acid residues that contain a bi-partite NLS, a conventional D-box and two TEK-like boxes. Site-directed mutagenesis of target sequences generated stabilized Ect2 proteins. Furthermore, such degradation-resistant mutants of Ect2 were found to activate RhoA and subsequent signalling pathways and are able to transform NIH3T3 cells. Conclusions/Significance: Our results identify Ect2 as a bona fide cell cycle-regulated protein and suggest that its ubiquitination-dependent degradation may play an important role in RhoA regulation at the time of mitosis. Our findings raise the possibility that the overexpression of Ect2 that has been reported in some human tumors might result not only from deregulated transcription, but also from impaired degradation

Expression of Constitutively Active CDK1 Stabilizes APC-Cdh1 Substrates and Potentiates Premature Spindle Assembly and Checkpoint Function in G1 Cells

Mitotic progression in eukaryotic cells depends upon the activation of cyclin-dependent kinase 1 (CDK1), followed by its inactivation through the anaphase-promoting complex (APC)/cyclosome-mediated degradation of M-phase cyclins. Previous work revealed that expression of a constitutively active CDK1 (CDK1AF) in HeLa cells permitted their division, but yielded G1 daughter cells that underwent premature S-phase and early mitotic events. While CDK1AF was found to impede the sustained activity of APC-Cdh1, it was unknown if this defect improperly stabilized mitotic substrates and contributed to the occurrence of these premature M phases. Here, we show that CDK1AF expression in HeLa cells improperly stabilized APC-Cdh1 substrates in G1-phase daughter cells, including mitotic kinases and the APC adaptor, Cdc20. Division of CDK1AF-expressing cells produced G1 daughters with an accelerated S-phase onset, interrupted by the formation of premature bipolar spindles capable of spindle assembly checkpoint function. Further characterization of these phenotypes induced by CDK1AF expression revealed that this early spindle formation depended upon premature CDK1 and Aurora B activities, and their inhibition induced rapid spindle disassembly. Following its normal M-phase degradation, we found that the absence of Wee1 in these prematurely cycling daughter cells permitted the endogenous CDK1 to contribute to these premature mitotic events, since expression of a non-degradable Wee1 reduced the number of cells that exhibited premature cyclin B1oscillations. Lastly, we discovered that Cdh1-ablated cells could not be forced into a premature M phase, despite cyclin B1 overexpression and proteasome inhibition. Together, these results demonstrate that expression of constitutively active CDK1AF hampers the destruction of critical APC-Cdh1 targets, and that this type of condition could prevent newly divided cells from properly maintaining a prolonged interphase state. We propose that this more subtle type of defect in activity of the APC-driven negative-feedback loop may have implications for triggering genome instability and tumorigenesis

Polo-Like Kinase-1 Controls Aurora A Destruction by Activating APC/C-Cdh1

Polo-like kinase-1 (Plk1) is activated before mitosis by Aurora A and its cofactor Bora. In mitosis, Bora is degraded in a manner dependent on Plk1 kinase activity and the E3 ubiquitin ligase SCF-βTrCP. Here, we show that Plk1 is also required for the timely destruction of its activator Aurora A in late anaphase. It has been shown that Aurora A destruction is controlled by the auxiliary subunit Cdh1 of the Anaphase-Promoting Complex/Cyclosome (APC/C). Remarkably, we found that Plk1-depletion prevented the efficient dephosphorylation of Cdh1 during mitotic exit. Plk1 mediated its effect on Cdh1, at least in part, through direct phosphorylation of the human phosphatase Cdc14A, controlling the phosphorylation state of Cdh1. We conclude that Plk1 facilitates efficient Aurora A degradation through APC/C-Cdh1 activation after mitosis, with a potential role for hCdc14A

Hedgehog-Regulated Ubiquitination Controls Smoothened Trafficking and Cell Surface Expression in Drosophila

Hedgehog transduces signal by promoting cell surface expression of the seven-transmembrane protein Smoothened (Smo) in Drosophila, but the underlying mechanism remains unknown. Here we demonstrate that Smo is downregulated by ubiquitin-mediated endocytosis and degradation, and that Hh increases Smo cell surface expression by inhibiting its ubiquitination. We find that Smo is ubiquitinated at multiple Lysine residues including those in its autoinhibitory domain (SAID), leading to endocytosis and degradation of Smo by both lysosome- and proteasome-dependent mechanisms. Hh inhibits Smo ubiquitination via PKA/CK1-mediated phosphorylation of SAID, leading to Smo cell surface accumulation. Inactivation of the ubiquitin activating enzyme Uba1 or perturbation of multiple components of the endocytic machinery leads to Smo accumulation and Hh pathway activation. In addition, we find that the non-visual β-arrestin Kurtz (Krz) interacts with Smo and acts in parallel with ubiquitination to downregulate Smo. Finally, we show that Smo ubiquitination is counteracted by the deubiquitinating enzyme UBPY/USP8. Gain and loss of UBPY lead to reciprocal changes in Smo cell surface expression. Taken together, our results suggest that ubiquitination plays a key role in the downregulation of Smo to keep Hh pathway activity off in the absence of the ligand, and that Hh-induced phosphorylation promotes Smo cell surface accumulation by inhibiting its ubiquitination, which contributes to Hh pathway activation