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  • The Rho GTPase Cdc42 is required for primary mammary epithelial cell morphogenesis in vitro. 22292127

    The Rho GTPase Cdc42 is overexpressed and hyperactivated in breast cancer, and several studies have described mechanisms by which it may promote tumor formation and progression. However, little is known about the role of Cdc42 during normal mammary epithelial cell (MEC) morphogenesis. Here we aimed to define the precise role for Cdc42 during primary mammary acinus formation in vitro. For these studies, MECs were isolated from Cdc42fl/fl conditional knockout mice, transduced with Adeno-cre-GFP virus to delete Cdc42 or Adeno-GFP control virus, and effects on morphogenesis were investigated using a three-dimensional (3D) culture assay. Interestingly, markedly fewer mammary acini developed in Cdc42 deficient cultures, and the acini that formed were significantly smaller and disorganized. Cellular proliferation and survival were reduced in the Cdc42 deficient acini. However, control and knockout MECs cultured as monolayers displayed similar cell cycle profiles, suggesting that Cdc42 is important for MEC proliferation in the context of 3D polarity. Overexpression of cyclin D1, which promotes cell cycle progression downstream of Cdc42, failed to rescue the defect in acinus size. Furthermore, lumen formation and apical-basal polarity were disrupted, and mitotic spindle orientation and Cdc42/aPKC polarity complex defects likely contributed to these phenotypes. Studies using dominant negative Cdc42 and siRNa to knockdown Cdc42 in MDcK and Caco-2 cell lines undergoing cystogenesis in 3D cultures revealed critical roles for Cdc42 in spindle orientation, polarity and lumen formation. Our studies, using complete knockout in primary epithelial cells, demonstrate that Cdc42 is not only an important regulator of polarity and lumen formation; it is also essential for proliferation and survival, which are key cellular processes that drive MEC morphogenesis in vitro and in vivo.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • The Rho kinase inhibitor Fasudil up-regulates astrocytic glutamate transport subsequent to actin remodelling in murine cultured astrocytes. 21309758

    Glutamate transporters play a major role in maintaining brain homeostasis and the astrocytic transporters, EAAT1 and EAAT2, are functionally dominant. Astrocytic excitatory amino acid transporters (EAATs) play important roles in various neuropathologies wherein astrocytes undergo cytoskeletal changes. Astrocytic plasticity is well documented, but the interface between EAAT function, actin and the astrocytic cytoskeleton is poorly understood. Because Rho kinase (ROCK) is a key determinant of actin polymerization, we investigated the effects of ROCK inhibitors on EAAT activity and astrocytic morphology.
    Document Type:
    Reference
    Product Catalog Number:
    AB141
  • Roles of Rho guanosine 5'-triphosphatase A, Rho kinases, and extracellular signal regulated kinase (1/2) in prostaglandin E2-mediated migration of first-trimester human e ... 18079197

    Prostaglandin (PG) E(2) may regulate invasiveness of human placenta because we previously reported stimulation of migration of placental trophoblasts by PGE(2) acting through PGE receptor (EP)-1 and activating calpain. RhoA GTPase and its important effector Rho kinase (ROCK) have also been previously shown to regulate trophoblast migration. Using immortalized HTR-8/SVneo trophoblast cells and first-trimester human chorionic villus explant cultures on matrigel, we further examined the role of RhoA/ROCK and MAPK (ERK1/2) pathways on PGE(2)-mediated stimulation of trophoblast migration. Migration of cytotrophoblasts was shown to be inhibited by treatment of the trophoblast cell line and chorionic villus explants with either cell-permeable C3 transferase or selective RhoA small interfering RNA. These inhibitions were significantly mitigated by the addition of PGE(2), an EP1/EP3 agonist or an EP3/EP4 agonist, suggesting that RhoA plays an important role in trophoblast migration but may not be obligatory for PGE(2) action. Treatment of HTR-8/SVneo cells with nonselective ROCK inhibitor Y27632 or ROCK small interfering RNAs inhibited migration of these cells, which could not be rescued with PGE(2) or the other two EP agonists, suggesting the obligatory role of ROCK in PGE(2)-induced migratory response. Furthermore, U0126, an inhibitor of MAPK kinases MEK1 and MEK2, abrogated PGE(2)-induced migration of trophoblasts, and PGE(2) or the other two EP agonists stimulated ERK1/2 activation in trophoblasts, which was not abrogated by pretreatment with C3 transferase, indicating that ERK signaling pathway is an efficient alternate pathway for RhoA in PGE(2)-mediated migration of trophoblasts. These results suggest that ROCK and ERK1/2 play more important roles than RhoA in PGE(2)-mediated migration stimulation of first-trimester trophoblasts.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • The Rho GTPase effector ROCK regulates cyclin A, cyclin D1, and p27Kip1 levels by distinct mechanisms. 16738326

    The members of the Rho GTPase family are well known for their regulation of actin cytoskeletal structures. In addition, they influence progression through the cell cycle. The RhoA and RhoC proteins regulate numerous effector proteins, with a central and vital signaling role mediated by the ROCK I and ROCK II serine/threonine kinases. The requirement for ROCK function in the proliferation of numerous cell types has been revealed by studies utilizing ROCK-selective inhibitors such as Y-27632. However, the mechanisms by which ROCK signaling promotes cell cycle progression have not been thoroughly characterized. Using a conditionally activated ROCK-estrogen receptor fusion protein, we found that ROCK activation is sufficient to stimulate G1/S cell cycle progression in NIH 3T3 mouse fibroblasts. Further analysis revealed that ROCK acts via independent pathways to alter the levels of cell cycle regulatory proteins: cyclin D1 and p21(Cip1) elevation via Ras and the mitogen-activated protein kinase pathway, increased cyclin A via LIM kinase 2, and reduction of p27(Kip1) protein levels. Therefore, the influence of ROCK on cell cycle regulatory proteins occurs by multiple independent mechanisms.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple
  • Rho activity can alter the translation of p27 mRNA and is important for RasV12-induced transformation in a manner dependent on p27 status. 11875067

    The amount of p27(Kip1) establishes a threshold to which G(1) cyclin-cyclin-dependent kinase complexes must surpass prior to cells progressing into S-phase. The amount of p27 is greatest in G(0) cells, intermediate in G(1) cells, and lowest in S-phase cells. However, there is little known regarding the pathways and mechanisms controlling p27 accumulation in G(0) cells. We report that inhibition of Rho, by either lovastatin or C3 exoenzyme, can increase the translational efficiency of p27 mRNA. Similar pharmacologic inhibition of the phosphatidylinositol 3-kinase, the S6 kinase, and the Mek1 kinase pathways all fail to increase translational efficiency in MDA468 cells. This Rho-responsive element lies within a 300-nucleotide region at the 3'-end of the mRNA. By supporting the significance of this signaling pathway to Rho function, we showed that the suppression of Ras(V12) transformation by RhoA(N19) is blocked in p27-/- cells. In contrast this activity is not blocked in Rb-/- or p16-/- cells. The resistance of p27-/- cells to RhoA(N19) is not associated with a failure of RhoA(N19) to accumulate to amounts sufficient to block Rho activity as measured by the organization of actin stress fibers. Together these results indicate a link between Rho and p27.
    Document Type:
    Reference
    Product Catalog Number:
    06-182