Summary IQGAP1 regulates cell proliferation through a novel CDC42-mTOR pathway

Results suggest that a variety of potential pathogens may be isolated from young crias with diarrhea. Many crias shed coronavirus, which may also have been affecting older camelids. Protozoa were isolated most often during wetter months, suggesting that crias born during these months may have greater exposure to protozoal pathogens.

SummaryDefining the mechanisms that control cell growth and division is crucial to understanding cell homeostasis, which impacts human diseases such as cancer and diabetes. IQGAP1, a widely conserved effector and/or regulator of the GTPase CDC42, is a putative oncoprotein that controls cell proliferation; however, its mechanism in tumorigenesis is unknown. The mechanistic target of rapamycin (mTOR) pathway, the center of cell growth control, is commonly activated in human cancers, but has proved to be an ineffective clinical target because of an incomplete understanding of its mechanisms in cell growth inhibition. Using complementary studies in yeast and mammalian cells, we examined a potential role for IQGAP1 in regulating the negative feedback loop (NFL) of mTOR complex 1 (mTORC1) that controls cell growth. Two-hybrid screens identified the yeast TORC1-specific subunit Tco89p as an Iqg1p-binding partner, sharing roles in rapamycin-sensitive growth, axial-bud-site selection and cytokinesis, thus coupling cell growth and division. Mammalian IQGAP1 binds mTORC1 and Akt1 and in response to epidermal growth factor (EGF), cells expressing the mTORC1-Akt1-binding region (IQGAP1 IR-WW ) contained attenuated phosphorylated ERK1/2 (ERK1/2-P) activity and inactive glycogen synthase kinase 3a/b (GSK3a/b), which control apoptosis. Interestingly, these cells displayed a high level of Akt1 S473-P, but an attenuated level of the mTORC1-dependent kinase S6K1 T389-P and induced mTORC1-Akt1-and EGF-dependent transformed phenotypes. Moreover, IQGAP1 appears to influence cell abscission and its activity is elevated in carcinoma cell lines. These findings support the hypothesis that IQGAP1 acts upstream on the mTORC1-S6K1RAkt1 NFL and downstream of it, to couple cell growth and division, and thus like a rheostat, regulates cell homeostasis, dysregulation of which leads to tumorigenesis or other diseases. These results could have implications for the development of the next generation of anticancer therapeutics.Key words: IQGAP1, Proliferation, Secretion, mTOR IntroductionThe mechanisms that control cell proliferation continue to be central to cell biology research (Tapon et al., 2001;Sturgill and Hall, 2007;Moseley et al., 2009) and to understanding prevalent human diseases such as diabetes and cancer. The evolutionarily conserved serine/threonine protein kinase mechanistic target of rapamycin (mTOR), the center of cell growth control, interfaces nutrient and growth factor signals to regulate cell proliferation Sabatini, 2007, Sengupta et al., 2010). It is believed that mTOR couples cell growth and division by integrating the nutrient and growth factor signals through the phosphoinositide 3-kinase-RAC-a serine/threonine protein kinase-mTOR (PI3K-Akt1-mTOR) pathway to control cell size, a pre-requisite to entry into the cell cycle, but despite much progress, how the two activities are integrated remains unclear (Tapon et al., 2001;Fingar and Blenis, 2004;Sabatini, 2006;Wullschleger et al., 2006;Polak and Hall, 2006;Sturgill and Hal...

Campylobacter jejuni was inoculated intravenously into pregnant ewes on gestation days 1 14 and 123 to reproduce ovine abortion. All ewes aborted 7-1 2 days post-inoculation. High numbers of C. jejuni were isolated from ewe tissues (caruncle, bile, cecal feces), fetal tissues, and placenta. C. jejuni colonies were identified in caruncles and placenta by light microscopy and immunoperoxidase techniques. Histologically, inoculated ewes had a severe purulent endometritis with vasculitis. Placentas from inoculated ewes and field cases showed necrosis and purulent inflammation; however, placentas from inoculated ewes had large numbers of bacterial colonies compared to few bacteria found in field cases. Histologically, only one fetus from the inoculated ewes showed lesions (purulent bronchopneumonia), whereas all fetuses from field cases had a distinct bronchopneumonia, and one fetus showed multifocal hepatic necrosis. These results suggest that C. jejuni (serotypes Penner 1 and Lior 2) is an important abortifacient organism for sheep. Campylobacteriosis is a highly contagious and economically significant disease in sheep and is most often caused by Campylobacter fetus subspecies fetus (previously named C. fetus var. intestinalis).15.32 It is characterized by abortion (third trimester), stillbirths, premature births, weak lambs, and occasional ewe deaths due to m e t r i t i~. '~,~~ Grossly, aborted or stillborn fetuses may have no lesions or they may show subcutaneous serosanguineous edema, serosanguineous body fluids, discrete necrotic liver lesions, or bronchopneumonia. Placental cotyledons are enlarged, yellowish, and covered with blood-tinged exudate, while the intercotyledonary stroma is edematous. Microscopically, placental lesions, which are predominant in hilar zones, consist of septa1 necrosis, arteriolitis, leukocyte infiltration, and accumulation of high numbers of bacteria within lacunae, chorionic trophoblasts, and endothelial cells. In humans, Campylobacter jejuni is recognized to be a common cause of acute dia~-rhea,~J~ and is associated with abortion and neonatal sepsis.33 Campylobacter organisms are small, curved, highly motile, noncapsulated, microaerophilic, gram-nega

Prostate cancer (PC) is a leading cause of death in men however the factors that regulate its progression and eventual metastasis to bone remain unclear. Here we show that WISP1/CCN4 expression in prostate cancer tissues was up-regulated in early stages of the disease and, further, that it correlated with increased circulating levels of WISP1 in the sera of patients at early stages of the disease. WISP1 was also elevated in the mouse prostate cancer model TRAMP in the hypoplastic diseased tissue that develops prior to advanced carcinoma formation. When the ability of anti-WISP1 antibodies to reduce the spread of PC3-Luc cells to distant sites was tested it showed that twice weekly injections of anti-WISP1 antibodies reduced the number and overall size of distant tumors developed after intracardiac (IC) injection of PC3-Luc cells in mice. The ability of antibodies against WISP1 to inhibit growth of PC3-Luc cancer cells in mice was also evaluated and showed that twice weekly injections of anti-WISP1 antibodies reduced local tumor growth when examined in xenografts. To better understand the mechanism of action, the migration of PC3-Luc cells through membranes with or without a Matrigel™ barrier showed the cells were attracted to WISP1, and that this attraction was inhibited by treatment with anti-WISP1 antibodies. We also show the expression of WISP1 at the bone-tumor interface and in the stroma of early grade cancers suggested WISP1 expression is well placed to play roles in both fostering growth of the cancer and its spread to bone. In summary, the up-regulation of WISP1 in the early stages of cancer development coupled with its ability to inhibit spread and growth of prostate cancer cells makes it both a potential target and an accessible diagnostic marker for prostate cancer.