Annexin II/annexin II receptor axis regulates adhesion, migration, homing, and growth of prostate cancer

One of the most life-threatening complications of prostate cancer is skeletal metastasis. In order to develop treatment for metastasis, it is important to understand its molecular mechanisms. Our work in this field has drawn parallels between hematopoietic stem cell and prostate cancer homing to the marrow. Our recent work demonstrated that annexin II expressed by osteoblasts and endothelial cells plays a critical role in niche selection. In this study, we demonstrate that annexin II and its receptor play a crucial role in establishing metastasis of prostate cancer. Prostate cancer cell lines migrate toward annexin II and the adhesion of prostate cancer to osteoblasts and endothelial cells was inhibited by annexin II. By blocking annexin II or its receptor in animal models, short-term and long-term localization of prostate cancers are limited. Annexin II may also facilitate the growth of prostate cancer in vitro and in vivo by the MAPK pathway. These data strongly suggest that annexin II and its receptor axis plays a central role in prostate cancer metastasis, and that prostate cancer utilize the hematopoietic stem cell homing mechanisms to gain access to the niche.     

Composition,size, and biomass of zooplankton in large productive Florida lakes

Crustacean zooplankton data were compiled from long-term observational studies at seven large shallow Florida lakes, to determine whether there are general characteristics in regard to species composition, body size, and biomass. In particular, we examined whether patterns in body size and species richness fit empirical models developed by Stanley Dodson. The lakes included range in size from 125 to 1730 km² and encompass mesotrophic to hyper-eutrophic conditions. We found that zooplankton biomass was strongly dominated by one species of calanoid copepod—Arctodiaptomus dorsalis. Large daphnids were absent, and Cladocera assemblages were dominated by small taxa such as Ceriodaphnia, Chydorus, and Eubosmina. The total number of species of pelagic cladocerans (8–12) was consistent with Dodson’s predictions based on lake area. The average size of crustacean zooplankton in Florida lakes is small in comparison with temperate communities. A. dorsalis is the smallest calanoid copepod in North America, and the mean length of Cladocera (0.6 mm) is consistent with Dodson’s results that size decreases from temperate to tropical zones. Total biomass of crustacean zooplankton was very low, ratios of zooplankton to phytoplankton biomass (0.01–0.1) are among the lowest reported in the literature, and the zooplankton displayed short-lasting early spring peaks in biomass. Cladocera were almost entirely absent in spring and summer. Factors known to occur in Florida lakes, which appear to explain these characteristics of biomass, include intense fish predation and high summer water temperature.     

Carbon dynamics in the 'grazing food chain' of a subtropical lake

Studies were conducted over a 13 month period at four pelagicsites in eutrophic Lake Okeechobee, Florida (USA), in orderto quantify carbon (C) uptake rates by size-fractionated phytoplankton,and subsequent transfers of C to zooplankton. This was accomplishedusing laboratory ¹⁴C tracer methods and natural plankton assemblages.The annual biomass of picoplankton (<2 µm), nanoplankton(2–20 µm) and microplankton (<20 µm averaged60, 389 and 100 µg C 1^–1 respectively, while correspondingrates of C uptake averaged 7, 51 and 13 µg C1^–1h^–1. The biomass of microzooplankton (40–200 µm)and macrozooplankton (<200 µm averaged 18 and 60 µgC 1^–1, respectively, while C uptake rates by these herbivoregroups averaged 2 and 3 µg C 1^–1 h^–1. Therewere no strong seasonal patterns in any of the plankton metrics.The ratio of zooplankton to phytoplankton C uptake averaged7% over the course of the study. This low value is typical ofthat observed in eutrophic temperate lakes with small zooplanktonand large inedible phytoplankton, and indicates ineffectiveC transfer in the grazing food chain. On a single occasion,there was a high density (<40 1^–1) of Daphnia lumholrzii,a large-bodied exotic cladoceran. At that time, zooplanktoncommunity C uptake was <20 µg C 1^–1 h^–1and the ratio of zooplankton to phytoplankton C uptake was near30%. If D.lumholrzii proliferates in Lake Okeechobee and theother Florida lakes where it has recently been observed, itmay substantially alter planktonic C dynamics.     

STUDY ON THE PROLIFERATIVE STATE OF HAEMOPOIETIC STEM CELLS (CFU)

Hydroxyurea was used to study the proliferation rate of haemopoietic stem cells (CFUJ in normal mice, after irradiation or transplantation into irradiated recipients. It was demonstrated that the proliferation rate of endogenous CFU_S (endo-CFU,) and exogenous CFU_S (exo-CFU_s) are identical. After irradiation (650 R) the surviving endo-CFU_s begin to proliferate immediately. By contrast exo-CFU, transplanted into the irradiated recipient mouse (850 R), begin to proliferate only after about 30 hr. However, injection of isoproterenol (which stimulates adenyl cyclase) or dibutyryl cyclic adenosine 3′,5′-monophosphate shortly after marrow cell graft, triggers the transplanted CFU_S into cell cycle as shown by an almost immediately increased sensitivity to hydroxyurea. Isoproterenol is capable of inducing DNA synthesis also in stem cells of normal mice but it takes about 20 hr before CFU, become to be increasingly sensitive to hydroxyurea.     

An Experimental Analysis of the Acid Sensitivity of the Common Planktonic Rotifer Keratella cochlearis

An in situ mesocosm experiment was performed at neutral pH Lake O'Woods, West Virginia, to assess the impacts of acidification on the common planktonic rotifer Keratella cochlearis. This rotifer is typically replaced by K. taurocephala during the acidification of North American lakes. Despite a rapid pH reduction in this experiment (from 7.0 to 4.8 in 14 days), the abundance, mean body length and egg ratio of K. cochlearis did not decline in the acid treatment as compared to the untreated control. These results support the hypothesis that K. cochlearis is acid-tolerant, and suggest that its disappearance from acid lakes is the result of biotic interactions within the plankton, rather than the result of toxic effects of altered water chemistry.     

Comparative analysis of nutrients,chlorophyll and transparency in two large shallow lakes (Lake Taihu,P.R. China and Lake Okeechobee,USA)

This article compares limnological attributes of two of the world’s largest shallow lakes—Lake Okeechobee in Florida, USA and Lake Taihu in P.R. China. Both the systems support an array of ecological and societal values including fish and wildlife habitat, public water supply, flood protection, and recreation. Both have extensive research programs, largely because of concern regarding the lakes’ frequent cyanobacterial blooms. By evaluating these systems together, we compare and contrast properties that can generally advance the understanding and management of large shallow lowland lakes. Because of shallow depth, long fetch, and unconsolidated mud sediments, water chemistry, and transparency in both the lakes are strongly influenced by resuspended sediments that affect light and nutrient conditions. In the central region of both the lakes, where depth is the greatest, evaluation of limiting factors by a trophic state index approach indicates that light most often limits phytoplankton biomass. In contrast, the more sheltered shoreline areas of both the lakes display evidence of nitrogen (N) limitation, which also has been confirmed in nutrient assays conducted in earlier studies. This N limitation most likely is a result of excessive levels of phosphorus (P) that have developed in the lakes due to high external loads over recent decades and the currently high internal P recycling. Comparisons of these lakes show that Lake Taihu has higher N than, similar total phosphorus (TP) and similar light conditions to that of Lake Okeechobee, but less chlorophyll a (CHL). The latter may be as a result of lower winter temperatures in Lake Taihu (around 5°C) compared to Lake Okeechobee (around 15°C), which could reduce phytoplankton growth and abundance through the other seasons of the year. In these systems, the important role of light, temperature, and nutrients in algal bloom dynamics must be considered, especially due to possible adverse and unintended effects that might occur with projects such as sediment removal, and in the long term, in regard to buffering lake responses to external load reduction. Handling editor: D. Hamilton     

Human Papillomavirus Type 16 Infection of Human Keratinocytes Requires Clathrin and Caveolin-1 and Is Brefeldin A Sensitive

Human papillomavirus type 16 (HPV16) has been identified as being the most common etiological agent leading to cervical cancer. Despite having a clear understanding of the role of HPV16 in oncogenesis, details of how HPV16 traffics during infection are poorly understood. HPV16 has been determined to enter via clathrin-mediated endocytosis, but the subsequent steps of HPV16 infection remain unclear. There is emerging evidence that several viruses take advantage of cross talk between routes of endocytosis. Specifically, JCV and bovine papillomavirus type 1 have been shown to enter cells by clathrin-dependent endocytosis and then require caveolin-1-mediated trafficking for infection. In this paper, we show that HPV16 is dependent on caveolin-1 after clathrin-mediated endocytosis. We provide evidence for the first time that HPV16 infection is dependent on trafficking to the endoplasmic reticulum (ER). This novel trafficking may explain the requirement for the caveolar pathway in HPV16 infection because clathrin-mediated endocytosis typically does not lead to the ER. Our data indicate that the infectious route for HPV16 following clathrin-mediated entry is caveolin-1 and COPI dependent. An understanding of the steps involved in HPV16 sorting and trafficking opens up the possibility of developing novel approaches to interfere with HPV16 infection and reduce the burden of papillomavirus diseases including cervical cancer.Human papillomavirus (PV) type 16 (HPV16) is a member of the family Papillomaviridae, a group of double-stranded DNA (dsDNA) viruses with a tropism for squamous epithelia (70). Most PV infections result in benign lesions, although a subset of high-risk HPVs are capable of malignant transformation, resulting in various cancers including cervical carcinoma (21, 38). Infection with HPV16 is responsible for causing approximately half of the cases of invasive cervical cancer (7). In spite of the link between HPV16 and cervical cancer, the intracellular movement of HPV16 through target keratinocyte cells during infection has not been defined in detail.Viruses can enter into target cells by taking advantage of the cell''s natural endocytosis machinery (60). One of the best-characterized modes of internalization is by receptor-mediated, clathrin-dependent endocytosis. In this mode of entry, clathrin-coated pits internalize cargo into clathrin-coated vesicles, which are pinched from the plasma membrane by dynamin-2 in order to internalize (68). The process of clathrin-mediated endocytosis occurs rapidly, resulting in the delivery of cargo to early/sorting endosomes within seconds to minutes (23, 31). From the sorting endosome, most clathrin-dependent ligands are trafficked back to the plasma membrane in recycling endosomes or to lysosomes for degradation (35, 56). Another well-studied model of ligand entry is caveolin-1-mediated endocytosis. The caveolar pathway typically involves entry via cholesterol-rich caveolae at the plasma membrane, which deliver their contents to pH-neutral organelles known as caveosomes (44, 65). The delivery of cargo from caveosomes to the Golgi apparatus and the endoplasmic reticulum (ER) was demonstrated previously (44, 46, 50). The traffickings of cargo internalized via clathrin- and caveolin-1-mediated endocytosis were once thought to be separate; however, it is becoming evident that viruses including bovine PV type 1 (BPV1), JCV, HPV31, and BKV rely on both pathways depending on the stage of infection (29, 32, 50, 63).PV internalization is preceded by virion attachment to the extracellular matrix, followed by binding to heparan sulfate (14, 15, 25). The involvement of a secondary receptor has been suggested, putatively an alpha-6 integrin (24, 37). Postbinding, a conformational change in the PV capsid results in a furin cleavage event at the N terminus of the minor capsid protein L2, which has been suggested to play a role in the endosomal escape of the viral genome (19, 30, 52). An increasing body of evidence supports the entry of HPV16 by clathrin-mediated endocytosis (9, 27, 62). Electron microscopy of HPV16 infection in COS-7 cells demonstrated HPV16 pseudovirions in clathrin-coated vesicles 20 min after entry and within structures resembling endosomes by 1 h postentry (9). HPV16 infection of HaCaT keratinocyte, COS-7, and 293TT cells has been blocked by chlorpromazine, an inhibitor of the formation of clathrin-coated pits (9, 27, 62, 67). Importantly, those studies showed that two inhibitors of caveolin-1-mediated internalization, filipin and nystatin, did not interfere with HPV16 infection (9, 27, 62). Our laboratory demonstrated the importance of dynamin in HPV16 infection, presumably in the scission of clathrin-coated vesicles from the plasma membrane (1). Recently, a clathrin-, caveolin-, and dynamin-independent endocytosis of HPV16 was suggested, although the use of the HPV18-positive, heteroploid HeLa cell line calls into question the relevance of this finding to natural infection (64).In a previous study, we described the postentry trafficking of BPV1 from endosomes to caveolin-1-positive vesicles, similarly to a related nonenveloped dsDNA virus, JCV (32, 50). Our data demonstrated that the infectious route of BPV1 involved entry by clathrin-mediated endocytosis followed by transport to the caveolar pathway in order to traffic to the ER (32). We found that BPV1 infection was neutralized by an antibody that prevented viral particle transport to the ER (33). The movement of BPV1 from the endosome to the caveosome provides a possible explanation for why BPV1 trafficking is so slow compared to those of other ligands of clathrin-mediated endocytosis (20, 26). The kinetics of BPV1 and HPV16 entry were previously reported to be identical, and the coincident internalization of HPV16 and BPV1 virus-like particles (VLPs) showed colocalization between the VLPs during infection (20, 62). These data suggest that HPV16 and BPV1 infection may be occurring by a similar mechanism.Our goal in the present study was to determine the intracellular trafficking events leading to HPV16 infection. The use of reporter virion technology has allowed the production of high-titer HPV16 virions by a method previously shown to yield virions that are infectious in vivo (16). In this study, we used HPV16 reporter virions to study HPV16 infection in the spontaneously immortalized human HaCaT keratinocyte cell line. Our data show that the infectious route of HPV16 is from early endosomes to caveolin-1-positive vesicles and then to the ER. Using immunofluorescence and short hairpin RNA (shRNA) against caveolin-1, we demonstrate the importance of the caveolar pathway after HPV16 has been internalized. We show that HPV16 infection was blocked by inhibiting the formation of COPI transport vesicles, which function in trafficking between the ER and the Golgi apparatus and from caveosomes to the ER (5, 39). We provide evidence that after reaching the caveosome, HPV16 requires passage to the ER for successful infection, a trafficking event made possible by COPI vesicle-mediated movement from the caveosome to the ER.