Two novel human NUMB isoforms provide a potential link between development and cancer

We previously identified four functionally distinct human NUMB isoforms. Here, we report the identification of two additional isoforms and propose a link between the expression of these isoforms and cancer. These novel isoforms, NUMB5 and NUMB6, lack exon 10 and are expressed in cells known for polarity and migratory behavior, such as human amniotic fluid cells, glioblastoma and metastatic tumor cells. RT-PCR and luciferase assays demonstrate that NUMB5 and NUMB6 are less antagonistic to NOTCH signaling than other NUMB isoforms. Immunocytochemistry analyses show that NUMB5 and NUMB6 interact and complex with CDC42, vimentin and the CDC42 regulator IQGAP1 (IQ (motif) GTPase activating protein 1). Furthermore, the ectopic expression of NUMB5 and NUMB6 induces the formation of lamellipodia (NUMB5) and filopodia (NUMB6) in a CDC42- and RAC1-dependent manner. These results are complemented by in vitro and in vivo studies, demonstrating that NUMB5 and NUMB6 alter the migratory behavior of cells. Together, these novel isoforms may play a role in further understanding the NUMB function in development and cancer

A five-year hedonic price breakdown for desktop personal computer attributes in Brazil

The purpose of this article is to identify the attributes that discriminate the prices of personal desktop computers. We employ the hedonic price method in evaluating such characteristics. This approach allows market prices to be expressed as a function, a set of attributes present in the products and services offered. Prices and characteristics of up to 3,779 desktop personal computers offered in the IT pages of one of the main Brazilian newspapers were collected from January 2003 to December 2007. Several specifications for the hedonic (multivariate) linear regression were tested. In this particular study, the main attributes were found to be hard drive capacity, screen technology, main board brand, random memory size, microprocessor brand, video board memory, digital video and compact disk recording devices, screen size and microprocessor speed. These results highlight the novel contribution of this study: the manner and means in which hedonic price indexes may be estimated in Brazil

Our file Narre refdrenca

copies of this thesis in microfom, paper or electronic formats. The author retains ownership of the copyright in this thesis. Neither the thesis nor substantial extracts kom it may be printed or othenvise reproduced without the author7s permission. L'auteur a accordé une licence non exclusive permettant à la Bibliothèque nationale du Canada de reproduire, prêter, distribuer ou vendre des copies de cette thèse sous la forme de microfiche/fïlm, de reproduction sur papier ou sur forma

Retinoic acid regulates Sox2 expression during neuronal and glial differentiation in mouse P19 cells

Retinoic acid (RA) is a small lipophilic molecule that plays important roles in embryonic development by regulating cell proliferation, signaling and differentiation. There is compelling evidence that RA signaling controls the expression of a number of transcription factors in a spatio-temporal manner during these processes. In particular, Sox2, a transcription factor known for its involvement in stem cell fate commitment and neurogenesis may serve as a target of RA. In this study, we have used mouse embryonic carcinoma (EC) P19 cells to examine the effect of RA on Sox2 expression during neuronal and glial differentiation. Undifferentiated P19 cells express abundant levels of Sox2 during proliferation, a fact further supported by Sox2-DNA interaction throughout various stages of mitosis. In the presence of RA, P19 cells form embryonic bodies (EB) and differentiate into neurons and astrocytes in a chronological order similar to that of cell differentiation in the brain. RT-PCR, western blot and immunocytochemistry analyses show that the level of Sox2 is significantly reduced in P19 cells, as they differentiate into neurons, whereas P19 astrocytes maintain Sox2 expression. These results show that Sox2 is differentially expressed during neurogenesis and gliogenesis, suggesting its distinct functions throughout these processes.NRC publication: Ye

Differentiation of mouse Neuro 2A cells into dopamine neurons

Neuro 2A (N2a) is a mouse neural crest-derived cell line that has been extensively used to study neuronal differentiation, axonal growth and signaling pathways. A convenient characteristic of these cells is their ability to differentiate into neurons within a few days. However, most differentiation methods reported for N2a cells do not provide information about the neuronal types obtained after each treatment. In this study, we evaluated the generation of N2a dopamine neurons following treatment with a number of factors known to induce neuronal differentiation. Our results showed that N2a cells express Nurr-related factor 1 (Nurr1) and produce low levels of tyrosine hydroxylase (TH) and dopamine. Both TH and dopamine levels were significantly enhanced in the presence of dibutyryl cyclic adenosine monophosphate (dbcAMP), as evidenced by Western blot, immunocytochemistry and high performance liquid chromatography (HPLC). In contrast to dbcAMP, other factors such as transforming growth factor \u3b21 (TGF\u3b21), bone morphogenetic protein 4 (BMP4), glial cell-derived neurotrophic factor (GDNF) and retinoic acid (RA) did not increase TH expression. Further investigation confirmed that the effect of dbcAMP on production of TH-positive neurons was mediated through cyclic AMP (cAMP) responsive element binding protein (CREB) and it was antagonized by RA. Thus, although various treatments can be used to generate N2a neurons, only dbcAMP significantly enhanced the formation of dopamine neurons. Taken together, this study provided a simple and reliable method to generate dopamine neurons for rapid and efficient physiological and pharmacological assays.Peer reviewed: YesNRC publication: Ye

Applications of amniotic membrane and fluid in stem cell biology and regenerative medicine

The amniotic membrane (AM) and amniotic fluid (AF) have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications.Peer reviewed: YesNRC publication: Ye

Chronic hyperhomocysteinemia impairs vascular function in ovariectomized rat carotid arteries

Homocysteine is an independent risk factor for coronary heart disease, as well as for cerebrovascular and peripheral vascular diseases. The purpose of this study was to investigate the effects of hyperhomocysteinemia (HHcy) on vascular reactivity within carotid artery segments isolated from ovariectomized female rats. Treatment with dl-Hcy thiolactone (1 g/kg body weight per day) reduced the phenylephrine-induced contraction of denuded rings. However, the treatment did not alter KCl-induced contractions, or relaxations induced by sodium nitroprusside or acetylcholine. We report elevated expressions of iNOS, eNOS, and nitrotyrosine in homocysteine-treated rat artery sections. Moreover, the inhibition of NOS by l-NAME, 1,400 W, or l-NNA restored phenylephrine-induced vasoconstriction in carotid artery segments from Hcy-treated rats. In conclusion, our findings show that severe HHCy can promote an acute decrease in the endothelium-independent contractile responses of carotid arteries to adrenergic agonists. This effect was restored by nitric oxide synthase inhibitors, which further supports the involvement of nitric oxide in HHcy-derived vascular dysfunction.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo

Neuroregenerative strategies in the brain: emerging significance of bonemorphogenetic protein 7 (BMP7)

Every year thousands of people suffer from brain injuries and stroke, anddevelop motor, sensory, and cognitive problems as a result of neuronal loss in thebrain. Unfortunately, the damaged brain has a limited ability to enact repair andcurrent modes of treatment are not sufficient to offset the damage. An extensivelist of growth factors, neurotrophic factors, cytokines, and drugs has been exploredas potential therapies. However, only a limited number of them may actually have thepotential to effectively offset the brain injury or stroke-related problems. One ofthe treatments considered for future brain repair is bone morphogenetic protein 7(BMP7), a factor currently used in patients to treat non-neurological diseases. The clinical application of BMP7 is based on its neuroprotective role in stroke animal models. This paper reviews the current approac hes considered for brain repair and discusses the novel convergent strategies by which BMP7 potentially can induce neuroregenerationNRC publication: Ye