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Full-Text Articles in Education
Enhanced Neurite Outgrowth In Pc12 Cells Mediated By Connexin Hemichannels And Atp, Daniel Belliveau, M. Bani-Yagoub, R. Mcgirr, C. Naus, W. Rushlow
Enhanced Neurite Outgrowth In Pc12 Cells Mediated By Connexin Hemichannels And Atp, Daniel Belliveau, M. Bani-Yagoub, R. Mcgirr, C. Naus, W. Rushlow
Daniel J. Belliveau
Gap junctions have traditionally been described as transmembrane channels that facilitate intercellular communication via the passage of small molecules. Connexins, the basic building blocks of gap junctions, are expressed in most mammalian tissues including the developing and adult central nervous system. During brain development, connexins are temporally and spatially regulated suggesting they play an important role in the proper formation of the central nervous system. In the current study, connexins 32 and 43 were overexpressed in PC12 cells to determine whether connexins are involved in neuronal differentiation. Both connexin 32 and 43 were appropriately trafficked to the cell membrane following …
Changes In Calcineurin Expression Induced In The Rat Brain By The Administration Of Antipsychotics, W. Rushlow, Y. Seah, Daniel Belliveau, N. Rajakumar
Changes In Calcineurin Expression Induced In The Rat Brain By The Administration Of Antipsychotics, W. Rushlow, Y. Seah, Daniel Belliveau, N. Rajakumar
Daniel J. Belliveau
Calcineurin (CN) was recently identified as a susceptibility gene for schizophrenia as well as showing altered RNA expression levels in the post-mortem brains of individuals with schizophrenia. CN knockout mice show a number of behaviours associated with schizophrenia, including deficits in sensorimotor gating, suggesting a link between CN and psychosis. Concurrently, we found, using genome screening techniques, that antipsychotics alter CN expression levels. Therefore, western blotting, in situ hybridization, immunocytochemistry and phosphatase assays were employed to determine what effect antipsychotics have on CN. The results indicate that clozapine, risperidone and haloperidol cause substantial reductions in the A subunit of CN …
Nerve Growth Factor Increases Connexin43 Phosphorylation And Gap Junctional Intercellular Communication, P. Cushing, R. Bhalla, A. Johnson, W. Rushlow, S. Meakin, Daniel Belliveau
Nerve Growth Factor Increases Connexin43 Phosphorylation And Gap Junctional Intercellular Communication, P. Cushing, R. Bhalla, A. Johnson, W. Rushlow, S. Meakin, Daniel Belliveau
Daniel J. Belliveau
The function of gap junctions is regulated by the phosphorylation state of their connexin subunits. Numerous growth factors are known to regulate connexin phosphorylation; however, the effect of nerve growth factor on gap junction function is not understood. The phosphorylation of connexin subunits is a key event during many aspects of the lifecycle of a connexin, including open/close states, assembly/trafficking, and degradation, and thus affects the functionality of the channel. PC12 cells infected with connexin43 (Cx43) retrovirus were used as a neuronal model to characterize the signal transduction pathways activated by nerve growth factor (NGF) that potentially affect the functional …
Differential Expression Of Gap Junctions In Neurons And Astrocytes Dervied From P19 Embryonal Carcinoma Cells, Daniel Belliveau, J. Bechberger, K. Rodgers, C. Naus
Differential Expression Of Gap Junctions In Neurons And Astrocytes Dervied From P19 Embryonal Carcinoma Cells, Daniel Belliveau, J. Bechberger, K. Rodgers, C. Naus
Daniel J. Belliveau
The P19 embryonal carcinoma cell line represents a pluripotential stem cell that can differentiate along the neural or muscle cell lineage when exposed to different environments. Exposure to retinoic acid induces P19 cells to differentiate into neurons and astrocytes that express similar developmental markers as their embryonic counterparts. We examined the expression of gap junction genes during differentiation of these stem cells into neurons and astrocytes. Untreated P19 cells express at least two gap junction proteins, connexins 26 and 43. Connexin32 could not be detected in these cells. Treatment for 96 hr with 0.3 mM retinoic acid induced the P19 …
Blocking Nerve Growth Factor Binding To The P75 Neurotrophin Receptor On Sympathetic Neurons Transiently Reduces Trka Activation But Does Not Affect Neuronal Survival, C. Lachance, Daniel Belliveau, P. Barker
Blocking Nerve Growth Factor Binding To The P75 Neurotrophin Receptor On Sympathetic Neurons Transiently Reduces Trka Activation But Does Not Affect Neuronal Survival, C. Lachance, Daniel Belliveau, P. Barker
Daniel J. Belliveau
Nerve growth factor interacts with the trkA tyrosine kinase receptor and with the p75 neurotrophin receptor. It is clear that trkA mediates most, if not all, of the stereotypical responses of sympathetic neurons to nerve growth factor but the role of the p75 neurotrophin receptor is unclear. In this study, we have asked whether a functional interaction between p75 neurotrophin receptor and trkA exists in primary sympathetic neurons by disrupting nerve growth factor binding to p75 neurotrophin receptor. Acute assays reveal that blocking antibodies directed against p75 neurotrophin receptor reduce nerve growth factor-mediated trkA tyrosine phosphorylation and reduce the amount …
Transgenic Mice Expressing The Intracellular Domain Of The P75 Neurotrophin Receptor Undergo Neuronal Apoptosis, M. Majdan, C. Lachance, A. Gloster, R. Aloyz, C. Zeindler, S. Bamji, A. Bhakar, Daniel Belliveau, J. Fawcett, F. Miller, P. Barker
Transgenic Mice Expressing The Intracellular Domain Of The P75 Neurotrophin Receptor Undergo Neuronal Apoptosis, M. Majdan, C. Lachance, A. Gloster, R. Aloyz, C. Zeindler, S. Bamji, A. Bhakar, Daniel Belliveau, J. Fawcett, F. Miller, P. Barker
Daniel J. Belliveau
We have asked whether p75NTR may play a role in neuronal apoptosis by producing transgenic mice that express the p75NTR intracellular domain within peripheral and central neurons. These animals showed profound reductions in numbers of sympathetic and peripheral sensory neurons as well as cell loss in the neocortex, where there is normally little or no p75NTR expression. Developmental loss of facial motor neurons was not observed, but induced expression of the p75NTR intracellular domain within adult animals led to increased motor neuron death after axotomy. Biochemical analyses suggest that these effects were not attributable to a p75NTR-dependent reduction in trk …
Ngf And Neurotrophin-3 Both Activate Trka On Sympathetic Neurons But Differentially Regulate Survival And Neuritogenesis, Daniel Belliveau, I. Krivko, C. Lachance, J. Kohn, D. Rusakov, D. Kaplan, F. Miller
Ngf And Neurotrophin-3 Both Activate Trka On Sympathetic Neurons But Differentially Regulate Survival And Neuritogenesis, Daniel Belliveau, I. Krivko, C. Lachance, J. Kohn, D. Rusakov, D. Kaplan, F. Miller
Daniel J. Belliveau
In this report we examine the biological and molecular basis of the control of sympathetic neuron differentiation and survival by NGF and neurotrophin-3 (NT-3). NT-3 is as efficient as NGF in mediating neuritogenesis and expression of growth-associated genes in NGF-dependent sympathetic neurons, but it is 20-40-fold less efficient in supporting their survival. Both NT-3 and NGF induce similar sustained, long-term activation of TrkA, while NGF is 10-fold more efficient than NT-3 in mediating acute, short-term TrkA activity. At similar acute levels of TrkA activation, NT-3 still mediates neuronal survival two- to threefold less well than NGF. However, a mutant NT-3 …
Adenovirus-Mediated Gene Transfer Of The Tumor Suppressor, P53, Induces Apoptosis In Postmitotic Neurons, R. Slack, Daniel Belliveau, M. Rosenberg, J. Atwal, H. Lochmuller, R. Aloyz, A. Haghighi, B. Lach, P. Seth, E. Cooper, F. Miller
Adenovirus-Mediated Gene Transfer Of The Tumor Suppressor, P53, Induces Apoptosis In Postmitotic Neurons, R. Slack, Daniel Belliveau, M. Rosenberg, J. Atwal, H. Lochmuller, R. Aloyz, A. Haghighi, B. Lach, P. Seth, E. Cooper, F. Miller
Daniel J. Belliveau
Programmed cell death is an ongoing process in both the developing and the mature nervous system. The tumor suppressor gene, p53, can induce apoptosis in a number of different cell types. Recently, the enhanced expression of p53 has been observed during acute neurological disease. To determine whether p53 overexpression could influence neuronal survival, we used a recombinant adenovirus vector carrying wild type p53 to transduce postmitotic neurons. A control consisting of the same adenovirus vector background but carrying the lacZ reporter expression cassette was used to establish working parameters for the effective genetic manipulation of sympathetic neurons. We have found …
Cellular Localization Of Gap Junction Mrnas In Developing Rat Brain, Daniel Belliveau, C. Naus
Cellular Localization Of Gap Junction Mrnas In Developing Rat Brain, Daniel Belliveau, C. Naus
Daniel J. Belliveau
We investigated the developmental expression and cellular resolution of connexin32 and 43 mRNA in the rat brain using in situ hybridization. Utilizing 35S-labelled probes, in situ hybridization was performed on sections of embryonic day 20 and postnatal days 3, 10, 15, 30 and adult brain. Connexin32 mRNA was first detected in brainstem nuclei at postnatal day 3 and in the midbrain at postnatal day 15. The level of this message continued to increase to postnatal day 30 where the level of message reached a plateau or slightly decreased by adulthood. The distribution of signal included the medial vestibular nucleus, dorsal …
Cortical Type 2 Astrocytes Are Not Dye Coupled Nor Do They Express The Major Gap Junction Genes Found In The Central Nervous System, Daniel Belliveau, C. Naus
Cortical Type 2 Astrocytes Are Not Dye Coupled Nor Do They Express The Major Gap Junction Genes Found In The Central Nervous System, Daniel Belliveau, C. Naus
Daniel J. Belliveau
The O‐2A progenitor cell first described from the rat optic nerve is a bipotential precursor of oligodendrocytes and type 2 astrocytes. Each cell expresses specific markers that distinguish them as unique cell types. O‐2A progenitors cultured in high serum preferentially differntiate into type 2 astrocytes and when exposed to defined medium or low serum develop along the oligodendrocyte lineage. We analyzed the gap junction gene expression of type 2 astrocytes to determine if they are coupled to form a syncytium, like their type 1 astrocyte counterparts. Dye coupling experiments demonstrated that cortical type 2 astrocytes are not coupled, while type …
Regulation Of Connexin32 And Connexin43 Mrna And Protein During Neural Development, Daniel Belliveau, G. Kidder, C. Naus
Regulation Of Connexin32 And Connexin43 Mrna And Protein During Neural Development, Daniel Belliveau, G. Kidder, C. Naus
Daniel J. Belliveau
No abstract provided.
Regional Differences In Connexin32 And Connexin43 Messenger Rnas In Rat Brain, C. Naus, Daniel Belliveau, J. Bechberger
Regional Differences In Connexin32 And Connexin43 Messenger Rnas In Rat Brain, C. Naus, Daniel Belliveau, J. Bechberger
Daniel J. Belliveau
The regional distribution of gap junction mRNAs was examined in the adult rat brain. The level of connexin43 mRNA is more abundant than connexin32, being homogeneously distributed throughout different regions of brain. In contrast, there is dramatic heterogeneity in the level of connexin32 mRNA, with the highest level in the hindbrain. These results suggest that the gap junction genes are differentially expressed in regions of the adult rat brain.