The aim of this application is to establish by which mechanisms Cx-proteins improve cellular survival following injury. We have in preliminary observations established that Cx-expression antagonizes cell death indicating that the connexin proteins have death-inhibitory or anti-apoptotic activity. In specific we will ask: Does an adaptive remodeling and reorganization of Cx43 contribute to the high resistance to injury of Cx43 expressing cells? A Cx43-eGFP fusion protein has been stably expressed in C6 cells and time-lapse analysis has revealed that Cx43-eGFP undergo major structural reorganization after injury. We will here test the preposition that Cx43 reorganization represents an adaptive response that improves survival and that the lower resistance of Cx-deficient cells results from their limited ability to initiate the same process after injury on a single cell level. The analysis will be extended to include primary astrocytes transfected with an adenoviral vector encoding Cx43-GFP. By which mechanisms do connexin proteins increase cellular resistance to injury? Is formation of functional gap junction channels a prerequisite for their anti-apoptotic action? Alternatively, do mutant Cx's with deficient channel function also provide injury-resistance indicating that yet undefined actions of Cx.proteins are responsible for the increased survival? We have established several cell lines with stable expression of either wildtype Cx43, or Cx-mutants with deficiencies in either channel function or membrane localization. These clones represent a powerful tool to establish at which level the Cx-proteins antagonize cell death. Is the increase in cellular resistance associated with Cx-expression dictated by the phenotypic transformation? Does loss of cytoskeletal organization increase cellular sensitivity to injury? We will in these studies test the preposition that the Cx-induced phenotypic transformation observed, in part, may contribute to the increased cellular resistance. Does the death-inhibitory activity of Cx require ATP secretion? Do purinergic receptor blockers antagonize the Cx-induced increase in cellular resistance? It is here postulated that ATP secreted from Cx-expressing cells acts as an autocoid differentiation factor that increases the cellular resistance to injury. The effects on cellular resistance of long-term treatment with purinergic-receptor agonist and antagonists will here be analyzed. Defining the pathways, by which connexin proteins increase cellular resistance to injury, may provide a potential new therapeutic target for preventing cell death in acute pathologies as stroke and head trauma.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS030007-12
Application #
6539730
Study Section
Special Emphasis Panel (ZRG1-MDCN-2 (01))
Program Officer
Behar, Toby
Project Start
1992-06-15
Project End
2005-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
12
Fiscal Year
2002
Total Cost
$352,125
Indirect Cost
Name
New York Medical College
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
City
Valhalla
State
NY
Country
United States
Zip Code
10595
Plog, Benjamin A; Moll, Katherine M; Kang, Hongyi et al. (2014) A novel technique for morphometric quantification of subarachnoid hemorrhage-induced microglia activation. J Neurosci Methods 229:44-52
Wang, Xiaohai; Takano, Takahiro; Nedergaard, Maiken (2009) Astrocytic calcium signaling: mechanism and implications for functional brain imaging. Methods Mol Biol 489:93-109
Lin, Jane H-C; Takano, Takahiro; Arcuino, Gregory et al. (2007) Purinergic signaling regulates neural progenitor cell expansion and neurogenesis. Dev Biol 302:356-66
Tian, Guo-Feng; Azmi, Hooman; Takano, Takahiro et al. (2005) An astrocytic basis of epilepsy. Nat Med 11:973-81
Liu, Qing-Song; Xu, Qiwu; Kang, Jian et al. (2004) Astrocyte activation of presynaptic metabotropic glutamate receptors modulates hippocampal inhibitory synaptic transmission. Neuron Glia Biol 1:307-316
Lin, Jane H C; Takano, Takahiro; Cotrina, Maria Luisa et al. (2002) Connexin 43 enhances the adhesivity and mediates the invasion of malignant glioma cells. J Neurosci 22:4302-11
Kang, J; Jiang, L; Goldman, S A et al. (1998) Astrocyte-mediated potentiation of inhibitory synaptic transmission. Nat Neurosci 1:683-92