Abstract 1459: Connexin 43 Hemi Channels are Permeable to Exogenously Added NAD: Implications in Protection of Cardiomyocytes against PARP-mediated Cell Death

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Vinodkumar B Pillai ◽  
Jyothish B Pillai ◽  
Senthilkumar Rajamohan ◽  
Madhu Gupta ◽  
Jai Raman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Gap Junction ◽  
Hela Cells ◽  
Connexin 43 ◽  
Neonatal Rat ◽  
Parp Activation ◽  
Junction Protein ◽  
Nad Depletion

Robust activation of poly (ADP ribose) polymerase-1 (PARP) following oxidative stress and DNA damage is a major cause of caspase independent cardiomyocyte cell death. PARP-mediated cell-death is associated with cellular NAD depletion. Connexin 43 (Cx43) is a major gap junction protein which forms hemi channels in cardiomyocytes. This study was designed to investigate whether exogenously added NAD can enter into cardiomyocytes via Cx43 hemi channels, and protect cells from PARP-mediated cell death. Primary cultures of neonatal rat heart myocytes were treated at various time points with a free-radical generating mixture of H 2 O 2 and FeSO4 (0.1mM each). To examine permeability of cells to NAD, myocytes were treated with FITC-tagged-NAD (NAD-FITC) and intracellular localization of NAD was determined by confocal microscopy. We found that following oxidative stress myocyte cell death was proportionally related to intensity of PARP activation and NAD depletion. In these cells with PARP activation, exogenously added NAD-FITC (green) readily entered into the cell interior. This NAD transport was abolished when myocytes were treated with gap junction blockers such as carbenoxolone or 18β-glycyrrhetinic acid. To further confirm a role of Cx43 in NAD transport, we utilized HeLa cells in which Cx43 was either epigenetically silenced or constitutively over expressed. We found that HeLa cells lacking Cx43 had no NAD transport activity, while cells over expressing Cx43 showed abundant entry of NAD into the cells, thus validating a role of Cx43 in cellular NAD transport. Addition of NAD into culture media prior to PARP activation also rescued cells from PARP-mediated cell death. Cellular NAD levels are known to control the activity of the longevity factor SIRT1 deacetylase. To test if SIRT1 could be involved in mediating the beneficial effects of NAD, we did an identical cell death experiment with myocytes in which SIRT1 levels were reduced 50% by siRNA silencing. In these cells we found no beneficial effect of NAD following oxidative stress, thus indicating that SIRT1 is taking part in cell survival effects of NAD. These results demonstrate that exogenously added NAD can enter into cardiomyocytes via Cx43 hemi channels and protect cells against PARP-mediated cell death.

scholarly journals Role of Bcl2-associated Athanogene 3 in Turnover of Gap Junction Protein, Connexin 43, in Neonatal Cardiomyocytes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Farzaneh Ghasemi Tahrir ◽  
Manish Gupta ◽  
Valerie Myers ◽  
Jennifer Gordon ◽  
Joseph Y. Cheung ◽  
...  
Keyword(s):  
Gap Junction ◽  
Connexin 43 ◽  
Neonatal Cardiomyocytes ◽  
Junction Protein ◽  
Gap Junction Protein

Chronic regulation of the expression of the gap junction protein connexin 43 in transfected HeLa cells

2003 ◽  
Vol 368 (1) ◽  
pp. 33-40 ◽  
Author(s):  
A. Salameh ◽  
L. Polontchouk ◽  
S. Dhein ◽  
A. Hagendorff ◽  
D. Pfeiffer
Keyword(s):  
Gap Junction ◽  
Hela Cells ◽  
Connexin 43 ◽  
Junction Protein ◽  
Gap Junction Protein

scholarly journals Role of hepcidin in oxidative stress and cell death of cultured mouse renal collecting duct cells: protection against iron and sensitization to cadmium

2021 ◽  
Author(s):  
Stephanie Probst ◽  
Johannes Fels ◽  
Bettina Scharner ◽  
Natascha A. Wolff ◽  
Eleni Roussa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Cell Fate ◽  
Catalase Activity ◽  
Metal Ion ◽  
Iron Homeostasis ◽  
Collecting Duct ◽  
Duct Cell ◽  
Plasmid Transfection

AbstractThe liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5–5 μmol/l) and/or Fe2+ (50–100 μmol/l) for 4–24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.

Combination of photodynamic therapy with doxorubicin in osteosarcoma: Cell death and the role of oxidative stress

2016 ◽  
Vol 61 ◽  
pp. S141
Author(s):  
B. Serambeque ◽  
G. Brites ◽  
M. Laranjo ◽  
G. Chohfi de Miguel ◽  
A. Serra ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Photodynamic Therapy ◽  
Osteosarcoma Cell

Phosphorylation of connexin 43 induced by traumatic brain injury promotes exosome release

2018 ◽  
Vol 119 (1) ◽  
pp. 305-311 ◽  
Author(s):  
Wei Chen ◽  
Yijun Guo ◽  
Wenjin Yang ◽  
Lei Chen ◽  
Dabin Ren ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Gap Junction ◽  
Connexin 43 ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Cx43 Expression ◽  
Term Potentiation ◽  
Junction Protein

Traumatic brain injury (TBI) caused by the external force leads to the neuronal dysfunction and even death. TBI has been reported to significantly increase the phosphorylation of glial gap junction protein connexin 43 (Cx43), which in turn propagates damages into surrounding brain tissues. However, the neuroprotective and anti-apoptosis effects of glia-derived exosomes have also been implicated in recent studies. Therefore, we detected whether TBI-induced phosphorylation of Cx43 would promote exosome release in rat brain. To generate TBI model, adult male Sprague-Dawley rats were subjected to lateral fluid percussion injury. Phosphorylated Cx43 protein levels and exosome activities were quantified using Western blot analysis following TBI. Long-term potentiation (LTP) was also tested in rat hippocampal slices. TBI significantly increased the phosphorylated Cx43 and exosome markers expression in rat ipsilateral hippocampus, but not cortex. Blocking the activity of Cx43 or ERK, but not JNK, significantly suppressed TBI-induced exosome release in hippocampus. Furthermore, TBI significantly inhibited the induction of LTP in hippocampal slices, which could be partially but significantly restored by pretreatment with exosomes. The results imply that TBI-activated Cx43 could mediate a nociceptive effect by propagating the brain damages, as well as a neuroprotective effect by promoting exosome release. NEW & NOTEWORTHY We have demonstrated in rat traumatic brain injury (TBI) models that both phosphorylated connexin 43 (p-Cx43) expression and exosome release were elevated in the hippocampus following TBI. The promoted exosome release depends on the phosphorylation of Cx43 and requires ERK signaling activation. Exosome treatment could partially restore the attenuated long-term potentiation. Our results provide new insight for future therapeutic direction on the functional recovery of TBI by promoting p-Cx43-dependent exosome release but limiting the gap junction-mediated bystander effect.

scholarly journals Role of Gap Junction Protein Connexin43 in Astrogliosis Induced by Brain Injury

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e47311 ◽  
Author(s):  
Nicolas Theodoric ◽  
John F. Bechberger ◽  
Christian C. Naus ◽  
Wun-Chey Sin
Keyword(s):  
Brain Injury ◽  
Gap Junction ◽  
Junction Protein ◽  
Gap Junction Protein

scholarly journals Connexin 43 Gap Junction Protein Expression during Follicular Development in the Porcine Ovary1

1998 ◽  
Vol 58 (2) ◽  
pp. 583-590 ◽  
Author(s):  
Judy A. Lenhart ◽  
Bruce R. Downey ◽  
Carol A. Bagnell
Keyword(s):  
Protein Expression ◽  
Gap Junction ◽  
Connexin 43 ◽  
Follicular Development ◽  
Junction Protein ◽  
Gap Junction Protein
Sign in / Sign up

Export Citation Format

Share Document