Institute of Molecular Biology and Biological Physics

Tbilisi, Georgia

Institute of Molecular Biology and Biological Physics

Tbilisi, Georgia
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Todorich B.,Pennsylvania State University | Olopade J.O.,Pennsylvania State University | Olopade J.O.,University of Ibadan | Surguladze N.,Pennsylvania State University | And 4 more authors.
Neurotoxicity Research | Year: 2011

The second post-natal week in rat is the period of the most intense oligodendrocyte development and myelination. This period coincides with peak iron import by oligodendrocytes. During that time oligodendrocyte progenitors (OPCs) are sensitive to agents that may disturb normal iron homeostasis and assimilation of iron into these cells. One mechanism by which iron homeostasis can be disrupted is by environmental exposure to other metals. Vanadium is a transition metal, and exposure to vanadium during early brain development produces hypomyelination with variety of related neuro-behavioral phenotypes. In the current study, we investigated mechanisms of hypomyelination induced by vanadium exposure in developing rat brain. We demonstrate that both in vivo and in vitro, OPCs are more sensitive to vanadium exposure than astrocytes or mature oligodendrocytes. Vanadium exposure in OPCs resulted in increased ROS generation and increased annexinV labeling suggestive of apoptosis. Because ferritin is a major iron delivery protein for oligodendrocytes, we exposed the cells to recombinant ferritin and iron both of which exacerbated vanadium cytotoxicity, while the iron chelator desferroxamine (DFO) prevented cytotoxic/apoptotic effects of vanadium. To illustrate relationship between ferritin and vanadium, we demonstrate that vanadium exacerbated DNA nicking produced by iron-rich spleen ferritin, but not iron-poor apoferritin, resulting in a single and double strand breaks in a DNA relaxation assay. We propose that developmental exposure to vanadium interferes with normal iron assimilation into oligodendrocytes resulting in oxidative stress and apoptosis. Therefore, depletion of OPCs due to vanadium exposure in early post-natal period may be an important mechanism of vanadium-induced hypomyelination. © 2010 Springer Science+Business Media, LLC.


Liu X.,Pennsylvania State University | Madhankumar A.B.,Pennsylvania State University | Slagle-Webb B.,Pennsylvania State University | Sheehan J.M.,Pennsylvania State University | And 2 more authors.
Cancer Research | Year: 2011

Approximately half of all gliomas are resistant to chemotherapy, and new therapeutic strategies are urgently needed to treat this cancer. We hypothesized that disrupting iron homeostasis in glioma cells could block tumor growth, based on an acute requirement for high levels of iron to meet energy requirements associated with their rapid growth. Ferritin is best known as an intracellular iron storage protein, but it also localizes to tumor cell nuclei where it seems to protect DNA from oxidative damage and to promote transcription. In this study, we hypothesize that silencing the H-ferritin (heavy chain ferritin) gene could increase tumor sensitivity to chemotoxins. To test this hypothesis, H-ferritin siRNA was delivered to several human cancer cell lines by using cationic liposomes (C-liposome). H-ferritin siRNA decreased protein expression by 80% within 48 hours, and this decrease was associated with more than 50% decrease in the LD50 for DNA-alkylating agent carmustine (BCNU), which is commonly used to treat glioma in clinic. In a subcutaneous mouse model of human glioma, intratumoral injections of liposomes containing H-ferritin siRNA reduced the effective dose of BCNU needed for tumor suppression by more than 50%. A plasmid supercoil relaxation assay showed that H-ferritin specifically and directly protected DNA from BCNU treatment. H-ferritin siRNA additionally seemed to increase apoptosis in glioma cells in vitro upon H-ferritin knockdown. Overall, our results illustrate how silencing H-ferritin can effectively sensitize tumors to chemotherapy and also show the ability of C-liposomes to serve as a novel in vivo delivery tool for siRNAs. ©2011 AACR.


Zaalishvili G.,Institute of Molecular Biology and Biological Physics | Margiani D.,Institute of Molecular Biology and Biological Physics | Kutalia K.,Institute of Molecular Biology and Biological Physics | Suladze S.,Institute of Molecular Biology and Biological Physics | Zaalishvili T.,Institute of Molecular Biology and Biological Physics
Biochemical and Biophysical Research Communications | Year: 2010

Poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme that catalyzes the NAD+-dependent addition of ADP-ribose polymers on a variety of nuclear proteins, has been shown to be associated with the nuclear matrix. As yet, the properties and conditions of this association are unclear. Here, we show the existence of two PARP-1 pools associated with the nuclear matrix of rat liver and the ability of PARP-1 automodification to facilitate its binding to the nuclear matrix. © 2010 Elsevier Inc. All rights reserved.


PubMed | Institute of Molecular Biology and Biological Physics
Type: Journal Article | Journal: Biochemical and biophysical research communications | Year: 2010

Poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme that catalyzes the NAD(+)-dependent addition of ADP-ribose polymers on a variety of nuclear proteins, has been shown to be associated with the nuclear matrix. As yet, the properties and conditions of this association are unclear. Here, we show the existence of two PARP-1 pools associated with the nuclear matrix of rat liver and the ability of PARP-1 automodification to facilitate its binding to the nuclear matrix.

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