title: Ultrastructure of cytoplasmic and nuclear inosine-5'-monophosphate dehydrogenase 2 "rods and rings" inclusions.
abstract: Inosine-5'-monophosphate dehydrogenase catalyzes the critical step in the de novo synthesis of guanosine nucleotides: the oxidation of inosine monophosphate to xanthosine monophosphate. This reaction can be inhibited by specific inhibitors, such as ribavirin or mycophenolic acid, which are widely used in clinical treatment when required to inhibit the proliferation of viruses or cells. However, it was recently found that such an inhibition affects the cells, leading to a redistribution of IMPDH2 and the appearance of IMPDH2 inclusions in the cytoplasm. According to their shape, these inclusions have been termed "Rods and Rings" (R&R). In this work, we focused on the subcellular localization of IMPDH2 protein and the ultrastructure of R&R inclusions. Using microscopy and western blot analysis, we show the presence of nuclear IMPDH2 in human cells. We also show that the nuclear pool has an ability to form Rod structures after inhibition by ribavirin. Concerning the ultrastructure, we observed that R&R inclusions in cellulo correspond to the accumulation of fibrous material that is not surrounded by a biological membrane. The individual fibers are composed of regularly repeating subunits with a length of approximately 11 nm. Together, our findings describe the localization of IMPDH2 inside the nucleus of human cells as well as the ultrastructure of R&R inclusions.
authors: Charles University in Prague, First Faculty of Medicine, Institute of Cellular Biology and Pathology, Czech Republic (PJ, JS, LK, IR)Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic (EB) pavel.juda@gmail.com.
authors: Pavel
authors: P
authors: Juda
authors: Charles University in Prague, First Faculty of Medicine, Institute of Cellular Biology and Pathology, Czech Republic (PJ, JS, LK, IR)Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic (EB).
authors: Jana
authors: J
authors: Smigová
authors: Charles University in Prague, First Faculty of Medicine, Institute of Cellular Biology and Pathology, Czech Republic (PJ, JS, LK, IR)Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic (EB).
authors: Lubomír
authors: L
authors: Kováčik
authors: Charles University in Prague, First Faculty of Medicine, Institute of Cellular Biology and Pathology, Czech Republic (PJ, JS, LK, IR)Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic (EB).
authors: Eva
authors: E
authors: Bártová
authors: Charles University in Prague, First Faculty of Medicine, Institute of Cellular Biology and Pathology, Czech Republic (PJ, JS, LK, IR)Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic (EB).
authors: Ivan
authors: I
authors: Raška
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure*; D003593:Cytoplasm / Q000201:enzymology* / Q000648:ultrastructure*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007168:IMP Dehydrogenase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D004791:Enzyme Inhibitors; D007168:IMP Dehydrogenase; C501687:IMPDH2 protein, human
keywords: Inosine-5′-monophosphate dehydrogenase; Rods and Rings; correlative light and electron microscopy; electron tomography; inclusions; inhibitors of IMPDH; ultrastructure