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Assembly of IMPDH2-based, CTPS-based, and mixed rod/ring structures is dependent on cell type and conditions of

Gerson Dierley Keppeke1, S John Calise2, Edward K L Chan2

  • 1Rheumatology Division, Federal University of Sao Paulo, Sao Paulo SP 04023-062, Brazil; Department of Oral Biology, University of Florida, Gainesville FL 32610-0424, USA.

Journal of Genetics and Genomics = Yi Chuan Xue Bao
|July 14, 2015
PubMed

Insights

Inhibiting nucleotide synthesis pathways forces cells to form rod/ring structures from CTPS and IMPDH2 enzymes. These structures

Area of Science:

  • Cell Biology
  • Biochemistry
  • Molecular Biology

Background:

  • Nucleotide biosynthesis pathways are crucial for cell function.
  • Inhibition of these pathways can lead to the formation of unique cellular structures.
  • Rod/ring (RR) structures, or cytoophidia, are composed of enzymes involved in nucleotide synthesis.

Purpose of the Study:

  • To investigate the interaction between cytidine triphosphate synthase (CTPS) and inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) in the formation of RR structures.
  • To understand how inhibition of guanosine triphosphate (GTP) and cytidine triphosphate (CTP) biosynthesis affects RR structure composition.

Main Methods:

  • Culturing HeLa and COS-7 cells under normal conditions and with inhibitors (DON, ribavirin, MPA).
  • Analyzing the composition of RR structures using immunofluorescence for CTPS and IMPDH2.
  • Transfecting cells with N-terminal hemagglutinin (NHA)-tagged CTPS1 and assessing RR formation under different treatments.

Main Results:

  • DON treatment induced RR structures in over 90% of cells, with varying proportions of CTPS, IMPDH2, or mixed composition depending on cell type.
  • Ribavirin and MPA treatments primarily induced IMPDH2-based RR structures.
  • Transfection studies showed that NHA-CTPS1 expression influenced RR formation, particularly in combination with DON or ribavirin treatment.

Conclusions:

  • The study elucidates the specific roles and interactions of CTPS and IMPDH2 in forming RR structures under nucleotide biosynthesis inhibition.
  • Findings contribute to understanding the relationship between CTP and GTP pathways and their impact on cytoophidia formation.
  • The results provide insights into the dynamic assembly of these filamentous structures.
Keywords:
CTPSEnzyme aggregationEnzyme inhibitionIMPDH2Nucleotide synthesis

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