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Published on: February 5, 2018
Choline deficiency induced by Mycoplasma fermentans enhances apoptosis of rat astrocytes
G Ben-Menachem1, A Mousa, T Brenner
1Department of Membrane and Ultrastructure Research, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Abstract:
A choline uptake system accumulating free choline in an energy-dependent process is described in Mycoplasma fermentans. The uptake system has a K(m) of 2.2x10(-5) M and a V(max) of 0.15 nmol 10 min(-1) mg(-1) cell protein and the choline incorporated could be recovered in the soluble fraction as free choline, phosphorylcholine and CDP-choline. Choline accumulation by M. fermentans resulted in a marked choline depletion of the growth medium. The choline depletion of an astrocyte cell culture induced by M. fermentans was associated with the apoptotic death of the cells. Apoptosis was not obtained with heat-inactivated mycoplasmas and could be reversed by the addition of free choline to the growth medium.
Insights
Mycoplasma fermentans utilizes an energy-dependent choline uptake system, leading to medium depletion. This depletion induces astrocyte apoptosis, which is preventable with free choline.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Mycoplasma fermentans possesses a choline uptake mechanism.
- Choline uptake is an energy-dependent process in M. fermentans.
Purpose of the Study:
- To characterize the choline uptake system in M. fermentans.
- To investigate the role of choline depletion in M. fermentans-induced astrocyte apoptosis.
Main Methods:
- Characterization of choline uptake kinetics (K(m), V(max)).
- Analysis of incorporated choline metabolites (free choline, phosphorylcholine, CDP-choline).
- Induction and reversal of astrocyte apoptosis by M. fermentans and free choline.
Main Results:
- M. fermentans exhibits a high-affinity choline uptake system (K(m) = 2.2x10(-5) M).
- Incorporated choline is found as free choline, phosphorylcholine, and CDP-choline.
- M. fermentans-induced choline depletion of growth media triggers astrocyte apoptosis, reversible by exogenous choline.
Conclusions:
- M. fermentans actively accumulates choline via a specific uptake system.
- Choline depletion by M. fermentans is a key factor in inducing astrocyte apoptosis.
- This highlights a novel mechanism of mycoplasma-induced cell death and potential therapeutic intervention.
