Details

Autor(en) / Beteiligte

• Marcelino, Helena
• Nogueira, Vanda C.
• Santos, Cecília R.A.
• Quelhas, Patrícia
• Carvalho, Tiago M.A.
• Fonseca‐Gomes, João
• Tomás, Joana
• Diógenes, Maria J.
• Sebastião, Ana M.
• Cascalheira, José F.

Titel

Adenosine inhibits human astrocyte proliferation independently of adenosine receptor activation

Ist Teil von

• Journal of neurochemistry, 2020-05, Vol.153 (4), p.455-467

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• Brain adenosine concentrations can reach micromolar concentrations in stressful situations such as stroke, neurodegenerative diseases or hypoxic regions of brain tumours. Adenosine can act by receptor‐independent mechanism by reversing the reaction catalysed by S‐adenosylhomocysteine (SAH) hydrolase, leading to SAH accumulation and inhibition of S‐adenosylmethionine (SAM)‐dependent methyltransferases. Astrocytes are essential in maintaining brain homeostasis but their pathological activation and uncontrolled proliferation plays a role in neurodegeneration and glioma. Adenosine can affect cell proliferation, but the effect of increased adenosine concentration on proliferation of astrocytes is not clarified and was addressed in present work. Human astrocytes (HA) were treated for 3 days with test drugs. Cell proliferation/viability was assessed by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium assay and by cell counting. Cell death was evaluated by assessing lactate dehydrogenase release and by western blot analysis of αII‐Spectrin cleavage. 30 µM‐Adenosine caused a 40% ± 3% (p < .05, n = 5) reduction in cell proliferation/viability, an effect reversed by 2U/ml‐adenosine deaminase, but unchanged in the presence of antagonists of any of the adenosine receptors. Adenosine alone did not induce cell death. 100 µM‐Homocysteine alone caused 16% ± 3% (p < .05) decrease in HA proliferation. Combined action of adenosine and homocysteine decreased HA proliferation by 76% ± 4%, an effect higher (p < .05) than the sum of the effects of adenosine and homocysteine alone (56% ± 5%). The inhibitory effect of adenosine on HA proliferation/viability was mimicked by two adenosine kinase inhibitors and attenuated in the presence of folate (100 µM) or SAM (50‐100 µM). The results suggest that adenosine reduces HA proliferation by a receptor‐independent mechanism probably involving reversal of SAH hydrolase‐catalysed reaction. Brain adenosine reaches micromolar concentrations in stressful situations. Astrocytes uncontrolled proliferation plays a role in neurodegeneration and glioma. The effect of increased adenosine concentration on astrocytes proliferation was addressed in present work. Human astrocytes (HA) were treated for 3 days with test drugs. 30 µM‐Adenosine caused a receptor‐independent inhibition of HA proliferation/viability. The adenosine effect was potentiated by homocysteine, mimicked by two adenosine kinase inhibitors (ABT‐702 and ITU) and attenuated in the presence of folate or SAM. Results suggest that adenosine reduces HA proliferation by a receptor‐independent mechanism probably involving reversal of SAH hydrolase‐catalysed reaction.