Sirtuins 1 and 2 in the Acute Period After Photothrombotic Stroke: Expression, Localization and Involvement in Apoptosis

Abstract

Sirtuins (SIRTs) are NAD+- dependent histone deacetylases. They are involved in a variety of biological pathways and are thought to be a promising target for treating several human disorders. Although evidence is piling up to support the neuroprotective role of SIRTs in ischemic stroke, the role of different sirtuin isoforms needs further investigation. We studied the effects of photothrombotic stroke (PTS) on the expression and localization of sirtuins SIRT1 and SIRT2 in neurons and astrocytes of the penumbra and tested the activity of their selective and non-selective inhibitors. SIRT1 levels significantly decreased in the penumbra cells nuclei and increased in their cytoplasm. This indicated a redistribution of SIRT1 from the nucleus to the cytoplasm after PTS. The expression and intracellular distribution of SIRT1 were also observed in astrocytes. Photothrombotic stroke caused a sharp increase in SIRT2 levels in the cytoplasmic fraction of the penumbra neurons. SIRT2 was not expressed in the penumbra astrocytes. SIRT1 and SIRT2 did not co-localize with TUNEL-positive apoptotic cells. Mice were injected with EX-527, a selective SIRT1 inhibitor; SirReal2, selective SIRT2 inhibitor or salermide, a nonspecific inhibitor of SIRT1 and SIRT2. These inhibitors did not demonstrate any change in the infarction volume or the apoptotic index, compared to the control samples. The studies presented indicate the involvement of these sirtuins in the response of brain cells to ischemia in the first 24 h, but the alterations in their expression and change in the localization of SIRT1 are not related to the regulation of penumbra cell apoptosis in the acute period after PTS.

Photochemicallly Induced Thrombosis as a Model of Ischemic Stroke

“…Моделирование фототромботического инсульта (ФТИ). Для индукции фототромбоза наркотизированным животным в кровеносную систему (внутривенно крысам или внутрибрюшинно мышам) вводят раствор светочувствительного красителя (чаще всего, это Бенгальский Розовый) [7]. Он почти не проникает в клетки и остается в сосудистой системе головного мозга.…”

“…Для более точного анализа можно дополнительно использовать методы иммуногистохимического окрашивания, которые позволяют обнаружить нейроны и глиальные клетки и выявить их гибель или пролиферацию. Так, белок NeuN является маркером зрелых нейронов, он используется для визуализации и анализа зоны инфаркта, а также для оценки гибели нейронов [7,17,40,42]. Для выявления зоны пенумбры используют такие маркеры, как c-fos и heart shock protein 90 [9].…”

“…Реакцию микроглии при повреждении мозга, вызванном ФТИ, оценивают с помощью метода иммуногистохимического окрашивания. В частности, для анализа степени активации микроглии, резидентных макрофагов головного мозга, используют антитела к CD68 и Iba1, которые являются маркерами макрофагов и клеток микроглии [7,17,41,44,45].…”

The roles of sirtuins in ferroptosis

“…Ferroptosis plays a significant role in tumors, neurodegenerative diseases, cardiovascular and cerebrovascular diseases, metabolic diseases, and respiratory diseases (Galaris et al, 2006;Dixon et al, 2012;Heemels, 2016;El Hout et al, 2018;Ma et al, 2019;Yoshida et al, 2019;Wang et al, 2021a;Cheng et al, 2021;Chen et al, 2022a). For instance, in neoplastic diseases, high ROS levels and high iron contents in cancer cells render them more susceptible to ferroptosis than normal cells due to their high metabolism (Dixon (Dai et al, 2018), Sirtinol (Grozinger et al, 2001), Suramin (Trapp et al, 2007), Tenovin (Botta et al, 2012), Salermide (Lara et al, 2009), Compound 15e (Sundriyal et al, 2017), SirReal2 (Eid et al, 2022), ELT-11c (Disch et al, 2013), Compound 8 (Mahajan et al, 2014), Compound 28e (Yang et al, 2017b), UBCS0137 (Sundriyal et al, 2017), 3′-(3-fluorophenethyloxy)-2anilinobenzamide (Suzuki et al, 2012) SRT2104 (Milne et al, 2007), Resveratrol (Dai et al, 2018), SRT1720 (Milne et al, 2007), SRT3657 (Gräff et al, 2013), SRT1460 (Pacholec et al, 2010), SRT2183 (Pacholec et al, 2010), piceatannol (Gertz et al, 2012), 1,4-DHP derivative (Mai et al, 2009), Ainsliadimer C (Chen et al, 2022c), Scopolin (Yoo et al, 2017), Tenovin-6 (Ladds et al, 2020), CAY10602 (Nayagam et al, 2006), YK-3-237…”