Due to its nootropic, neuroprotective, and immunomodulatory effects, the peptide Semax is utilized in the treatment of ischemic stroke. Our earlier RNA-Seq analysis of the transcriptome in an ischemic model of transient occlusion of the middle cerebral artery showed an increase in the mRNA levels of many proinflammatory genes, and the suppression of their induction by Semax. However, for many relevant genes, including Il1a, Il1b, Il6 and Tnfa, the levels of their expression were too low for detailed quantitative evaluation. Here we utilize qRT-PCR to analyze the effects of the Semax peptide on the expression of weakly expressed mRNAs encoding several proinflammatory mediators, and show that exposure to Semax leads to a statistically significant decrease in the Il1a, Il1b, Il6, Ccl3, and Cxcl2 mRNAs, which compensates for the increase in the transcription of these genes induced by ischemia-reperfusion. We conclude that the observed protective effect of Semax in the model of stroke may be due to its anti-inflammatory effects. We also discuss the limitations of the RNA-Seq when applied to quantifying less abundant transcripts as compared to the real-time RT-PCR method.

Синтетический пептид АКТГ(4-7)PGP ускоряет регресс неврологических нарушений при ишемическом инсульте, однако молекулярные механизмы его действия полностью не известны. На модели полуторачасовой окклюзии средней мозговой артерии крыс был проведен анализ влияния пептида на экспрессию ряда генов и белков, вовлеченных в сигнальные пути, приводящие к воспалению и гибели клеток в условиях ишемии-реперфузии. Показано, что пептид через 24 ч от начала окклюзии снижает повышенный при ишемии уровень экспрессии в ишемизированной ткани мозга крыс мРНК провоспалительных цитокинов и хемокинов IL-1α, IL-1β, IL-6, TNF-α, Cxcl2 и Ccl3. Пептид снижал повышенные при ишемии уровни экспрессии белков металлопротеиназы ММР-9, транскрипционного фактора c-Fos, активных JNK киназ и предотвращал ишемическое снижение уровня активного транскрипционного фактора CREB. The synthetic peptide ACTH (4-7) PGP accelerates the regression of neurological disorders in ischemic stroke, but the molecular mechanisms of its action are not completely known. On the model of an hour and a half occlusion of the rat middle cerebral artery, an analysis was made of the effect of the peptide on the expression of a number of genes and proteins involved in signaling pathways leading to inflammation and cell death under conditions of ischemia-reperfusion. It was shown that the peptide 24 hours after the onset of occlusion reduces the level of expression of mRNA of pro-inflammatory cytokines and chemokines IL-1α, IL-1β, IL-6, TNF-α, Cxcl2 and Ccl3 in ischemic brain tissue. The peptide decreased the levels of expression of proteins metalloproteinase MMP-9, transcription factor c-Fos, active JNK kinases wich were increased under ischemia, and prevented ischemic decrease in the level of active transcription factor CREB.

В целях исследования молекулярных механизмов действия пептидов меланокортинового ряда был проведен сравнительный анализ действия семакса и его структурного аналога АКТГ(6-9)PGP на транскриптом гиппокампа крыс в норме и условиях острого стресса с помощью метода RNA-Seq. Полученные результаты выявили общие и специфические эффекты пептидов меланокортинового ряда в регулировании экспрессии генов в условиях острого стресса и нормы. Предложена модель формирования ответа транскриптома на введение пептидов, основанная на аллостерическом взаимодействии пептидов с рецепторами. In order to study the molecular mechanisms of action of the peptides of the melanocortin series, a comparative analysis of the effect of Semax and its structural analogue of ACTH(6-9)PGP on transcripts of rat hippocampus under normal and acute stress conditions was performed using the RNA-Seq method. The results revealed common and specific effects of peptides in the regulation of gene expression under acute stress and normal conditions. We proposed a model for the formation of transcriptome response to peptide administration based on allosteric interaction of peptides with receptors.

Методом ПЦР в реальном времени в подкорковых структурах мозга крыс, содержащих очаг ишемического повреждения, показано активирующее влияние ишемии на экспрессию циклических РНК (циклоРНК) генов Ece1, Mvp, Egfem1 и Cdyl, а также репрессирующее влияние на экспрессию циклоРНК гена Rgs9. Биоинформатический анализ выявил возможные цис-регуляторные взаимодействия между микроРНК, а также циклоРНК и мРНК исследуемых генов, что указывает на функциональную роль данных циклоРНК в ответе клеток мозга на ишемию. Using real-time PCR, the activating effect of ischemia on the expression of circular RNAs (circRNAs) of Ece1, Mvp, Egfem1 and Cdyl genes, as well as the repressing effect on the expression of circRNA of the Rgs9 gene, is shown in the subcortical structures of the rat brain containing the focus of ischemic damage. Bioinformatics analysis revealed possible cis-regulatory interactions between miRNAs, as well as circRNAs and mRNAs of the studied genes. The result indicates the functional role of these circRNAs in the response of brain cells to ischemia.

В условиях модели экспериментальной ишемии мозга крыс, вызванной обратимой окклюзией правой средней мозговой артерии, с использованием методов RNA-Seq и ПЦР в реальном времени были выявлены гены, значительно меняющие свою активность в мозге крыс. Для 38 наиболее активных генов были определены гены-ортологи у человека. С использованием баз данных проекта 1000 геномов (популяция CEU) был изучен полиморфизм каждого из генов и отобраны локусы, которые демонстрировали максимальное число ассоциаций с другими полиморфизмами (tagSNPs). На первом этапе был исследован полиморфизм генов DRD2, CCL23, SOCS3, HSPB1 и CHRM4, в каждом из которых были идентифицированы от одного до трех tagSNPs. С использованием метода ПЦР в режиме реального времени (TaqMan) аллельные варианты отобранных локусов были генотипированы в выборке больных ишемическим инсультом (100 чел.) и контрольной группе (100 чел.). Частоты встречаемости генотипов исследованных полиморфизмов в контрольной группе, в большинстве случаев, оказались близкими таковым в группе больных с ишемическим инсультом. Наиболее существенные различия в распределении генотипов между выборками (p = 0,088) были продемонстрированы для локуса rs8069976 из региона локализации гена SOCS3. Для уточнения направленности выявленных различий планируется их проверка на выборках больных и контроля больших размеров. In a model of experimental rat brain ischemia caused by the right transient middle cerebral artery occlusion using RNA-Seq and real-time PCR, genes that significantly change their activity in the rat brain were revealed. For 38 most active rat genes their human orthologous genes were identified. Using the genotype data from the 1000 genome project (CEU population), we explored the polymorphism of each of the genes and identified the loci showed the maximum number of associations with other polymorphisms (tagSNPs). At the first stage, the polymorphisms in DRD2, CCL23, SOCS3, HSPB1 and CHRM genes were studied. From one to three tagSNPs were selected for further analysis in each gene. Using TaqMan real-time PCR assays, allelic variants of the selected loci were genotyped in 100 patients with ischemic stroke and in 100 controls. In the most cases the frequencies of genotypes of the SNPs in the control group were similar to those in the group of patients with ischemic stroke. The most substantial differences in the distribution of genotypes between the groups (p = 0.088) were demonstrated for the SNP rs8069976 from the region of SOCS3 gene. To clarify the direction of the differences revealed, their testing in the patient and control samples of larger sizes is planned.

Neurotrophins stimulate the regeneration of neural tissue after lesions. It is also known that the sources of neurogenesis and cerebral function recovery are predominantly located in subcortical brain structures. The effects of ischemia on the expression of genes that encode neurotrophins (Bdnf, Ngf, Nt-3) and their receptors (TrkB, TrkA, TrkC, p75) in brain structures outside the lesion site were studied 3, 24, and 72 h after irreversible unilateral occlusion of the middle cerebral artery in rats. Changes in the mRNA expression of these genes were assessed by relative quantification using real-time RT-PCR. Sham surgery was found to stimulate the expression of genes that encode neurotrophins (Bdnf, Ngf) and their receptor (p75). It has been shown that ischemia influenced the expression of neurotrophins (Bdnf, Ngf, Nt-3) and their receptors (TrkB, TrkA, TrkC, p75) in brain structures outside the lesion focus, including the contralateral hemisphere. The downregulation of Bdnf and TrkB transcripts and Ngf and TrkA upregulation in the contralateral cortex on the first day of ischemia obviously reflected stress response. On day 3, Nt-3 transcription increased in all investigated structures outside the lesion focus. In the contralateral hemisphere, relative levels of TrkA and TrkC mRNA expression increased, while p75 expression decreased. Presumably, the observed changes in gene transcription serve to facilitate neuroplasticity and neural tissue regeneration.

Vascular endothelial growth factor (VEGF-A) is hypoxia-inducible signal glycoprotein. VEGF-A induces vascular endothelial cell proliferation, which leads to the reconstitution of the vascular network in brain regions damaged by ischemia. However, this protein is also involved in the processes of inflammation and edema in early stages of ischemia. The synthetic peptide Semax has neuroprotective and anti-inflammatory properties and is actively used in the treatment of cerebral ischemia. We have previously shown that Semax reduces vascular injury and activates the mRNA synthesis of neurotrophins and their receptors during global cerebral ischemia in rats. In this work, we studied the effect of Semax and its C-terminal Pro-Gly-Pro tripeptide on Vegfa mRNA expression in different regions of the rat brain after 0.5, 1, 2, 4, 8, 12 and 24 h, which is the irreversible occlusion of the common carotid arteries. It was shown that ischemia increases the levels of Vegfa mRNA in rat brains (4 h after occlusion in cerebellum, cerebral cortex, and hippocampus; 8 h after occlusion in the cortex and hippocampus; and 24 h after occlusion in the cortex). Treatment with Semax reduces the levels of Vegfa mRNA in the frontal cortex (4, 8 and 12 h after occlusion) and the hippocampus (2 and 4 h after occlusion). The effect of PGP on the Vegfa gene expression was almost negligible. It was shown that Semax prevents the activating effect of hypoxia on the expression of the Vegfa gene at early stages of global cerebral ischemia. In turn, an increase in the level of Vegfa mRNA in the hippocampus 24 h after occlusion and Semax administration apparently reflects the neuroprotective properties of the drug.