Density Gene Expression Research Articles

Sevoflurane augments neuroinflammation by regulating DUSP6 via YTHDF1 in postoperative cognitive dysfunction.

Postoperative cognitive dysfunction (POCD) is a generally recognized complication experienced by patients who receive anesthesia during surgery. Sevoflurane, the most commonly used inhaled anesthetic, has been shown to trigger neuroinflammation that promotes to POCD. This study examined the pathological mechanism by which sevoflurane causes neuroinflammation, participating in POCD. To establish a neurocyte injury model, the human neuroblastoma cell lines SH-SY5Y and SK-N-SH were treated with sevoflurane. Cell viability was determined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assays. The reactive oxygen species (ROS) level was evaluated by DCFH-DA assays. A lactate dehydrogenase (LDH) Cytotoxicity Assay Kit was used to measure LDH levels. Inflammatory cytokine levels were measured using enzyme-linked immunosorbent assay assays. Gene expression densities and protein abundance were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR) or western blotting. The interaction between YTHDF1 and dual specific phosphatase 6 (DUSP6) was validated using RNA immunoprecipitation (RIP)-qPCR and methylated RIP (MeRIP)-qPCR assays. Flow cytometry was performed to determine apoptosis. Sevoflurane promoted apoptosis, oxidative stress, and neuroinflammation and repressed the expression levels of YTHDF1 and DUSP6. Furthermore, YTHDF1 overexpression reversed sevoflurane-induced neuroinflammation in neurocytes. DUSP6 overexpression could alleviate the neuroinflammation induced by sevoflurane via regulating the extracellular signal-regulated kinase (ERK)1/2 signaling pathway. Moreover, YTHDF1 enhanced DUSP6 expression. Sevoflurane-stimulated neuroinflammation by regulating DUSP6 via YTHDF1. Sevoflurane promoted neuroinflammation by regulating DUSP6 via YTHDF1 in an in vitro model of POCD.

Knockdown of 5‐HT1A Receptors in the Nucleus Tractus Solitarius Attenuates Respiratory‐Related Oscillations of Sympathetic Activity in Unanesthetized Male Rats

Our prior studies demonstrate that systemic administration of 5‐HT1A receptor (5‐HT1AR) agonists protect against metabolic acidosis in male rats subjected to acute hypotensive blood loss as well as profound hemorrhagic shock. Protection is dependent on activation of 5‐HT1AR in the hindbrain that causes increases in sympathetic‐mediated venoconstriction, cardiac output and tissue perfusion. This phenomenon is dependent on sensory afferent input carried by sinoaortic nerves. However, the central mechanism of 5‐HT1AR‐mediated protection is unknown. Knockdown of 5‐HT1AR in the dorsomedial brainstem region that includes the nucleus tractus solitarius (NTS) delays recovery of sympathetic activity and exacerbates lactic acidosis following hypotensive hemorrhage. Here, we investigated the effect of 5‐HT1AR knockdown in the dorsomedial brainstem on frequency oscillations of renal sympathetic activity (RSNA) before and during hypotensive hemorrhage, and subsequent 5‐HT1AR agonist administration in the freely moving, unanesthetized male rat. Adeno‐associated viral vectors harboring genes encoding either shRNA targeting rat 5‐HT1AR mRNA (n= 6) or scrambled shRNA (n=7) were bilaterally injected into the NTS under ketamine anesthetic. Four weeks later renal sympathetic recording electrodes and vascular catheters were implanted under ketamine. The next day, RSNA, blood pressure (BP) and heart rate (HR) were recorded during withdrawal of blood from the femoral artery (14.5 mls in 10 min) of freely moving unanesthetized rats. 8‐OH‐DPAT (30 nmol/kg, iv) was given 7 minutes after start of blood withdraw. 5‐HT1AR knockdown had no effect on baseline BP and HR, but reduced respiratory‐related oscillations in RSNA (−54%). Knockdown did not affect the rate of decline in RSNA, BP or HR during hemorrhage. In control rats subjected to hemorrhage, 8‐OH‐DPAT increased BP (+45±4 mmHg), and HR (+98± 8 bpm) as well as total RSNA (75 ± 20% baseline) and power density of RSNA in the respiratory‐related frequency (+34 ± 5% of baseline) within 2 minute of injection. Rats subjected to 5‐HT1AR knockdown showed an attenuated recovery of BP (+24 mmHg, p<0.01), and trends for reduced recovery of HR (+75±17 bpm) and total RSNA (+47±20%). Knockdown completely prevented drug‐induced increases in the power density of RSNA in the respiratory‐related frequency. In situ hybridization studies showed 5‐HT1AR gene expression density in the NTS was greatest in large GABAergic cells found on the lateral edge of the interstitial subnucleus of the NTS at the levels just caudal to area postrema. Previous studies suggest these cells maybe the pump cells that receive excitatory input from slowly adapting pulmonary stretch receptors and inhibit sympathetic activity. Together, these findings suggest that activation of 5‐HT1ARs on GABAergic cells of the NTS during hemorrhage may disinhibit reflex sympathetic activation. This phenomenon may contribute to hemodynamic recovery following blood loss.

Chromosomal "stress-response" domains govern the spatiotemporal expression of the bacterial virulence program.

ABSTRACTRecent studies strongly suggest that the gene expression sustaining both normal and pathogenic bacterial growth is governed by the structural dynamics of the chromosome. However, the mechanistic device coordinating the chromosomal configuration with selective expression of the adaptive traits remains largely unknown. We used a holistic approach exploring the inherent relationships between the physicochemical properties of the DNA and the expression of adaptive traits, including virulence factors, in the pathogen Dickeya dadantii (formerly Erwinia chrysanthemi). In the transcriptomes obtained under adverse conditions encountered during bacterial infection, we explored the patterns of chromosomal DNA sequence organization, supercoil dynamics, and gene expression densities, together with the long-range regulatory impacts of the abundant DNA architectural proteins implicated in pathogenicity control. By integrating these data, we identified transient chromosomal domains of coherent gene expression featuring distinct couplings between DNA thermodynamic stability, supercoil dynamics, and virulence traits.