Regulation of the expression of proinflammatory cytokines induced by SARS-CoV-2

An outbreak of a novel coronavirus was reported in Wuhan,China,in late 2019.It has spread rapidly through China and many other countries,causing a global pandemic.Since February 2020,over 28 countries/regions have reported confirmed cases.Individuals with the infection known as coronavirus disease-19(COVID-19)have similar clinical features as severe acute respiratory syndrome first encountered 17 years ago,with fever,cough,and upper airway congestion,along with high production of proinflammatory cytokines(PICs),which form a cytokine storm.PICs induced by COVID-19 include interleukin(IL)-6,IL-17,and monocyte chemoattractant protein-1.The production of cytokines is regulated by activated nuclear factor-kB and involves downstream pathways such as Janus kinase/signal transducers and activators transcription.Protein expression is also regulated by post-translational modification of chromosomal markers.Lysine residues in the peptide tails stretching out from the core of histones bind the sequence upstream of the coding portion of genomic DNA.Covalent modification,particularly methylation,activates or represses gene transcription.PICs have been reported to be induced by histone modification and stimulate exudation of hyaluronic acid,which is implicated in the occurrence of COVID-19.These findings indicate the impact of the expression of PICs on the pathogenesis and therapeutic targeting of COVID-19.

ZMYND10 downregulates cyclins B1 and D1 to arrest cell cycle by trimethylating lysine 9 on histone 3

The BLU gene coding for zinc finger,MYND-type containing 10(ZMYND10)protein is mapped on chromosomal region 3p21.It is frequently lost in some kinds of cancers due to hypermethylation on its promoter region and identified as a tumour suppressor gene.The underlying mechanisms for BLU-mediated tumor suppression remain unclear.BLU has been reported to disturb cell cycle progression.The present study aims at examining whether ZMYND10 prevents progression of the cell cycle by targeting to repressive histone marks and downregulating the level of cyclins.Proteins structurally similar with ZMYND10 have been shown to recognize DNA sequence upstream of coding portion of the gene encoding cell cycle regulators.Enzymes,notably demethylases modifying the lysine residues are over-expressed line oncoproteins,and targeted in anti-cancer therapy.BLU was re-expressed in H1299 and HepG2 cells.The level of cyclin D1,cyclin B1 and trimethylate lysine 9 on histone 3(H3K9me3)and the binding of BLU with SIN3A(a component of the co-repressor)were detected.Cell cycle profile was measured.The evolutionary relationship between ZMYND10 and other ZMYND proteins was analysed by phylogenetic tree construction.We found that BLU expression induced G1 arrest in H1299 cells,and induced G1/G2 arrest in HepG2 cells.Cell cycle arrest was correlated with reduced activities and levels of cyclins;cyclin D1 was downregulated in H1299 cells;Both cyclin B1 and D1 were downregulated in HepG2 cells;and that BLU was associated with SIN3A.In both cell lines,the expression of H3K9me3 was induced.BLU was clustered with histone methyltransferase SMYD3 and SMYD1 on the same clade of the deduced phylogenetic tree.The results thus suggested that ZMYND10 encoded by BLU inhibited cyclins activity to prevent cell cycle progression through interaction with repressors and histone repressive marks to block the expression of genes coding for cyclins.