Intracellular trafficking and glycosylation of hydroxyproline-O-glycosylation module in tobacco BY-2 cells is dependent on medium composition and transcriptome analysis.

Expression of recombinant proteins in plant cells with a "designer" hydroxyproline (Hyp)-O-glycosylated peptide (HypGP), such as tandem repeats of a "Ser-Pro" motif, has been shown to boost the secreted protein yields. However, dramatic secretion and Hyp-O-glycosylation of HypGP-tagged proteins can only be achieved when the plant cells were grown in nitrogen-deficient SH medium. Only trace amounts of secreted fusion protein were detected in MS medium. This study aims to gain a deeper understanding of the possible mechanism underlying these results by examining the intracellular trafficking and Hyp-O-glycosylation of enhanced green fluorescent protein (EGFP) fused with a (SP)32 tag, consisting of 32 repeats of a "Ser-Pro" motif, in tobacco BY-2 cells. When cells were grown in MS medium, the (SP)32-EGFP formed protein body-like aggregate and was retained in the ER, without undergoing Hyp-O-glycosylation. In contrast, the fusion protein becomes fully Hyp-O-glycosylated, and then secreted in SH medium. Transcriptome analysis of the BY-2 cells grown in SH medium vs. MS medium revealed over 16,000 DEGs, with many upregulated DEGs associated with the microtubule-based movement, movement of subcellular component, and microtubule binding. These DEGs are presumably responsible for the enhanced ER-Golgi transport of HypGP-tagged proteins, enabling their glycosylation and secretion in SH medium.

Novel Transcriptomic Interactomes of Noncoding RNAs in the Heart under Altered Thyroid Hormonal States.

Noncoding RNAs are emerging as vital players in cardiovascular diseases. Thyroid hormones (THs) are crucial for cardiovascular survival; however, correction of systemic hypothyroidism (low serum THs) may not improve cardiac tissue-level hypothyroidism or cardiac function. Mechanistically, the understanding of noncoding transcriptomic interactions influencing TH-mediated cardiac effects is unclear. Adult C57BL/6J mixed-sex mice were randomized into Control, Hypothyroid (HypoTH), Hyperthyroid (HyperTH), and HypoTH-Triiodothyronine restoration groups. Physiological, morphological, biochemical, molecular, and whole transcriptomic studies and appropriate statistical analyses were performed. HypoTH showed significant atrophy, depressed cardiac function, and decreased serum THs versus controls, and Triiodothyronine supplementation restored them. HyperTH significantly increased serum THs with hypertrophy. Real-time PCR showed significantly altered inflammatory and immune lncRNAs. The transcriptomic sequencing revealed significant differential expressions of lncRNAs, miRNAs, and mRNAs. Eleven novel circRNAs significantly decreased with increased THs. Multiple pathways were GO-/KEGG-enriched, including cardiac, thyroid, cancer, mitochondrial, inflammatory, adrenergic, metabolic, immune-mediated, vesicular, etc. We also uncovered significant novel co-expression and interactions of lncRNA-miRNA, lncRNA-miRNA-mRNA, lncRNA-mRNA, circRNA-miRNA, and miRNA-mRNA, and splicing events. This includes a novel pathway by which the predominant cardiac TH receptor alpha may interact with specific lncRNAs and miRNAs. This is the first study reporting a comprehensive transcriptome-wide interactome in the cardiac-thyroid axis.

Cellular iron homeostasis and therapeutic implications of iron chelators in cancer.

Iron metabolism and homeostasis are imperative for the maintenance of normal physiological activities due to the element's critical involvement in a wide variety of crucial biological processes like cellular respiration, metabolic pathways, DNA replication, repair, detoxification, neurotransmission and cellular signaling. Being a key contributor of crucial machineries regulating cellular proliferation and survival, it facilitates the process of tumor growth and development. Thus, tumor cells strive to acquire higher amount of iron than non-malignant cells to satisfy their elevated rate of metabolism. Perhaps, not surprisingly chelation of this metal ion was thought to be effective in treating cancer, but due to a variety of side effects, the use of iron chelators was clinically insignificant. However, discovery of various new classes of iron chelators with lesser side effects and selective toxicity towards cancer cells has revived the possibilities of using iron chelators in anti-cancer therapy. In this review, we have discussed the role of iron in promoting malignant mechanisms and the prospects of usage of different classes of iron chelators in cancer therapeutics.

DNA damage induced activation of Cygb stabilizes p53 and mediates G1 arrest.

Cytoglobin (Cygb) is an emerging tumor suppressor gene silenced by promoter hypermethylation in many human tumors. So far, the precise molecular mechanism underlying its tumor suppressive function remains poorly understood. Here, we identified Cygb as a genotoxic stress-responsive hemoprotein upregulated upon sensing cellular DNA damage. Our studies demonstrated that Cygb physically associates with and stabilizes p53, a key cellular DNA damage signaling factor. We provide evidence that Cygb extends the half-life of p53 by blocking its ubiquitination and subsequent degradation. We show that, upon DNA damage, cells overexpressing Cygb displayed proliferation defect by rapid accumulation of p53 and its target gene p21, while Cygb knockdown cells failed to efficiently arrest in G1 phase in response to DNA insult. These results suggest a possible involvement of Cygb in mediating cellular response to DNA damage and thereby contributing in the maintenance of genomic integrity. Our study thus presents a novel insight into the mechanistic role of Cygb in tumor suppression.

Cytoglobin in tumor hypoxia: novel insights into cancer suppression.

Emerging new and intriguing roles of cytoglobin (Cygb) have attracted considerable attention of cancer researchers in recent years. Hypoxic upregulation of Cygb as well as its altered expression in various human cancers suggest another possible role of this newly discovered globin in tumor cell response under low oxygen tension. Since tumor hypoxia is strongly associated with malignant progression of disease and poor treatment response, it constitutes an area of paramount importance for rational design of cancer selective therapies. However, the mechanisms involved during this process are still elusive. This review outlines the current understanding of Cygb's involvement in tumor hypoxia and discusses its role in tumorigenesis. A better perception of Cygb in tumor hypoxia response is likely to open novel perspectives for future tumor therapy.