Unexpected Role of Sterol Synthesis in RNA Stability and Translation in Leishmania

Leishmania species are parasitic protozoans which cause leishmaniasis affecting millions of people worldwide. Sterols are important components of plasma and organellar membranes and serve as precursors for the synthesis of signaling molecules. In contrast to animals, Leishmania do not produce cholesterol but instead synthesize ergostane-based sterols. C14-demethylase is a key enzyme involved in the biosynthesis of sterols in Leishmania parasites and an important drug target. Its inactivation leads to multiple defects including increased plasma membrane fluidity, mitochondrion dysfunction, hypersensitivity to stress and reduced virulence. In this study, we revealed a novel role for sterol synthesis in the maintenance of RNA stability and translation. Sterol alteration in C14-demethylase knockout mutant leads to increased RNA degradation, reduced translation and impaired heat shock response. Thus, sterol biosynthesis plays an unexpected role in global gene regulation in Leishmania parasites.

Download Full-text

Unexpected Role of Sterol Synthesis in RNA Stability and Translation in Leishmania

Biomedicines ◽

10.3390/biomedicines9060696 ◽

2021 ◽

Vol 9 (6) ◽

pp. 696

Author(s):

Zemfira N. Karamysheva ◽

Samrat Moitra ◽

Andrea Perez ◽

Sumit Mukherjee ◽

Elena B. Tikhonova ◽

...

Keyword(s):

Rna Stability ◽

Rna Degradation ◽

Sterol Synthesis ◽

Knockout Mutant ◽

Plasma Membrane Fluidity ◽

Global Gene Regulation ◽

Key Enzyme ◽

Important Drug ◽

Leishmania Parasites

Leishmania parasites are trypanosomatid protozoans that cause leishmaniasis affecting millions of people worldwide. Sterols are important components of the plasma and organellar membranes. They also serve as precursors for the synthesis of signaling molecules. Unlike animals, Leishmania does not synthesize cholesterol but makes ergostane-based sterols instead. C-14-demethylase is a key enzyme involved in the biosynthesis of sterols and an important drug target. In Leishmania parasites, the inactivation of C-14-demethylase leads to multiple defects, including increased plasma membrane fluidity, mitochondrion dysfunction, hypersensitivity to stress and reduced virulence. In this study, we revealed a novel role for sterol synthesis in the maintenance of RNA stability and translation. Sterol alteration in C-14-demethylase knockout mutant leads to increased RNA degradation, reduced translation and impaired heat shock response. Thus, sterol biosynthesis in Leishmania plays an unexpected role in global gene regulation.

Download Full-text

Epitranscriptomic(N6-methyladenosine) Modification of Viral RNA and Virus-Host Interactions

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2020.584283 ◽

2020 ◽

Vol 10 ◽

Author(s):

Hasan Imam ◽

Geon-Woo Kim ◽

Aleem Siddiqui

Keyword(s):

Rna Folding ◽

Rna Stability ◽

Viral Pathogenesis ◽

Rna Degradation ◽

Viral Rna ◽

Reversible Process ◽

Dna Viruses ◽

Host Interactions ◽

Novel Approaches

N6-methyladenosine (m6A) is the most prevalent and internal modification of eukaryotic mRNA. Multiple m6A methylation sites have been identified in the viral RNA genome and transcripts of DNA viruses in recent years. m6A modification is involved in all the phases of RNA metabolism, including RNA stability, splicing, nuclear exporting, RNA folding, translational modulation, and RNA degradation. Three protein groups, methyltransferases (m6A-writers), demethylases (m6A-erasers), and m6A-binding proteins (m6A-readers) regulate this dynamic reversible process. Here, we have reviewed the role of m6A modification dictating viral replication, morphogenesis, life cycle, and its contribution to disease progression. A better understanding of the m6A methylation process during viral pathogenesis is required to reveal novel approaches to combat the virus-associated diseases.

Download Full-text

Role of small nuclear RNAs in eukaryotic gene expression

Essays in Biochemistry ◽

10.1042/bse0540079 ◽

2013 ◽

Vol 54 ◽

pp. 79-90 ◽

Cited By ~ 34

Author(s):

Saba Valadkhan ◽

Lalith S. Gunawardane

Keyword(s):

Gene Expression ◽

Protein Interactions ◽

Rna Stability ◽

Splice Sites ◽

Branch Site ◽

Small Nuclear Rnas ◽

Eukaryotic Gene Expression ◽

Eukaryotic Gene ◽

Rna Biogenesis

Eukaryotic cells contain small, highly abundant, nuclear-localized non-coding RNAs [snRNAs (small nuclear RNAs)] which play important roles in splicing of introns from primary genomic transcripts. Through a combination of RNA–RNA and RNA–protein interactions, two of the snRNPs, U1 and U2, recognize the splice sites and the branch site of introns. A complex remodelling of RNA–RNA and protein-based interactions follows, resulting in the assembly of catalytically competent spliceosomes, in which the snRNAs and their bound proteins play central roles. This process involves formation of extensive base-pairing interactions between U2 and U6, U6 and the 5′ splice site, and U5 and the exonic sequences immediately adjacent to the 5′ and 3′ splice sites. Thus RNA–RNA interactions involving U2, U5 and U6 help position the reacting groups of the first and second steps of splicing. In addition, U6 is also thought to participate in formation of the spliceosomal active site. Furthermore, emerging evidence suggests additional roles for snRNAs in regulation of various aspects of RNA biogenesis, from transcription to polyadenylation and RNA stability. These snRNP-mediated regulatory roles probably serve to ensure the co-ordination of the different processes involved in biogenesis of RNAs and point to the central importance of snRNAs in eukaryotic gene expression.

Download Full-text

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831.76.1.28 ◽

2006 ◽

Vol 76 (1) ◽

pp. 28-33 ◽

Cited By ~ 7

Author(s):

Yukari Egashira ◽

Shin Nagaki ◽

Hiroo Sanada

Keyword(s):

Body Weight ◽

Urinary Excretion ◽

Enzyme Activities ◽

Treated Group ◽

Control Group ◽

Puromycin Aminonucleoside ◽

Low Level ◽

Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

Download Full-text

Acid ceramidase, a double-edged sword in cancer aggression: A minireview

Current Cancer Drug Targets ◽

10.2174/1568009620666201223154621 ◽

2020 ◽

Vol 20 ◽

Author(s):

Helen Shiphrah Vethakanraj ◽

Niveditha Chandrasekaran ◽

Ashok Kumar Sekar

Keyword(s):

Cell Fate ◽

Cancer Progression ◽

Potential Role ◽

Tumour Progression ◽

Acid Ceramidase ◽

The Core ◽

The Past ◽

Sphingosine 1 Phosphate ◽

Key Enzyme

: Acid ceramidase (AC), the key enzyme of the ceramide metabolic pathway hydrolyzes pro-apoptotic ceramide to sphingosine, which by the action of sphingosine-1-kinase is metabolized to mitogenic sphingosine-1-phosphate. The intracellular level of AC determines ceramide/sphingosine-1-phosphate rheostat which in turn decides the cell fate. The upregulated AC expression during cancerous condition acts as a “double-edged sword” by converting pro-apoptotic ceramide to anti-apoptotic sphingosine-1-phosphate, wherein on one end, the level of ceramide is decreased and on the other end, the level of sphingosine-1-phosphate is increased, thus altogether aggravating the cancer progression. In addition, cancer cells with upregulated AC expression exhibited increased cell proliferation, metastasis, chemoresistance, radioresistance and numerous strategies were developed in the past to effectively target the enzyme. Gene silencing and pharmacological inhibition of AC sensitized the resistant cells to chemo/radiotherapy thereby promoting cell death. The core objective of this review is to explore AC mediated tumour progression and the potential role of AC inhibitors in various cancer cell lines/models.

Download Full-text

Moonlighting in Bacillus subtilis: The Small Proteins SR1P and SR7P Regulate the Moonlighting Activity of Glyceraldehyde 3-Phosphate Dehydrogenase A (GapA) and Enolase in RNA Degradation

Microorganisms ◽

10.3390/microorganisms9051046 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1046

Author(s):

Inam Ul Haq ◽

Sabine Brantl

Keyword(s):

Bacillus Subtilis ◽

Antisense Rna ◽

Rna Binding ◽

Rna Degradation ◽

Metabolic Enzyme ◽

Dual Function ◽

Small Proteins ◽

Moonlighting Proteins ◽

Rnase Y

Moonlighting proteins are proteins with more than one function. During the past 25 years, they have been found to be rather widespread in bacteria. In Bacillus subtilis, moonlighting has been disclosed to occur via DNA, protein or RNA binding or protein phosphorylation. In addition, two metabolic enzymes, enolase and phosphofructokinase, were localized in the degradosome-like network (DLN) where they were thought to be scaffolding components. The DLN comprises the major endoribonuclease RNase Y, 3′-5′ exoribonuclease PnpA, endo/5′-3′ exoribonucleases J1/J2 and helicase CshA. We have ascertained that the metabolic enzyme GapA is an additional component of the DLN. In addition, we identified two small proteins that bind scaffolding components of the degradosome: SR1P encoded by the dual-function sRNA SR1 binds GapA, promotes the GapA-RNase J1 interaction and increases the RNase J1 activity. SR7P encoded by the dual-function antisense RNA SR7 binds to enolase thereby enhancing the enzymatic activity of enolase bound RNase Y. We discuss the role of small proteins in modulating the activity of two moonlighting proteins.

Download Full-text

The Role of CD1a expression in the diagnosis of cutaneous leishmaniasis, its relationship with Leishmania species and clinicopathological features

Dermatologic Therapy ◽

10.1111/dth.14977 ◽

2021 ◽

Author(s):

Yasemin Yuyucu Karabulut ◽

Funda KuŞ Bozkurt ◽

Ümit Türsen ◽

Gül Bayram ◽

Gülhan Örekeci Temel ◽

...

Keyword(s):

Cutaneous Leishmaniasis ◽

Leishmania Species ◽

Clinicopathological Features

Download Full-text

Selectivity of mRNA degradation by autophagy in yeast

Nature Communications ◽

10.1038/s41467-021-22574-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shiho Makino ◽

Tomoko Kawamata ◽

Shintaro Iwasaki ◽

Yoshinori Ohsumi

Keyword(s):

Ribosomal Proteins ◽

Rna Degradation ◽

Mrna Degradation ◽

Ribosome Profiling ◽

Genome Wide ◽

Tightly Coupled ◽

Response To Stress ◽

Transcriptional Gene Regulation ◽

Synthesis And Degradation

AbstractSynthesis and degradation of cellular constituents must be balanced to maintain cellular homeostasis, especially during adaptation to environmental stress. The role of autophagy in the degradation of proteins and organelles is well-characterized. However, autophagy-mediated RNA degradation in response to stress and the potential preference of specific RNAs to undergo autophagy-mediated degradation have not been examined. In this study, we demonstrate selective mRNA degradation by rapamycin-induced autophagy in yeast. Profiling of mRNAs from the vacuole reveals that subsets of mRNAs, such as those encoding amino acid biosynthesis and ribosomal proteins, are preferentially delivered to the vacuole by autophagy for degradation. We also reveal that autophagy-mediated mRNA degradation is tightly coupled with translation by ribosomes. Genome-wide ribosome profiling suggested a high correspondence between ribosome association and targeting to the vacuole. We propose that autophagy-mediated mRNA degradation is a unique and previously-unappreciated function of autophagy that affords post-transcriptional gene regulation.

Download Full-text

Terminal uridyltransferase 7 regulates TLR4-triggered inflammation by controlling Regnase-1 mRNA uridylation and degradation

Nature Communications ◽

10.1038/s41467-021-24177-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Chia-Ching Lin ◽

Yi-Ru Shen ◽

Chi-Chih Chang ◽

Xiang-Yi Guo ◽

Yun-Yun Young ◽

...

Keyword(s):

Posttranscriptional Regulation ◽

Inflammatory Responses ◽

Rna Stability ◽

Innate Immune ◽

Stem Loop ◽

Stem Loop Structure ◽

Tlr4 Activation ◽

Harmful Effects ◽

Different Levels

AbstractDifferent levels of regulatory mechanisms, including posttranscriptional regulation, are needed to elaborately regulate inflammatory responses to prevent harmful effects. Terminal uridyltransferase 7 (TUT7) controls RNA stability by adding uridines to its 3′ ends, but its function in innate immune response remains obscure. Here we reveal that TLR4 activation induces TUT7, which in turn selectively regulates the production of a subset of cytokines, including Interleukin 6 (IL-6). TUT7 regulates IL-6 expression by controlling ribonuclease Regnase-1 mRNA (encoded by Zc3h12a gene) stability. Mechanistically, TLR4 activation causes TUT7 to bind directly to the stem-loop structure on Zc3h12a 3′-UTR, thereby promotes Zc3h12a uridylation and degradation. Zc3h12a from LPS-treated TUT7-sufficient macrophages possesses increased oligo-uridylated ends with shorter poly(A) tails, whereas oligo-uridylated Zc3h12a is significantly reduced in Tut7-/- cells after TLR4 activation. Together, our findings reveal the functional role of TUT7 in sculpting TLR4-driven responses by modulating mRNA stability of a selected set of inflammatory mediators.

Download Full-text