The Diabetes Gene JAZF1 Is Essential for the Homeostatic Control of Ribosome Biogenesis and Function in Metabolic Stress

Gene expression is an essential process for cellular growth, proliferation, and differentiation. The transcription of protein-coding genes and non-coding loci depends on RNA polymerases. Interestingly, numerous loci encode long non-coding (lnc)RNA transcripts that are transcribed by RNA polymerase II (RNAPII) and fine-tune the RNA metabolism. The nucleolus is a prime example of how different lncRNA species concomitantly regulate gene expression by facilitating the production and processing of ribosomal (r)RNA for ribosome biogenesis. Here, we summarise the current findings on how RNAPII influences nucleolar structure and function. We describe how RNAPII-dependent lncRNA can both promote nucleolar integrity and inhibit ribosomal (r)RNA synthesis by modulating the availability of rRNA synthesis factors in trans. Surprisingly, some lncRNA transcripts can directly originate from nucleolar loci and function in cis. The nucleolar intergenic spacer (IGS), for example, encodes nucleolar transcripts that counteract spurious rRNA synthesis in unperturbed cells. In response to DNA damage, RNAPII-dependent lncRNA originates directly at broken ribosomal (r)DNA loci and is processed into small ncRNA, possibly to modulate DNA repair. Thus, lncRNA-mediated regulation of nucleolar biology occurs by several modes of action and is more direct than anticipated, pointing to an intimate crosstalk of RNA metabolic events.

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Ubiquitin and Ubiquitin-Like Proteins and Domains in Ribosome Production and Function: Chance or Necessity?

International Journal of Molecular Sciences ◽

10.3390/ijms22094359 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4359

Author(s):

Sara Martín-Villanueva ◽

Gabriel Gutiérrez ◽

Dieter Kressler ◽

Jesús de la Cruz

Keyword(s):

Ribosomal Proteins ◽

Ribosome Biogenesis ◽

Ribosome Assembly ◽

Cellular Processes ◽

Substrate Protein ◽

Precursor Proteins ◽

Assembly Factors ◽

Ubiquitin Moiety ◽

And Function

Ubiquitin is a small protein that is highly conserved throughout eukaryotes. It operates as a reversible post-translational modifier through a process known as ubiquitination, which involves the addition of one or several ubiquitin moieties to a substrate protein. These modifications mark proteins for proteasome-dependent degradation or alter their localization or activity in a variety of cellular processes. In most eukaryotes, ubiquitin is generated by the proteolytic cleavage of precursor proteins in which it is fused either to itself, constituting a polyubiquitin precursor, or as a single N-terminal moiety to ribosomal proteins, which are practically invariably eL40 and eS31. Herein, we summarize the contribution of the ubiquitin moiety within precursors of ribosomal proteins to ribosome biogenesis and function and discuss the biological relevance of having maintained the explicit fusion to eL40 and eS31 during evolution. There are other ubiquitin-like proteins, which also work as post-translational modifiers, among them the small ubiquitin-like modifier (SUMO). Both ubiquitin and SUMO are able to modify ribosome assembly factors and ribosomal proteins to regulate ribosome biogenesis and function. Strikingly, ubiquitin-like domains are also found within two ribosome assembly factors; hence, the functional role of these proteins will also be highlighted.

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MiR 208a Regulates Mitochondrial Biogenesis in Metabolically Challenged Cardiomyocytes

Cells ◽

10.3390/cells10113152 ◽

2021 ◽

Vol 10 (11) ◽

pp. 3152

Author(s):

Naveen Mekala ◽

Jacob Kurdys ◽

Alexis Paige Vicenze ◽

Leana Rose Weiler ◽

Carmen Avramut ◽

...

Keyword(s):

Mitochondrial Biogenesis ◽

Protein Trafficking ◽

Cardiac Contractility ◽

Metabolic Stress ◽

Mitochondrial Translation ◽

Human Cardiomyocytes ◽

Bioenergetic Metabolism ◽

Mitochondrial Defects ◽

And Function ◽

High Albumin

Metabolic syndrome increases the risk for cardiovascular disease including metabolic cardiomyopathy that may progress to heart failure. The decline in mitochondrial metabolism is considered a critical pathogenic mechanism that drives this progression. Considering its cardiac specificity, we hypothesized that miR 208a regulates the bioenergetic metabolism in human cardiomyocytes exposed to metabolic challenges. We screened in silico for potential miR 208a targets focusing on mitochondrial outcomes, and we found that mRNA species for mediator complex subunit 7, mitochondrial ribosomal protein 28, stanniocalcin 1, and Sortin nexin 10 are rescued by the CRISPR deletion of miR 208a in human SV40 cardiomyocytes exposed to metabolic challenges (high glucose and high albumin-bound palmitate). These mRNAs translate into proteins that are involved in nuclear transcription, mitochondrial translation, mitochondrial integrity, and protein trafficking. MiR 208a suppression prevented the decrease in myosin heavy chain α isoform induced by the metabolic stress suggesting protection against a decrease in cardiac contractility. MiR 208a deficiency opposed the decrease in the mitochondrial biogenesis signaling pathway, mtDNA, mitochondrial markers, and respiratory properties induced by metabolic challenges. The benefit of miR 208a suppression on mitochondrial function was canceled by the reinsertion of miR 208a. In summary, miR 208a regulates mitochondrial biogenesis and function in cardiomyocytes exposed to diabetic conditions. MiR 208a may be a therapeutic target to promote mitochondrial biogenesis in chronic diseases associated with mitochondrial defects.

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Expanding Role of Ubiquitin in Translational Control

International Journal of Molecular Sciences ◽

10.3390/ijms21031151 ◽

2020 ◽

Vol 21 (3) ◽

pp. 1151 ◽

Cited By ~ 3

Author(s):

Shannon E. Dougherty ◽

Austin O. Maduka ◽

Toshifumi Inada ◽

Gustavo M. Silva

Keyword(s):

Translational Control ◽

Ribosomal Proteins ◽

Ribosome Biogenesis ◽

Rna Binding ◽

Protein Quality ◽

Rna Binding Proteins ◽

Ubiquitin Chain ◽

Molecular Aspects ◽

And Function

The eukaryotic proteome has to be precisely regulated at multiple levels of gene expression, from transcription, translation, and degradation of RNA and protein to adjust to several cellular conditions. Particularly at the translational level, regulation is controlled by a variety of RNA binding proteins, translation and associated factors, numerous enzymes, and by post-translational modifications (PTM). Ubiquitination, a prominent PTM discovered as the signal for protein degradation, has newly emerged as a modulator of protein synthesis by controlling several processes in translation. Advances in proteomics and cryo-electron microscopy have identified ubiquitin modifications of several ribosomal proteins and provided numerous insights on how this modification affects ribosome structure and function. The variety of pathways and functions of translation controlled by ubiquitin are determined by the various enzymes involved in ubiquitin conjugation and removal, by the ubiquitin chain type used, by the target sites of ubiquitination, and by the physiologic signals triggering its accumulation. Current research is now elucidating multiple ubiquitin-mediated mechanisms of translational control, including ribosome biogenesis, ribosome degradation, ribosome-associated protein quality control (RQC), and redox control of translation by ubiquitin (RTU). This review discusses the central role of ubiquitin in modulating the dynamism of the cellular proteome and explores the molecular aspects responsible for the expanding puzzle of ubiquitin signals and functions in translation.

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The Intricate Role of p53 in Adipocyte Differentiation and Function

Cells ◽

10.3390/cells9122621 ◽

2020 ◽

Vol 9 (12) ◽

pp. 2621

Author(s):

Yun Kyung Lee ◽

Yu Seong Chung ◽

Ji Hye Lee ◽

Jin Mi Chun ◽

Jun Hong Park

Keyword(s):

Adipocyte Differentiation ◽

Metabolic Diseases ◽

Metabolic Stress ◽

Health Concern ◽

Metabolic Dysfunction ◽

Direct Role ◽

Proliferation And Apoptosis ◽

Response To Stress ◽

And Function

For more than three decades, numerous studies have demonstrated the function of p53 in cell cycle, cellular senescence, autophagy, apoptosis, and metabolism. Among diverse functions, the essential role of p53 is to maintain cellular homeostatic response to stress by regulating proliferation and apoptosis. Recently, adipocytes have been studied with increasing intensity owing to the increased prevalence of metabolic diseases posing a serious public health concern and because metabolic dysfunction can directly induce tumorigenesis. The prevalence of metabolic diseases has steadily increased worldwide, and a growing interest in these diseases has led to the focus on the role of p53 in metabolism and adipocyte differentiation with or without metabolic stress. However, our collective understanding of the direct role of p53 in adipocyte differentiation and function remains insufficient. Therefore, this review focuses on the newly discovered roles of p53 in adipocyte differentiation and function.

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Nutrition support in acute cardiac care

10.1093/med/9780199687039.003.0032_update_001 ◽

2016 ◽

Author(s):

Michael P Casaer ◽

Greet Van den Berghe

Keyword(s):

Critical Illness ◽

Critically Ill ◽

Metabolic Stress ◽

Nutrition Therapy ◽

Nutrition Support ◽

Critically Ill Patient ◽

Refeeding Syndrome ◽

New Findings ◽

Early Parenteral Nutrition ◽

And Function

Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.

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Nutrition support in acute cardiac care

10.1093/med/9780199687039.003.0032 ◽

2015 ◽

Author(s):

Michael P Casaer ◽

Greet Van den Berghe

Keyword(s):

Critical Illness ◽

Critically Ill ◽

Metabolic Stress ◽

Nutrition Therapy ◽

Nutrition Support ◽

Critically Ill Patient ◽

Refeeding Syndrome ◽

New Findings ◽

Early Parenteral Nutrition ◽

And Function

Malnutrition in cardiac and critical illness is associated with a compromised clinical outcome. The aim of nutrition therapy is to prevent these complications and particularly to attenuate lean tissue wasting and the loss of muscle force and of physical function. During the last decade, several well-powered randomized controlled nutrition trials have been performed. Their results challenge the existing nutrition practices in critically ill patients. Enhancing the nutritional intake and the administration of specialized formulations failed to evoke clinical benefit. Some interventions even provoked an increased mortality or a delayed recovery. These unexpected new findings might be, in part, caused by an important leap forward in the methodological quality in the recent trials. Perhaps reversing early catabolism in the critically ill patient by nutrition or anabolic interventions is impossible or even inappropriate. Nutrients effectively suppress the catabolic intracellular autophagy pathway. But autophagy is crucial for cellular integrity and function during metabolic stress, and consequently its inhibition early in critical illness might be deleterious. Evidence from large nutrition trials, particularly in acute cardiac illness, is scarce. Nutrition therapy is therefore focused on avoiding iatrogenic harm. Some enteral nutrition is administered if possible and eventually temporary hypocaloric feeding is tolerated. Above all, the refeeding syndrome and other nutrition-related complications should be prevented. There is no indication for early parenteral nutrition, increased protein doses, specific amino acids, or modified lipids in critical illness.

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Autophagy Is Required For Long-Term Hematopoietic Stem Cell (HSC) Function and G-CSF-Induced HSC Mobilization

Blood ◽

10.1182/blood.v122.21.892.892 ◽

2013 ◽

Vol 122 (21) ◽

pp. 892-892

Author(s):

Lucie Leveque ◽

Therese Vu ◽

Rachel D Kuns ◽

Bianca E Teal ◽

Mary Lor ◽

...

Keyword(s):

Cell Imaging ◽

Metabolic Stress ◽

Autophagosome Formation ◽

Hematopoietic Stem ◽

Imaging Flow Cytometry ◽

Single Cell Imaging ◽

Autophagic Activity ◽

And Function ◽

Hsc Transplantation

Abstract Hematopoiesis originates from a rare pool of hematopoietic stem cells (HSC) that are uniquely capable of both self-renewal and terminal differentiation into lineage-committed progenitor cells. Autophagy is a process of cytoplasmic protein recycling which maintains cellular homeostasis and protects the cell during periods of metabolic stress and nutrient deprivation and has an established role in the survival and function of immunological cells. Recent publications have linked autophagy with preservation of normal long term HSCs (LT-HSCs) during aging (Nature; 2013: 494:323-7). We therefore sought to determine the role of autophagy in LT-HSC function at homeostasis and during the clinically relevant stress of G-CSF-induced HSC mobilization. Using single cell imaging flow cytometry to monitor autophagosome formation in LC3-GFP transgenic mice (LC3-GFP punctae formation is a reporter of autophagy activity) we demonstrated autophagic activity in HSC populations but not in committed myeloid progenitors. In line with this, inhibition of autophagy degradation by chloroquine administration resulted in the accumulation of autophagy related protein p62 in purified HSCs compared to myeloid progenitors. To determine the contribution of autophagy to HSC development and function, we analyzed mice deficient in Atg5, a protein essential for autophagosome formation. Autophagy was not required for fetal liver (FL) HSC development, however, Atg5-/- FL HSCs showed mildly reduced long-term repopulating function in bone marrow (BM) transplantation assays (16 weeks peripheral blood (PB) engraftment Atg5-/- 83.45% vs. WT 93.10%, n=12, p<0.001). Importantly, Atg5-/- LT-HSCs (Lin-Sca-1+c-kit+Flk2-CD150+CD48-) were markedly reduced in congenic recipients compared to WT FL LT-HSCs (Atg5-/- 0.02% vs. WT 0.04%, n=11, p<0.001). Secondary competitive transplantation was used to determine the effect of autophagy loss on LT-HSC function in vivo. Atg5-/- LT-HSCs exhibited a profound impairment in the repopulation of secondary congenic recipients (Atg5-/-4.65% vs. WT 32.3%, n=5, p<0.01). Mechanistically, microarray analysis of purified LT-HSCs from Atg5-/- vs. WT FL chimeras demonstrated clear differences in gene expression by unsupervised hierarchical clustering. Differentially expressed genes included Cxcl12, Sdc2 and Apex1, regulators of HSC fate. Gene Ontology enrichment analysis demonstrated that autophagy deficient LT-HSCs had impaired metabolism, enhanced cellular differentiation, enforced proliferation and increased apoptosis. Validating these findings, there was a loss of quiescence in the Atg5-/- compared to WT LT-HSC (quiescent Atg5-/- 30% vs. WT 39%, n=16 p<0.05) and Atg5-/- FL HSCs exhibited enhanced apoptosis after culture in cytokine enriched media (Atg5-/-21.2% vs. WT 14.2%, n=5, p<0.01). Given the requirement for autophagy in homeostasis of LT-HSC and its role in proliferation and metabolic stress, we next investigated whether autophagy participated in the HSC response to G-CSF. G-CSF is commonly used to ameliorate neutropenia in patients treated with chemotherapy and is also used to mobilize HSCs for patients undergoing HSC transplantation. Using single cell imaging flow cytometry, autophagosome formation was enhanced in HSCs after 6 days of G-CSF mobilization (10mcg/day). G-CSF treatment efficiently mobilized PB neutrophils and colony forming units (CFU) in WT chimeras, however Atg5-/- chimeras showed a striking reduction in G-CSF-induced neutrophil (Atg5-/- 4.95 x106/mL vs. WT 10.46 x106/mL, n=20, p<0.0001) and PB CFU mobilization post-G-CSF (Atg5-/- 47/100µL vs. WT 126/100µL, n=5, p<0.01). BM CFU numbers were similar in Atg5-/- and WT FL chimeras both pre- and post-G-CSF mobilization. Atg5-/-neutrophils demonstrated increased apoptosis after G-CSF treatment suggesting that autophagy limits PB neutrophil survival, but not BM neutrophil development during G-CSF mobilization. These data demonstrate that autophagy is an active process in LT-HSCs and that genetic deletion of Atg5 results in the failure of adult LT-HSC maintenance and function. Autophagic activity is augmented by G-CSF-induced HSC stress and is required for G-CSF-induced HSC mobilization. These findings are particularly relevant to HSC transplantation and hematopoietic function in the context of a rapid rise in the clinical use of agents that have modulatory effects on autophagy. Disclosures: No relevant conflicts of interest to declare.

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Origin of a rapidly evolving homeostatic control system programming testis function

Journal of Endocrinology ◽

10.1530/joe-17-0250 ◽

2017 ◽

Vol 234 (2) ◽

pp. 217-232 ◽

Cited By ~ 1

Author(s):

Pengli Bu ◽

Shintaro Yagi ◽

Kunio Shiota ◽

S M Khorshed Alam ◽

Jay L Vivian ◽

...

Keyword(s):

Control System ◽

Leydig Cell ◽

Protein Product ◽

Specific Pattern ◽

Individual Species ◽

Alternative Transcript ◽

Homeostatic Control ◽

Reproductive Axis ◽

And Function ◽

System Programming

Mammals share common strategies for regulating reproduction, including a conserved hypothalamic–pituitary–gonadal axis; yet, individual species exhibit differences in reproductive performance. In this report, we describe the discovery of a species-restricted homeostatic control system programming testis growth and function. Prl3c1 is a member of the prolactin gene family and its protein product (PLP-J) was discovered as a uterine cytokine contributing to the establishment of pregnancy. We utilized mouse mutagenesis of Prl3c1 and revealed its involvement in the regulation of the male reproductive axis. The Prl3c1-null male reproductive phenotype was characterized by testiculomegaly and hyperandrogenism. The larger testes in the Prl3c1-null mice were associated with an expansion of the Leydig cell compartment. Prl3c1 locus is a template for two transcripts (Prl3c1-v1 and Prl3c1-v2) expressed in a tissue-specific pattern. Prl3c1-v1 is expressed in uterine decidua, while Prl3c1-v2 is expressed in Leydig cells of the testis. 5′RACE, chromatin immunoprecipitation and DNA methylation analyses were used to define cell-specific promoter usage and alternative transcript expression. We examined the Prl3c1 locus in five murid rodents and showed that the testicular transcript and encoded protein are the result of a recent retrotransposition event at the Mus musculus Prl3c1 locus. Prl3c1-v1 encodes PLP-J V1 and Prl3c1-v2 encodes PLP-J V2. Each protein exhibits distinct intracellular targeting and actions. PLP-J V2 possesses Leydig cell-static actions consistent with the Prl3c1-null testicular phenotype. Analysis of the biology of the Prl3c1 gene has provided insight into a previously unappreciated homeostatic setpoint control system programming testicular growth and function.

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Functional ribosome biogenesis is a prerequisite for p53 destabilization: impact of chemotherapy on nucleolar functions and RNA metabolism

Biological Chemistry ◽

10.1515/hsz-2013-0153 ◽

2013 ◽

Vol 394 (9) ◽

pp. 1133-1143 ◽

Cited By ~ 17

Author(s):

Kaspar Burger ◽

Dirk Eick

Keyword(s):

Ribosomal Rna ◽

Ribosome Biogenesis ◽

Rna Metabolism ◽

Chemotherapeutic Drugs ◽

Tumor Suppressor P53 ◽

Nucleolar Structure ◽

Highly Sensitive ◽

Important Regulator ◽

Sensitive Sensor ◽

And Function

Abstract The production and processing of ribosomal RNA is a complex and well-coordinated nucleolar process for ribosome biogenesis. Progress in understanding nucleolar structure and function has lead to the unexpected discovery of the nucleolus as a highly sensitive sensor of cellular stress and an important regulator of the tumor suppressor p53. Inhibition of ribosomal RNA metabolism has been shown to activate a signaling pathway for p53 induction. This review elucidates the potential of classical and recently developed chemotherapeutic drugs to stabilize p53 by inhibiting nucleolar functions.

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