The Cell Fate Determinant Musashi Is Controlled Through Dynamic Protein:Protein Interactions

Abstract The Musashi RNA-binding protein functions as a gatekeeper of cell maturation and plasticity through the control of target mRNA translation. It is understood that Musashi promotes stem cell self-renewal and opposes differentiation. While Musashi is best characterized as a repressor of target mRNA translation, we have shown that Musashi can activate target mRNA translation in a cell context specific manner via regulatory phosphorylation on two evolutionarily conserved C-terminal serine residues. Our recent work has found that Musashi is expressed in pituitary stem cells as well as in differentiated hormone producing cell lineages in the adult pituitary. We hypothesize that Musashi maintains cell fate plasticity in the adult pituitary to allow the gland to modulate hormone production in response to changing organismal needs. Here, we seek to understand the regulation of Musashi function. Both Musashi isoforms (Musashi1 and Musashi2) contain two RNA-recognition motifs (RRMs) that bind to specific sequences in the 3’-UTR of target mRNA transcripts; however, neither isoform has enzymatic properties and thus functions through interactions with other proteins to regulate translational outcomes, but the identity and role of Musashi partner proteins is largely unknown. In this study, we have identified co-associated partner proteins that functionally contribute to Musashi-dependent mRNA translational activation during the maturation of Xenopus oocytes. Using mass spectrometry, we identified 29 co-associated proteins that interact specifically with Musashi1 during oocyte maturation and determined that the Musashi co-associated proteins ePABP, PABP4, LSM14A/B, CELF2, PUM1, ELAV1, ELAV2, and DDX6 attenuated oocyte maturation through individual antisense DNA oligo knockdowns. An assessment of the role of these cofactors in the control of Musashi-dependent target mRNA translation is in progress. In addition to studying co-associated proteins, we have created a computational 3D model of the Musashi1 molecule to assist in our investigation Musashi dimerization. This model has indicated that both Musashi1 dimerization and Musashi1:Musashi2 heterodimerization are energetically favorable, and co-pulldown studies have verified both Musashi1 homo-dimerization and Musashi1:Musashi2 heterodimerization in vivo. Computational modeling of Musashi dimer complexes has also identified the key amino acids necessary for these interactions. The contribution of each co-associated protein’s influence on Musashi-dependent translation, relative to the requirement for Musashi:Musashi dimerization, is expected to provide unparalleled insight into regulation of Musashi action. Moreover, cell type specific regulation of association of Musashi co-factors would directly influence Musashi target mRNA translation in oocyte maturation and during pituitary cell plasticity.

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144. ROLE OF RNA-BINDING PROTEIN, MUSASHI-1 (Msi-1), IN MURINE FOLLICULOGENESIS AND OOCYTE DEVELOPMENT

Reproduction Fertility and Development ◽

10.1071/srb09abs144 ◽

2009 ◽

Vol 21 (9) ◽

pp. 62

Author(s):

K. M. Gunter ◽

B. A. Fraser ◽

A. P. Sobinoff ◽

N. A. Siddall ◽

G. R. Hime ◽

...

Keyword(s):

Real Time ◽

Oocyte Maturation ◽

Real Time Pcr ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Mrna Translation ◽

Oocyte Development ◽

Target Mrna ◽

P21 Waf1

Follicular development and oocyte maturation in mammals requires the temporal and spatial control of protein production. Consequently, it is hypothesised that the preovulatory follicle represses mRNA translation until specific proteins are required during oocyte maturation. Increasingly RNA-binding proteins are being recognised as important contributors to germ cell development, particularly during oocyte transcriptional quiescence. We have identified the presence of RNA-binding protein musashi-1 (Msi-1) mRNA within the mouse ovary and mature mouse oocyte, where the protein is believed to act as a translational repressor by binding to specific sequences within the 3' UTR of target mRNA molecules. Recent studies in various mammalian systems have identified p21 WAF1, cdkn2a, notch and m-numb as potential targets of Msi-1. We have also identified morf4l1 as a potential target through preliminary pulldown and microarray analysis using a GST tagged Msi-1 recombinant protein. To further study these potential targets, a transgenic Msi-1 mouse was produced to overexpress the RNA-binding protein in the developing oocyte. Real time PCR, performed on intact ovaries of WT and Tg mice, has so far demonstrated a 1.5-fold increase in Msi-1 expression in tgMsi-1/+ ovaries, above WT ovary expression. Real time PCR analysis of Msi-1 target mRNA expression has also shown an overall increase in expression in the tgMsi-1/+ ovaries of p21 WAF1 (~2.5-fold), cdkn2a (~2-fold), and notch (~3-fold). However m-numb and morf4l1 do not appear to be targets of Msi-1 in the oocyte, with no significant difference in expression between the WT and tgMsi-1/+ ovaries analysed. Functional quantification of oocyte development reveals a significantly less oocytes produced from superovulated juvenile mice compared with wild type litter mates. Therefore, preliminary analysis suggests that Msi-1 may play a role in binding the transcripts of genes necessary for cell cycle regulation and chromatin remodelling, characteristic of meiotic progression and oocyte development.

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The Role of Translation Initiation Regulation in Haematopoiesis

Comparative and Functional Genomics ◽

10.1155/2012/576540 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 7

Author(s):

Godfrey Grech ◽

Marieke von Lindern

Keyword(s):

Gene Expression ◽

Translation Initiation ◽

Translational Control ◽

Molecular Mechanisms ◽

Rna Binding ◽

Regulation Of Gene Expression ◽

Mrna Translation ◽

Translation Control ◽

Haematological Disorders

Organisation of RNAs into functional subgroups that are translated in response to extrinsic and intrinsic factors underlines a relatively unexplored gene expression modulation that drives cell fate in the same manner as regulation of the transcriptome by transcription factors. Recent studies on the molecular mechanisms of inflammatory responses and haematological disorders indicate clearly that the regulation of mRNA translation at the level of translation initiation, mRNA stability, and protein isoform synthesis is implicated in the tight regulation of gene expression. This paper outlines how these posttranscriptional control mechanisms, including control at the level of translation initiation factors and the role of RNA binding proteins, affect hematopoiesis. The clinical relevance of these mechanisms in haematological disorders indicates clearly the potential therapeutic implications and the need of molecular tools that allow measurement at the level of translational control. Although the importance of miRNAs in translation control is well recognised and studied extensively, this paper will exclude detailed account of this level of control.

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Cell Delivery and Recirculation

Tissue Engineering ◽

10.1093/oso/9780195141306.003.0016 ◽

2004 ◽

Author(s):

W. Mark Saltzman

Keyword(s):

Tissue Engineering ◽

Cell Adhesion ◽

Cell Fate ◽

Critical Role ◽

Cell Movement ◽

The Body ◽

Associated Proteins ◽

Adult Organism ◽

Adenine Deaminase

Perhaps the simplest realization of tissue engineering involves the direct administration of a suspension of engineered cells—cells that have been isolated, characterized, manipulated, and amplified outside of the body. One can imagine engineering diverse and useful properties into the injected cells: functional enzymes, secretion of drugs, resistance to immune recognition, and growth control. We are most familiar with methods for manipulating the cell internal chemistry by introduction or removal of genes; for example, the first gene therapy experiments involved cells that were engineered to produce a deficient enzyme, adenine deaminase (see Chapter 2). But genes also encode systems that enable cell movement, cell mechanics, and cell adhesion. Conceivably, these systems can be modified to direct the interactions of an administered cell with its new host. For example, cell adhesion signals could be introduced to provide tissue targeting, cytoskeleton-associated proteins could be added to alter viscosity and deformability (in order to prolong circulation time), and motor proteins could be added to facilitate cell migration. Ideally, cell fate would also be engineered, so that the cell would move to the appropriate location in the body, no matter how it was administered; for example, transfused liver cells would circulate in the blood and, eventually, crawl into the liver parenchyma. Cells find their place in developing organisms by a variety of chemotactic and adhesive signals, but can these same signaling mechanisms be engaged to target cells administered to an adult organism? We have already considered the critical role of cell movement in development in Chapter 3. In this chapter, the utility of cell trafficking in tissue engineering is approached by first considering the normal role of cell recirculation and trafficking within the adult organism. Most cells can be easily introduced into the body by intravenous injection or infusion. This procedure is particularly appropriate for cells that function within the circulation; for example, red blood cells (RBCs) and lymphocytes. The first blood transfusions into humans were performed by Jean-Baptiste Denis, a French physician, in 1667. This early appearance of transfusion is startling, since the circulatory system was described by William Harvey only a few decades earlier, in 1628.

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The RNA-binding protein DAZL functions as repressor and activator of mRNA translation during oocyte maturation

Nature Communications ◽

10.1038/s41467-020-15209-9 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Cai-Rong Yang ◽

Gabriel Rajkovic ◽

Enrico Maria Daldello ◽

Xuan G. Luong ◽

Jing Chen ◽

...

Keyword(s):

Oocyte Maturation ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Mrna Translation

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The APC/CFZY–1/Cdc20 Complex Coordinates With OMA-1 to Regulate the Oocyte-to-Embryo Transition in Caenorhabditis elegans

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.749654 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yabing Hu ◽

Xuewen Hu ◽

Dongchen Li ◽

Zhenzhen Du ◽

Kun Shi ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Cell Fate ◽

Zinc Finger ◽

Oocyte Maturation ◽

Rna Binding ◽

Gain Of Function ◽

Ccch Zinc Finger ◽

C Complex ◽

Fate Determinants ◽

Cell Fate Determinants

During oocyte maturation and the oocyte-to-embryo transition, key developmental regulators such as RNA-binding proteins coordinate translation of particular messenger RNA (mRNAs) and related developmental processes by binding to their cognate maternal mRNAs. In the nematode Caenorhabditis elegans, these processes are regulated by a set of CCCH zinc finger proteins. Oocyte maturation defective-1 (OMA-1) and OMA-2 are two functionally redundant CCCH zinc finger proteins that turnover rapidly during the first embryonic cell division. These turnovers are required for proper transition from oogenesis to embryogenesis. A gain-of-function mutant of OMA-1, oma-1(zu405), stabilizes and delays degradation of OMA-1, resulting in delayed turnover and mis-segregation of other cell fate determinants, which eventually causes embryonic lethality. We performed a large-scale forward genetic screen to identify suppressors of the oma-1(zu405) mutant. We show here that multiple alleles affecting functions of various anaphase promoting complex/cyclosome (APC/C) subunits, including MAT-1, MAT-2, MAT-3, EMB-30, and FZY-1, suppress the gain-of-function mutant of OMA-1. Transcriptome analysis suggested that overall transcription in early embryos occurred after introducing mutations in APC/C genes into the oma-1(zu405) mutant. Mutations in APC/C genes prevent OMA-1 enrichment in P granules and correct delayed degradation of downstream cell fate determinants including pharynx and intestine in excess-1 (PIE-1), posterior segregation-1 (POS-1), muscle excess-3 (MEX-3), and maternal effect germ-cell defective-1 (MEG-1). We demonstrated that only the activator FZY-1, but not FZR-1, is incorporated in the APC/C complex to regulate the oocyte-to-embryo transition. Our findings suggested a genetic relationship linking the APC/C complex and OMA-1, and support a model in which the APC/C complex promotes P granule accumulation and modifies RNA binding of OMA-1 to regulate the oocyte-to-embryo transition process.

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POS-1 and GLD-1 repress glp-1 translation through a conserved binding-site cluster

Molecular Biology of the Cell ◽

10.1091/mbc.e12-03-0216 ◽

2012 ◽

Vol 23 (23) ◽

pp. 4473-4483 ◽

Cited By ~ 15

Author(s):

Brian M. Farley ◽

Sean P. Ryder

Keyword(s):

Cell Fate ◽

Binding Sites ◽

Rna Binding ◽

Zinc Finger Protein ◽

Rna Binding Proteins ◽

Mrna Translation ◽

Regulatory Elements ◽

Regulatory Sequence ◽

Regulatory Pathways ◽

Fate Specification

RNA-binding proteins (RBPs) coordinate cell fate specification and differentiation in a variety of systems. RNA regulation is critical during oocyte development and early embryogenesis, in which RBPs control expression from maternal mRNAs encoding key cell fate determinants. The Caenorhabditis elegans Notch homologue glp-1 coordinates germline progenitor cell proliferation and anterior fate specification in embryos. A network of sequence-specific RBPs is required to pattern GLP-1 translation. Here, we map the cis-regulatory elements that guide glp-1 regulation by the CCCH-type tandem zinc finger protein POS-1 and the STAR-domain protein GLD-1. Our results demonstrate that both proteins recognize the glp-1 3′ untranslated region (UTR) through adjacent, overlapping binding sites and that POS-1 binding excludes GLD-1 binding. Both factors are required to repress glp-1 translation in the embryo, suggesting that they function in parallel regulatory pathways. It is intriguing that two equivalent POS-1–binding sites are present in the glp-1 3′ UTR, but only one, which overlaps with a translational derepression element, is functional in vivo. We propose that POS-1 regulates glp-1 mRNA translation by blocking access of other RBPs to a key regulatory sequence.

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Role of nuclear-cytoplasmic protein localization during Drosophila neuroblast development

Genome ◽

10.1139/gen-2020-0039 ◽

2020 ◽

pp. 1-11

Author(s):

Sophie E. Keegan ◽

Sarah C. Hughes

Keyword(s):

Cell Fate ◽

Neurodegenerative Disorders ◽

Rna Binding ◽

Rna Binding Proteins ◽

Protein Localization ◽

Cell Activity ◽

Cytoplasmic Protein ◽

Cytoplasmic Localization ◽

Cell Fate Decisions

Nuclear-cytoplasmic localization is an efficient way to regulate transcription factors and chromatin remodelers. Altering the location of existing protein pools also facilitates a more rapid response to changes in cell activity or extracellular signals. There are several examples of proteins that are regulated by nucleo-cytoplasmic shuttling, which are required for Drosophila neuroblast development. Disruption of the localization of homologs of these proteins has also been linked to several neurodegenerative disorders in humans. Drosophila has been used extensively to model the neurodegenerative disorders caused by aberrant nucleo-cytoplasmic localization. Here, we focus on the role of alternative nucleo-cytoplasmic protein localization in regulating proliferation and cell fate decisions in the Drosophila neuroblast and in neurodegenerative disorders. We also explore the analogous role of RNA binding proteins and mRNA localization in the context of regulation of nucleo-cytoplasmic localization during neural development and a role in neurodegenerative disorders.

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The Musashi1 RNA-Binding Protein Functions as a Leptin-Regulated Enforcer of Pituitary Cell Fate and Hormone Production

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.1333 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A654-A654

Author(s):

Jewel Banik* ◽

Juchan Lim* ◽

Hardy L Linda ◽

Angela Katherine Odle ◽

Gwen V Childs ◽

...

Keyword(s):

Cell Fate ◽

Anterior Pituitary ◽

Binding Protein ◽

Mrna Translation ◽

Pituitary Cell ◽

Pituitary Hormone ◽

Hormone Production ◽

Lineage Specification ◽

Regulatory Phosphorylation ◽

Translational Activation

Abstract The pituitary gland is the major endocrine organ that produces and secretes hormones in response to hypothalamic signals to regulate important processes like growth, reproduction, and stress. The anterior pituitary adapts to metabolic and reproductive needs by exhibiting cellular plasticity, resulting in altered hormone production and secretion. The adipokine, leptin, serves a critical role to couple energy status to pituitary function. We have recently reported that the cell fate determinant, Musashi, functions as a post-transcriptional regulator of target mRNA translation in the mouse pituitary and have speculated that Musashi may modulate pituitary cell plasticity. However, the underlying mechanisms governing such pituitary plasticity are not fully understood. Musashi is an mRNA binding protein that is required for self-renewal, proliferation, and to control the differentiation of stem and progenitor cells. We have recently shown that Musashi is expressed in Sox2+ pituitary stem cells and surprisingly, we also found Musashi expression in all differentiated hormone expressing cell lineages in the adult anterior pituitary. The role of Musashi in these mature differentiated cells is unknown. We have observed that a range of critical pituitary mRNAs, including the lineage specification transcription factors Prop1 and Pou1f1, as well as hormone mRNAs including Tshb, Prl, and Gnrhr, all contain consensus Musashi binding elements (MBEs) in their 3’ untranslated regions (3’ UTRs). Using RNA electrophoretic mobility shift assays (EMSAs) and luciferase mRNA translation reporter assays we show that Musashi binds to these mRNAs and exerts inhibitory control of mRNA translation. Moreover, we determined that leptin stimulation opposes the ability of Musashi to exert translational repression of the Pou1f1 and Gnrhr 3’ UTRs. This de-repression does not require regulatory phosphorylation of Musashi on two conserved C-terminal serine residues. Interestingly in the same cell assay system, Musashi exerts translational activation of the Prop1 3’ UTR. We observed that this translational activation requires Musashi phosphorylation on the two regulatory C-terminal serine residues, consistent with the requirement for regulatory phosphorylation to drive translational activation of Musashi target mRNAs during Xenopus oocyte cell maturation. The distinction between MBEs in 3’ UTRs that exert repression (Pou1f1, Prl, Tshb, and Gnrhr) and the Prop1 3’ UTR that directs translational activation is under investigation. We propose that Musashi acts as a bifunctional regulator of pituitary hormone production and lineage specification and may function to maintain pituitary hormone plasticity in response to changing organismal needs.

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Alteration of mRNA 5-Methylcytosine Modification in Neurons After OGD/R and Potential Roles in Cell Stress Response and Apoptosis

Frontiers in Genetics ◽

10.3389/fgene.2021.633681 ◽

2021 ◽

Vol 12 ◽

Author(s):

Huan Jian ◽

Chi Zhang ◽

ZhangYang Qi ◽

Xueying Li ◽

Yongfu Lou ◽

...

Keyword(s):

Rna Binding ◽

Ischemia Reperfusion Injury ◽

Rna Binding Proteins ◽

Ischemia Reperfusion ◽

Mrna Translation ◽

Cerebral Injury ◽

Rna Modification ◽

Hypermethylated Genes

Epigenetic modifications play an important role in central nervous system disorders. As a widespread posttranscriptional RNA modification, the role of the m5C modification in cerebral ischemia-reperfusion injury (IRI) remains poorly defined. Here, we successfully constructed a neuronal oxygen-glucose deprivation/reoxygenation (OGD/R) model and obtained an overview of the transcriptome-wide m5C profiles using RNA-BS-seq. We discovered that the distribution of neuronal m5C modifications was highly conserved, significantly enriched in CG-rich regions and concentrated in the mRNA translation initiation regions. After OGD/R, modification level of m5C increased, whereas the number of methylated mRNA genes decreased. The amount of overlap of m5C sites with the binding sites of most RNA-binding proteins increased significantly, except for that of the RBM3-binding protein. Moreover, hypermethylated genes in neurons were significantly enriched in pathological processes, and the hub hypermethylated genes RPL8 and RPS9 identified by the protein-protein interaction network were significantly related to cerebral injury. Furthermore, the upregulated transcripts with hypermethylated modification were enriched in the processes involved in response to stress and regulation of apoptosis, and these processes were not identified in hypomethylated transcripts. In final, we verified that OGD/R induced neuronal apoptosis in vitro using TUNEL and western blot assays. Our study identified novel m5C mRNAs associated with ischemia-reperfusion in neurons, providing valuable perspectives for future studies on the role of the RNA methylation in cerebral IRI.

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The G4 resolvase RHAU modulates mRNA translation and stability to sustain postnatal heart function and regeneration

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.014948 ◽

2020 ◽

pp. jbc.RA120.014948

Author(s):

Mingyang Jiang ◽

Han Hu ◽

Ke Zhao ◽

Ruomin Di ◽

Xinyi Huang ◽

...

Keyword(s):

Heart Development ◽

Rna Binding ◽

Rna Binding Proteins ◽

Heart Function ◽

Mrna Translation ◽

Mrna Levels ◽

Protein Levels ◽

Post Transcriptional Regulation ◽

Heart Physiology

Post-transcriptional regulation of mRNA translation and stability is primarily achieved by RNA binding proteins (RBPs), which is of increasing importance for heart function. Furthermore, G-quadruplex (G4) and G4 resolvase activity are involved in a variety of biological processes. However, the role of G4 resolvase activity in heart function remains unknown. The present study aims to investigate the role of RHAU, an RBP with G4 resolvase activity in postnatal heart function through deletion of Rhau in the cardiomyocytes of postnatal mice. RHAU-deficient mice displayed progressive pathological remodeling leading to heart failure and mortality, and impaired neonatal heart regeneration. RHAU ablation reduced the protein levels but enhanced mRNA levels of Yap1 and Hexim1 that are important regulators for heart development and postnatal heart function. Furthermore, RHAU was found to associate with both the 5’- and 3’- UTRs of these genes to destabilize mRNA but to enhance translation. Thus, we have demonstrated the important functions of RHAU in the dual regulation of mRNA translation and stability, which is vital for heart physiology.

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