scholarly journals Lipid Body Dynamics in Shoot Meristems: Production, Enlargement, and Putative Organellar Interactions and Plasmodesmal Targeting

2021 ◽  
Vol 12 ◽  
Author(s):  
Manikandan Veerabagu ◽  
Päivi L. H. Rinne ◽  
Morten Skaugen ◽  
Laju K. Paul ◽  
Christiaan van der Schoot
Keyword(s):  
Gene Expression ◽  
Lipid Droplet ◽  
Major Gene ◽  
Lipid Body ◽  
Rab Gtpase ◽  
Embryonic Cells ◽  
Interacting Protein ◽  
Associated Proteins ◽  
Myosin Xi

Post-embryonic cells contain minute lipid bodies (LBs) that are transient, mobile, engage in organellar interactions, and target plasmodesmata (PD). While LBs can deliver γ-clade 1,3-β-glucanases to PD, the nature of other cargo is elusive. To gain insight into the poorly understood role of LBs in meristems, we investigated their dynamics by microscopy, gene expression analyzes, and proteomics. In developing buds, meristems accumulated LBs, upregulated several LB-specific OLEOSIN genes and produced OLEOSINs. During bud maturation, the major gene OLE6 was strongly downregulated, OLEOSINs disappeared from bud extracts, whereas lipid biosynthesis genes were upregulated, and LBs were enlarged. Proteomic analyses of the LB fraction of dormant buds confirmed that OLEOSINs were no longer present. Instead, we identified the LB-associated proteins CALEOSIN (CLO1), Oil Body Lipase 1 (OBL1), Lipid Droplet Interacting Protein (LDIP), Lipid Droplet Associated Protein1a/b (LDAP1a/b) and LDAP3a/b, and crucial components of the OLEOSIN-deubiquitinating and degradation machinery, such as PUX10 and CDC48A. All mRFP-tagged LDAPs localized to LBs when transiently expressed in Nicotiana benthamiana. Together with gene expression analyzes, this suggests that during bud maturation, OLEOSINs were replaced by LDIP/LDAPs at enlarging LBs. The LB fraction contained the meristem-related actin7 (ACT7), “myosin XI tail-binding” RAB GTPase C2A, an LB/PD-associated γ-clade 1,3-β-glucanase, and various organelle- and/or PD-localized proteins. The results are congruent with a model in which LBs, motorized by myosin XI-k/1/2, traffic on F-actin, transiently interact with other organelles, and deliver a diverse cargo to PD.

scholarly journals Trans-10,cis-12 CLA increases adipocyte lipolysis and alters lipid droplet-associated proteins: role of mTOR and ERK signaling

2005 ◽  
Vol 46 (5) ◽  
pp. 885-895 ◽  
Author(s):  
Soonkyu Chung ◽  
Jonathan Mark Brown ◽  
Maria Boysen Sandberg ◽  
Michael McIntosh
Keyword(s):  
Lipid Droplet ◽  
Erk Signaling ◽  
Associated Proteins

scholarly journals Multiplex image-based autophagy RNAi screening identifies SMCR8 as ULK1 kinase activity and gene expression regulator

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Jennifer Jung ◽  
Arnab Nayak ◽  
Véronique Schaeffer ◽  
Tatjana Starzetz ◽  
Achim K Kirsch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Membrane Trafficking ◽  
Gene Locus ◽  
Kinase Activity ◽  
Degradation Pathway ◽  
Rab Gtpase ◽  
Rab Gtpases ◽  
Mrna Expression Analysis ◽  
Different Populations

Autophagy is an intracellular recycling and degradation pathway that depends on membrane trafficking. Rab GTPases are central for autophagy but their regulation especially through the activity of Rab GEFs remains largely elusive. We employed a RNAi screen simultaneously monitoring different populations of autophagosomes and identified 34 out of 186 Rab GTPase, GAP and GEF family members as potential autophagy regulators, amongst them SMCR8. SMCR8 uses overlapping binding regions to associate with C9ORF72 or with a C9ORF72-ULK1 kinase complex holo-assembly, which function in maturation and formation of autophagosomes, respectively. While focusing on the role of SMCR8 during autophagy initiation, we found that kinase activity and gene expression of ULK1 are increased upon SMCR8 depletion. The latter phenotype involved association of SMCR8 with the ULK1 gene locus. Global mRNA expression analysis revealed that SMCR8 regulates transcription of several other autophagy genes including WIPI2. Collectively, we established SMCR8 as multifaceted negative autophagy regulator.

scholarly journals A Ras-LSD1 axis activates PI3K signaling through PIK3IP1 suppression

Oncogenesis ◽  
2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyunghee Lee ◽  
Mayumi Kitagawa ◽  
Pei Ju Liao ◽  
David M. Virshup ◽  
Sang Hyun Lee
Keyword(s):  
Gene Expression ◽  
Cancer Cells ◽  
Molecular Mechanisms ◽  
Gene Promoter ◽  
Pi3k Pathway ◽  
Pi3k Signaling ◽  
Interacting Protein ◽  
Lysine Specific Demethylase ◽  
Ras Activation

AbstractPI3K Interacting Protein 1 (PIK3IP1) is a suppressor of the PI3K/Akt/mTOR pathway. We previously reported that activated Ras suppresses PIK3IP1 expression to positively regulate the PI3K pathway in cancer cells. Using doxycycline-inducible PIK3IP1, here we confirm that reversing the effect of Ras by inducing expression of PIK3IP1 suppresses Ras-induced anchorage-independent growth, supporting the central role of PIK3IP1 in transformation. However, the molecular mechanisms by which Ras-activation that causes loss of PIK3IP1 expression are unknown. We find that Ras activity represses PIK3IP1 expression via the recruitment of lysine-specific demethylase 1 (LSD1) to the PIK3IP1 gene promoter and enhancer, resulting in erasure of active histone marks. These studies demonstrate cross-activation of Ras/Raf/MEK/ERK and PI3K/AKT/mTOR pathways, where Ras decommissions PIK3IP1 gene expression by enhancing LSD1 and its corepressor activities to suppress PIK3IP1 transcription.

scholarly journals The Nuclear Lamina as an Organizer of Chromosome Architecture

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 136 ◽  
Author(s):  
Yuri Y. Shevelyov ◽  
Sergey V. Ulianov
Keyword(s):  
Gene Expression ◽  
Interphase Nucleus ◽  
Spatial Organization ◽  
Nuclear Lamina ◽  
Cell Types ◽  
Embryonic Cells ◽  
Chromosome Architecture ◽  
Differentiated Cells ◽  
Chromatin Interactions ◽  
Associated Proteins

The nuclear lamina (NL) is a meshwork of lamins and lamin-associated proteins adjoining the inner side of the nuclear envelope. In early embryonic cells, the NL mainly suppresses background transcription, whereas, in differentiated cell types, its disruption affects gene expression more severely. Normally, the NL serves as a backbone for multiple chromatin anchoring sites, thus shaping the spatial organization of chromosomes in the interphase nucleus. However, upon cell senescence, aging, or in some types of terminally differentiated cells and lamin-associated diseases, the loss of NL-chromatin tethering causes drastic alterations in chromosome architecture. Here, we provide an overview of the recent advances in the field of NL-chromatin interactions, focusing on their impact on chromatin positioning, compaction, repression, and spatial organization.

(beta)-catenin mediates the specification of endoderm cells in ascidian embryos

Development ◽  
2000 ◽  
Vol 127 (14) ◽  
pp. 3009-3020 ◽  
Author(s):  
K. Imai ◽  
N. Takada ◽  
N. Satoh ◽  
Y. Satou
Keyword(s):  
Gene Expression ◽  
Alkaline Phosphatase ◽  
Cell Differentiation ◽  
Beta Catenin ◽  
Embryonic Cells ◽  
Specific Alkaline Phosphatase ◽  
Endoderm Differentiation ◽  
Notochord Cells ◽  
Ascidian Embryos

In the present study, we addressed the role of (beta)-catenin in the specification of embryonic cells of the ascidians Ciona intestinalis and C. savignyi and obtained the following results: (1) During cleavages, (beta)-catenin accumulated in the nuclei of vegetal blastomeres, suggesting that it plays a role in the specification of endoderm. (2) Mis- and/or overexpression of (beta)-catenin induced the development of an endoderm-specific alkaline phosphatase (AP) in presumptive notochord cells and epidermis cells without affecting differentiation of primary lineage muscle cells. (3) Downregulation of (beta)-catenin induced by the overexpression of cadherin resulted in the suppression of endoderm cell differentiation. This suppression was compensated for by the differentiation of extra epidermis cells. (4) Specification of notochord cells did not take place in the absence of endoderm differentiation. Both the overexpression of (beta)-catenin in presumptive notochord cells and the downregulation of (beta)-catenin in presumptive endoderm cells led to the suppression of Brachyury gene expression, resulting in the failure of notochord specification. These results suggest that the accumulation of (beta)-catenin in the nuclei of endoderm progenitor cells is the first step in the process of ascidian endoderm specification.

scholarly journals The role of retinoblastoma-associated proteins 46 and 48 in estrogen receptor α mediated gene expression

2008 ◽  
Vol 291 (1-2) ◽  
pp. 79-86 ◽  
Author(s):  
Amy L. Creekmore ◽  
Kjirsten A. Walt ◽  
Jennifer R. Schultz-Norton ◽  
Yvonne S. Ziegler ◽  
Ian X. McLeod ◽  
...  
Keyword(s):  
Gene Expression ◽  
Estrogen Receptor ◽  
Estrogen Receptor Α ◽  
Associated Proteins

scholarly journals RAB18 impacts autophagy via lipid droplet-derived lipid transfer and is rescued by ATG9A

2018 ◽  
Author(s):  
Fazilet Bekbulat ◽  
Daniel Schmitt ◽  
Anne Feldmann ◽  
Heike Huesmann ◽  
Stefan Eimer ◽  
...  
Keyword(s):  
Lipid Droplet ◽  
Transmembrane Protein ◽  
Degradation Pathway ◽  
Rab Gtpase ◽  
Lipid Transfer ◽  
Lysosomal Degradation ◽  
Autophagosome Formation ◽  
Autophagic Activity ◽  
Rescue Mechanism

AbstractAutophagy is a lysosomal degradation pathway that mediates protein and organelle turnover and maintains cellular homeostasis. Autophagosomes transport cargo to lysosomes and their formation is dependent on an appropriate lipid supply. Here, we show that the knockout of the RAB GTPase RAB18 interferes with lipid droplet (LD) metabolism, resulting in an impaired fatty acid mobilization. The reduced LD-derived lipid availability influences autophagy and provokes adaptive modifications of the autophagy network, which include increased ATG2B expression and ATG12-ATG5 conjugate formation as well as enhanced ATG2B and ATG9A phosphorylation. Phosphorylation of ATG9A directs this transmembrane protein to the site of autophagosome formation and this particular modification is sufficient to rescue autophagic activity under basal conditions in the absence of RAB18. However, it is incapable of enabling an increased autophagy under inductive conditions. Thus, we illustrate the role of RAB18 in connecting LDs and autophagy, further emphasize the importance of LD-derived lipids for the degradative pathway, and characterize an ATG9A phosphorylation-dependent autophagy rescue mechanism as an adaptive response that maintains autophagy under conditions of reduced LD-derived lipid availability.

scholarly journals Imaging cytoplasmic lipid droplets in vivo with fluorescent perilipin 2 and perilipin 3 knock-in zebrafish

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Meredith H Wilson ◽  
Stephen C Ekker ◽  
Steven Arthur Farber
Keyword(s):  
Lipid Droplet ◽  
Lipid Droplets ◽  
Cultured Cells ◽  
Droplet Dynamics ◽  
Associated Proteins ◽  
Perilipin 2 ◽  
Cytoplasmic Lipid Droplets ◽  
Endogenous Loci

Cytoplasmic lipid droplets are highly dynamic storage organelles that are critical for cellular lipid homeostasis. While the molecular details of lipid droplet dynamics are a very active area of investigation, this work has been primarily performed in cultured cells. Taking advantage of the powerful transgenic and in vivo imaging opportunities available in zebrafish, we built a suite of tools to study lipid droplets in real-time from the subcellular to the whole organism level. Fluorescently tagging the lipid-droplet-associated proteins, perilipin 2 and perilipin 3, in the endogenous loci permits visualization of lipid droplets in the intestine, liver, and adipose tissue. Using these tools, we found that perilipin 3 is rapidly loaded on intestinal lipid droplets following a high-fat meal and later replaced by perilipin 2. These powerful new tools will facilitate studies on the role of lipid droplets in different tissues, under different genetic and physiological manipulations, and in a variety of human disease models.

Thyroid Hormone Deficiency Modifies Hepatic Lipid Droplet Morphology and Molecular Properties in Lithogenic-Diet Supplemented Mice

2021 ◽  
Author(s):  
Irina Kube ◽  
Holger Jastrow ◽  
Dagmar Führer ◽  
Denise Zwanziger
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Molecular Properties ◽  
Hormone Deficiency ◽  
Hepatic Lipid ◽  
Lithogenic Diet ◽  
Associated Proteins ◽  
Droplet Morphology

Abstract Objective Thyroid hormones have been associated with a hepatic lipid lowering effect and thyroid function has been shown to play a substantial role in development of non-alcoholic fatty liver disease. Hepatic lipid droplets differ in the number, size and molecular properties depending on metabolic state or pathological condition. However, in how far thyroid hormone deficiency affects hepatic lipid droplet morphology and molecular properties is still poorly understood. Therefore, we performed a study in mice using a lithogenic diet model of steatohepatitis and modulated the thyroid hormone status. Methods Male and female three months old C57BL/6 mice were divided into a euthyroid (control), a lithogenic (litho) and a lithogenic+thyroid hormone deficient (litho+hypo) group and treated for six weeks. Hepatic transmission electron microscopy and gene expression analysis of lipid-droplet associated proteins were performed. Results Increased mean diameters of hepatic lipid droplets and a shift towards raised electron-density in lipid droplets was observed under thyroid hormone deficiency. Furthermore thyroid hormone deficiency altered hepatic expression of genes involved in lipophagy and triacylglycerol mobilization. Interestingly, while the impact of thyroid hormone deficiency on lipid droplet morphology seems to be sex-independent, hepatic lipid droplet-associated gene expression differed significantly between both sexes. Conclusion This study demonstrates that thyroid hormone deficiency alters hepatic lipid droplet morphology and hepatic gene expression of lipid droplet-associated proteins in a lithogenic diet mouse model of steatohepatitis.

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