scholarly journals ER-localized phosphatidylethanolamine synthase plays a conserved role in lipid droplet formation

2021 ◽  
Author(s):  
Mehmet Oguz Gok ◽  
Natalie Ortiz Speer ◽  
W. Mike Henne ◽  
Jonathan R. Friedman
Keyword(s):  
Lipid Droplet ◽  
Fundamental Principle ◽  
Cellular Growth ◽  
Asymmetric Distribution ◽  
Mitochondrial Inner Membrane ◽  
Attachment Sites ◽  
Spatial Positioning ◽  
And Function ◽  
Cellular Compartmentalization

The asymmetric distribution of phospholipids in membranes is a fundamental principle of cellular compartmentalization and organization. Phosphatidylethanolamine (PE), a nonbilayer phospholipid that contributes to organelle shape and function, is synthesized at several subcellular localizations via semi-redundant pathways. Previously, we demonstrated in budding yeast that the PE synthase Psd1, which primarily operates on the mitochondrial inner membrane, is additionally targeted to the ER. While ER-localized Psd1 is required to support cellular growth in the absence of redundant pathways, its physiological function is unclear. We now demonstrate that ER-localized Psd1 sub-localizes on the ER to lipid droplet (LD) attachment sites and show it is specifically required for normal LD formation. We also find that the role of phosphatidylserine decarboxylase (PSD) enzymes in LD formation is conserved in other organisms. Thus, we have identified PSD enzymes as novel regulators of LDs and demonstrate that both mitochondria and LDs in yeast are organized and shaped by the spatial positioning of a single PE synthesis enzyme.

scholarly journals ER-localized phosphatidylethanolamine synthase plays a conserved role in lipid droplet formation

2021 ◽  
Author(s):  
Mehmet Oguz Gok ◽  
Natalie Ortiz Speer ◽  
W. Mike Henne ◽  
Jonathan R. Friedman
Keyword(s):  
Lipid Droplet ◽  
Fundamental Principle ◽  
Cellular Growth ◽  
Asymmetric Distribution ◽  
Mitochondrial Inner Membrane ◽  
Attachment Sites ◽  
Spatial Positioning ◽  
And Function ◽  
Cellular Compartmentalization

AbstractThe asymmetric distribution of phospholipids in membranes is a fundamental principle of cellular compartmentalization and organization. Phosphatidylethanolamine (PE), a nonbilayer phospholipid that contributes to organelle shape and function, is synthesized at several subcellular localizations via semi-redundant pathways. Previously, we demonstrated in the yeast Saccharomyces cerevisiae that the PE synthase Psd1, which primarily operates on the mitochondrial inner membrane, is additionally targeted to the endoplasmic reticulum (ER). While ER-localized Psd1 is required to support cellular growth in the absence of redundant pathways, its physiological function at the ER is unclear. We now demonstrate that ER-localized Psd1 sub-localizes on the ER to lipid droplet (LD) attachment sites and further show it is specifically required for normal LD formation. We also find that the role of PSD enzymes in LD formation is conserved in other organisms. Thus, we have identified PSD enzymes as novel regulators of LDs and demonstrate that both mitochondria and LDs in yeast are organized and shaped by the spatial positioning of a single PE synthesis enzyme.

scholarly journals Expression and Function Studies of CYC/TB1-Like Genes in the Asymmetric Flower Canna (Cannaceae, Zingiberales)

2020 ◽  
Vol 11 ◽  
Author(s):  
Qianxia Yu ◽  
Xueyi Tian ◽  
Canjia Lin ◽  
Chelsea D. Specht ◽  
Jingping Liao
Keyword(s):  
Flower Development ◽  
Expression Patterns ◽  
Asymmetric Distribution ◽  
Inflorescence Architecture ◽  
Flower Primordia ◽  
Fertile Stamen ◽  
Spatiotemporal Expression ◽  
And Function

The asymmetric flower, lacking any plane of symmetry, is rare among angiosperms. Canna indica L. has conspicuously asymmetric flowers resulting from the presence of a half-fertile stamen, while the other androecial members develop as petaloid staminodes or abort early during development. The molecular basis of the asymmetric distribution of fertility and petaloidy in the androecial whorls remains unknown. Ontogenetic studies have shown that Canna flowers are borne on monochasial (cincinnus) partial florescences within a racemose inflorescence, with floral asymmetry likely corresponding to the inflorescence architecture. Given the hypothesized role of CYC/TB1 genes in establishing floral symmetry in response to the influence of the underlying inflorescence architecture, the spatiotemporal expression patterns of three Canna CYC/TB1 homologs (CiTBL1a, CiTBL1b-1, and CiTBL1b-2) were analyzed during inflorescence and floral development using RNA in situ hybridization and qRT-PCR. In the young inflorescence, both CiTBL1a and CiTBL1b-1 were found to be expressed in the bracts and at the base of the lateral florescence branches, whereas transcripts of CiTBL1b-2 were mainly detected in flower primordia and inflorescence primordia. During early flower development, expression of CiTBL1a and CiTBL1b-1 were both restricted to the developing sepals and petals. In later flower development, expression of CiTBL1a was reduced to a very low level while CiTBL1b-1 was detected with extremely high expression levels in the petaloid androecial structures including the petaloid staminodes, the labellum, and the petaloid appendage of the fertile stamen. In contrast, expression of CiTBL1b-2 was strongest in the fertile stamen throughout flower development, from early initiation of the stamen primordium to maturity of the ½ anther. Heterologous overexpression of CiTBL genes in Arabidopsis led to dwarf plants with smaller petals and fewer stamens, and altered the symmetry of mature flowers. These data provide evidence for the involvement of CYC/TB1 homologs in the development of the asymmetric Cannaceae flower.

scholarly journals Mitochondrial carrier protein biogenesis: role of the chaperones Hsc70 and Hsp90

2009 ◽  
Vol 419 (2) ◽  
pp. 369-375 ◽  
Author(s):  
Vincenzo Zara ◽  
Alessandra Ferramosca ◽  
Philippe Robitaille-Foucher ◽  
Ferdinando Palmieri ◽  
Jason C. Young
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein 90 ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Carrier ◽  
Mitochondrial Inner Membrane ◽  
Heat Shock Cognate 70 ◽  
Protein Biogenesis ◽  
And Function ◽  
Import Receptor

Metabolite carrier proteins of the mitochondrial inner membrane share homology in their transmembrane domains, which also carries their targeting information. In addition, some carriers have cleavable presequences which are not essential for targeting, but have some other function before import. The cytosolic chaperones Hsc70 (heat-shock cognate 70) and Hsp90 (heat-shock protein 90) complex with carrier precursors and interact specifically with the Tom (translocase of the mitochondrial outer membrane) 70 import receptor to promote import. We analysed how the presequences of the PiC (phosphate carrier) and CIC (citrate carrier) relate to the mechanisms of chaperone-mediated import. Deletion of the PiC presequence reduced the efficiency of import but, notably, not by causing aggregation. Instead, binding of the protein to Hsc70 was reduced, as well as the dependence on Hsc70 for import. Hsp90 binding and function in import was not greatly affected, but it could not entirely compensate for the lack of Hsc70 interaction. Deletion of the presequence from CIC was shown to cause its aggregation, but had little effect on the contribution to import of either Hsc70 or Hsp90. The presequence of PiC, but not that of CIC, conferred Hsc70 binding to dihydrofolate reductase fusion proteins. In comparison, OGC (oxoglutarate carrier) lacks a presequence and was more soluble, though it is still dependent on both Hsc70 and Hsp90. We propose that carrier presequences evolved to improve targeting competence by different mechanisms, depending on physical properties of the precursors in the cytosolic targeting environment.

Targeting MUC15 Protein in Cancer: Molecular Mechanisms and Therapeutic Perspectives

2020 ◽  
Vol 20 (9) ◽  
pp. 647-653
Author(s):  
Simei Zhang ◽  
Wunai Zhang ◽  
Ying Xiao ◽  
Tao Qin ◽  
Yangyang Yue ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Malignant Tumors ◽  
Transmembrane Protein ◽  
Cellular Growth ◽  
Current Evidence ◽  
Aberrant Expression ◽  
Different Types ◽  
And Function ◽  
Precise Role

MUC15, a member of the mucin family, is a heavily glycosylated transmembrane protein with the primary functions of lubricating surfaces, establishing a selective molecular barrier at the epithelium and mediating signal transduction. Aberrant expression of MUC15 plays a crucial role in the progression of multiple diseases, including malignant tumors. MUC15 has been identified as a tumor suppressor, but current evidence indicate its function as an oncogene in different types of cancers. MUC15 has been shown to be involved in the development of cancer and influence cellular growth, adhesion, invasion, metastasis and immune immunomodulation. However, the precise role of MUC15 in tumour development has not been thoroughly clarified. Here, we systematically summarize the structure and function of MUC15 in cancer, and discuss its potential role in cancer treatment.

scholarly journals The genetic interactome of prohibitins: coordinated control of cardiolipin and phosphatidylethanolamine by conserved regulators in mitochondria

2009 ◽  
Vol 184 (4) ◽  
pp. 583-596 ◽  
Author(s):  
Christof Osman ◽  
Mathias Haag ◽  
Christoph Potting ◽  
Jonathan Rodenfels ◽  
Phat Vinh Dip ◽  
...  
Keyword(s):  
Critical Role ◽  
Yeast Cells ◽  
Lipid Profiling ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Ring Complexes ◽  
Higher Eukaryotes ◽  
Dynamics And Function ◽  
And Function

Prohibitin ring complexes in the mitochondrial inner membrane regulate cell proliferation as well as the dynamics and function of mitochondria. Although prohibitins are essential in higher eukaryotes, prohibitin-deficient yeast cells are viable and exhibit a reduced replicative life span. Here, we define the genetic interactome of prohibitins in yeast using synthetic genetic arrays, and identify 35 genetic interactors of prohibitins (GEP genes) required for cell survival in the absence of prohibitins. Proteins encoded by these genes include members of a conserved protein family, Ups1 and Gep1, which affect the processing of the dynamin-like GTPase Mgm1 and thereby modulate cristae morphogenesis. We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner. Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells. We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

scholarly journals A single-headed fission yeast myosin V transports actin in a tropomyosin-dependent manner

2016 ◽  
Vol 214 (2) ◽  
pp. 167-179 ◽  
Author(s):  
Qing Tang ◽  
Neil Billington ◽  
Elena B. Krementsova ◽  
Carol S. Bookwalter ◽  
Matthew Lord ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Cellular Localization ◽  
Dependent Manner ◽  
Myosin V ◽  
Contractile Ring ◽  
Class V ◽  
Ring Assembly ◽  
Attachment Sites ◽  
And Function

Myo51, a class V myosin in fission yeast, localizes to and assists in the assembly of the contractile ring, a conserved eukaryotic actomyosin structure that facilitates cytokinesis. Rng8 and Rng9 are binding partners that dictate the cellular localization and function of Myo51. Myo51 was expressed in insect cells in the presence or absence of Rng8/9. Surprisingly, electron microscopy of negatively stained images and hydrodynamic measurements showed that Myo51 is single headed, unlike most class V myosins. When Myo51–Rng8/9 was bound to actin-tropomyosin, two attachment sites were observed: the typical ATP-dependent motor domain attachment and a novel ATP-independent binding of the tail mediated by Rng8/9. A modified motility assay showed that this additional binding site anchors Myo51–Rng8/9 so that it can cross-link and slide actin-tropomyosin filaments relative to one another, functions that may explain the role of this motor in contractile ring assembly.

scholarly journals Comparative Genomic Characterization of Buffalo Fibronectin Type III Domain Proteins: Exploring the Novel Role of FNDC5/Irisin as a Ligand of Gonadal Receptors

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1207
Author(s):  
Siwen Wu ◽  
Faiz-ul Hassan ◽  
Yuhong Luo ◽  
Israr Fatima ◽  
Ishtiaq Ahmed ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Cellular Growth ◽  
Comparative Genomic ◽  
Fibronectin Type Iii ◽  
Genomic Characterization ◽  
Fibronectin Type Iii Domain ◽  
And Function ◽  
First Time ◽  
Estrogen Related Receptor

FN-III proteins are widely distributed in mammals and are usually involved in cellular growth, differentiation, and adhesion. The FNDC5/irisin regulates energy metabolism and is present in different tissues (liver, brain, etc.). The present study aimed to investigate the physiochemical characteristics and the evolution of FN-III proteins and FNDC5/irisin as a ligand targeting the gonadal receptors including androgen (AR), DDB1 and CUL4 associated factor 6 (DCAF6), estrogen-related receptor β (ERR-β), estrogen-related receptor γ (ERR-γ), Krüppel-like factor 15 (KLF15), and nuclear receptor subfamily 3 group C member 1 (NR3C1). Moreover, the putative role of irisin in folliculogenesis and spermatogenesis was also elucidated. We presented the molecular structure and function of 29 FN-III genes widely distributed in the buffalo genome. Phylogenetic analysis, motif, and conserved domain pattern demonstrated the evolutionary well-conserved nature of FN-III proteins with a variety of stable to unstable, hydrophobic to hydrophilic, and thermostable to thermo-unstable properties. The comparative structural configuration of FNDC5 revealed amino acid variations but still the FNDC5 structure of humans, buffalo, and cattle was quite similar to each other. For the first time, we predicted the binding scores and interface residues of FNDC5/irisin as a ligand for six representative receptors having a functional role in energy homeostasis, and a significant involvement in folliculogenesis and spermatogenesis in buffalo.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

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