Microtubule associated protein WAVE DAMPENED2-LIKE (WDL) controls microtubule bundling and the stability of the site of tip-growth in Marchantia polymorpha rhizoids

Tip-growth is a mode of polarized cell expansion where incorporation of new membrane and wall is stably restricted to a single, small domain of the cell surface resulting in the formation of a tubular projection that extends away from the body of the cell. The organization of the microtubule cytoskeleton is conserved among tip-growing cells of land plants: bundles of microtubules run longitudinally along the non-growing shank and a network of fine microtubules grow into the apical dome where growth occurs. Together, these microtubule networks control the stable positioning of the growth site at the cell surface. This conserved dynamic organization is required for the spatial stability of tip-growth, as demonstrated by the formation of sinuous tip-growing cells upon treatment with microtubule-stabilizing or microtubule-destabilizing drugs. Microtubule associated proteins (MAPs) that either stabilize or destabilize microtubule networks are required for the maintenance of stable tip-growth in root hairs of flowering plants. NIMA RELATED KINASE (NEK) is a MAP that destabilizes microtubule growing ends in the apical dome of tip-growing rhizoid cells in the liverwort Marchantia polymorpha. We hypothesized that both microtubule stabilizing and destabilizing MAPs are required for the maintenance of the stable tip-growth in liverworts. To identify genes encoding microtubule-stabilizing and microtubule-destabilizing activities we generated 120,000 UV-B mutagenized and 336,000 T-DNA transformed Marchantia polymorpha plants and screened for defective rhizoid phenotypes. We identified 119 mutants and retained 30 mutants in which the sinuous rhizoid phenotype was inherited. The 30 mutants were classified into at least 4 linkage groups. Characterisation of two of the linkage groups showed that MAP genes–WAVE DAMPENED2-LIKE (WDL) and NIMA-RELATED KINASE (NEK)–are required to stabilize the site of tip growth in elongating rhizoids. Furthermore, we show that MpWDL is required for the formation of a bundled array of parallel and longitudinally orientated microtubules in the non-growing shank of rhizoids where MpWDL-YFP localizes to microtubule bundles. We propose a model where the opposite functions of MpWDL and MpNEK on microtubule bundling are spatially separated and promote tip-growth spatial stability.

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Microtubules are at the tips of root hairs and form helical patterns corresponding to inner wall fibrils

Journal of Cell Science ◽

10.1242/jcs.75.1.225 ◽

1985 ◽

Vol 75 (1) ◽

pp. 225-238 ◽

Cited By ~ 1

Author(s):

C.W. Lloyd ◽

B. Wells

Keyword(s):

Cell Wall ◽

Phosphate Buffer ◽

Tip Growth ◽

Root Hairs ◽

Onion Root ◽

Apical Dome ◽

Radish Root ◽

Contradictory Evidence ◽

Shadow Cast ◽

Optimized Conditions

Root hairs have sometimes provided contradictory evidence for microtubule/microfibril parallelism. This tissue was re-examined using optimized conditions for the fixation, before immunofluorescence, of root hairs. In phosphate buffer, microtubules did not enter the apical tip of radish root hairs and were clearly fragmented. However, in an osmotically adjusted microtubule-stabilizing buffer, microtubules were observed within the apical dome and appeared unfragmented. Microtubules are not, therefore, absent from the region where new cell wall is presumed to be generated during tip growth. A spiralling of microtubules was seen at the apices of onion root hairs. Using shadow-cast preparations of macerated radish root hairs, it was confirmed that steeply helical microtubules matched the texture of the inner wall. In onion, the 45 degrees microtubular helices are accompanied by similarly wound inner wall fibrils. Results do not support the view that microtubules are not involved in the oriented deposition of fibrils in root hairs. Instead, they are interpreted in terms of a flexible helical cytoskeleton, which is capable of changing its pitch but is sensitive to fixation conditions.

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An Evolutionarily Conserved Receptor-like Kinases Signaling Module Controls Cell Wall Integrity During Tip-Growth

10.1101/704601 ◽

2019 ◽

Author(s):

Jens Westermann ◽

Susanna Streubel ◽

Christina Maria Franck ◽

Roswitha Lentz ◽

Liam Dolan ◽

...

Keyword(s):

Cell Wall ◽

Tip Growth ◽

Root Hairs ◽

Pollen Tubes ◽

Cell Wall Integrity ◽

Marchantia Polymorpha ◽

Evolutionarily Conserved ◽

Receptor Kinases ◽

The Common ◽

Encoding Genes

AbstractRooting cells and pollen tubes – key adaptative innovations that evolved during the colonization and subsequent radiation of plants on land – expand by tip-growth. Tip-growth relies on a tight coordination between the protoplast growth and the synthesis/remodeling of the external cell wall. In root hairs and pollen tubes of the seed plant Arabidopsis thaliana, cell wall integrity (CWI) mechanisms monitor this coordination through the Malectin-like receptor kinases (MLRs) such as AtANXUR1 and AtFERONIA that act upstream of the AtMARIS PTI1-like kinase. Here, we show that rhizoid growth in the early diverging plant, Marchantia polymorpha, is also controlled by an MLR and PTI1-like signaling module. Rhizoids, root hairs and pollen tubes respond similarly to disruption of MLR and PTI1-like encoding genes. Thus, the MLR/PTI1-like signaling module that controls CWI during tip-growth is conserved between M. polymorpha and A. thaliana suggesting it was active in the common ancestor of land plants.

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Insulin’s Discovery: New Insights on Its Hundredth Birthday: From Insulin Action and Clearance to Sweet Networks

International Journal of Molecular Sciences ◽

10.3390/ijms22031030 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1030

Author(s):

Melanie Leroux ◽

Martial Boutchueng-Djidjou ◽

Robert Faure

Keyword(s):

Type 1 Diabetes ◽

Cell Surface ◽

20Th Century ◽

Insulin Action ◽

100Th Anniversary ◽

The Body ◽

Nobel Lecture ◽

Surface Receptors ◽

The Third

In 2021, the 100th anniversary of the isolation of insulin and the rescue of a child with type 1 diabetes from death will be marked. In this review, we highlight advances since the ingenious work of the four discoverers, Frederick Grant Banting, John James Rickard Macleod, James Bertram Collip and Charles Herbert Best. Macleoad closed his Nobel Lecture speech by raising the question of the mechanism of insulin action in the body. This challenge attracted many investigators, and the question remained unanswered until the third part of the 20th century. We summarize what has been learned, from the discovery of cell surface receptors, insulin action, and clearance, to network and precision medicine.

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Limbic Expression of mRNA Coding for Chemoreceptors in Human Brain—Lessons from Brain Atlases

International Journal of Molecular Sciences ◽

10.3390/ijms22136858 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6858

Author(s):

Fanny Gaudel ◽

Gaëlle Guiraudie-Capraz ◽

François Féron

Keyword(s):

G Proteins ◽

The Body ◽

Trace Amines ◽

Chemical Senses ◽

Brain Areas ◽

Genes Encoding ◽

The Central Nervous System ◽

Human Brains ◽

The Brain ◽

Brain Atlases

Animals strongly rely on chemical senses to uncover the outside world and adjust their behaviour. Chemical signals are perceived by facial sensitive chemosensors that can be clustered into three families, namely the gustatory (TASR), olfactory (OR, TAAR) and pheromonal (VNR, FPR) receptors. Over recent decades, chemoreceptors were identified in non-facial parts of the body, including the brain. In order to map chemoreceptors within the encephalon, we performed a study based on four brain atlases. The transcript expression of selected members of the three chemoreceptor families and their canonical partners was analysed in major areas of healthy and demented human brains. Genes encoding all studied chemoreceptors are transcribed in the central nervous system, particularly in the limbic system. RNA of their canonical transduction partners (G proteins, ion channels) are also observed in all studied brain areas, reinforcing the suggestion that cerebral chemoreceptors are functional. In addition, we noticed that: (i) bitterness-associated receptors display an enriched expression, (ii) the brain is equipped to sense trace amines and pheromonal cues and (iii) chemoreceptor RNA expression varies with age, but not dementia or brain trauma. Extensive studies are now required to further understand how the brain makes sense of endogenous chemicals.

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Nedd4-2 but not Nedd4-1 is critical for protein kinase C-regulated ubiquitination, expression, and transport activity of human organic anion transporter 1

AJP Renal Physiology ◽

10.1152/ajprenal.00522.2015 ◽

2016 ◽

Vol 310 (9) ◽

pp. F821-F831 ◽

Cited By ~ 11

Author(s):

Da Xu ◽

Haoxun Wang ◽

Qiang Zhang ◽

Guofeng You

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Cell Surface ◽

Organic Anion ◽

The Body ◽

Organic Anion Transporter ◽

Transport Activity ◽

Kinase C ◽

Anion Transporter ◽

In Cells

Human organic anion transporter 1 (hOAT1) expressed at the membrane of the kidney proximal tubule cells mediates the body disposition of a diverse array of clinically important drugs, including anti-HIV therapeutics, antitumor drugs, antibiotics, antihypertensives, and antiinflammatories. Therefore, understanding the regulation of hOAT1 will provide significant insights into kidney function and dysfunction. We previously established that hOAT1 transport activity is inhibited by activation of protein kinase C (PKC) through accelerating hOAT1 internalization from cell surface into intracellular endosomes and subsequent degradation. We further established that PKC-induced hOAT1 ubiquitination is an important step preceding hOAT1 internalization. In the current study, we identified two closely related E3 ubiquitin ligases, neural precursor cell expressed, developmentally downregulated 4-1 and 4-2 (Nedd4-1 and Nedd4-2), as important regulators for hOAT1: overexpression of Nedd4-1 or Nedd4-2 enhanced hOAT1 ubiquitination, reduced the hOAT1 amount at the cell surface, and suppressed hOAT1 transport activity. In further exploring the relationship among PKC, Nedd4-1, and Nedd4-2, we discovered that PKC-dependent changes in hOAT1 ubiquitination, expression, and transport activity were significantly blocked in cells transfected with the ligase-dead mutant of Nedd4-2 (Nedd4-2/C821A) or with Nedd4-2-specific siRNA to knockdown endogenous Nedd4-2 but not in cells transfected with the ligase-dead mutant of Nedd4-1 (Nedd4-1/C867S) or with Nedd4-1-specific siRNA to knockdown endogenous Nedd4-1. In conclusion, this is the first demonstration that both Nedd4-1 and Nedd4-2 are important regulators for hOAT1 ubiquitination, expression, and function. Yet they play distinct roles, as Nedd4-2 but not Nedd4-1 is a critical mediator for PKC-regulated hOAT1 ubiquitination, expression, and transport activity.

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Molecular hallmarks of heterochronic parabiosis at single cell resolution

10.1101/2020.11.06.367078 ◽

2020 ◽

Author(s):

Róbert Pálovics ◽

Andreas Keller ◽

Nicholas Schaum ◽

Weilun Tan ◽

Tobias Fehlmann ◽

...

Keyword(s):

Gene Expression ◽

Single Cell ◽

Disease Risk ◽

Global Gene Expression ◽

Cell Types ◽

The Body ◽

Hematopoietic Stem ◽

Gene Sets ◽

Genes Encoding ◽

Systemic Understanding

Slowing or reversing biological ageing would have major implications for mitigating disease risk and maintaining vitality. While an increasing number of interventions show promise for rejuvenation, the effectiveness on disparate cell types across the body and the molecular pathways susceptible to rejuvenation remain largely unexplored. We performed single-cell RNA-sequencing on 13 organs to reveal cell type specific responses to young or aged blood in heterochronic parabiosis. Adipose mesenchymal stromal cells, hematopoietic stem cells, hepatocytes, and endothelial cells from multiple tissues appear especially responsive. On the pathway level, young blood invokes novel gene sets in addition to reversing established ageing patterns, with the global rescue of genes encoding electron transport chain subunits pinpointing a prominent role of mitochondrial function in parabiosis-mediated rejuvenation. Intriguingly, we observed an almost universal loss of gene expression with age that is largely mimicked by parabiosis: aged blood reduces global gene expression, and young blood restores it. Altogether, these data lay the groundwork for a systemic understanding of the interplay between blood-borne factors and cellular integrity.

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The molecular link between auxin and ROS-Mediated polar root hair growth

10.1101/116517 ◽

2017 ◽

Author(s):

Silvina Mangano ◽

Silvina Paola Denita-Juarez ◽

Hee-Seung Choi ◽

Eliana Marzol ◽

Youra Hwang ◽

...

Keyword(s):

Cell Size ◽

Root Hair ◽

Hair Growth ◽

Molecular Mechanisms ◽

Root Hairs ◽

Oxygen Species ◽

Polar Growth ◽

Genes Encoding ◽

Root Hair Growth ◽

Original Size

AbstractRoot hair polar growth is endogenously controlled by auxin and sustained by oscillating levels of reactive oxygen species (ROS). These cells extend several hundred-fold their original size toward signals important for plant survival. Although their final cell size is of fundamental importance, the molecular mechanisms that control it remain largely unknown. Here, we show that ROS production is controlled by the transcription factors RSL4, which in turn is transcriptionally regulated by auxin through several Auxin Responsive Factors (ARFs). In this manner, auxin controls ROS-mediated polar growth by activating RSL4, which then upregulates the expression of genes encoding NADPH oxidases (also known as RBOHs, RESPIRATORY BURST OXIDASE HOMOLOG proteins) and Class-III Peroxidases (PER), which catalyse ROS production. Chemical or genetic interference with the ROS balance or peroxidase activity affect root hair final cell size. Overall, our findings establish a molecular link between auxin regulated ARFs-RSL4 and ROS-mediated polar root hair growth.Significance StatementTip-growing root hairs are excellent model systems to decipher the molecular mechanism underlying reactive oxygen species (ROS)-mediated cell elongation. Root hairs are able to expand in response to external signals, increasing several hundred-fold their original size, which is important for survival of the plant. Although their final cell size is of fundamental importance, the molecular mechanisms that control it remain largely unknown. In this study, we propose a molecular mechanism that links the auxin-Auxin Response Factors (ARFs) module to activation of RSL4, which directly targets genes encoding ROS-producing enzymes, such as NADPH oxidases (or RBOHs) and secreted type-III peroxidases (PERs). Activation of these genes impacts apoplastic ROS homeostasis, thereby stimulating root hair cell elongation.

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Microtubules and microfilaments in tip growth: evidence that microtubules impose polarity on protonemal growth in Physcomitrella patens

Journal of Cell Science ◽

10.1242/jcs.89.4.533 ◽

1988 ◽

Vol 89 (4) ◽

pp. 533-540 ◽

Cited By ~ 1

Author(s):

J. H. DOONAN ◽

D. J. COVE ◽

C. W. LLOYD

Keyword(s):

Tip Growth ◽

Physcomitrella Patens ◽

Cytochalasin D ◽

Immunofluorescence Study ◽

Apical Dome ◽

High Concentrations ◽

Cytoskeletal Elements ◽

Drug Studies ◽

Tip Cells ◽

Cytoskeletal Drugs

In this study we compare the contributions of Factin and microtubules to tip growth in filamentous cells of the moss Physcomitrella patens. In tip growth, expansion seems to be restricted to the hemispherical apical dome. Cytoskeletal elements have been suspected, from drug studies, to be involved in this but electron microscopy has generally not confirmed the presence of an apical cytoskeleton. However, in a previous immunofluorescence study we reported that microtubules could be seen to focus upon the apical dome in tip cells of the moss P. patens. In the present investigation F-actin has also been detected at the apices of these cells. Anti-cytoskeletal drugs were therefore used to differentiate between the roles of actin filaments and microtubules in tip growth. At high concentrations (30μM), the herbicide cremart de-polymerized microtubules and caused tip swelling. F-actin was still present under such conditions but its fragmentation by cytochalasin D suppressed this herbicide-induced swelling. On its own, cytochalasin D arrested tip growth without causing swollen tips. At lower concentrations, cremart disorganized microtubules rather than causing their complete depolymerization. Under these conditions, new but swollen growing points were initiated along the filament. The addition of taxol to cremart-treated filaments tended to reduce swelling and to re-polarize outgrowth. With particular combinations of these drugs, multiple lateral out-growths were initiated in the vicinity of the nucleus. It is concluded: (1) that F-actin is present at the tips of Physcomitrella caulonemal apical cells; (2) that unfragmented F-actin is necessary for outgrowth; (3) that even disorganized microtubules permit some degree of outgrowth but that an unperturbed distribution of axial microtubules, focussing upon an apex, is essential in order to impose tubular shape and directionality upon expansion.

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Regulation of collagen I gene expression by ras

Molecular and Cellular Biology ◽

10.1128/mcb.12.10.4714-4723.1992 ◽

1992 ◽

Vol 12 (10) ◽

pp. 4714-4723

Author(s):

J L Slack ◽

M I Parker ◽

V R Robinson ◽

P Bornstein

Keyword(s):

Type I Collagen ◽

The Body ◽

Transformed Cells ◽

Type I ◽

Mrna Levels ◽

Oncogenic Ras ◽

Genes Encoding ◽

Flanking Region ◽

Collagen Genes ◽

I Gene

Although transformation of rodent fibroblasts can lead to dramatic changes in expression of extracellular matrix genes, the molecular basis and physiological significance of these changes remain poorly understood. In this study, we have investigated the mechanism(s) by which ras affects expression of the genes encoding type I collagen. Levels of both alpha 1(I) and alpha 2(I) collagen mRNAs were markedly reduced in Rat 1 fibroblasts overexpressing either the N-rasLys-61 or the Ha-rasVal-12 oncogene. In fibroblasts conditionally transformed with N-rasLys-61, alpha 1(I) transcript levels began to decline within 8 h of ras induction and reached 1 to 5% of control levels after 96 h. In contrast, overexpression of normal ras p21 had no effect on alpha 1(I) or alpha 2(I) mRNA levels. Nuclear run-on experiments demonstrated that the transcription rates of both the alpha 1(I) and alpha 2(I) genes were significantly reduced in ras-transformed cells compared with those in parental cells. In addition, the alpha 1(I) transcript was less stable in transformed cells. Chimeric plasmids containing up to 3.6 kb of alpha 1(I) 5'-flanking DNA and up to 2.3 kb of the 3'-flanking region were expressed at equivalent levels in both normal and ras-transformed fibroblasts. However, a cosmid clone containing the entire mouse alpha 1(I) gene, including 3.7 kb of 5'- and 4 kb of 3'-flanking DNA, was expressed at reduced levels in fibroblasts overexpressing oncogenic ras. We conclude that oncogenic ras regulates the type I collagen genes at both transcriptional and posttranscriptional levels and that this effect, at least for the alpha 1(I) gene, may be mediated by sequences located either within the body of the gene itself or in the distal 3'-flanking region.

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Consistency and Change

Molecules, Microbes, and Meals ◽

10.1093/oso/9780190687694.003.0006 ◽

2019 ◽

Author(s):

Alan Kelly

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Living Organism ◽

Peptide Bond ◽

The Body ◽

Blood Proteins ◽

Genes Encoding ◽

Fundamental Phenomenon ◽

P Proteins

Proteins are, in my view, the most impressive molecules in food. They influence the texture, crunch, chew, flow, color, flavor, and nutritional quality of food. Not only that, but they can radically change their properties and how they behave depending on the environment and, critically for food, in response to processes like heating. Even when broken down into smaller components they are important, for example giving cheese many of its critical flavor notes. Indeed, I would argue that perhaps the most fundamental phenomenon we encounter in cooking or processing food is the denaturation of proteins, as will be explained shortly. Beyond food, the value of proteins and their properties is widespread across biology. Many of the most significant molecules in our body and that of any living organism (including plants and animals) are proteins. These include those that make hair and skin what they are, as well as the hemoglobin that transports oxygen around the body in our blood. Proteins are built from amino acids, a family of 20 closely related small molecules, which all have in chemical terms the same two ends (chemically speaking, an amino end and an acidic end, hence the name) but differ in the middle. This bit in the middle varies from amino acid to amino acid, from simple (a hydrogen atom in the case of glycine, the simplest amino acid) to much more complex structures. Amino acids can link up very neatly, as the amino end of one can form a bond (called a peptide bond) with the acid end of another, and so forth, so that chains of amino acids are formed that, when big enough (more than a few dozen amino acids), we call proteins. Our bodies produce thousands of proteins for different functions, and the instructions for which amino acids combine to make which proteins are essentially what the genetic code encrypted in our DNA specifies. We hear a lot about our genes encoding the secrets of life, but what that code spells is basically P-R-O-T-E-I-N. Yes, these are very important molecules!

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