Transcription of the Spec 1-like gene of Lytechinus is selectively inhibited in response to disruption of the extracellular matrix

Development ◽  
1989 ◽  
Vol 106 (2) ◽  
pp. 355-365 ◽  
Author(s):  
G.M. Wessel ◽  
W. Zhang ◽  
C.R. Tomlinson ◽  
W.J. Lennarz ◽  
W.H. Klein

The influence of the extracellular matrix (ECM) on differential gene expression during sea urchin development was explored using cell-type-specific cDNA probes. The ECM of three species of sea urchin, Strongylocentrotus purpuratus, Lytechinus variegatus and Lytechinus pictus, was disrupted with the lathrytic agent beta-aminopropionitrile (BAPN), which inhibits collagen deposition in the ECM and arrests gastrulation (Wessel & McClay, Devl Biol. 121: 149, 1987). The levels of several mRNAs (Spec 1, Spec 2, CyIIa actin, CyIIIa actin and collagen in S. purpuratus, and metallothionine, ubiquitin and LpS3 in L. pictus and L. variegatus) were compared in BAPN-treated and control embryos. These mRNAs accumulated normally during BAPN treatment, even though the embryos did not gastrulate. To determine if the expression of any gene product is sensitive to ECM disruption, a differential cDNA screen compared poly (A+) RNA from BAPN-arrested and control embryos in Lytechinus. A cDNA clone was isolated from this screen that represented a 2.1 kb mRNA that did not accumulate during BAPN treatment. Removal of BAPN resulted in the accumulation of this transcript coincident with the onset of gastrulation. This cDNA clone encodes a L. variegatus homologue of LpS1, recently demonstrated to be an ancestral homologue of the aboral ectoderm-specific Spec 1-Spec 2 gene family in S. purpuratus. Nuclear run-on assays in L. pictus suggested that transcriptional activity of LpS1 was selectively inhibited by BAPN treatment. Thus, although the accumulation of many gene products occurred independently of the embryonic collagenous matrix, the accumulation of LpS1 and LvS1 appeared to be mediated by the ECM.

2020 ◽  
Vol 167 (6) ◽  
pp. 541-547 ◽  
Author(s):  
Yoshio Hirabayashi ◽  
Yeon-Jeong Kim

Abstract In the past decade, physiological roles and molecular functions of GPRC5 family receptors, originally identified as retinoic acid-induced gene products, have been uncovered, even though their intrinsic agonists are still a mystery. They are differentially distributed in certain tissues and cells in the body suggesting that cell-type-specific regulations and functions are significant. Molecular biological approaches and knockout mouse studies reveal that GPRC5 family proteins have pivotal roles in cancer progression and control of metabolic homeostasis pathways. Remarkably, GPRC5B-mediated tyrosine-phosphorylation signalling cascades play a critical role in development of obesity and insulin resistance through dynamic sphingolipid metabolism.


1988 ◽  
Vol 252 (1) ◽  
pp. 257-262 ◽  
Author(s):  
I Crossley ◽  
K Swann ◽  
E Chambers ◽  
M Whitaker

We investigated the contribution of external calcium ions to inositol phosphate-induced exocytosis in sea urchin eggs. We show that: (a) inositol phosphates activate eggs of the sea urchin species Lytechinus pictus and Lytechinus variegatus independently of external calcium ions; (b) the magnitude and duration of the inositol phosphate induced calcium changes are independent of external calcium; (c) in calcium-free seawater, increasing the volume of inositol trisphosphate solution injected decreased the extent of egg activation; (d) eggs in calcium-free sea water are more easily damaged by microinjection; microinjection of larger volumes increased leakage from eggs pre-loaded with fluorescent dye. We conclude that inositol phosphates do not require external calcium ions to activate sea urchin eggs. This is entirely consistent with their role as internal messengers at fertilization. The increased damage caused to eggs in calcium-free seawater injected with large volumes may allow the EGTA present in the seawater to enter the egg and chelate any calcium released by the inositol phosphates. This may explain the discrepancy between this and earlier reports.


Development ◽  
1988 ◽  
Vol 104 (3) ◽  
pp. 391-402 ◽  
Author(s):  
D.L. Adelson ◽  
T. Humphreys

We have generated and characterized a monoclonal antibody (McA Tg-HYL) that recognizes sea urchin hyalin as evidenced by immunofluorescence staining of the hyaline layer (HL) and immunoblot staining of the hyalin protein band. On immunoblots of HL extracts only the hyalin protein reacted with McA Tg-HYL. Immunoprecipitates of radioactive proteins from embryos incubated with [35S]methionine yielded radioactive hyalin and 190, 140 and 105 × 10(3) Mr proteins associated with hyalin. McA Tg-HYL was generated against Tripneustes gratilla embryos but reacts with hyalin from the distantly related sea urchin species, Colobocentrotus atratus, Strongylocentrotus purpuratus, Arbacia punctulata, Lytechinus variegatus and Lytechinus pictus. Developing embryos of the above-mentioned six species were treated with McA Tg-HYL and did not gastrulate or form arms. Observations of treated embryos revealed areas of separation of the hyaline layer from the underlying embryonic cells, suggesting that McA Tg-HYL was interfering with binding of the cells to the HL. Using the centrifugation-based adhesion assay of McClay et al. (Proc. natn. Acad. Sci. U.S.A. 78, 4975–4979, 1981), Fab' fragments of McA Tg-HYL were found to inhibit cell-hyalin binding. McA Tg-HYL did not inhibit hyalin gelation in vitro or the reaggregation of dissociated blastula cells. We postulate that McA Tg-HYL recognizes an evolutionarily conserved hyalin domain involved in cell-hyalin binding and required for normal epithelial folding.


Author(s):  
Barry Bonnell ◽  
Carolyn Larabell ◽  
Douglas Chandler

Eggs of many species including those of echinoderms, amphibians and mammals exhibit an extensive extracellular matrix (ECM) that is important both in the reception of sperm and in providing a block to polyspermy after fertilization.In sea urchin eggs there are two distinctive coats, the vitelline layer which contains glycoprotein sperm receptors and the jelly layer that contains fucose sulfate glycoconjugates which trigger the acrosomal reaction and small peptides which act as chemoattractants for sperm. The vitelline layer (VL), as visualized by quick-freezing, deep-etching, and rotary-shadowing (QFDE-RS), is a fishnet-like structure, anchored to the plasma membrane by short posts. Orbiting above the VL are horizontal filaments which are thought to anchor the thicker jelly layer to the egg. Upon fertilization, the VL elevates and is transformed by cortical granule secretions into the fertilization envelope (FE). The rounded casts of microvilli in the VL are transformed into angular peaks and the envelope becomes coated inside and out with sheets of paracrystalline protein having a quasi-two dimensional crystalline structure.


Aquaculture ◽  
2006 ◽  
Vol 254 (1-4) ◽  
pp. 483-495 ◽  
Author(s):  
Hugh Hammer ◽  
Stephen Watts ◽  
Addison Lawrence ◽  
John Lawrence ◽  
Renee Desmond

1971 ◽  
Vol 50 (2) ◽  
pp. 516-528 ◽  
Author(s):  
Rudolf A. Raff ◽  
Gerald Greenhouse ◽  
Kenneth W. Gross ◽  
Paul R. Gross

Studies employing colchicine binding, precipitation with vinblastine sulfate, and acrylamide gel electrophoresis confirm earlier proposals that Arbacia punctulata and Lytechinus pictus eggs and embryos contain a store of microtubule proteins. Treatment of 150,000 g supernatants from sea urchin homogenates with vinblastine sulfate precipitates about 5% of the total soluble protein, and 75% of the colchicine-binding activity. Electrophoretic examination of the precipitate reveals two very prominent bands. These have migration rates identical to those of the A and B microtubule proteins of cilia. These proteins can be made radioactive at the 16 cell stage and at hatching by pulse labeling with tritiated amino acids. By labeling for 1 hr with leucine-3H in early cleavage, then culturing embryos in the presence of unlabeled leucine, removal of newly synthesized microtubule proteins from the soluble pool can be demonstrated. Incorporation of labeled amino acids into microtubule proteins is not affected by culturing embryos continuously in 20 µg/ml of actinomycin D. Microtubule proteins appear, therefore, to be synthesized on "maternal" messenger RNA. This provides the first protein encoded by stored or "masked" mRNA in sea urchin embryos to be identified.


Zygote ◽  
2008 ◽  
Vol 16 (1) ◽  
pp. 73-78 ◽  
Author(s):  
M. Alvarez ◽  
J. Nnoli ◽  
E.J. Carroll ◽  
V. Hutchins-Carroll ◽  
Z. Razinia ◽  
...  

SummaryThe 330 kDa fibrillar glycoprotein hyalin is a well known component of the sea urchin embryo extracellular hyaline layer. Only recently, the main component of hyalin, the hyalin repeat domain, has been identified in organisms as widely divergent as bacteria and humans using the GenBank database and therefore its possible function has garnered a great deal of interest. In the sea urchin, hyalin serves as an adhesive substrate in the developing embryo and we have recently shown that exogenously added purified hyalin from Strongylocentrotus purpuratus embryos blocks a model cellular interaction in these embryos, archenteron elongation/attachment to the blastocoel roof. It is important to demonstrate the generality of this result by observing if hyalin from one species of sea urchin blocks archenteron elongation/attachment in another species. Here we show in three repeated experiments, with 30 replicate samples for each condition, that the same concentration of S. purpuratus hyalin (57 μg/ml) that blocked the interaction in living S. purpuratus embryos blocked the same interaction in living Lytechinus pictus embryos. These results correspond with the known crossreactivity of antibody against S. purpuratus hyalin with L. pictus hyalin. We propose that hyalin–hyalin receptor binding may mediate this adhesive interaction. The use of a microplate assay that allows precise quantification of developmental effects should help facilitate identification of the function of hyalin in organisms as divergent as bacteria and humans.


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