scholarly journals Ala/Thr201 in Extracellular Loop 2 and Leu/Phe290 in Transmembrane Domain 6 of Type 1 Frog Gonadotropin-Releasing Hormone Receptor Confer Differential Ligand Sensitivity and Signal Transduction

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 454-466 ◽  
Author(s):  
Jae Young Seong ◽  
Li Wang ◽  
Da Young Oh ◽  
Oim Yun ◽  
Kaushik Maiti ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Signaling Pathways ◽  
Transmembrane Domain ◽  
Inositol Phosphate ◽  
Signal Transduction Pathway ◽  
Extracellular Loop ◽  
Loop 2 ◽  
Ligand Sensitivity

Recently, we have identified three distinct types of bullfrog GnRH receptor (designated bfGnRHR-1, bfGnRHR-2, and bfGnRHR-3). In the present study, we have isolated three GnRHR clones in Rana dybowskii (dyGnRHR-1, dyGnRHR-2, and dyGnRHR-3). Despite high homology of dyGnRHRs with the corresponding bfGnRHRs, dyGnRHRs revealed different signaling pathways and ligand sensitivity compared with the bfGnRHR counterparts. Activation of dyGnRHRs with GnRH stimulated cAMP-mediated gene expression. However, dyGnRHR-3 but not dyGnRHR-1 and -2 induced c-fos promoter-driven gene expression. Consistently, dyGnRHR-1 and dyGnRHR-2 were not able to increase GnRH-induced inositol phosphate accumulation, whereas all bfGnRHRs and dyGnRHR-3 were, indicating that dyGnRHR-1 and dyGnRHR-2 are coupled to solely Gs, whereas all bfGnRHRs and dyGnRHR-3 are coupled to both Gs and Gq/11. Moreover, dyGnRHR-1 and dyGnRHR-2 showed about 10-fold less sensitivity to each ligand than that of the bfGnRHR counterparts. Using type 1 chimeric and point-mutated receptors, we further elucidated that specific amino acids, Ala/Thr201 in extracellular loop 2 and Leu/Phe290 in transmembrane domain 6 of the type 1 receptor, are responsible for ligand sensitivity and signal transduction pathway. Particularly, substitution of Leu290 to Phe in dyGnRHR-1 increased GnRH-induced inositol phosphate production as well as c-fos promoter-driven gene expression whereas substitution of Phe290 to Leu in bfGnRHR-1 decreased those activities. Collectively, these results demonstrate the presence of three types of GnRHR in amphibians, and suggest species- and type-specific ligand recognition and different signaling pathways in frog GnRHRs.

scholarly journals Modulation of Bovine Endometrial Cell Receptors and Signaling Pathways as a Nanotherapeutic Exploration against Dairy Cow Postpartum Endometritis

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1516
Author(s):  
Ayodele Olaolu Oladejo ◽  
Yajuan Li ◽  
Xiaohu Wu ◽  
Bereket Habte Imam ◽  
Jie Yang ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Signaling Pathways ◽  
Inflammatory Cytokines ◽  
Signal Transduction Pathway ◽  
Endometrial Cell ◽  
Cell Receptors ◽  
Endometrial Cells ◽  
Microbial Invasion ◽  
Pass Through ◽  
Pro Inflammatory Cytokines

In order to control and prevent bovine endometritis, there is a need to understand the molecular pathogenesis of the infectious disease. Bovine endometrium is usually invaded by a massive mobilization of microorganisms, especially bacteria, during postpartum dairy cows. Several reports have implicated the Gram-negative bacteria in the pathogenesis of bovine endometritis, with information dearth on the potentials of Gram-positive bacteria and their endotoxins. The invasive bacteria and their ligands pass through cellular receptors such as TLRs, NLRs, and biomolecular proteins of cells activate the specific receptors, which spontaneously stimulates cellular signaling pathways like MAPK, NF-kB and sequentially triggers upregulation of pro-inflammatory cytokines. The cascade of inflammatory induction involves a dual signaling pathway; the transcription factor NF-κB is released from its inhibitory molecule and can bind to various inflammatory genes promoter. The MAPK pathways are concomitantly activated, leading to specific phosphorylation of the NF-κB. The provision of detailed information on the molecular pathomechanism of bovine endometritis with the interaction between host endometrial cells and invasive bacteria in this review would widen the gap of exploring the potential of receptors and signal transduction pathways in nanotechnology-based drug delivery system. The nanotherapeutic discovery of endometrial cell receptors, signal transduction pathway, and cell biomolecules inhibitors could be developed for strategic inhibition of infectious signals at the various cell receptors and signal transduction levels, interfering on transcription factors activation and pro-inflammatory cytokines and genes expression, which may significantly protect endometrium against postpartum microbial invasion.

scholarly journals Differential Expression of the CO2 Fixation Operons of Rhodobacter sphaeroides by the Prr/Reg Two-Component System during Chemoautotrophic Growth

2002 ◽  
Vol 184 (23) ◽  
pp. 6654-6664 ◽  
Author(s):  
Janet L. Gibson ◽  
James M. Dubbs ◽  
F. Robert Tabita
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Cytochrome Oxidase ◽  
Rhodobacter Sphaeroides ◽  
Rhodobacter Capsulatus ◽  
Response Regulator ◽  
Signal Transduction Pathway ◽  
Pentose Phosphate ◽  
Bisphosphate Carboxylase

ABSTRACT In Rhodobacter sphaeroides, the two cbb operons encoding duplicated Calvin-Benson Bassham (CBB) CO2 fixation reductive pentose phosphate cycle structural genes are differentially controlled. In attempts to define the molecular basis for the differential regulation, the effects of mutations in genes encoding a subunit of Cbb3 cytochrome oxidase, ccoP, and a global response regulator, prrA (regA), were characterized with respect to CO2 fixation (cbb) gene expression by using translational lac fusions to the R. sphaeroides cbb I and cbbII promoters. Inactivation of the ccoP gene resulted in derepression of both promoters during chemoheterotophic growth, where cbb expression is normally repressed; expression was also enhanced over normal levels during phototrophic growth. The prrA mutation effected reduced expression of cbbI and cbbII promoters during chemoheterotrophic growth, whereas intermediate levels of expression were observed in a double ccoP prrA mutant. PrrA and ccoP1 prrA strains cannot grow phototrophically, so it is impossible to examine cbb expression in these backgrounds under this growth mode. In this study, however, we found that PrrA mutants of R. sphaeroides were capable of chemoautotrophic growth, allowing, for the first time, an opportunity to directly examine the requirement of PrrA for cbb gene expression in vivo under growth conditions where the CBB cycle and CO2 fixation are required. Expression from the cbbII promoter was severely reduced in the PrrA mutants during chemoautotrophic growth, whereas cbbI expression was either unaffected or enhanced. Mutations in ccoQ had no effect on expression from either promoter. These observations suggest that the Prr signal transduction pathway is not always directly linked to Cbb3 cytochrome oxidase activity, at least with respect to cbb gene expression. In addition, lac fusions containing various lengths of the cbbI promoter demonstrated distinct sequences involved in positive regulation during photoautotrophic versus chemoautotrophic growth, suggesting that different regulatory proteins may be involved. In Rhodobacter capsulatus, ribulose 1,5-bisphosphate carboxylase-oxygenase (RubisCO) expression was not affected by cco mutations during photoheterotrophic growth, suggesting that differences exist in signal transduction pathways regulating cbb genes in the related organisms.

Phytochrome signal-transduction: characterization of pathways and isolation of mutants

1995 ◽  
Vol 350 (1331) ◽  
pp. 67-74 ◽  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Red Light ◽  
Signal Transduction Pathway ◽  
Regulatory Elements ◽  
Signal Transduction Pathways ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Regulated Gene Expression ◽  
Dependent Pathway

The study of phytochrome signalling has yielded a wealth of data describing both the perception of light by the receptor, and the terminal steps in phytochrome-regulated gene expression by a number of transcription factors. We are now focusing on establishing the intervening steps linking phytochrome photoactivation to gene expression, and the regulation and interactions of these signalling pathways. Recent work has utilized both a pharmacological approach in phototrophic soybean suspension cultures and microinjection techniques in tomato to establish three distinct phytochrome signal-transduction pathways: (i) a calcium-dependent pathway that regulates the expression of genes encoding the chlorophyll a/b binding protein ( CAB ) and other components of photosystem II; (ii) a cGMP-dependent pathway that regulates the expression of the gene encoding chalcone synthase ( CHS ) and the production of anthocyanin pigments; and (iii) a pathway dependent upon both calcium and cGMP that regulates the expression of genes encoding components of photosystem I and is necessary for the production of mature chloroplasts. To study the components and the regulation of phytochrome signal-transduction pathways, mutants with altered photomorphogenic responses have been isolated by a number of laboratories. However, with several possible exceptions, little real progress has been made towards the isolation of mutants in positive regulatory elements of the phytochrome signal-transduction pathway. We have characterized a novel phytochrome A (phyA)-mediated far-red light (FR) response in Arabidopsis seedlings which we are currently using to screen for specific phyA signal-transduction mutants.

scholarly journals Interactions between the extracellular domain and the extracellular loops as well as the 6th transmembrane domain are necessary for TSH receptor activation

2005 ◽  
Vol 152 (4) ◽  
pp. 625-634 ◽  
Author(s):  
Susanne Neumann ◽  
Maren Claus ◽  
Ralf Paschke
Keyword(s):  
Signal Transduction ◽  
Molecular Mechanisms ◽  
Transmembrane Domain ◽  
Inositol Phosphate ◽  
Extracellular Domain ◽  
Receptor Activation ◽  
Tsh Receptor ◽  
Constitutive Activity ◽  
Extracellular Loops ◽  
Activating Mutation

Objective: The molecular mechanisms of TSH receptor (TSHR) activation and intramolecular signal transduction are largely unknown. Deletion of the extracellular domain (ECD) of the TSHR results in increased constitutive activity, which suggests a self-inhibitory interaction between the ECD and the extracellular loops (ECLs) or the transmembrane domains (TMDs). To investigate these potential interactions and to pursue the idea that mutations in the ECD affect the constitutive activity of mutants in the ECLs or TMDs we generated double mutants between position 281 in the ECD and mutants in all three ECLs as well as the 6th TMD. Design: We combined mutation S281D, characterized by an impaired TSH-stimulated cAMP response, with the constitutively activating in vivo mutations I486F (1st ECL), I568T (2nd ECL), V656F (3rd ECL) and D633F (6th TMD). Further, we constructed double mutants containing the constitutively activating mutation S281N and one of the inactivating mutations D474E, T477I (1st ECL) and D633K (6th TMD). Results: The cAMP level of the double mutants with S281N and the inactive mutants in the 1st ECL was decreased below the level of the inactive single mutants, demonstrating that a constitutively activating mutation in the ECD cannot bypass disruption of signal transduction in the serpentine domain. In double mutants with S281D, basal and TSH-induced cAMP and inositol phosphate production of constitutively active mutants was reduced to the level of S281D. Conclusion: The dominance of S281D and the dependence of constitutively activating mutations in the ECLs on the functionally intact ECD strongly suggest that interactions between these receptor domains are required for TSHR activation and intramolecular signal transduction.

scholarly journals A Cyclic Dodecapeptide–Multiple-Antigen Peptide Conjugate from the Undecapeptidyl Arch (from Arg168 to Cys178) of Extracellular Loop 2 in CCR5 as a Novel Human Immunodeficiency Virus Type 1 Vaccine

2001 ◽  
Vol 75 (23) ◽  
pp. 11614-11620 ◽  
Author(s):  
Shogo Misumi ◽  
Reina Nakajima ◽  
Nobutoki Takamune ◽  
Shozo Shoji
Keyword(s):  
Human Immunodeficiency Virus ◽  
Extracellular Loop ◽  
Specific Domain ◽  
Multiple Antigen ◽  
Immunodeficiency Virus ◽  
Antigen Peptide ◽  
Multiple Antigen Peptide ◽  
Loop 2 ◽  
Hiv 1

ABSTRACT A cyclic closed-chain dodecapeptide (cDDR5) mimicking the conformation-specific domain of CCR5 was prepared in which Gly-Asp, as a dipeptide forming a spacer arm, links the amino and carboxyl termini of the decapeptidyl linear chain (Arg168 to Thr177) derived from the undecapeptidyl arch (UPA; Arg168 to Cys178) of extracellular loop 2 (ECL2) in CCR5. Novel monoclonal antibodies were raised against cDDR5 conjugated with a multiple-antigen peptide (cDDR5-MAP), and the purified antibody [KB8C12, immunoglobulin M(κ)] reacted with cDDR5, but not with linear DDR5, in real-time biomolecular interaction analysis using surface plasmon resonance. The antibody also reacted with cells expressing CCR5, but not with cells expressing CXCR4, and the immunoreaction was competed by cDDR5-MAP. The antibody significantly interfered with chemotaxis induced by macrophage inflammatory protein, 1β, and at a concentration of 1.67 nM it almost completely inhibited infection by human immunodeficiency virus type 1 (HIV-1) R5, but not by HIV-1 X4, as observed by use of a new phenotypic assay for drug susceptibility of HIV-1 using the CCR5-expressing HeLa CD4+ cell clone 1-10 (MAGIC-5). Furthermore, cDDR5-MAP suppressed infection by HIV-1 R5 at relatively high concentrations (50 to 400 μM) in a dose-dependent manner but did not suppress infection by HIV-1 X4. Taken together, these results indicate that the antibody is conformation specific and recognizes the conformation-specific domain of the UPA of ECL2. Moreover, both the antibody and its immunogen, the cDDR5-MAP conjugate, may be useful in developing a new candidate vaccine for HIV therapy.

Signal Transduction Pathway Leading to Hsp27 and Hsp70 Gene Expression during Myocardial Adaptation to Stressa

1998 ◽  
Vol 851 (1 STRESS OF LIF) ◽  
pp. 129-138 ◽  
Author(s):  
DIPAK K. DAS ◽  
NILANJANA MAULIK ◽  
RICHARD M. ENGELMAN ◽  
JOHN A. ROUSOU ◽  
DAVID DEATON ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Signal Transduction Pathway ◽  
Hsp70 Gene ◽  
Transduction Pathway ◽  
Myocardial Adaptation

scholarly journals MicroRNAs in Platelets: Should I Stay or Should I Go?

Platelets ◽  
2020 ◽  
Author(s):  
Sonia Águila ◽  
Ernesto Cuenca-Zamora ◽  
Constantino Martínez ◽  
Raúl Teruel-Montoya
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Extracellular Vesicles ◽  
Intercellular Communication ◽  
Noncoding Rnas ◽  
Signal Transduction Pathway ◽  
Response To Therapy ◽  
Transduction Pathway ◽  
Small Noncoding Rnas ◽  
And Function

In this chapter, we discuss different topics always using the microRNA as the guiding thread of the review. MicroRNAs, member of small noncoding RNAs family, are an important element involved in gene expression. We cover different issues such as their importance in the differentiation and maturation of megakaryocytes (megakaryopoiesis), as well as the role in platelets formation (thrombopoiesis) focusing on the described relationship between miRNA and critical myeloid lineage transcription factors such as RUNX1, chemokines receptors as CRCX4, or central hormones in platelet homeostasis like TPO, as well as its receptor (MPL) and the TPO signal transduction pathway, that is JAK/STAT. In addition to platelet biogenesis, we review the microRNA participation in platelets physiology and function. This review also introduces the use of miRNAs as biomarkers of platelet function since the detection of pathogenic situations or response to therapy using these noncoding RNAs is getting increasing interest in disease management. Finally, this chapter describes the participation of platelets in cellular interplay, since extracellular vesicles have been demonstrated to have the ability to deliver microRNAs to others cells, modulating their function through intercellular communication, redefining the extracellular vesicles from the so-called “platelet dust” to become mediators of intercellular communication.

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