Significance Thyroid cancer is common and has an excellent outcome in many cases, although a proportion of these tumors have progressive clinical course high mortality. Using whole-transcriptome (RNA-sequencing) analysis, we discovered previously unknown genetic events, anaplastic lymphoma kinase ( ALK ) gene fusions, thyroid demonstrate that they occur more often aggressive cancers. The most fusion identified involved the striatin STRN gene, show it transforming tumorigenic vivo. Finally,...

Current understanding infers a neural crest origin of thyroid C cells, the major source calcitonin in mammals and ancestors to neuroendocrine tumors. The concept is primarily based on investigations quail-chick chimeras involving fate-mapping cells ultimobranchial glands that regulate Ca2+ homeostasis birds, reptiles, amphibians fishes, but whether mammalian cell development implicates homologous ontogenetic trajectory has not been experimentally verified. With lineage tracing we now provide...

It has been widely reported that the small GTP-binding protein Rap1 an anti-Ras and anti-mitogenic activity. Thus, it is generally accepted a normal physiological role of proteins to antagonize Ras mitogenic signals, presumably by forming nonproductive complexes with are typically effectors or modulators Ras. activated signals raise intracellular levels cAMP, molecule long known exert both inhibitory stimulatory effects on cell growth. We have now tested intriguing hypothesis could in...

Erythropoietin is the major regulator of proliferation and differentiation erythroid precursors, but little known about its molecular mechanism action. Using a human erythroleukemic cell line (HEL), we investigated whether p21ras involved in erythropoietin signal transduction. We found that stimulation HEL cells with induces 5-fold increase amount GTP bound to endogenous p21ras. This effect dose-dependent occurs very rapidly. also observed causes tyrosine phosphorylation several proteins...

Rap1 proteins belong to the Ras superfamily of small molecular weight GTP-binding proteins. Although and share approximately 50% overall amino acid sequence identity, effector domains two are identical, suggesting either similar or antagonistic signaling roles. Several pathways leading activation have been defined, including those initiated by agonist binding tyrosine kinase Gi-coupled receptors. Nothing is known about such events for The cAMP-mediated inhibition Ras-dependent MAP well...

Thyroid cancer is the most common type of endocrine malignancy, encompassing tumors with various levels invasive growth and aggressiveness. Rap1GAP, a Rap1 GTPase-activating protein, inhibits RAS superfamily protein by facilitating hydrolysis GTP to GDP. In this study, we analyzed 197 thyroid tumor samples showed that Rap1GAP was frequently lost or downregulated in types tumors, particularly aggressive forms cancer. The downregulation due promoter hypermethylation and/or loss heterozygosity,...

cAMP stimulates proliferation in many cell types. For years, cAMP-dependent protein kinase (PKA) represented the only known effector. PKA, however, does not fully mimic action of cAMP, indicating existence a PKA-independent component. Since cAMP-mediated activation G-protein Rap1 and its phosphorylation by PKA are strictly required for effects on mitogenesis, we hypothesized that activator Epac might represent factor. Here report acts synergistically with mitogenesis. We have generated new...

We have shown that the small GTPase Rap1b, a protein known to antagonize mitogenic and transforming activity of Ras, is endowed with both tumorigenic properties. Rap1b can be activated by cAMP, an intracellular message either stimulate or inhibit cell proliferation. The oncogenic property was revealed in model system which cAMP stimulates proliferation linked Rap's ability promote S phase entry. now tested significance action physiologically relevant model, differentiated thyroid follicular...

Rap1b has been implicated in the transduction of cAMP mitogenic signal. is phosphorylated and activated by cAMP, its expression cells where leads to an increase G(1)/S phase entry tumor formation. The PCCL3 thyroid follicular represent a differentiated physiologically relevant system that requires thyrotropin (TSH), acting via for full response. In this model system, stimulation DNA synthesis activation phosphorylation cAMP-dependent protein kinase A (PKA). This scenario presents challenge...

Although Ras and Rap1 share interaction with common candidate effector proteins, lacks the transforming activity exhibited by proteins. It has been speculated that Rap antagonizes transformation through formation of nonproductive complexes critical targets. To understand further distinct biological functions these two closely related we searched for Rap1b-binding proteins yeast two-hybrid screening. We identified multiple clones encode COOH-terminal sequences a protein shares sequence...

Rap1b, a member of the Ras superfamily low molecular weight GTP-binding proteins, can be phosphorylated by cAMP-dependent protein kinase (protein A). The experiments presented here were undertaken to determine precise site this phosphorylation. Because Rap1 proteins are highly homologous, there no specific antibodies able discriminate between them. To overcome problem, we used transient expression system fused containing in NH2 terminus an epitope for known antibody. Using system,...

Insulin-like growth factor-I (IGF-I) stimulates the production of 3-inositides and markedly increases phosphatidylinositol 3-kinase activity that is immunoprecipitated by anti-phosphotyrosine antibodies, a portion which also associated with IGF-I receptor. In this study, recombinant p85, regulatory subunit 3-kinase, fusion proteins containing various subdomains were used to investigate association p85 receptor demonstrate direct in vitro substrate kinase. Solubilized was immobilized on...

Rap1b has been implicated in the transduction of cAMP mitogenic signal. It is phosphorylated and activated by cAMP, its expression models where leads to proliferation tumorigenesis. Akt a likely downstream effector cAMP-Rap1 action. elevation induced rapid transient inhibition that required Rap1b. However, mechanism(s) which cAMP-Rap regulates remains unclear. Here we show (i) upstream regulators, PIK PDK1, are not target(s) inhibitory action; (ii) constitutively active calyculin...

cAMP, a key player in many physiological processes, was classically considered to originate solely from the plasma membrane (PM). This view recently challenged by observations showing that upon internalization GsPCRs can sustain signaling endosomes and/or trans-Golgi network (TGN). In this new view, after first PM-generated cAMP wave, of and ACs generates second wave strictly associated with nuclear transcriptional events responsible for triggering specific biological responses. Here, we...

Guanine nucleotide exchange factors (GEFs) and their associated GTP-binding proteins (G-proteins) are key regulatory elements in the signal transduction machinery that relays information from extracellular environment into specific intracellular responses. Among them, MAPK cascades represent ubiquitous downstream effector pathways. We have previously described that, analogous to Ras-dependent activation of Erk-1/2 pathway, members Rho family small G-proteins activate JNK cascade when GTP is...

Rap1b has been implicated in the transduction of cAMP mitogenic response. Agonists that increase intracellular rapidly activate (i.e. GTP binding) and phosphorylate on Ser(179) at its C terminus. cAMP-dependent protein kinase (PKA)-mediated phosphorylation is required for mitogenesis, tumorigenesis, inhibition AKT activity. However, role still remains unknown. In this study, we utilized amide hydrogen/deuterium exchange mass spectroscopy (DXMS) to assess potential conformational changes...

cAMP is an ubiquitous second messenger. Localized areas with high concentration, i.e. microdomains, provide elegant mechanism to generate signaling specificity and transduction efficiency. However, the mechanisms underlying effector targeting into these compartments still unclear. Here we report identification of radixin as a scaffolding unit for both effectors, Epac PKA. This complex localizes in submembrane compartment where synthesis occurs. Compartment disruption by shRNA dominant...

ABSTRACT The developmental program that regulates thyroid progenitor cell proliferation is largely unknown. Here, we show branching-like morphogenesis a driving force to attain final size of the embryonic gland in mice. Sox9, key factor branching organ development, distinguishes Nkx2-1+ cells bud from progenitors originally form placode anterior endoderm. As lobes develop primordial tissue branches several generations. Sox9 and Fgfr2b are co-expressed distally epithelium prior...

Background: Thyroid tumor progression from well-differentiated cancer to poorly differentiated thyroid carcinoma (PDTC) and anaplastic (ATC) involves step-wise dedifferentiation associated with loss of iodine avidity poor outcomes. ALK fusions, typically STRN-ALK, are found higher incidence in human PDTC compared and, as previously shown, can drive the development murine PDTC. The aim this study was evaluate initiation mice concomitant expression STRN-ALK inactivation suppressor p53 (Trp53)...

Significance cAMP is a second messenger present in most cells, synthesized by adenylyl cyclase. Different isoforms are eukaryotes with distinct modes of regulation. In yeast, cyclase regulated Ras2 CAP1-dependent manner. CAP1 conserved mammals; however, its regulatory component considered to be lost during evolution. We show that binds and activates mammalian reveal role for Rap1, partner, regulation cells. These findings indicate Rap1 not just downstream player but the context able modulate...

cAMP signaling leads to activation and phosphorylation of Rap1b. Using cellular models where stimulates cell proliferation, we have demonstrated that cAMP-mediated activation, as well Rap1b, is critical for stimulation DNA synthesis. To determine whether Rap1b mitogenesis in vivo, constructed a transgenic mouse constitutively active G12V-Rap1b, flanked by Cre recombinase LoxP sites, followed the dominant negative S17N mutant. Employing this novel model, switched, tissue-specific (thyroid)...