Biomedical subjects

D Wang

Publications and source records attributed to D Wang.

At least 541 records · Page 30Linked to original sources

PubMed1998

Autocrine transforming growth factor alpha provides a growth advantage to malignant cells by facilitating re-entry into the cell cycle from suboptimal growth states.

CBS human colon carcinoma cells are poorly tumorigenic in athymic nude mice, whereas FET colon carcinoma cells are non-tumorigenic. Both cell lines have well differentiated properties in tissue culture. Transforming growth factor alpha (TGF-alpha) was ectopically expressed by stable transfection of a TGF-alpha cDNA under repressible tetracycline control. The TGF-alpha-transfected cells showed enhanced clonal initiation and shortened lag phase growth in tissue culture without an alteration in doubling time in exponential phase relative to untransfected cells. Furthermore, the TGF-alpha transfectants showed increased independence from exogenous growth factors in clonal growth assays and induction of DNA synthesis after release from quiescence. Growth factor independence was associated with sustained epidermal growth factor receptor activation in quiescent TGF-alpha-transfected cells and the requirement of exogenous insulin for stimulation of quiescent cells to re-enter the cell cycle. Higher cloning, reduced lag time in tissue, and the acquisition of growth factor independence for DNA synthesis without a change in doubling time of TGF-alpha-transfected cells indicate that autocrine TGF-alpha functions by facilitating re-entry into the cell cycle from sub-optimal growth states rather than promoting or controlling the proliferation of actively cycling cells. The modulation of growth regulation by autocrine TGF-alpha was associated with increased malignant properties as TGF-alpha transfectants showed increased tumorigenicity in athymic nude mice. The administration of tetracycline reversed the effects of TGF-alpha expression in these cells both in vivo and in vitro, indicating that the alterations of the biological properties were due to the expression of TGF-alpha. Since these cells are continuously grown in a completely chemically defined medium without serum supplementation, it was possible to assign the mechanism underlying the generation of growth factor independence to the replacement of a requirement for exogenous insulin in parental cells by autocrine TGF-alpha.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Identification of two Escherichia coli pseudouridine synthases that show multisite specificity for 23S RNA.

Several putative Escherichia coli pseudouridine (Psi) synthases have been identified by iterative searching of genomic databases for ORFs homologous to known Psi synthases [Gustafsson et al. (1996) Nucleic Acids Res. 24, 3756-3762]. Of these, yceC and yfiI were proposed to encode Psi synthases which modify 23S rRNA. In the present work, yceC and yfiI were cloned and overexpressed in E. coli, and the encoded enzymes, YceC and YfiI, were purified to homogeneity. Both proteins converted Urd residues of rRNA to Psi, thus confirming their identities as Psi synthases. However, in in vitro experiments both enzymes extensively modified Urd residues of both 23S rRNA and 16S rRNA. Gene-disruption of yceCresulted in the absence of Psi modification at positions U955, 2504, and 2580 of 23S RNA, thus identifying these sites as in vivo targets for YceC. Likewise, yfiI disruption resulted in the absence of Psi modification at positions U1911, 1917, and possibly 1915 of 23S RNA. Disruption of yceC did not affect the growth under the conditions tested, whereas yfiI-disrupted cells showed a dramatic decrease in growth rate. Since YceC and YfiI hypermodify RNA in vitro, factors in addition to ribonucleotide sequence must contribute to the in vivo specificity of these enzymes.

Bacterial Proteins↗

PubMed1998

Activation of nuclear factor-kappaB-dependent transcription by tumor necrosis factor-alpha is mediated through phosphorylation of RelA/p65 on serine 529.

Nuclear factor-kappaB (NF-kappaB) is an essential transcription factor in the control of expression of genes involved in immune and inflammatory responses. In unstimulated cells, NF-kappaB complexes are sequestered in the cytoplasm through interactions with IkappaBalpha and other IkappaB proteins. Extracellular stimuli that activate NF-kappaB, such as tumor necrosis factor alpha (TNFalpha), cause rapid phosphorylation of IkappaBalpha at serines 32 and 36. The inducible phosphorylation of IkappaBalpha is followed by its ubiquitination and degradation, allowing NF-kappaB complexes to translocate into the nucleus and to activate gene expression. Previously, it has been shown that TNFalpha as well as other stimuli also lead to the phosphorylation of the RelA/p65 subunit of NF-kappaB. In this report, we demonstrate that the TNFalpha-induced phosphorylation of the RelA/p65 subunit occurs on serine 529, which is in the C-terminal (TA1) transactivation domain. Accordingly, the TNFalpha-induced phosphorylation of Rel/p65 increases NF-kappaB transcriptional activity but does not affect nuclear translocation or DNA binding affinity.

Amino Acid Sequence↗

PubMed1998

Chemosignal transduction in the vomeronasal organ of garter snakes: cloning of a gene encoding adenylate cyclase from the vomeronasal organ of garter snakes.

We previously reported that ES20-receptor binding activates phosphoinositide (PI) turnover, resulting in an increase in inositol-1,4,5-trisphosphate, which in turn mobilizes intracellularly stored calcium in the vomeronasal (VN) sensory epithelium of garter snakes. We also found that the activity of adenylate cyclase (AC) in the VN organ is very sensitive to Ca2+ but insensitive to calmodulin regulation. A 250-bp fragment of adenylate cyclase type VI (AC-VI) was obtained from brain cDNA of garter snake by RT-PCR with degenerate primers. The 250-bp fragments were amplified, cloned, and sequenced. Both Northern blot and RNase protection assays revealed that the vomeronasal organ (VNO) and brain contained more abundance of AC type VI than the main olfactory epithelium. A 3.8-kb cDNA was then cloned from the vomeronasal cDNA library of garter snakes and sequenced. The 5' cDNA was obtained by means of 5' RACE PCR and sequenced. We have successfully cloned a 5200-nucleotide cDNA from VNO of garter snakes containing an open reading frame++ encoding 1150 amino acids of AC-VI protein. The vomeronasal AC is termed AC(VN) . AC(VN) shows a high degree of homology with type VI AC of rat, mouse, or human. In situ hybridization with digoxigenin-labeled cRNA demonstrated that AC(VN) mRNA was abundant in the sensory epithelium but not in the nonsensory epithelium of the mushroom body of the vomeronasal organ of garter snakes.

Adenylyl Cyclases↗

PubMed1998

[Loss of heterozygosity microsatellite DNA on chromosome loci 3, 5, 7, 9 and 18 in human pancreatic cancer].

OBJECTIVE: Detecting the loss of heterozygosity in paraffin-embedded pancreatic cancer tissues. METHODS: Analysing loss of heterzygosity (LOH) of microsatellite DNA on chromosome loci 3,5,7,9 and 18 with PCR-SSLP-silver stain method in pancreatic cancer. RESULTS: In 45 sporadic pancreatic cancer samples and their paired control tissue, LOH was detected on site for D18S46( 18q21.1,31.0%), D18S474 (18q21.1, 20.0%), D9S176 (9q22-31,20.0%), D3S1234 (3p14.2,17.5%),D 3S1289 (3p21.1, 15.7%), D3S1481 (3p14.2,4.9%), D7S486 (7q22,3.6%), D5S365 (5q32, 3.2%) and D3S587 (3p24-26, 2.6%). CONCLUSION: Different percentages of loss of heterzygosity on specific chromosomal regions were found, and the meaning of the results was discussed. Some key genes may play a role in the pathogenesis of pancreatic cancer.

Adult↗

PubMed1998

Synthesis in Escherichia coli of two smaller enzymically active analogues of Coxiella burnetii macrophage infectivity potentiator (CbMip) protein utilizing a single open reading frame from the cbmip gene.

FK506-binding proteins (FKBPs) have been identified in a variety of eukaryotic and prokaryotic organisms. Macrophage infectivity potentiator (CbMip, 23.5 kDa) protein of the obligate intracellular bacterium, Coxiella burnetii, was shown previously to belong to the family of FKBPs based on sequence homology and peptidyl-prolyl cis/trans isomerase (PPIase) activity. Further characterization of the cbmip gene has identified two additional proteins with molecular masses of 15.5 and 15.0 kDa that are synthesized, in addition to the 23.5 kDa CbMip, when expressed in Escherichia coli. Amino acid sequencing at the N-terminus combined with transcription and translation fusion expression revealed that the two proteins were synthesized from the same open reading frame of the cbmip gene, but starting at different internal translation start codons, probably by translational reinitiation. When the internal methionines serving as start sites were replaced with lysine by site-directed mutagenesis, the synthesis of 15.5 and 15.0 kDa proteins was abolished even though the synthesis of 23.5 kDa CbMip was intact. This confirmed that the 15.5 and 15.0 kDa proteins are indeed generated by translational reinitiation and are not degradation products of the 23.5 kDa protein. Like other FKBPs, both 15.5 and 15.0 kDa proteins exhibit PPIase activity. Because they share significant sequence homology with FKBPs and have a similar PPIase activity, 15.5 and 15. 0 kDa proteins are designated as C. burnetii FKBP (Cb-FKBP) analogues I and II, respectively. TnphoA mutagenesis demonstrated that whereas the large protein (CbMip) is secreted, Cb-FKBP analogues I and II are cytoplasmic, indicating that structural variations could allow for different subcellular compartmentalization of similar proteins. Western-blot analysis of lysates of purified C. burnetii using a CbMip-specific monoclonal antibody revealed the presence of a protein migrating at approximately 15 kDa, indicating the presence of smaller Cb-FKBP analogue(s) in C. burnetii, although at much lower levels compared with 23.5 kDa CbMip. This unique gene organization seen with cbmip may provide the organism with a mechanism of efficient use of its limited genetic information to synthesize proteins that are structurally different yet functionally similar.

Amino Acid Sequence↗

PubMed1998

Mutational analysis of the transforming growth factor beta receptor type II gene in human ovarian carcinoma.

In the present study, we evaluated a series of sporadic ovarian carcinomas for mutations within the entire coding region of TbetaR-II. Using reverse transcription-PCR and "Cold" single-strand conformational polymorphism analysis, 6 of 24 samples (25%) were found to contain code-altering mutations in TbetaR-II: (a) four mutations resulting in amino acid substitutions in the highly conserved serine/threonine kinase domain; (b) one mutation resulting in a conservative amino acid change in the transmembrane domain; and (c) a 1-bp insertion in the polyadenylic acid microsatellite region resulting in a reading frameshift. In addition, six cases (25%) exhibited a common bp substitution (C-->T at nucleotide 1322) in both tumor and patient-matched normal tissues. This is the first report of such TbetaR-II mutations in primary human ovarian carcinomas. Immunohistochemical analysis demonstrated a loss of expression of TbetaR-II in 5 of 22 available tumors (23%; 4 of which also had mutations in the coding region) and decreased expression of TbetaR-II in 10 of 22 available tumors (44%; 1 of which had a mutation in the coding region). Thus, the loss or decreased expression of TbetaR-II seems to be a common event in sporadic ovarian carcinomas, and mutational inactivation, due to either frameshift mutations in the polyadenylic acid microsatellite region or point mutations in conserved functional domains, is one mechanism by which this occurs.

Adult↗

PubMed1998

Insulin stimulation of the fatty acid synthase promoter is mediated by the phosphatidylinositol 3-kinase pathway. Involvement of protein kinase B/Akt.

Fatty acid synthase (FAS) is a critical enzyme in de novo lipogenesis. It catalyzes the seven steps in the conversion of malonyl-CoA and acetyl-CoA to palmitate. We have shown that the rate of FAS transcription is induced dramatically when fasted animals are refed with a high carbohydrate, fat-free diet or when streptozotocin-diabetic mice are given insulin. The FAS promoter was up-regulated by insulin through the proximal insulin response sequence containing an E-box motif at the -65-base pair position. Binding of upstream stimulatory factors to the -65 E-box is functionally required for insulin regulation of the FAS promoter. In the present study, we characterized signaling pathways in the insulin stimulation of FAS transcription using specific inhibitors for various signaling molecules and transfecting engineered phosphatidylinositol (PI) 3-kinase subunits and protein kinase B (PKB)/Akt. PD98059 and rapamycin, which inhibit MAP kinase and P70 S6 kinase, respectively, had little effect on the insulin-stimulated FAS promoter activity in 3T3-L1 adipocytes. On the other hand, wortmannin and LY294002, which specifically inactivate PI 3-kinase, strongly inhibited the insulin-stimulated FAS promoter activity. As shown in RNase protection assays, LY294002 also inhibited insulin stimulation of the endogenous FAS mRNA levels in 3T3-L1 adipocytes. Cotransfection of expression vectors for the constitutively active P110 subunit of PI 3-kinase resulted in an elevated FAS promoter activity in the absence of insulin and a loss of further insulin stimulation. Transfecting a dominant negative P85 subunit of PI 3-kinase decreased FAS promoter activity and blocked insulin stimulation. Furthermore, cotransfected wild-type PKB/Akt increased FAS promoter activity in the absence of insulin and a loss of insulin responsiveness of the FAS promoter. On the other hand, kinase-dead PKB/Akt acted in a dominant negative manner to decrease the FAS promoter activity and abolished its insulin responsiveness. These results demonstrate that insulin stimulation of fatty acid synthase promoter is mediated by the PI 3-kinase pathway and that PKB/Akt is involved as a downstream effector.

Animals↗

PubMed1998

Mechanisms of spectral tuning in blue cone visual pigments. Visible and raman spectroscopy of blue-shifted rhodopsin mutants.

Spectral tuning by visual pigments involves the modulation of the physical properties of the chromophore (11-cis-retinal) by amino acid side chains that compose the chromophore-binding pocket. We identified 12 amino acid residues in the human blue cone pigment that might induce the required green-to-blue opsin shift. The simultaneous substitution of nine of these sites in rhodopsin (M86L, G90S, A117G, E122L, A124T, W265Y, A292S, A295S, and A299C) shifted the absorption maximum from 500 to 438 nm, accounting for 2,830 cm-1, or 80%, of the opsin shift between rhodopsin and the blue cone pigment. Raman spectroscopy of mutant pigments shows that the dielectric character and architecture of the chromophore-binding pocket are specifically altered. An increase in the number of dipolar side chains near the protonated Schiff base of retinal increases the ground-excited state energy gap via long range dipole-dipole Coulomb interaction. In addition, the W265Y substitution causes a decrease in solvent polarizability near the chromophore ring structure. Finally, two substitutions on transmembrane helix 3 (A117G and E122L) act in combination with the other substitutions to alter the binding-pocket structure, resulting in stronger interaction of the protonated Schiff base group with the surrounding dipolar groups and the counterion. Taken together, these results identify the amino acid side chains and the underlying physical mechanisms responsible for a majority of the opsin shift in blue visual pigments.

Amino Acid Sequence↗

PubMed1998

Efficient expression of CFTR function with adeno-associated virus vectors that carry shortened CFTR genes.

Adeno-associated virus (AAV)-based vectors have been shown to be effective in transferring the cystic fibrosis gene (CFTR) into airway epithelial cells in animal models and in patients. However, the level of CFTR gene expression has been low because the vector cannot accommodate the CFTR gene together with a promoter. In this study, we described a strategy to reduce the size of the CFTR cDNA to allow the incorporation of an effective promoter with the CFTR gene into AAV vectors. We engineered and tested 20 CFTR mini-genes containing deletions that were targeted to regions that may contain nonessential sequences. Functional analyses showed that four of the shortened CFTRs (one with combined deletions) retained the function and the characteristics of a wild-type CFTR, as measured by open probability, time voltage dependence, and regulation by cAMP. By using an AAV vector with a P5 promoter, we transduced these short forms of CFTR genes into target cells and demonstrated high levels of CFTR expression. We also demonstrated that smaller AAV/CFTR vectors with a P5 promoter expressed the CFTR gene more efficiently than larger vectors or a vector in which CFTR gene was expressed from the AAV inverted terminal repeat sequence. The CFTR mini-gene with combined deletions was packaged into AAV virions more efficiently, generated higher titers of transducing virions, and more effectively transferred CFTR function into target cells. These new vectors should circumvent the limitations of AAV vector for CFTR expression. Our strategy also may be applicable to other genes, the sizes of which exceed the packaging limit of an AAV vector.

Cell Line↗

PubMed1998

Structure changes in hemoglobin upon deletion of C-terminal residues, monitored by resonance Raman spectroscopy.

Loss of C-terminal residues in hemoglobin raises oxygen affinity and reduces both cooperativity and the Bohr effect. These functional changes are expected from the loss of C-terminal salt bridges, which are seen crystallographically to stabilize the T quaternary structure. Ultraviolet resonance Raman (UVRR) difference spectroscopy confirms that the strength of the T state contacts is diminished when the C-terminal and also the penultimate residues are removed chemically. Deoxy minus CO difference signals arising from the Trpbeta37-Aspalpha94 and Tyralpha42-Aspbeta99 H bonds at the alpha1 beta2 subunit interface are diminished, and at pH 9, the difference spectra reveal a shift to the R quaternary structure. These effects are small for desHisbeta146 Hb and large for desArgalpha141 Hb, consistent with the order of functional changes. In addition, the H bond between the A and E helices is strengthened by removal of Argalpha141 and is further strengthened when the effector molecule IHP (inositol hexaphosphate) is added to deoxy-desArgalpha141 Hb or when its pH is lowered to 5.8. This effect is attributed to the loss of the C-terminal anchor of the alpha chain H helix, which supports the F and A helices. The beta chain is not as sensitive because it has extra F-H interhelix H bonds. Removal of both Hisbeta146 and Tauyrbeta145 produce UVRR changes which are intermediate between desHisbeta146 and desArgalpha141 Hb, although the functional consequences are greater than for desArgalpha141 Hb. Removal of Tyralpha140 as well as Argalpha141 abolishes cooperative binding as well as the Bohr effect, and the UVRR difference signals are also lost, suggesting that quaternary constraints are removed in both the T and the R states. When the approximately 220 cm-1 iron-histidine stretching vibration of the deoxy-proteins is examined, using Raman excitation in resonance with the heme Soret band, the frequency is observed to diminish toward that of deoxyHb A (215 cm-1) as the pH is lowered and IHP is added and to increase toward a completely relaxed value (223 cm-1) as the pH is raised to 9. The relaxation is in the same order as the functional perturbations: desHisbeta146 < desArgalpha141 < desHisbeta146-Tyrbeta145 < desArgalpha141-Tyralpha140. However, even desArgalpha141-Tyralpha140 Hb shows significant reduction in the Fe-His frequency as IHP is added at low pH. The Fe-His frequency is sensitive to both tertiary and quaternary structure changes and is a global indicator of forces at the heme. The order of affinity changes can be understood on the basis of the number of stabilizing H bonds between the F and H helices. Titration curves of the Fe-His frequency against pH are not sigmoidal, consistent with a multiplicity of contributions to the Bohr effect.

Adult↗

PubMed1998

Identification of a dihydropyridine as a potent alpha1a adrenoceptor-selective antagonist that inhibits phenylephrine-induced contraction of the human prostate.

A number of novel dihydropyridine derivatives based upon 1, 4-dihydro-3-(methoxycarbonyl)-2, 6-dimethyl-4-(4-nitrophenyl)-5-((3-(4, 4-diphenylpiperidin-1-yl)propyl)aminocarbonyl)pyridine (4) have been synthesized and tested at cloned human alpha adrenoceptors as well as the rat L-type calcium channel. Within this compound series, 5-(aminocarbonyl)-1,4-dihydro-2, 6-dimethyl-4-(4-nitrophenyl)-3-((3-(4, 4-diphenylpiperidin-1-yl)propyl)aminocarbonyl)pyridine (19) displayed good binding affinity and selectivity for the alpha1a adrenoceptor (pKi = 8.73) and potently inhibited (pA2 = 9.23) phenylephrine-induced contraction of the human prostate.

Adrenergic alpha-Agonists↗

PubMed1998

Differential roles of Ca2+/calmodulin-dependent kinases in posttetanic potentiation at input selective glutamatergic pathways.

The electrosensory lateral line lobe (ELL) of the electric fish Apteronotus leptorhynchus is a layered medullary region receiving electroreceptor input that terminates on basal dendrites of interneurons and projection (pyramidal) cells. The molecular layer of the ELL contains two distinct glutamatergic feedback pathways that terminate on the proximal (ventral molecular layer, VML) and distal (dorsal molecular layer) apical dendrites of pyramidal cells. Western blot analysis with an antibody directed against mammalian Ca2+/calmodulin-dependent kinase 2, alpha subunit (CaMK2alpha) recognized a protein of identical size in the brain of A. leptorhynchus. Immunohistochemistry demonstrated that CaMK2 alpha expression in the ELL was restricted to fibers and terminals in the VML. Posttetanic potentiation (PTP) could be readily elicited in pyramidal cells by stimulation of either VML or DML in brain slices of the ELL. PTP in the VML was blocked by extracellular application of a CaMK2 antagonist (KN62) while intracellular application of KN62 or a CaMK2 inhibitory peptide had no effect, consistent with the presynaptic localization of CaMK2 alpha in VML. PTP in the dorsal molecular layer was not affected by extracellular application of KN62. Anti-Hebbian plasticity has also been demonstrated in the VML, but was not affected by KN62. These results demonstrate that, while PTP can occur independent of CaMK2, it is, in some synapses, dependent on this kinase.

Animals↗

PubMed1998

Stat5a and Stat5b proteins have essential and nonessential, or redundant, roles in cytokine responses.

A variety of cytokines mediate the activation of Janus protein tyrosine kinases (Jaks). The Jaks then phosphorylate cellular substrates, including members of the signal transducers and activators of transcription (Stat) family of transcription factors. Among the Stats, the two highly related proteins, Stat5a and Stat5b, are activated by a variety of cytokines. To assess the role of the Stat5 proteins, mutant mice were derived that have the genes deleted individually or together. The phenotypes of the mice demonstrate an essential, and often redundant, role for the two Stat5 proteins in a spectrum of physiological responses associated with growth hormone and prolactin. Conversely, the responses to a variety of cytokines that activate the Stat5 proteins, including erythropoietin, are largely unaffected.

Animals↗

PubMed1998

Ultrastructural and temporal observations of the potyvirus cylindrical inclusions (Cls) show that the Cl protein acts transiently in aiding virus movement.

A systematic ultrastructural study across the edge of an advancing infection in pea seed-borne mosaic potyvirus-infected pea cotyledons showed the cylindrical inclusion (CI) protein to exist in transient functional states. Initially, the characteristic CI pinwheel inclusion bodies were positioned centrally over the plasmodesmal apertures (including those of plasmodesmata connected to the previously infected cell), in agreement with a proposed role in virus movement (Carrington et al., 1998, Plant J., 13, in press). The viral coat protein was associated with these structures and was seen within the modified plasmodesma, most notably in a continuous channel that passed along the axis of the pinwheel and through the plasmodesma. The CI protein was not detected within the plasmodesmal cavities. Later in the infection (i.e., behind the zone of active virus replication) the CI was no longer associated with cell walls, or with coat protein, and showed signs of structural degeneration. In contrast, the coat protein remained within plasmodesmal cavities. The role of the CI in assisting virus movement is not known but the presence of the CI was linked with an apparent transient reduction in callose in the vicinity of the plasmodesmata.

Inclusion Bodies, Viral↗

PubMed1998

Mutagenicity and repair of oxidative DNA damage: insights from studies using defined lesions.

Oxidative DNA damage has been implicated in mutagenesis, carcinogenesis and aging. Endogenous cellular processes such as aerobic metabolism generate reactive oxygen species (ROS) that interact with DNA to form dozens of DNA lesions. If unrepaired, these lesions can exert a number of deleterious effects including the induction of mutations. In an effort to understand the genetic consequences of cellular oxidative damage, many laboratories have determined the patterns of mutations generated by the interaction of ROS with DNA. Compilation of these mutational spectra has revealed that GC-->AT transitions and GC-->TA transversions are the most commonly observed mutations resulting from oxidative damage to DNA. Since mutational spectra convey only the end result of a complex cascade of events, which includes formation of multiple adducts, repair processing, and polymerase errors, it is difficult if not impossible to assess the mutational specificity of individual DNA lesions directly from these spectra. This problem is especially complicated in the case of oxidative DNA damage owing to the multiplicity of lesions formed by a single damaging agent. The task of assigning specific features of mutational spectra to individual DNA lesions has been made possible with the advent of a technology to analyze the mutational properties of single defined adducts, in vitro and in vivo. At the same time, parallel progress in the discovery and cloning of repair enzymes has advanced understanding of the biochemical mechanisms by which cells excise DNA damage. This combination of tools has brought our understanding of DNA lesions to a new level of sophistication. In this review, we summarize the known properties of individual oxidative lesions in terms of their structure, mutagenicity and repairability.

Animals↗

PubMed1998

Co-localization of mu-opioid receptor-like immunoreactivity with substance P-LI, calcitonin gene-related peptide-LI and nitric oxide synthase-LI in vagal and glossopharyngeal afferent neurons of the rat.

Co-localization of mu-opioid receptor (MOR)-like immunoreactivity (-LI) with substance P (SP)-LI, calcitonin gene-related peptide (CGRP)-LI and nitric oxide synthase (NOS)-LI in the nodose, petrosal and jugular ganglia was examined in the rat by a double immunofluorescence histochemical method. About 0.6%, 41% and 95% of neurons with MOR-LI, respectively, in the nodose, petrosal and jugular ganglia showed SP-LI; about 2%, 51% and 66% of MOR-like immunoreactive neurons displayed CGRP-LI in the nodose, petrosal and jugular ganglia, respectively. In addition, about 59% of MOR-like immunoreactive neurons in the nodose ganglia displayed NOS-LI, whereas no NOS-LI was detected in the petrosal or jugular ganglion. These data provide evidence for co-localization of MOR-LI with SP-LI, CGRP-LI and NOS-LI in the vagal and glossopharyngeal afferent neurons, and suggest that MOR may regulate the release of SP, CGRP and nitric oxide from the visceral primary afferent terminals in the nucleus of the solitary tract of the rat.

Animals↗

PubMed1998

Jak2 is essential for signaling through a variety of cytokine receptors.

A variety of cytokines activate receptor-associated members of the Janus family of protein tyrosine kinases (Jaks). To assess the role of Jak2, we have derived Jak2-deficient mice. The mutation causes an embryonic lethality due to the absence of definitive erythropoiesis. Fetal liver myeloid progenitors, although present based on the expression of lineage specific markers, fail to respond to erythropoietin, thrombopoietin, interleukin-3 (IL-3), or granulocyte/macrophage colony-stimulating factor. In contrast, the response to granulocyte specific colony-stimulating factor is unaffected. Jak2-deficient fibroblasts failed to respond to interferon gamma (IFNgamma), although the responses to IFNalpha/beta and IL-6 were unaffected. Lastly, reconstitution experiments demonstrate that Jak2 is not required for the generation of lymphoid progenitors, their amplification, or functional differentiation. Therefore, Jak2 plays a critical, nonredundant role in the function of a specific group of cytokines receptors.

Animals↗