scholarly journals Abberant chemotaxis and differentiation in Dictyostelium mutant fgdC with a defective regulation of receptor-stimulated phosphoinositidase C

1991 ◽  
Vol 100 (4) ◽  
pp. 825-831 ◽  
Author(s):  
A.A. Bominaar ◽  
F. Kesbeke ◽  
B.E. Snaar-Jagalska ◽  
D.J. Peters ◽  
P. Schaap ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Guanylate Cyclase ◽  
Specific Gene ◽  
Wild Type ◽  
Cell Type ◽  
Surface Receptors ◽  
Cell Type Specific ◽  
Stimulation Of

Dictyostelium cells use extracellular cyclic AMP both as a chemoattractant and as a morphogen inducing cell-type-specific gene expression. Cyclic AMP binds to surface receptors, activates one or more G-proteins, and stimulates adenylate cyclase, guanylate cyclase and phosphoinositidase C. Mutant fgdC showed aberrant chemotaxis, and was devoid of cyclic AMP-induced gene expression and differentiation. Both the receptor- and G-protein-mediated stimulation of adenylate cyclase and guanylate cyclase were unaltered in mutant fgdC as compared to wild-type cells. In wild-type cells phosphoinositidase C was activated about twofold by the cyclic AMP receptor. In mutant fgdC cells, however, the enzyme was inhibited by about 60%. These results suggest that phosphoinositidase C is regulated by a receptor-operated activation/inhibition switch that is defective in mutant fgdC. We conclude that activation of phosphoinositidase C is essential for Dictyostelium development.

scholarly journals A Ubiquitin-Conjugating Enzyme Is Essential for Developmental Transitions in Dictyostelium

1997 ◽  
Vol 8 (10) ◽  
pp. 1989-2002 ◽  
Author(s):  
Alexandra Clark ◽  
Anson Nomura ◽  
Sudhasri Mohanty ◽  
Richard A. Firtel
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Specific Gene ◽  
Wild Type ◽  
Cell Type ◽  
Protein Ubiquitination ◽  
High Amino Acid ◽  
Cell Type Specific ◽  
Very High

We have identified a developmentally essential gene,UbcB, by insertional mutagenesis. The encoded protein (UBC1) shows very high amino acid sequence identity to ubiquitin-conjugating enzymes from other organisms, suggesting that UBC1 is involved in protein ubiquitination and possibly degradation during Dictyostelium development. Consistent with the homology of the UBC1 protein to UBCs, the developmental pattern of protein ubiquitination is altered in ubcB-null cells.ubcB-null cells are blocked in the ability to properly execute the developmental transition that occurs between the induction of postaggregative gene expression during mound formation and the induction of cell-type differentiation and subsequent morphogenesis.ubcB-null cells plated on agar form mounds with normal kinetics; however, they remain at this stage for ∼10 h before forming multiple tips and fingers that then arrest. Under other conditions, some of the fingers form migrating slugs, but no culmination is observed. In ubcB-null cells, postaggregative gene transcripts accumulate to very high levels and do not decrease significantly with time as they do in wild-type cells. Expression of cell-type-specific genes is very delayed, with the level of prespore-specific gene expression being significantly reduced compared with that in wild-type cells. lacZ reporter studies using developmentally regulated and cell-type-specific promoters suggest that ubcB-null cells show an unusually elevated level of staining of lacZ reporters expressed in anterior-like cells, a regulatory cell population found scattered throughout the aggregate, and reduced staining of a prespore reporter.ubcB-null cells in a chimeric organism containing predominantly wild-type cells are able to undergo terminal differentiation but show altered spatial localization. In contrast, in chimeras containing only a small fraction of wild-type cells, the mature fruiting body is very small and composed almost exclusively of wild-type cells, with the ubcB-null cells being present as a mass of cells located in extreme posterior of the developing organism. The amino acid sequence analysis of the UbcBopen reading frame (ORF) and the analysis of the developmental phenotypes suggest that tip formation and subsequent development requires specific protein ubiquitination, and possibly degradation.

scholarly journals A secreted factor and cyclic AMP jointly regulate cell-type-specific gene expression in Dictyostelium discoideum.

1985 ◽  
Vol 5 (4) ◽  
pp. 705-713 ◽  
Author(s):  
M C Mehdy ◽  
R A Firtel
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Conditioned Medium ◽  
Dictyostelium Discoideum ◽  
Single Cells ◽  
Gene Induction ◽  
Specific Gene ◽  
Additional Parameter ◽  
Cell Type ◽  
Cell Type Specific

We are studying cell differentiation in Dictyostelium discoideum by examining the regulation of genes that are preferentially expressed in different cell types. A system has been established in which prestalk- and prespore-cell-specific genes are expressed in single cells in response to culture conditions. We confirm our previous results showing that cyclic AMP induces prestalk genes and now show that it is also required for prespore gene induction. The expression of both classes of genes is additionally dependent on the presence of a factor(s) secreted by developing cells which we call conditioned medium factor(s). An assay for conditioned medium factor(s) shows that it is detectable within 2.5 h after the onset of development. Conditioned medium factor(s) also promotes the expression of genes induced early in development, but has no detectable effect on the expression of actin genes and a gene expressed maximally in vegetative cells. In the presence of conditioned medium factor(s), exogenous cyclic AMP at the onset of starvation fails to induce the prespore and prestalk genes. The addition of cyclic AMP between 2 and 12 h of starvation results in rapid prestalk gene expression, whereas prespore genes are induced at an invarient time (approximately 18 h after the onset of starvation). These data suggest that cyclic AMP and conditioned medium factor(s) are sufficient for prestalk gene induction, whereas an additional parameter(s) is involved in the control of prespore gene induction. In contrast to several previous studies, we show that multicellularity is not essential for the expression of either prespore or prestalk genes. These data indicate that prespore and prestalk genes have cell-type-specific as well as shared regulatory factors.

A secreted factor and cyclic AMP jointly regulate cell-type-specific gene expression in Dictyostelium discoideum

1985 ◽  
Vol 5 (4) ◽  
pp. 705-713
Author(s):  
M C Mehdy ◽  
R A Firtel
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Conditioned Medium ◽  
Dictyostelium Discoideum ◽  
Single Cells ◽  
Gene Induction ◽  
Specific Gene ◽  
Additional Parameter ◽  
Cell Type ◽  
Cell Type Specific

We are studying cell differentiation in Dictyostelium discoideum by examining the regulation of genes that are preferentially expressed in different cell types. A system has been established in which prestalk- and prespore-cell-specific genes are expressed in single cells in response to culture conditions. We confirm our previous results showing that cyclic AMP induces prestalk genes and now show that it is also required for prespore gene induction. The expression of both classes of genes is additionally dependent on the presence of a factor(s) secreted by developing cells which we call conditioned medium factor(s). An assay for conditioned medium factor(s) shows that it is detectable within 2.5 h after the onset of development. Conditioned medium factor(s) also promotes the expression of genes induced early in development, but has no detectable effect on the expression of actin genes and a gene expressed maximally in vegetative cells. In the presence of conditioned medium factor(s), exogenous cyclic AMP at the onset of starvation fails to induce the prespore and prestalk genes. The addition of cyclic AMP between 2 and 12 h of starvation results in rapid prestalk gene expression, whereas prespore genes are induced at an invarient time (approximately 18 h after the onset of starvation). These data suggest that cyclic AMP and conditioned medium factor(s) are sufficient for prestalk gene induction, whereas an additional parameter(s) is involved in the control of prespore gene induction. In contrast to several previous studies, we show that multicellularity is not essential for the expression of either prespore or prestalk genes. These data indicate that prespore and prestalk genes have cell-type-specific as well as shared regulatory factors.

scholarly journals Rel Induces Interferon Regulatory Factor 4 (IRF-4) Expression in Lymphocytes

2000 ◽  
Vol 191 (8) ◽  
pp. 1281-1292 ◽  
Author(s):  
Raelene J. Grumont ◽  
Steve Gerondakis
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Nuclear Factor Κb ◽  
Wild Type ◽  
Cell Type ◽  
Regulatory Factor ◽  
Specific Manner ◽  
A Cell ◽  
Cell Type Specific ◽  
Interferon Regulatory Factor 4

In lymphocytes, the Rel transcription factor is essential in establishing a pattern of gene expression that promotes cell proliferation, survival, and differentiation. Here we show that mitogen-induced expression of interferon (IFN) regulatory factor 4 (IRF-4), a lymphoid-specific member of the IFN family of transcription factors, is Rel dependent. Consistent with IRF-4 functioning as a repressor of IFN-induced gene expression, the absence of IRF-4 expression in c-rel−/− B cells coincided with a greater sensitivity of these cells to the antiproliferative activity of IFNs. In turn, enforced expression of an IRF-4 transgene restored IFN modulated c-rel−/− B cell proliferation to that of wild-type cells. This cross-regulation between two different signaling pathways represents a novel mechanism that Rel/nuclear factor κB can repress the transcription of IFN-regulated genes in a cell type–specific manner.

Cell type-specific requirement of the MAPK pathway for the growth factor action of gastrin

1999 ◽  
Vol 276 (6) ◽  
pp. G1363-G1372 ◽  
Author(s):  
Vinzenz M. Stepan ◽  
Chris J. Dickinson ◽  
John del Valle ◽  
Masashi Matsushima ◽  
Andrea Todisco
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Cell Type ◽  
Ar42j Cells ◽  
Cell Type Specific ◽  
Ar42j Cell ◽  
Stimulation Of

Gastrin (G17) has a CCKBreceptor-mediated growth-promoting effect on the AR42J rat acinar cell line that is linked to induction of both mitogen-activated protein kinase (MAPK) and c- fos gene expression. We investigated the mechanisms that regulate the growth factor action of G17 on the rat pituitary adenoma cell line GH3. Both AR42J and GH3cells displayed equal levels of CCKBreceptor expression and similar binding kinetics of125I-labeled G17. G17 stimulation of cell proliferation was identical in both cell lines. G17 stimulation of GH3cell proliferation was completely blocked by the CCKBreceptor antagonist D2 but not by the MEK inhibitor PD-98059 or the protein kinase C inhibitor GF-109203X, which completely inhibited G17 induction of AR42J cell proliferation. G17 induced a c- fos SRE-luciferase reporter gene plasmid more than fourfold in the AR42J cells, whereas it had no effect in the GH3cells. In contrast to what we observed in the AR42J cells, G17 failed to stimulate MAPK activation and Shc tyrosyl phosphorylation and association with the adapter protein Grb2. Epidermal growth factor induced the MAPK pathway in the GH3cells, demonstrating the integrity of this signaling system. G17 induced Ca2+mobilization in both the GH3and AR42J cells. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide inhibited AR42J cell proliferation by 20%, whereas it completely blocked G17 induction of GH3cell growth. The Ca2+ionophore ionomycin stimulated GH3cell proliferation to a level similar to that observed in response to G17, but it had no effect on AR42J cell proliferation. Thus there are cell type specific differences in the requirement of the MAPK pathway for the growth factor action of G17. Whereas in the AR42J cells G17 stimulates cell growth through activation of MAPK and c- fos gene expression, in the GH3cells, G17 fails to activate MAPK, and it induces cell proliferation through Ca2+-dependent signaling pathways. Furthermore, induction of Ca2+mobilization in the AR42J cells appears not to be sufficient to sustain cell proliferation.

scholarly journals Genetic influences on cell type specific gene expression and splicing during neurogenesis elucidate regulatory mechanisms of brain traits

2020 ◽  
Author(s):  
Nil Aygün ◽  
Angela L. Elwell ◽  
Dan Liang ◽  
Michael J. Lafferty ◽  
Kerry E. Cheek ◽  
...  
Keyword(s):  
Gene Expression ◽  
Regulatory Elements ◽  
Regulatory Mechanisms ◽  
Specific Gene ◽  
Cell Type ◽  
Specific Expression ◽  
Risk Variants ◽  
Allele Specific ◽  
Cell Type Specific ◽  
Regulatory Effects

SummaryInterpretation of the function of non-coding risk loci for neuropsychiatric disorders and brain-relevant traits via gene expression and alternative splicing is mainly performed in bulk post-mortem adult tissue. However, genetic risk loci are enriched in regulatory elements of cells present during neocortical differentiation, and regulatory effects of risk variants may be masked by heterogeneity in bulk tissue. Here, we map e/sQTLs and allele specific expression in primary human neural progenitors (n=85) and their sorted neuronal progeny (n=74). Using colocalization and TWAS, we uncover cell-type specific regulatory mechanisms underlying risk for these traits.

scholarly journals Srf destabilizes cellular identity by suppressing cell-type-specific gene expression programs

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Takashi Ikeda ◽  
Takafusa Hikichi ◽  
Hisashi Miura ◽  
Hirofumi Shibata ◽  
Kanae Mitsunaga ◽  
...  
Keyword(s):  
Gene Expression ◽  
Specific Gene ◽  
Cell Type ◽  
Specific Gene Expression ◽  
Cell Type Specific ◽  
Cellular Identity
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