| 1. |
- Andrae, Johanna, et al.
(författare)
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Analysis of Mice Lacking the Heparin-Binding Splice Isoform of Platelet-Derived Growth Factor A
- 2013
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 33:20, s. 4030-4040
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor A-chain (PDGF-A) exists in two evolutionarily conserved isoforms, PDGF-Along and PDGF-Ashort, generated by alternative RNA splicing. They differ by the presence (in PDGF-Along) or absence (in PDGF-Ashort) of a carboxyterminal heparin/heparan sulfate proteoglycan-binding motif. In mice, similar motifs present in other members of the PDGF and vascular endothelial growth factor (VEGF) families have been functionally analyzed in vivo, but the specific physiological importance of PDGF-A(long) has not been explored previously. Here, we analyzed the absolute and relative expression of the two PDGF-A splice isoforms during early postnatal organ development in the mouse and report on the generation of a Pdgfa allele (Pdgfa(Delta ex6) incapable of producing PDGF-A(long) due to a deletion of the exon 6 splice acceptor site. In situations of limiting PDGF-A signaling through PDGF receptor alpha (PDGFR alpha), or in mice lacking PDGF-C, homozygous carriers of Pdgfa(Delta ex6) showed abnormal development of the lung, intestine, and vertebral column, pinpointing developmental processes where PDGF-A(long) may play a physiological role.
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| 2. |
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| 3. |
- Annicotte, Jean-Sébastien, et al.
(författare)
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Pancreatic-duodenal homeobox 1 regulates expression of liver receptor homolog 1 during pancreas development.
- 2003
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 23:19, s. 6713-6124
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Tidskriftsartikel (refereegranskat)abstract
- Liver receptor homolog 1 (LRH-1) and pancreatic-duodenal homeobox 1 (PDX-1) are coexpressed in the pancreas during mouse embryonic development. Analysis of the regulatory region of the human LRH-1 gene demonstrated the presence of three functional binding sites for PDX-1. Electrophoretic mobility shift assays and chromatin immunoprecipitation analysis showed that PDX-1 bound to the LRH-1 promoter, both in cultured cells in vitro and during pancreatic development in vivo. Retroviral expression of PDX-1 in pancreatic cells induced the transcription of LRH-1, whereas reduced PDX-1 levels by RNA interference attenuated its expression. Consistent with direct regulation of LRH-1 expression by PDX-1, PDX-1(-/-) mice expressed smaller amounts of LRH-1 mRNA in the embryonic pancreas. Taken together, our data indicate that PDX-1 controls LRH-1 expression and identify LRH-1 as a novel downstream target in the PDX-1 regulatory cascade governing pancreatic development, differentiation, and function.
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| 4. |
- Antonsson, Åsa, et al.
(författare)
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Regulation of c-Rel Nuclear Localization by Binding of Ca2+/Calmodulin
- 2003
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Ingår i: Molecular and Cellular Biology. - : American Society for Microbiology. - 0270-7306 .- 1098-5549. ; 23:4, s. 1418-1427
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Tidskriftsartikel (refereegranskat)abstract
- The NF-κB/Rel family of transcription factors participates in the control of a wide array of genes, including genes involved in embryonic development and regulation of immune, inflammation, and stress responses. In most cells, inhibitory IκB proteins sequester NF-κB/Rel in the cytoplasm. Cellular stimulation results in the degradation of IκB and modification of NF-κB/Rel proteins, allowing NF-κB/Rel to translocate to the nucleus and act on its target genes. Calmodulin (CaM) is a highly conserved, ubiquitously expressed Ca2+ binding protein that serves as a key mediator of intracellular Ca2+ signals. Here we report that two members of the NF-κB/Rel family, c-Rel and RelA, interact directly with Ca2+-loaded CaM. The interaction with CaM is greatly enhanced by cell stimulation, and this enhancement is blocked by addition of IκB. c-Rel and RelA interact with CaM through a similar sequence near the nuclear localization signal. Compared to the wild-type protein, CaM binding-deficient mutants of c-Rel exhibit increases in both nuclear accumulation and transcriptional activity on the interleukin 2 and granulocyte macrophage colony-stimulating factor promoters in the presence of a Ca2+ signal. Conversely, for RelA neither nuclear accumulation nor transcriptional activity on these promoters is increased by mutation of the sequence interacting with CaM. Our results suggest that CaM binds c-Rel and RelA after their release from IκB and can inhibit nuclear import of c-Rel while letting RelA translocate to the nucleus and act on its target genes. CaM can therefore differentially regulate the activation of NF-κB/Rel proteins following stimulation.
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| 5. |
- Arvidsson, Ann-Kristin, et al.
(författare)
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Tyr-716 in the platelet-derived growth factor beta-receptor kinase insertis involved in GRB2 binding and Ras activation
- 1994
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Ingår i: Molecular and Cellular Biology. - : American Society for Microbiology. - 0270-7306 .- 1098-5549. ; 14:10, s. 6715-6726
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Tidskriftsartikel (refereegranskat)abstract
- Ligand stimulation of the platelet-derived growth factor (PDGF) beta-receptor leads to activation of its intrinsic tyrosine kinase and autophosphorylation of the intracellular part of the receptor. The autophosphorylated tyrosine residues mediate interactions with downstream signal transduction molecules and thereby initiate different signalling pathways. A pathway leading to activation of the GTP-binding protein Ras involves the adaptor molecule GRB2. Here we show that Tyr-716, a novel autophosphorylation site in the PDGF beta-receptor kinase insert, mediates direct binding of GRB2 in vitro and in vivo. In a panel of mutant PDGF beta-receptors, in which Tyr-716 and the previously known autophosphorylation sites were individually mutated, only PDGFR beta Y716F failed to bind GRB2. Furthermore, a synthetic phosphorylated peptide containing Tyr-716 bound GRB2, and this peptide specifically interrupted the interaction between GRB2 and the wild-type receptor. In addition, the Y716(P) peptide significantly decreased the amount of GTP bound to Ras in response to PDGF in permeabilized fibroblasts as well as in porcine aortic endothelial cells expressing transfected PDGF beta-receptors. The mutant PDGFR beta Y716F still mediated activation of mitogen-activated protein kinases and an increased DNA synthesis in response to PDGF, indicating that multiple signal transduction pathways transduce mitogenic signals from the activated PDGF beta-receptor.
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| 6. |
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| 7. |
- Banyai, Gabor, et al.
(författare)
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Mediator Can Regulate Mitotic Entry and Direct Periodic Transcription in Fission Yeast
- 2014
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 34:21, s. 4008-4018
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Tidskriftsartikel (refereegranskat)abstract
- Cdk8 is required for correct timing of mitotic progression in fission yeast. How the activity of Cdk8 is regulated is unclear, since the kinase is not activated by T-loop phosphorylation and its partner, CycC, does not oscillate. Cdk8 is, however, a component of the multiprotein Mediator complex, a conserved coregulator of eukaryotic transcription that is connected to a number of intracellular signaling pathways. We demonstrate here that other Mediator components regulate the activity of Cdk8 in vivo and thereby direct the timing of mitotic entry. Deletion of Mediator components Med12 and Med13 leads to higher cellular Cdk8 protein levels, premature phosphorylation of the Cdk8 target Fkh2, and earlier entry into mitosis. We also demonstrate that Mediator is recruited to clusters of mitotic genes in a periodic fashion and that the complex is required for the transcription of these genes. We suggest that Mediator functions as a hub for coordinated regulation of mitotic progression and cell cycle-dependent transcription. The many signaling pathways and activator proteins shown to function via Mediator may influence the timing of these cell cycle events.
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| 8. |
- Bao, W J, et al.
(författare)
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Cell attachment to the extracellular matrix induces proteasomal degradation of p21(CIP1) via Cdc42/Rac1 signaling
- 2002
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 22:13, s. 4587-4597
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Tidskriftsartikel (refereegranskat)abstract
- The cyclin-dependent kinase 2 (Cdk2) inhibitors p21(CIP1) and p27(KIP1) are negatively regulated by anchorage during cell proliferation, but it is unclear how integrin signaling may affect these Cdk2 inhibitors. Here, we demonstrate that integrin ligation led to rapid reduction of p21(CIp1) and p27(KIP1) protein levels in three distinct cell types upon attachment to various extracellular matrix (ECM) proteins, including fibronectin (FN), or to immobilized agonistic anti-integrin monoclonal antibodies. Cell attachment to FN did not rapidly influence p21(CIp1) mRNA levels, while the protein stability of p21(CIp1) was decreased. Importantly, the down-regulation of p21(CIP1) and p27(KIP1) was completely blocked by three distinct proteasome inhibitors, demonstrating that integrin ligation induced proteasomal degradation of these Cdk2 inhibitors. Interestingly, ECM-induced proteasomal proteolysis of a ubiquitination-deficient p21(CIP1) mutant (p21K6R) also occurred, showing that the proteasomal degradation of p21(CIP1) was ubiquitin independent. Concomitant with our finding that the small GTPases Cdc42 and Rac1 were activated by attachment to FN, constitutively active (ca) Cdc42 and ca Rac1 promoted down-regulation of p21(CIP1). However, dominant negative (dn) Cdc42 and do Rac1 mutants blocked the anchorage-induced degradation of p21(CIP1), suggesting that an integrin-induced Cdc42/Rac1 signaling pathway activates proteasomal degradation of p21(CIP1). Our results indicate that integrin-regulated proteasomal proteolysis might contribute to anchorage-dependent cell cycle control.
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