Glucose and forskolin regulate IAPP gene expression through different signal transduction pathways

2001 ◽  
Vol 281 (5) ◽  
pp. E938-E945 ◽  
Author(s):  
Wei-Qun Ding ◽  
Eileen Holicky ◽  
Laurence J. Miller
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Gene Transcription ◽  
Molecular Mechanisms ◽  
Dependent Manner ◽  
Β Cell ◽  
Regulatory Pathways ◽  
Gene Assay ◽  
Kinase A

Molecular mechanisms for the regulation of islet amyloid polypeptide (IAPP) gene expression remain unclear. In the present study, we investigated the effects of glucose and forskolin on IAPP gene regulation in the INS-1 islet β-cell line. Both glucose and forskolin increased the level of expression of this gene, as measured by Northern blot analysis, and increased IAPP gene transcription in a time- and concentration-dependent manner, as demonstrated in a reporter gene assay. Although inhibition of protein kinase A activity with H-89 eliminated the effect of forskolin on this gene, the glucose effect was unaffected. This supported the predominant use of a protein kinase A-independent signaling pathway for glucose regulation of the IAPP gene. Electrophoretic mobility shift assay further indicated that glucose and forskolin regulated expression of this gene by targeting different elements of the promoter. Mutation of the cAMP regulatory element flanking the IAPP coding region resulted in the loss of most of the forskolin-stimulated IAPP gene promoter activity, whereas glucose-enhanced IAPP gene transcription was unaffected. These results demonstrate parallel and distinct regulatory pathways involved in glucose- and forskolin-induced IAPP gene expression in this model β-cell system.

High glucose-associated osmolality promotes adipocytogenic differentiation of primary rat osteoblasts in a protein kinase A and phosphatidylinositol 3-kinase/Akt-dependent manner

Biologia ◽  
2015 ◽  
Vol 70 (10) ◽  
Author(s):  
Yu Zhang ◽  
Pu Feng ◽  
Jianhong Yang
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Real Time ◽  
High Glucose ◽  
Marker Gene ◽  
Dependent Manner ◽  
Phosphatidylinositol 3 Kinase ◽  
Marker Gene Expression ◽  
Kinase A

AbstractIncreased risk of osteoporosis in patients with diabetes mellitus may be related to hyperglycemia. However, the potential mechanisms accounting for diabetic bone disorder remain unresolved. The present study investigated the effects of high glucose-associated osmolality on differentiation of primary rat calvarial osteoblasts. Osteoblastogenic differentiation was determined by bone nodule staining for mineralization assay, enzyme-linked immunosorbent assay for type I collagen production and real-time polymerase chain reaction (PCR) for osteoblastogenic marker gene expression. Adipocytogenic differentiation was assessed by oil red O staining for lipid accumulation and real-time PCR for adipocytogenic marker gene expression. The phosphorylations of protein kinase A (PKA) and Akt were measured with or without specific inhibitors to confirm osmolality involved signalling pathways. The results showed that high glucose-associated osmolality significantly promoted adipocytogenic differentiation, manifested by increased lipid droplet formation and gene expression of adipocytogenic markers including adipocyte fatty acid binding protein (aP2), adipsin and peroxisome proliferator-activated receptor gamma (PPARγ). Meanwhile, high glucose-associated osmolality inhibited osteoblastogenic differentiation, characterized by decreased collagen I protein production and cell mineralization, as well as gene expression of osteoblastogenic markers including collagen I, osteocalcin and runt-related transcription factor 2 (Runx2). More importantly, we demonstrated for the first time that high glucose-associated osmolality induced adipocytogenic differentiation and suppressed osteoblastogenic differentiation in a PKA and phosphatidylinositol 3-kinase (PI3K)/Akt-dependent manner. These results indicated that osmolality was involved in high glucose-induced osteoblast trans-differentiation into adipocyte-like cell and suppression of cellular osmolality could provide novel therapeutic approach for diabetic osteopenia.

scholarly journals Glucocorticoids and protein kinase A coordinately modulate transcription factor recruitment at a glucocorticoid-responsive unit.

1995 ◽  
Vol 15 (10) ◽  
pp. 5346-5354 ◽  
Author(s):  
M L Espinás ◽  
J Roux ◽  
R Pictet ◽  
T Grange
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Cell Lines ◽  
Transcription Factor Binding ◽  
Tyrosine Aminotransferase ◽  
Dependent Manner ◽  
Regulatory Pathways ◽  
Factor Binding ◽  
Kinase A

The rat tyrosine aminotransferase gene is a model system to study transcriptional regulation by glucocorticoid hormones. We analyzed transcription factor binding to the tyrosine aminotransferase gene glucocorticoid-responsive unit (GRU) at kb -2.5, using in vivo footprinting studies with both dimethyl sulfate and DNase I. At this GRU, glucocorticoid activation triggers a disruption of the nucleosomal structure. We show here that various regulatory pathways affect transcription factor binding to this GRU. The binding differs in two closely related glucocorticoid-responsive hepatoma cell lines. In line H4II, glucocorticoid induction promotes the recruitment of hepatocyte nuclear factor 3 (HNF3), presumably through the nucleosomal disruption. However, the footprint of the glucocorticoid receptor (GR) is not visible, even though a regular but transient interaction of the GR is necessary to maintain HNF3 binding. In contrast, in line FTO2B, HNF3 binds to the GRU in the absence of glucocorticoids and nucleosomal disruption, showing that a "closed" chromatin conformation does not repress the binding of certain transcription factors in a uniform manner. In FTO2B cells, the footprint of the GR is detectable, but this requires the activation of protein kinase A. In addition, protein kinase A stimulation also improves the recruitment of HNF3 independently of glucocorticoids and enhances the glucocorticoid response mediated by this GRU in an HNF3-dependent manner. In conclusion, the differences in the behavior of this regulatory sequence in the two cell lines show that various regulatory pathways are integrated at this GRU through modulation of interrelated events: transcription factor binding to DNA and nucleosomal disruption.

scholarly journals Molecular mechanisms of sperm motility are conserved in an early-branching metazoan

2021 ◽  
Vol 118 (48) ◽  
pp. e2109993118
Author(s):  
Kelsey F. Speer ◽  
Luella Allen-Waller ◽  
Dana R. Novikov ◽  
Katie L. Barott
Keyword(s):  
Protein Kinase ◽  
Reproductive Success ◽  
Protein Kinase A ◽  
Sperm Motility ◽  
Molecular Mechanisms ◽  
Camp Signaling ◽  
Dependent Manner ◽  
Marine Animals ◽  
Ph Dependent ◽  
Kinase A

Efficient and targeted sperm motility is essential for animal reproductive success. Sperm from mammals and echinoderms utilize a highly conserved signaling mechanism in which sperm motility is stimulated by pH-dependent activation of the cAMP-producing enzyme soluble adenylyl cyclase (sAC). However, the presence of this pathway in early-branching metazoans has remained unexplored. Here, we found that elevating cytoplasmic pH induced a rapid burst of cAMP signaling and triggered the onset of motility in sperm from the reef-building coral Montipora capitata in a sAC-dependent manner. Expression of sAC in the mitochondrial-rich midpiece and flagellum of coral sperm support a dual role for this molecular pH sensor in regulating mitochondrial respiration and flagellar beating and thus motility. In addition, we found that additional members of the homologous signaling pathway described in echinoderms, both upstream and downstream of sAC, are expressed in coral sperm. These include the Na+/H+ exchanger SLC9C1, protein kinase A, and the CatSper Ca2+ channel conserved even in mammalian sperm. Indeed, the onset of motility corresponded with increased protein kinase A activity. Our discovery of this pathway in an early-branching metazoan species highlights the ancient origin of the pH-sAC-cAMP signaling node in sperm physiology and suggests that it may be present in many other marine invertebrate taxa for which sperm motility mechanisms remain unexplored. These results emphasize the need to better understand the role of pH-dependent signaling in the reproductive success of marine animals, particularly as climate change stressors continue to alter the physiology of corals and other marine invertebrates.

scholarly journals Target of Rapamycin Complex 1 (TORC1), Protein Kinase A (PKA) and Cytosolic pH Regulate a Transcriptional Circuit for Lipid Droplet Formation

2021 ◽  
Vol 22 (16) ◽  
pp. 9017
Author(s):  
Vitor Teixeira ◽  
Telma S. Martins ◽  
William A. Prinz ◽  
Vítor Costa
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Molecular Mechanisms ◽  
Nutrient Sensing ◽  
Target Of Rapamycin ◽  
Significant Advance ◽  
Transcriptional Level ◽  
Dependent Manner ◽  
Cytosolic Ph ◽  
Kinase A

Lipid droplets (LDs) are ubiquitous organelles that fulfill essential roles in response to metabolic cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). However, our understanding of signaling networks, especially transcriptional mechanisms, regulating membrane biogenesis is very limited. Here, we show that the nutrient-sensing Target of Rapamycin Complex 1 (TORC1) regulates LD formation at a transcriptional level, by targeting DGA1 expression, in a Sit4-, Mks1-, and Sfp1-dependent manner. We show that cytosolic pH (pHc), co-regulated by the plasma membrane H+-ATPase Pma1 and the vacuolar ATPase (V-ATPase), acts as a second messenger, upstream of protein kinase A (PKA), to adjust the localization and activity of the major transcription factor repressor Opi1, which in turn controls the metabolic switch between phospholipid metabolism and lipid storage. Together, this work delineates hitherto unknown molecular mechanisms that couple nutrient availability and pHc to LD formation through a transcriptional circuit regulated by major signaling transduction pathways.

Molecular mechanisms for protein kinase A-mediated modulation of immune function

2002 ◽  
Vol 14 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Knut Martin Torgersen ◽  
Torkel Vang ◽  
Hilde Abrahamsen ◽  
Sheraz Yaqub ◽  
Kjetil Taskén
Keyword(s):  
Protein Kinase ◽  
Immune Function ◽  
Protein Kinase A ◽  
Molecular Mechanisms ◽  
Kinase A

Protein kinase A activity modulates natriuretic peptide-dependent cGMP accumulation in renal cells

1997 ◽  
Vol 272 (1) ◽  
pp. C82-C89 ◽  
Author(s):  
S. Ledoux ◽  
J. C. Dussaule ◽  
C. Chatziantoniou ◽  
N. Ardaillou ◽  
S. Vandermeersch ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Cholera Toxin ◽  
Natriuretic Peptide ◽  
Cell Types ◽  
Inhibitory Effect ◽  
Nitric Oxide Donor ◽  
Dependent Manner ◽  
Cgmp Production ◽  
Kinase A

The purpose of this work was to examine whether the level of cAMP accumulation and protein kinase A (PKA) activity influence atrial natriuretic factor (ANF)-dependent guanosine 3',5'-cyclic monophosphate (cGMP) production in two renal cell types: rabbit cortical vascular smooth muscle cells (RCSMC) and SV-40-transformed human glomerular visceral epithelial cells (HGVEC-SV1). N-[2-(p-bromocinnamylamino)ethyl]- 5-isoquinolinesulfonamide (H-89), a PKA inhibitor, decreased ANF-stimulated cGMP production in RCSMC in a time- and concentration-dependent manner. ANF-stimulated cGMP production was markedly inhibited after prolonged 9- and 18-h incubations with 25 microM H-89 (52 and 65%, respectively) but was not altered after exposure of cells to this agent for 1 h. 1-(5-Isoquinolinylsulfonyl)-2-methylpiperazine and N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide, protein kinase inhibitors not selective for PKA, did not reproduce the effect of H-89, even at higher concentrations (50 and 100 microM). Cycloheximide (10 microM), a protein synthesis inhibitor, limited the inhibitory effect of H-89, although alone it did not modify the ANF-stimulated cGMP production. H-89 did not affect cGMP production when it was stimulated by SIN-1, a nitric oxide donor. Prolonged incubation (18 h) with 8-bromo cAMP or cholera toxin, an activator of Gs protein resulting in adenylate cyclase stimulation, enhanced ANF-dependent cGMP production by 225 and 176%, respectively. This stimulatory effect was blocked by 25 microM H-89. 125I-ANF binding to RCSMC at 4 degrees C was not affected by preincubation of the cells with H-89. There was a 44% decrease in the expression of ANF C receptors measured as the ANF-(4-23)-displaceable 125I-ANF binding at 37 degrees C, which could not, however, explain the inhibitory effect of H-89 on cGMP production. Modulation of ANF- and C-type natriuretic peptide-dependent cGMP production by H-89 and cholera toxin was also found in HGVEC-SV1 with the same characteristics as in RCSMC. Taken together, these results suggest that PKA activity controls the function of natriuretic peptide guanylate cyclase-coupled receptors in the two cell types studied. PKA-dependent inhibition of a negatively regulatory protein distinct from the receptor itself seems necessary for a full cGMP response.

scholarly journals Complex effects of kinase localization revealed by compartment-specific regulation of protein kinase A activity

2021 ◽  
Author(s):  
Rebecca LaCroix ◽  
Benjamin Lin ◽  
Andre Levchenko
Keyword(s):  
Cell Migration ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Kinase Activity ◽  
Single Cells ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Specific Regulation ◽  
Kinase A

SummaryKinase activity in signaling networks frequently depends on regulatory subunits that can both inhibit activity by interacting with the catalytic subunits and target the kinase to distinct molecular partners and subcellular compartments. Here, using a new synthetic molecular interaction system, we show that translocation of a regulatory subunit of the protein kinase A (PKA-R) to the plasma membrane has a paradoxical effect on the membrane kinase activity. It can both enhance it at lower translocation levels, even in the absence of signaling inputs, and inhibit it at higher translocation levels, suggesting its role as a linker that can both couple and decouple signaling processes in a concentration-dependent manner. We further demonstrate that superposition of gradients of PKA-R abundance across single cells can control the directionality of cell migration, reversing it at high enough input levels. Thus complex in vivo patterns of PKA-R localization can drive complex phenotypes, including cell migration.

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