Glucagon-like Peptide-2 Receptor Activation Engages Bad and Glycogen Synthase Kinase-3 in a Protein Kinase A-dependent Manner and Prevents Apoptosis following Inhibition of Phosphatidylinositol 3-Kinase

ABSTRACT Phosphorylation is the main mode by which signals are transmitted to key regulators of developmental pathways. The glycogen synthase kinase 3 family plays pivotal roles in the development and well-being of all eukaryotic organisms. Similarly, the budding yeast homolog Rim11 is essential for the exit of diploid cells from the cell cycle and for entry into the meiotic developmental pathway. In this report we show that in vivo, in cells grown in a medium promoting vegetative growth with acetate as the sole carbon source (SA medium), Rim11 phosphorylates Ime1, the master transcriptional activator required for entry into the meiotic cycle and for the transcription of early meiosis-specific genes. We demonstrate that in the presence of glucose, the kinase activity of Rim11 is inhibited. This inhibition could be due to phosphorylation on Ser-5, Ser-8, and/or Ser-12 because in the rim11S5AS8AS12A mutant, Ime1 is incorrectly phosphorylated in the presence of glucose and cells undergo sporulation. We further show that this nutrient signal is transmitted to Rim11 and consequently to Ime1 by the cyclic AMP/protein kinase A signal transduction pathway. Ime1 is phosphorylated in SA medium on at least two residues, Tyr-359 and Ser-302 and/or Ser-306. Ser-302 and Ser-306 are part of a consensus site for the mammalian homolog of Rim11, glycogen synthase kinase 3-β. Phosphorylation on Tyr-359 but not Ser-302 or Ser-306 is essential for the transcription of early meiosis-specific genes and sporulation. We show that Tyr-359 is phosphorylated by Rim11.

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Faculty Opinions recommendation of Multisite protein kinase A and glycogen synthase kinase 3beta phosphorylation leads to Gli3 ubiquitination by SCFbetaTrCP.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1033261.375213 ◽

2006 ◽

Author(s):

James Woodgett

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Glycogen Synthase ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3Beta ◽

Kinase A

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

Biologia ◽

10.1515/biolog-2015-0156 ◽

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.

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Convergence of 3′,5′-Cyclic Adenosine 5′-Monophosphate/Protein Kinase A and Glycogen Synthase Kinase-3β/β-Catenin Signaling in Corpus Luteum Progesterone Synthesis

Endocrinology ◽

10.1210/en.2009-0771 ◽

2009 ◽

Vol 150 (11) ◽

pp. 5036-5045 ◽

Cited By ~ 37

Author(s):

Lynn Roy ◽

Claudia A. McDonald ◽

Chao Jiang ◽

Dulce Maroni ◽

Anthony J. Zeleznik ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase A ◽

Corpus Luteum ◽

Glycogen Synthase ◽

Regulatory Protein ◽

Glycogen Synthase Kinase ◽

Proximal Promoter ◽

Progesterone Secretion ◽

Progesterone Synthesis ◽

Kinase A

Progesterone secretion by the steroidogenic cells of the corpus luteum (CL) is essential for reproduction. Progesterone synthesis is under the control of LH, but the exact mechanism of this regulation is unknown. It is established that LH stimulates the LH receptor/choriogonadotropin receptor, a G-protein coupled receptor, to increase cAMP and activate cAMP-dependent protein kinase A (PKA). In the present study, we tested the hypothesis that cAMP/PKA-dependent regulation of the Wnt pathway components glycogen synthase kinase (GSK)-3β and β-catenin contributes to LH-dependent steroidogenesis in luteal cells. We observed that LH via a cAMP/PKA-dependent mechanism stimulated the phosphorylation of GSK3β at N-terminal Ser9 causing its inactivation and resulted in the accumulation of β-catenin. Overexpression of N-terminal truncated β-catenin (Δ90 β-catenin), which lacks the phosphorylation sites responsible for its destruction, significantly augmented LH-stimulated progesterone secretion. In contrast, overexpression of a constitutively active mutant of GSK3β (GSK-S9A) reduced β-catenin levels and inhibited LH-stimulated steroidogenesis. Chromatin immunoprecipitation assays demonstrated the association of β-catenin with the proximal promoter of the StAR gene, a gene that expresses the steroidogenic acute regulatory protein, which is a cholesterol transport protein that controls a rate-limiting step in steroidogenesis. Collectively these data suggest that cAMP/PKA regulation of GSK3β/β-catenin signaling may contribute to the acute increase in progesterone production in response to LH.

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