scholarly journals Regulation of Placental Leptin Expression by Cyclic Adenosine 5′-Monophosphate Involves Cross Talk between Protein Kinase A and Mitogen-Activated Protein Kinase Signaling Pathways

Endocrinology ◽  
2010 ◽  
Vol 151 (8) ◽  
pp. 3738-3751 ◽  
Author(s):  
Julieta L. Maymó ◽  
Antonio Pérez Pérez ◽  
José L. Dueñas ◽  
Juan Carlos Calvo ◽  
Víctor Sánchez-Margalet ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Western Blot ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Promoter Activity ◽  
Transient Transfection ◽  
Leptin Expression ◽  
Kinase A

Leptin, a 16-kDa protein mainly produced by adipose tissue, has been involved in the control of energy balance through its hypothalamic receptor. However, pleiotropic effects of leptin have been identified in reproduction and pregnancy, particularly in placenta, where it was found to be expressed. In the current study, we examined the effect of cAMP in the regulation of leptin expression in trophoblastic cells. We found that dibutyryl cAMP [(Bu)2cAMP], a cAMP analog, showed an inducing effect on endogenous leptin expression in BeWo and JEG-3 cell lines when analyzed by Western blot analysis and quantitative RT-PCR. Maximal effect was achieved at 100 μM. Leptin promoter activity was also stimulated, evaluated by transient transfection with a reporter plasmid construction. Similar results were obtained with human term placental explants, thus indicating physiological relevance. Because cAMP usually exerts its actions through activation of protein kinase A (PKA) signaling, this pathway was analyzed. We found that cAMP response element-binding protein (CREB) phosphorylation was significantly increased with (Bu)2cAMP treatment. Furthermore, cotransfection with the catalytic subunit of PKA and/or the transcription factor CREB caused a significant stimulation on leptin promoter activity. On the other hand, the cotransfection with a dominant negative mutant of the regulatory subunit of PKA inhibited leptin promoter activity. We determined that cAMP effect could be blocked by pharmacologic inhibition of PKA or adenylyl ciclase in BeWo cells and in human placental explants. Thereafter, we decided to investigate the involvement of the MAPK/ERK signaling pathway in the cAMP effect on leptin induction. We found that 50 μm PD98059, a MAPK kinase inhibitor, partially blocked leptin induction by cAMP, measured both by Western blot analysis and reporter transient transfection assay. Moreover, ERK 1/2 phosphorylation was significantly increased with (Bu)2cAMP treatment, and this effect was dose dependent. Finally, we observed that 50 μm PD98059 inhibited cAMP-dependent phosphorylation of CREB in placental explants. In summary, we provide some evidence suggesting that cAMP induces leptin expression in placental cells and that this effect seems to be mediated by a cross talk between PKA and MAPK signaling pathways.

scholarly journals Role of vaspin in porcine ovary: effect on signaling pathways and steroid synthesis via GRP78 receptor and protein kinase A†

2020 ◽  
Vol 102 (6) ◽  
pp. 1290-1305 ◽  
Author(s):  
Patrycja Kurowska ◽  
Ewa Mlyczyńska ◽  
Monika Dawid ◽  
Joelle Dupont ◽  
Agnieszka Rak
Keyword(s):  
Protein Kinase ◽  
Western Blot ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Dependent Manner ◽  
Steroid Synthesis ◽  
Ovarian Cells ◽  
Vitro Effect ◽  
Kinase A

Abstract Vaspin, visceral-adipose-tissue-derived serine protease inhibitor, is involved in the development of obesity, insulin resistance, inflammation, and energy metabolism. Our previous study showed vaspin expression and its regulation in the ovary; however, the role of this adipokine in ovarian cells has never been studied. Here, we studied the in vitro effect of vaspin on various kinase-signaling pathways: mitogen-activated kinase (MAP3/1), serine/threonine kinase (AKT), signal transducer and activator of transcription 3 (STAT3) protein kinase AMP (PRKAA1), protein kinase A (PKA), and on expression of nuclear factor kappa B (NFKB2) as well as on steroid synthesis by porcine ovarian cells. By using western blot, we found that vaspin (1 ng/ml), in a time-dependent manner, increased phosphorylation of MAP3/1, AKT, STAT3, PRKAA1, and PKA, while it decreased the expression of NFKB2. We observed that vaspin, in a dose-dependent manner, increased the basal steroid hormone secretion (progesterone and estradiol), mRNA and protein expression of steroid enzymes using real-time PCR and western blot, respectively, and the mRNA of gonadotropins (FSHR, LHCGR) and steroids (PGR, ESR2) receptors. The stimulatory effect of vaspin on basal steroidogenesis was reversed when ovarian cells were cultured in the presence of a PKA pharmacological inhibitor (KT5720) and when GRP78 receptor was knocked down (siRNA). However, in the presence of insulin-like growth factor type 1 and gonadotropins, vaspin reduced steroidogenesis. Thus, vaspin, by activation of various signaling pathways and stimulation of basal steroid production via GRP78 receptor and PKA, could be a new regulator of porcine ovarian function.

scholarly journals Cooperative Activation of Lipolysis by Protein Kinase A and Protein Kinase C Pathways in 3T3-L1 Adipocytes

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4940-4947 ◽  
Author(s):  
Katrin Fricke ◽  
Aleksandra Heitland ◽  
Erik Maronde
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Hormone Sensitive Lipase ◽  
Glycerol Release ◽  
Kinase C ◽  
Lipolytic Effect ◽  
Pka Pathway ◽  
Kinase A

Abstract In the present study, we investigate the coherence of signaling pathways leading to lipolysis in 3T3-L1 adipocytes. We observe two linear signaling pathways: one well known, acting via cAMP and protein kinase A (PKA) activation, and a second one induced by phorbol 12-myristate 13-acetate treatment involving protein kinase C (PKC) and MAPK. We demonstrate that both the PKA regulatory subunits RIα and RIIβ are expressed in 3T3-L1 adipocytes and are responsible for the lipolytic effect mediated via the cAMP/PKA pathway. Inhibition of the PKA pathway by the selective PKA inhibitor Rp-8-CPT-cAMPS does not impair lipolysis induced by PKC activation, and neither PD98059 nor U0126, as known MAPK kinase inhibitors, changes the level of glycerol release caused by PKA activation, indicating no cross-talk between these two pathways when only one is activated. However, when both are activated, they act synergistically on glycerol release. Additional experiments focusing on this synergy show no involvement of MAPK phosphorylation and cAMP formation. Phosphorylation of hormone-sensitive lipase is similar upon stimulation of either pathway, but we demonstrate a difference in the ability of both PKA and the PKC pathway activation to phosphorylate perilipin, which in turn may be an explanation for the different maximal lipolytic effect of both pathways.

scholarly journals Fucoxanthin Inhibits Myofibroblast Differentiation and Extracellular Matrix Production in Nasal Polyp-Derived Fibroblasts via Modulation of Smad-Dependent and Smad-Independent Signaling Pathways

Marine Drugs ◽  
2018 ◽  
Vol 16 (9) ◽  
pp. 323 ◽  
Author(s):  
Hyun Jung ◽  
Dae-Sung Lee ◽  
Seong Park ◽  
Jung Choi ◽  
Won-Kyo Jung ◽  
...  
Keyword(s):  
Western Blot ◽  
Signaling Pathways ◽  
Nasal Polyp ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Transforming Growth Factor ◽  
Smooth Muscle Actin ◽  
Type I ◽  
Molecular Signaling ◽  
Tgf Β1

Nasal polyps (NPs) are a multifactorial disorder associated with a chronic inflammatory state of the nasal mucosa. Fucoxanthin (Fx) is a characteristic orange carotenoid obtained from brown algae and has diverse immunological properties. The present study investigated whether Fx inhibits fibrosis-related effects in nasal polyp-derived fibroblasts (NPDFs) and elucidated the molecular signaling pathways involved. The production of collagen type I (Col-1) was investigated in NP tissue via immunohistochemistry and western blot analysis. NPDFs were treated with transforming growth factor (TGF)-β1 (1 ng/mL) in the presence or absence of Fx (5–30 µM). The levels of α-smooth muscle actin (α-SMA), Col-1, and phosphorylated (p)-Smad 2/3, signal protein-1 (SP-1), MAPKs (mitogen-activated protein kinases), and Akt were measured by western blot analysis. The expression of Col-1 was detected in NP tissues. TGF-β1 stimulated the production of α-SMA and Col-1, and stimulated the contraction of collagen gel. However, pretreatment with Fx attenuated these effects. Furthermore, these inhibitory effects were mediated through modulation of both Smad 2/3 and Akt/SP-1 signaling pathways in TGF-β1-induced NPDFs. The results from the present study suggest that Fx may be a novel anti-fibrotic agent for the treatment of NP formation.

Monoclonal Antibody Against ROR1 in Chronic Lymphocytic Leukemia Cells Induced Apoptosis Via PI3-Kinase/AKT/CREB Pathway

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1769-1769
Author(s):  
Amir Hossein Daneshmanesh ◽  
Mohammad Hojjat-Farsangi ◽  
Asa Sandin ◽  
Abdul Salam Khan ◽  
Ali Moshfegh ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Western Blot ◽  
Signaling Pathways ◽  
Blot Analysis ◽  
Western Blot Analysis ◽  
Pi3 Kinase ◽  
Signaling Proteins ◽  
Downstream Signaling ◽  
Induced Apoptosis ◽  
Creb Pathway

Abstract Abstract 1769 Background: Phosphoinositide 3-kinase (PI3K)/AKT cascade regulates cell survival, proliferation and differentiation in a variety of cells. In CLL cells PI3K pathway is constitutively activated leading to AKT activation and phosphorylation of cAMP response element-binding protein (CREB). CREB is a transcription factor overexpressed and constitutively phosphorylated in a variety of cancers and seems to have a role in tumor pathobiology. There is a great need to develop novel strategies for targeted therapy in CLL. Monoclonal antibodies (mAbs) specifically targeting leukemic cells might be a rewarding approach. ROR1 is a type I transmembrane receptor tyrosine kinase belonging to one of the twenty families of receptor tyrosine kinases (RTKs). ROR1 is overexpressed on CLL cells but not in white blood cells of healthy donors. ROR1 is constitutively phosphorylated in CLL and siRNA transfection induced apoptosis. We have developed a unique anti-ROR1 mAb directed against CRD (cysteine-rich domain) of the extracellular region of ROR1 capable of inducing direct apoptosis of primary CLL cells. Our anti-CRD mAb induced dephosphorylation of the ROR1 molecule. Aims: To study the apoptotic effect of an anti-ROR1 CRD mAb and effects on downstream signaling pathways involved in CLL, specially the PI3-kinase/AKT/CREB pathway using primary CLL cells. Methods: Using a peptide-based mouse mAb generation method we produced several mAbs against the three extracellular domains of ROR1. In the current study we used one of the best anti-ROR1 antibodies, an anti-CRD mAb raised against the CRD region of ROR1 (Daneshmanesh et al., Leukemia. 2012 Jun;26(6):1348-55). Flow cytometry was used for surface staining of ROR1. Primary CLL cells were incubated with the anti-ROR1 CRD mAb and apoptosis was detected by the MTT assay and Annexin V/propidium iodide (flow cytometry) methods in a 24 h assay. Antibody untreated and treated cell lysates were prepared and subjected to Western blot analysis for identification of signaling molecules involved in apoptosis induced by the anti-ROR1 CRD mAb. We analysed total and phosphorylated levels of the following signaling proteins: AKT, p-AKT, PI3K, p-PI3K, CREB, p-CREB, ERK, p-ERK, PKC and p-PKC. Phosphoproteins were measured before incubation with the mAb and after 20 min-2 h. Results: ROR1 surface expression was detected on 80–85% of the CLL cells. The frequency of apoptotic cells induced by the anti-CRD mAb was in the range of 45–50% which is in accordance with our previous reports (see above). Time kinetics experiments using anti-ROR1 CRD mAb incubated with primary CLL cells revealed dephosphorylation of ROR1 downstream signaling molecules. We analysed the following molecules known to be involved in CLL: PKC, PI3-kinase and ERK1/2. After co-culturing CLL cells with the anti-ROR1 CRD mAb, Western blot analysis showed decreased level of phosphorylated AKT in treated compared to untreated samples. No changes in the phosphorylation levels of ERK1/2 and PKC proteins were seen. Furthermore, we analysed the PI3-kinase protein which is upstream of AKT, and noticed that in CLL cells treated with the anti-ROR1 CRD mAb, the phosphorylation intensity of PI3-kinase p85 isoform has decreased but not p55 isoforrn. Moreover, we also studied the CREB phosphorylation in treated and untreated CLL samples and detected dephosphorylation of CREB in treated as compared to untreated samples. Conclusion: Incubation of CLL cells with an anti-ROR1 CRD mAb induced apoptosis of primary CLL cells. Apoptosis was preceded by dephosphorylation within 2 h of PI3-kinase, AKT and CREB proteins indicating deactivation of these signaling proteins by the anti-ROR1 mab. In untreated CLL cells no effect on phosphorylation of these proteins was noted. Furthermore our ROR1 mAb did not dephosphorylate PKC or ERK. Our data may suggest that activation of CREB molecule might occur via the PI3K/AKT pathway and may be a survival signal in CLL cells associated with the aberrant expression of ROR1. The constitutive phosphorylation of PKC and ERK1/2 seen in CLL might not be related to the overexpression of ROR1. Further studies are warranted for a better understanding of signaling pathways associated with ROR1 and the downstream signaling effects of ROR1 targeting drugs. Disclosures: No relevant conflicts of interest to declare.

What is the Impact of Bisphenol A on Sperm Function and Related Signaling Pathways: A Mini-review?

2020 ◽  
Vol 26 (37) ◽  
pp. 4822-4828
Author(s):  
Yian Zhou ◽  
Wenqing Xu ◽  
Yuan Yuan ◽  
Tao Luo
Keyword(s):  
Protein Kinase ◽  
Animal Models ◽  
Bisphenol A ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Male Reproduction ◽  
Sperm Function ◽  
Epigenetic Changes ◽  
The Impact ◽  
Kinase A

Bisphenol A (BPA) is an organic synthetic compound that is ubiquitously present in daily life. It is a typical environmental endocrine disruptor that affects the functions of endogenous hormones. There is a significant negative correlation between BPA and male reproduction. This mini-review describes current research data on the negative effects of BPA on sperm functions in humans and animal models, as well as on its supposed mechanisms of action, such as CATSPER-Ca2+ signaling, cAMP-protein kinase A signaling, and epigenetic changes. The published evidence showed an adverse impact of BPA on sperm tail morphology, counts, motility, and acrosome reaction action. Sperm function related signaling pathways, such as CATSPER-Ca2+ signaling, cAMP-protein kinase A signaling, and phosphorylation signaling, as well as epigenetic changes and sperm aging, are associated with BPA exposure in human and animal models. The clear risks of BPA exposure can provide greater awareness of the potential threat of environmental contaminants on male fertility.

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