Endothelin-1 Couples βPix to p66Shc: Role of βPix in Cell Proliferation through FOXO3a Phosphorylation and p27kip1 Down-Regulation Independently of Akt

The phosphorylation of forkhead transcription factor FOXO3a by Akt is critical regulator of cell proliferation induced by serum. We show that endothelin-1 (ET-1) stimulation of primary human mesangial cells (HMCs) induces βPix and p66Shc up-regulation, resulting in the formation of the βPix/p66Shc complex. In transformed HMCs, ET-1 induces a biphasic phosphorylation of p66Shc and FOXO3a. The second phase leads to p27kip1 down-regulation independently of Akt. Depletion of βPix blocks the second phase of p66Shc and FOXO3a phosphorylation and prevents p27kip1 down-regulation induced by ET-1. Depletion of either βPix or p66Shc inhibits ET-1–induced cell proliferation. The expression of β1Pix induces FOXO3a phosphorylation through activation of Rac1, ERK1/2, and p66Shc. Using either p66Shc- or Akt-depleted cells; we show that β1Pix-induced FOXO3a phosphorylation requires p66Shc but not Akt. β1Pix-induced p27kip1 down-regulation was blocked by U0126 but not by wortmannin. Endogenous βPix and FOXO3a are constitutively associated with endogenous p66Shc. FOXO3a and p66Shc binding requires β1Pix homodimerization. Expression of β1Pix homodimerization deficient mutant abrogates β1Pix-induced p27kip1 down-regulation and cell proliferation. Our results identify p66Shc and FOXO3a as novel partners of β1Pix and represent the first direct evidence of β1Pix in cell proliferation via Erk/p66Shc-dependent and Akt-independent mechanisms.

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NH2 terminus of serum and glucocorticoid-regulated kinase 1 binds to phosphoinositides and is essential for isoform-specific physiological functions

AJP Renal Physiology ◽

10.1152/ajprenal.00027.2007 ◽

2007 ◽

Vol 292 (6) ◽

pp. F1741-F1750 ◽

Cited By ~ 28

Author(s):

Alan C. Pao ◽

James A. McCormick ◽

Hongyan Li ◽

John Siu ◽

Cedric Govaerts ◽

...

Keyword(s):

Cell Proliferation ◽

Kinase Activity ◽

Regulatory Protein ◽

Forkhead Transcription Factor ◽

Cellular Processes ◽

Cellular Compartments ◽

Stimulation Of

Serum and glucocorticoid regulated kinase 1 (SGK1) has been identified as a key regulatory protein that controls a diverse set of cellular processes including sodium (Na+) homeostasis, osmoregulation, cell survival, and cell proliferation. Two other SGK isoforms, SGK2 and SGK3, have been identified, which differ most markedly from SGK1 in their NH2-terminal domains. We found that SGK1 and SGK3 are potent stimulators of epithelial Na+ channel (ENaC)-dependent Na+ transport, while SGK2, which has a short NH2 terminus, is a weak stimulator of ENaC. Further characterization of the role of the SGK1 NH2 terminus revealed that its deletion does not affect in vitro kinase activity but profoundly limits the ability of SGK1 either to stimulate ENaC-dependent Na+ transport or inhibit Forkhead-dependent gene transcription. The NH2 terminus of SGK1, which shares sequence homology with the phosphoinositide 3-phosphate [PI( 3 )P] binding domain of SGK3, binds phosphoinositides in protein lipid overlay assays, interacting specifically with PI( 3 )P, PI( 4 )P, and PI( 5 )P, but not with PI( 3 , 4 , 5 )P3. Moreover, a point mutation that reduces phosphoinositide binding to the NH2 terminus also reduces SGK1 effects on Na+ transport and Forkhead activity. These data suggest that the NH2 terminus, although not required for PI 3-kinase-dependent modulation of SGK1 catalytic activity, is required for multiple SGK1 functions, including stimulation of ENaC and inhibition of the proapoptotic Forkhead transcription factor. Together, these observations support the idea that the NH2-terminal domain acts downstream of PI 3-kinase-dependent activation to target the kinase to specific cellular compartments and/or substrates, possibly through its interactions with a subset of phosphoinositides.

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Faculty Opinions recommendation of Spleen tyrosine kinase is important in the production of proinflammatory cytokines and cell proliferation in human mesangial cells following stimulation with IgA1 isolated from IgA nephropathy patients.

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

10.3410/f.718077294.793513964 ◽

2016 ◽

Author(s):

Kar Neng Lai

Keyword(s):

Cell Proliferation ◽

Tyrosine Kinase ◽

Iga Nephropathy ◽

Proinflammatory Cytokines ◽

Mesangial Cells ◽

Spleen Tyrosine Kinase ◽

Human Mesangial Cells

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Mesangial cells express PDGF mRNAs and proliferate in response to PDGF

AJP Renal Physiology ◽

10.1152/ajprenal.1988.255.4.f674 ◽

1988 ◽

Vol 255 (4) ◽

pp. F674-F684 ◽

Cited By ~ 13

Author(s):

P. J. Shultz ◽

P. E. DiCorleto ◽

B. J. Silver ◽

H. E. Abboud

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Northern Blot Analysis ◽

Mesangial Cells ◽

Glomerular Mesangial Cells ◽

Human Mesangial Cells ◽

Human Foreskin Fibroblasts ◽

Human Glomerular Mesangial Cells ◽

Paracrine Growth Factor

Platelet-derived growth factor (PDGF) is a potent mitogen for cells of mesenchymal origin and is released and/or synthesized by platelets, macrophages, endothelial cells, and rat mesangial cells. In the present investigation, we found that human glomerular mesangial cells in culture release a PDGF-like protein which competes for 125I-PDGF binding to human foreskin fibroblasts and is mitogenic for these fibroblasts. The competing and to a lesser extent the mitogenic activities present in the conditioned medium are partially recognized by an anti-PDGF antibody. Northern blot analysis of poly(A)+ RNA from human mesangial cells demonstrates the expression of both PDGF A- and B-chain mRNAs. PDGF also binds to mesangial cells in a specific manner and stimulates DNA synthesis and cell proliferation. These data suggest that a PDGF-like protein secreted by mesangial cells or released from platelets, monocytes, or endothelial cells during glomerular inflammation may function as an autocrine or a paracrine growth factor for these cells. The biological role of PDGF in mediating proliferative and other inflammatory events in the glomerulus remains to be identified.

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Dexamethasone upregulates ANP C-receptor protein in human mesangial cells without affecting mRNA

AJP Renal Physiology ◽

10.1152/ajprenal.1996.270.3.f440 ◽

1996 ◽

Vol 270 (3) ◽

pp. F440-F446 ◽

Cited By ~ 3

Author(s):

N. Ardaillou ◽

V. Blaise ◽

S. Placier ◽

F. Amestoy ◽

R. Ardaillou

Keyword(s):

Glucocorticoid Receptor ◽

Natriuretic Peptide ◽

Mesangial Cells ◽

Receptor Protein ◽

C Protein ◽

Human Mesangial Cells ◽

Receptor Inhibition ◽

Target Sites ◽

Dissociation Constant Kd

The objective of this study was to examine the role of dexamethasone on the expression of natriuretic peptide B-type and C-type receptors (ANPR-B and ANPR-C) in cultured human mesangial cells, which only possess these two subtypes. Dexamethasone caused concentration- and time-dependent increases in 125I-labeled ANP binding, which were prevented by glucocorticoid receptor inhibition with RU-38486. A lag time of 24 h and a concentration of dexamethasone of at least 1 nmol/l were necessary for this effect to occur. Dexamethasone-induced upregulation of 125I-ANP binding resulted from increased receptor density. No change in dissociation constant (Kd) was observed. Only ANPR-C were affected by dexamethasone. Indeed, dexamethasone did not modify C-type natriuretic peptide (i.e., CNP)-dependent cGMP production by mesangial cells. Moreover, dexamethasone upregulated ANPR-C protein expression as shown by Western blot analysis and by an increase in ANPR-C immunoreactivity at the cell surface. In contrast, dexamethasone did not modify ANPR-C mRNA expression. In conclusion, glucocorticoids increase ANPR-C density on mesangial cells through a mechanism implying, successively, interaction with the glucocorticoid receptor and increase of ANPR-C protein synthesis at a posttranscriptional stage. Thus dexamethasone may influence availability of natriuretic peptides at their glomerular target sites.

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Involvement of phospholipase C in endothelin 1–induced stimulation of Ca++ channels and basilar artery contraction in rabbits

Journal of Neurosurgery ◽

10.3171/jns.2006.105.2.288 ◽

2006 ◽

Vol 105 (2) ◽

pp. 288-293 ◽

Cited By ~ 16

Author(s):

Yoshifumi Kawanabe ◽

Tomoh Masaki ◽

Nobuo Hashimoto

Keyword(s):

Phospholipase C ◽

Essential Role ◽

Ca Channels ◽

Endothelin 1 ◽

Nonselective Cation Channels ◽

Basilar Arteries ◽

Independent Cascade ◽

Dependent Pathway ◽

Stimulation Of

Object Endothelin 1 (ET-1) is a major cause of cerebral vasospasm after subarachnoid hemorrhage (SAH), and extracellular Ca++ influx plays an essential role in ET-1–induced vasospasm. The authors recently demonstrated that ET-1 activates two types of Ca++-permeable nonselective cation channels (designated NSCC-1 and NSCC-2) and a store-operated Ca++ channel (SOCC) in vascular smooth-muscle cells located in the basilar arteries (BAs) of rabbits. In the present study, they investigate the effects of phospholipase C (PLC) on ET-1–induced activation of these Ca++ channels and BA contraction by using the PLC inhibitor U73122. Methods To determine which Ca++ channels are activated via a PLC-dependent pathway, these investigators monitored the intracellular free Ca++ concentration ([Ca++]i). The role of PLC in ET-1–induced vascular contraction was examined by performing a tension study of rabbit BA rings. The U73122 inhibited the ET-1–induced transient increase in [Ca++]i, which resulted from mobilization of Ca++; from the intracellular store. Phospholipase C also inhibited ET-1–induced extracellular Ca++ influx through the SOCC and NSCC-2, but not through the NSCC-1. The U73122 inhibited the ET-1–induced contraction of the rabbit BA rings, which depended on extracellular Ca++ influx through the SOCC and NSCC-2. Conclusions These results indicate the following. 1) The SOCC and NSCC-2 are stimulated by ET-1 via a PLC-dependent cascade whereas NSCC-1 is stimulated via a PLC-independent cascade. 2) The PLC is involved in the ET-1–induced contraction of rabbit BA rings, which depends on extracellular Ca++ influx through the SOCC and NSCC-2.

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A positive feedback loop involving Erk5 and Akt turns on mesangial cell proliferation in response to PDGF

AJP Cell Physiology ◽

10.1152/ajpcell.00387.2013 ◽

2014 ◽

Vol 306 (11) ◽

pp. C1089-C1100 ◽

Cited By ~ 18

Author(s):

Amit Bera ◽

Falguni Das ◽

Nandini Ghosh-Choudhury ◽

Xiaonan Li ◽

Sanjay Pal ◽

...

Keyword(s):

Cell Proliferation ◽

Dna Synthesis ◽

Cyclin D1 ◽

Positive Feedback ◽

Mesangial Cell ◽

Mesangial Cells ◽

Pi3 Kinase ◽

Dominant Negative ◽

Mesangial Cell Proliferation

Platelet-derived growth factor BB and its receptor (PDGFRβ) play a pivotal role in the development of renal glomerular mesangial cells. Their roles in increased mesangial cell proliferation during mesangioproliferative glomerulonephritis have long been noted, but the operating logic of signaling mechanisms regulating these changes remains poorly understood. We examined the role of a recently identified MAPK, Erk5, in this process. PDGF increased the activating phosphorylation of Erk5 and tyrosine phosphorylation of proteins in a time-dependent manner. A pharmacologic inhibitor of Erk5, XMD8-92, abrogated PDGF-induced DNA synthesis and mesangial cell proliferation. Similarly, expression of dominant negative Erk5 or siRNAs against Erk5 blocked PDGF-stimulated DNA synthesis and proliferation. Inhibition of Erk5 attenuated expression of cyclin D1 mRNA and protein, resulting in suppression of CDK4-mediated phosphorylation of the tumor suppressor protein pRb. Expression of cyclin D1 or CDK4 prevented the dominant negative Erk5- or siErk5-mediated inhibition of DNA synthesis and mesangial cell proliferation induced by PDGF. We have previously shown that phosphatidylinositol 3-kinase (PI3-kinase) contributes to PDGF-induced proliferation of mesangial cells. Inhibition of PI3-kinase blocked PDGF-induced phosphorylation of Erk5. Since PI3-kinase acts through Akt, we determined the role of Erk5 on Akt phosphorylation. XMD8-92, dominant negative Erk5, and siErk5 inhibited phosphorylation of Akt by PDGF. Interestingly, we found inhibition of PDGF-induced Erk5 phosphorylation by a pharmacological inhibitor of Akt kinase and kinase dead Akt in mesangial cells. Thus our data unfold the presence of a positive feedback microcircuit between Erk5 and Akt downstream of PI3-kinase nodal point for PDGF-induced mesangial cell proliferation.

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Multiple P2X receptors are involved in the modulation of apoptosis in human mesangial cells: evidence for a role of P2X4

AJP Renal Physiology ◽

10.1152/ajprenal.00440.2006 ◽

2007 ◽

Vol 292 (5) ◽

pp. F1537-F1547 ◽

Cited By ~ 20

Author(s):

Anna Solini ◽

Eleonora Santini ◽

Daniele Chimenti ◽

Paola Chiozzi ◽

Federico Pratesi ◽

...

Keyword(s):

Mesangial Cells ◽

Chronic Renal Disease ◽

Morphological Changes ◽

Purinergic Signaling ◽

Annexin V ◽

Renal Tissue ◽

P2x Receptor ◽

Main Role ◽

Human Mesangial Cells

Apoptosis, a normal event in renal tissue homeostasis, has been considered as a major mechanism for either resolution of glomerular hypercellularity in glomerulonephritis or loss of cellularity and progression to glomerulosclerosis in chronic renal disease. This study was aimed at investigating the role of extracellular ATP (eATP) in mediating apoptosis in human mesangial cells (HMC) and identifying the subtype(s) of purinergic receptors involved. eATP, but not uridin-5′-triphosphate (UTP), caused dose-dependent modifications of cellular morphology, as assessed by contrast-phase microscopy, and late apoptosis, as measured by Annexin V/propidium iodide-based flow cytometry and caspase-3 activation. Both phenomena were prevented by the P2X antagonist oxidized-ATP. 2′, 3′-O-(4-benzoylbenzoyl)adenosine 5′-triphosphate (BzATP) was less effective than ATP, whereas 1[N,O-bis (5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl] -4-phenylpiperazine (KN62), a selective inhibitor of human P2X7, prevented morphological changes but potentiated apoptosis induced by BzATP. P2X7 was barely expressed in HMC and showed a relatively scarce functional activity, as assessed by monitoring nucleotide-induced intracellular calcium surge and plasma membrane depolarization by Fura-2/AM and bis[1,3-diethylthiobarbiturate]trimethineoxonal uptake, respectively. These data indicated a negligible role of P2X7 in eATP-mediated apoptosis and pointed to the involvement of other P2X receptor(s). Molecular and inhibitor studies suggested a main role for P2X4 receptor in nucleotide-induced apoptosis in HMC, indicating a relevant role for purinergic signaling in regulating death rate in these cells.

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