LKB1 suppression promotes cardiomyocyte regeneration via LKB1-AMPK-YAP axis

The regenerative potential of cardiomyocytes in adult mammals is limited. Previous studies reported that cardiomyocyte proliferation is suppressed by AMP-activated protein kinase (AMPK). The role of liver kinase B1 (LKB1), as the major upstream kinase for AMPK, on cardiomyocyte proliferation is unclear. In this study, we found that the LKB1 levels rapidly increased after birth. With loss- and gain-of-function study, our data demonstrated that LKB1 levels negatively correlate with cardiomyocyte proliferation. We next identified Yes-associated protein (YAP) as the downstream effector of LKB1 using high-throughput RNA sequencing. Our results also demonstrated that AMPK plays an essential role in Lkb1 knockdown-induced cardiomyocyte proliferation. Importantly, deactivated AMPK abolished the LKB1-mediated regulation of YAP nuclear translocation and cardiomyocyte proliferation. Thus, our findings suggested the role of LKB1-AMPK-YAP axis during cardiomyocyte proliferation, which could be used as a potential target for inducing cardiac regeneration after injury

SRY gene transferred by extracellular vesicles accelerates atherosclerosis by promotion of leucocyte adherence to endothelial cells

Abstract We set out to investigate whether and how SRY (sex-determining region, Y) DNAs in plasma EVs (extracellular vesicles) is involved in the pathogenesis of atherosclerosis. PCR and gene sequencing found the SRY gene fragment in plasma EVs from male, but not female, patients; EVs from male patients with CAD (coronary artery disease) had a higher SRY GCN (gene copy number) than healthy subjects. Additional studies found that leucocytes, the major source of plasma EVs, had higher SRY GCN and mRNA and protein expression in male CAD patients than controls. After incubation with EVs from SRY-transfected HEK (human embryonic kidney)-293 cells, monocytes (THP-1) and HUVECs (human umbilical vein endothelial cells), which do not endogenously express SRY protein, were found to express newly synthesized SRY protein. This resulted in an increase in the adherence factors CD11-a in THP-1 cells and ICAM-1 (intercellular adhesion molecule 1) in HUVECs. EMSA showed that SRY protein increased the promoter activity of CD11-a in THP-1 cells and ICAM-1 in HUVECs. There was an increase in THP-1 cells adherent to HUVECs after incubation with SRY-EVs. SRY DNAs transferred from EVs have pathophysiological significance in vivo; injection of SRY EVs into ApoE −/− (apolipoprotein-knockout) mice accelerated atherosclerosis. The SRY gene in plasma EVs transferred to vascular endothelial cells may play an important role in the pathogenesis of atherosclerosis; this mechanism provides a new approach to the understanding of inheritable CAD in men

Effect of D Dopamine Receptor on Na-K-ATPase Activity in Renal Proximal Tubule Cells

UNLABELLED: Dopamine, via its receptors, plays a vital role in the maintenance of blood pressure by modulating renal sodium transport. However, the role of the D dopamine receptor (D receptor) in renal proximal tubules (PRTs) is still unclear. This study aimed to verify the hypothesis that activation of D receptor directly inhibits the activity of the Na-K-ATPase (NKA) in RPT cells. METHODS: NKA activity, nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) levels were measured in RPT cells treated with the D receptor agonist PD168077 and/or the D receptor antagonist L745870, the NO synthase inhibitor NG-nitro-L-arginine-methyl ester (L-NAME) or the soluble guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ). Total D receptor expression and its expression in the plasma membrane were investigated by immunoblotting in RPT cells from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). RESULTS: Activation of D receptors with PD168077, inhibited NKA activity in RPT cells from WKY rats in a concentration- and time-dependent manner. The inhibitory effect of PD168077 on NKA activity was prevented by the addition of the D receptor antagonist L745870, which by itself had no effect. The NO synthase inhibitor L-NAME and the soluble guanylyl cyclase inhibitor ODQ, which by themselves had no effect on NKA activity, eliminated the inhibitory effect of PD168077 on NKA activity. Activation of D receptors also increased NO levels in the culture medium and cGMP levels in RPT cells. However, the inhibitory effect of D receptors on NKA activity was absent in RPT cells from SHRs, which could be related to decreased plasma membrane expression of D receptors in SHR RPT cells. CONCLUSIONS: Activation of D receptors directly inhibits NKA activity via the NO/cGMP signaling pathway in RPT cells from WKY rats but not SHRs. Aberrant regulation of NKA activity in RPT cells may be involved in the pathogenesis of hypertension

Impaired Stimulatory Effect of ETB Receptor on D3 Receptor in Immortalized Renal Proximal Tubule Cells of Spontaneously Hypertensive Rats

Background: Activation of renal D3 receptor induces natriuresis and diuresis in Wistar-Kyoto (WKY) rats; in the presence of ETB receptor antagonist, the natriuretic effect of D3 receptor in WKY rats is reduced. We hypothesize that ETB receptor activation may regulate D3 receptor expression in renal proximal tubule (RPT) cells from WKY rats, which is impaired in RPT cells from spontaneously hypertensive rats (SHRs). Methods: D3 receptor expression was determined by immunoblotting; the D 3/ETB receptor linkage was checked by coimmunoprecipitation; Na +-K+-ATPase activity was determined as the rate of inorganic phosphate released in the presence or absence of ouabain. Results: In RPT cells from WKY rats, the ETB receptor agonist BQ3020 increased D3 receptor protein. In contrast, in RPT cells from SHRs, BQ3020 did not increase D3 receptor. There was coimmunoprecipitation between D3 and ETB receptors in RPT cells from WKY and SHRs. Activation of ETB receptor increased D3/ETB coimmunoprecipitation in RPT cells from WKY rats, but not from SHRs. The basal levels of D3/ETB receptor coimmunoprecipitation were greater in RPT cells from WKY rats than in those from SHRs. Stimulation of D3 receptor inhibited Na+-K +-ATPase activity, which was augmented by the pretreatment with the ETB receptor agonist BQ3020 in WKY RPT cells, but not in SHR RPT cells. Conclusion: ETB receptors regulate and physically interact with D3 receptors differently in WKY rats and SHRs. The impaired natriuretic effect in SHRs may be, in part, related to impaired ETB and D3 receptor interactions. Copyright © 2011 S. Karger AG

Gastrin and D\u3csub\u3e1\u3c/sub\u3e dopamine receptor interact to induce natriuresis and diuresis

Oral NaCl produces a greater natriuresis and diuresis than the intravenous infusion of the same amount of NaCl. Gastrin is the major gastrointestinal hormone taken up by renal proximal tubule (RPT) cells. We hypothesized that renal gastrin and dopamine receptors interact to synergistically increase sodium excretion, an impaired interaction of which may be involved in the pathogenesis of hypertension. In Wistar-Kyoto rats, infusion of gastrin induced natriuresis and diuresis, which was abrogated in the presence of a gastrin (cholecystokinin B receptor [CCKBR]; CI-988) or a D1-like receptor antagonist (SCH23390). Similarly, the natriuretic and diuretic effects of fenoldopam, a D1-like receptor agonist, were blocked by SCH23390, as well as by CI-988. However, the natriuretic effects of gastrin and fenoldopam were not observed in spontaneously hypertensive rats. The gastrin/D1-like receptor interaction was also confirmed in RPT cells. In RPT cells from Wistar-Kyoto but not spontaneously hypertensive rats, stimulation of either D1-like receptor or gastrin receptor inhibited Na-K-ATPase activity, an effect that was blocked in the presence of SCH23390 or CI-988. In RPT cells from Wistar-Kyoto and spontaneously hypertensive rats, CCKBR and D1 receptor coimmunoprecipitated, which was increased after stimulation of either D1 receptor or CCKBR in RPT cells from Wistar-Kyoto rats; stimulation of one receptor increased the RPT cell membrane expression of the other receptor, effects that were not observed in spontaneously hypertensive rats. These data suggest that there is a synergism between CCKBR and D1-like receptors to increase sodium excretion. An aberrant interaction between the renal CCK BR and D1-like receptors (eg, D1 receptor) may play a role in the pathogenesis of hypertension. © 2013 American Heart Association, Inc

Corrigendum to Calorie Restriction Protects against Contrast-Induced Nephropathy via SIRT1/GPX4 Activation

[This corrects the article DOI: 10.1155/2021/2999296.]

Inhibitory effect of the D\u3csub\u3e3\u3c/sub\u3e dopamine receptor on insulin receptor expression and function in vascular smooth muscle cells

Background Vascular smooth muscle cell (VSMC) proliferation is regulated by numerous hormones and humoral factors. Our previous study found that stimulation of D1-like dopamine receptors inhibited insulin receptor expression and function in VSMCs. We hypothesize that there is also an interaction between D3 dopamine and insulin receptors, i.e., stimulation of the D3 receptor inhibits insulin receptor expression and function. Methods Receptor expression was determined by immunoblotting, immunohistochemisty, and reverse transcriptase-PCR; VSMC proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-diphenyl-tetrazolium bromide (MTT) assay and cell number. Results Insulin receptor protein is increased in the aorta of D3 receptor deficient mice. Stimulation of the D3 receptor inhibited insulin receptor mRNA and protein expression and insulin-mediated VSMC proliferation, and increased protein kinase A (PKA) activity, insulin receptor phosphorylation, and degradation in immortalized aortic VSMCs (A10 cells). These effects were blocked by a PKA inhibitor, indicating that the D3 receptor-mediated decrease in insulin receptor expression was related to a decrease in transcription/post-transcription and increased degradation, involving PKA signaling. Conclusions D3 receptor stimulation may be a target to reduce the adverse effect of insulin in hypertension by inhibition of insulin receptor expression and function in arterial VSMCs. © 2011 American Journal of Hypertension, Ltd

Extracellular vesicle-mediated transfer of donor genomic DNA to recipient cells is a novel mechanism for genetic influence between cells

Extracellular vesicles (EVs) carry signals within or at their limiting membranes, providing a mechanism by which cells can exchange more complex information than what was previously thought. In addition to mRNAs and microRNAs, there are DNA fragments in EVs. Solexa sequencing indicated the presence of at least 16434 genomic DNA (gDNA) fragments in the EVs from human plasma. Immunofluorescence study showed direct evidence that acridine orange-stained EV DNAs could be transferred into the cells and localize to and inside the nuclear membrane. However, whether the transferred EV DNAs are functional or not is not clear. We found that EV gDNAs could be homologously or heterologously transferred from donor cells to recipient cells, and increase gDNA-coding mRNA, protein expression, and function (e.g. AT1 receptor). An endogenous promoter of the AT1 receptor, NF-κB, could be recruited to the transferred DNAs in the nucleus, and increase the transcription of AT1 receptor in the recipient cells. Moreover, the transferred EV gDNAs have pathophysiological significance. BCR/ABL hybrid gene, involved in the pathogenesis of chronic myeloid leukemia, could be transferred from K562 EVs to HEK293 cells or neutrophils. Our present study shows that the gDNAs transferred from EVs to cells have physiological significance, not only to increase the gDNA-coding mRNA and protein levels, but also to influence function in recipient cells. © 2013 © The Author (2013). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. All rights reserved

D \u3csub\u3e3\u3c/sub\u3e dopamine receptor regulation of D \u3csub\u3e5\u3c/sub\u3e receptor expression and function in renal proximal tubule cells

Dopamine receptor, via D 1-like and D 2-like receptors, increases sodium excretion in kidney. We have reported positive interactions between D 3 and D 1 receptors in renal proximal tubule (RPT) cells. These reports, however do not preclude that there may be also interaction between D 3 and D 5 receptors, because of the lack of selective D 1 and D 5 receptor agonists or antagonists. We hypothesize that D 3 receptors can regulate D 5 receptors, and that D 3 receptor regulation of D 5 receptors in RPTs is impaired in spontaneously hypertensive rats (SHRs). It showed that a D 3 receptor agonist, PD128907, by the activation of protein kinase C activity, increased the expression of D 5 receptors in a concentration- and time-dependent manner in RPT cells from Wistar-Kyoto (WKY) rats. The stimulatory effect of the D 3 receptor on D 5 receptor expression was impaired in RPT cells from SHRs. The effect of D 3 receptor on D 5 receptor is functionally relevant; stimulation of D 5 receptor decreases Na +-K + adenosine triphosphatase (ATPase) activity in WKY cells. Pretreatment with D 3 receptor agonist for 24 h enhances the D 5 receptor expression and D 5 receptor-mediated inhibitory effect on Na +-K + ATPase activity in WKY cells, but decreases them in SHR cells. The effect of D 3 receptor on D 5 receptor expression and function was also confirmed in the D 5 receptor-transfected HEK293 cells. It indicates that activation of D 3 receptor increases D 5 receptor expression and function. Altered regulation of D 3 receptor on D 5 receptors may have a role in the pathogenesis of hypertension. © 2012 The Japanese Society of Hypertension All rights reserved

Activation of D4 dopamine receptor decreases angiotensin II type 1 receptor expression in rat renal proximal tubule cells.

The dopaminergic and renin angiotensin systems interact to regulate blood pressure. Disruption of the D(4) dopamine receptor gene in mice produces hypertension that is associated with increased renal AT(1) receptor expression. We hypothesize that the D(4) receptor can inhibit AT(1) receptor expression and function in renal proximal tubules (RPTs) cells from Wistar-Kyoto (WKY) rats but the D(4) receptor regulation of AT(1) receptor is aberrant in RPT cells from spontaneously hypertensive rats (SHRs). The D(4) receptor agonist, PD168077, decreased AT(1) receptor protein expression in a time and concentration-dependent manner in WKY cells. By contrast, in SHR cells, PD168077 increased AT(1) receptor protein expression. The inhibitory effect of D(4) receptor on AT(1) receptor expression in WKY cells was blocked by a calcium channel blocker, nicardipine, or calcium-free medium, indicating that calcium is involved in the D(4) receptor-mediated signaling pathway. Angiotensin II increased Na(+)-K(+) ATPase activity in WKY cells. Pretreatment with PD168077 decreased the stimulatory effect of angiotensin II on Na(+)-K(+) ATPase activity in WKY cells. In SHR cells, the inhibitory effect of D(4) receptor on angiotensin II-mediated stimulation of Na(+)-K(+) ATPase activity was aberrant; pretreatment with PD168077 augmented the stimulatory effect of AT(1) receptor on Na(+)-K(+) ATPase activity in SHR cells. This was confirmed in vivo; pre-treatment with PD128077 for one week augmented the anti-hypertensive and natriuretic effect of losartan in SHRs but not in WKY rats. We suggest that an aberrant interaction between D(4) and AT(1) receptors may play a role in the abnormal regulation of sodium excretion in hypertension