Search

AIM: lo investigate the role of phosphoenolpyruvate carboxykinase 1 ^PCK1) in the proliferation and migration of mouse vascular smooth muscle cells (VSMCs) and the underlying mechanism. METHODS: The proliferation and migration of mouse VSMCs were induced by platelet-derived growth factor (PDGF)-BB. The cells were divided into a vehicle group and a PDGF-BB group. The expression of PCK1 was detected by Western blot and immunofluorescence staining. The mouse Pckl siRNA (siPckl) were transfected into mouse VSMCs to silence PCK1. The cells were divided into the vehicle, siPckl+vehicle, PDGF-BB and siPckl+PDGF-BB groups. The protein level of PCK1 was detected by Western blot. The proliferation was explored by Ki-67 immunofluorescence staining and the viability was detected by CCK-8 assay. The migration was determined by a scratch test. Mitochondrial dynamics were observed via transmission electron microscopy. A lentivirus carrying dynamin-related protein 1 (Drpl) gene (lenti-Drpl) was transfected into VSMCs to induce them to overexpress DRP1. The cells were divided into the PDGF-BB, siPckl +PDGF-BB, lenti-Drpl + PDGF-BB and lenti-Drpl+siPck1+PDGF-BB groups. Proliferation, migration and mitochondrial dynamics were measured as described above. RESULTS: PDGF-BB increased the protein expression of PCK1 and DRP1, cell viability, the percentage of Ki-67-positive cells, the wound healing rate and mitochondrial division in VSMCs. These effects were suppressed when PCK1 protein expression was silenced. After DRP1 was overexpressed, the inhibitory effects of PCK1 silencing on cell viability, the percentage of Ki-67-positive cells, the wound healing rate and mitochondrial division were significantly reversed. CONCLUSION: PCK1 promotes the mitochondrial division, proliferation and migration of VSMCs in mice by upregulating the expression of DRP1. [ABSTRACT FROM AUTHOR]

Abstract Background Autoantibodies develop in autoimmune diseases, cancer, diabetes mellitus (DM), and atherosclerosis-related diseases. However, autoantibody biomarkers have not been successfully examined for diagnosis and therapy. Methods Serological identification of antigens through recombinant cDNA expression cloning (SEREX) was used for primary screening of antigens. The cDNA product was expressed in bacteria and purified. Amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) was used to evaluate antibody levels in serum samples. Results Phosphoenolpyruvate carboxykinase 1 (PCK1) was recognized as an antigen by serum IgG antibodies in the sera of patients with atherosclerosis. AlphaLISA showed significantly higher serum antibody levels against recombinant PCK1 protein in patients with DM and cardiovascular disease than in healthy donors, but not in those with acute ischemic stroke, transient ischemic attack, or obstructive sleep apnea syndrome. The area under the receiver operating characteristic curve for anti-PCK1 antibodies was 0.7024 for DM. The serum anti-PCK1 antibody levels were associated with age, platelet count, and blood pressure. Anti-PCK1-antibody-positive patients showed significantly lower overall survival than the negative patients. Conclusions Serum anti-PCK1 antibody levels were found to be associated with DM. The anti-PCK1 antibody marker is useful for predicting the overall survival of patients with DM.

Background: Autoantibodies develop in autoimmune diseases, cancer, diabetes mellitus (DM), and atherosclerosis-related diseases. However, autoantibody biomarkers have not been successfully examined for diagnosis and therapy. Methods: Serological identification of antigens through recombinant cDNA expression cloning (SEREX) was used for primary screening of antigens. The cDNA product was expressed in bacteria and purified. Amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) was used to evaluate antibody levels in serum samples. Results: Phosphoenolpyruvate carboxykinase 1 (PCK1) was recognized as an antigen by serum IgG antibodies in the sera of patients with atherosclerosis. AlphaLISA showed significantly higher serum antibody levels against recombinant PCK1 protein in patients with DM and cardiovascular disease than in healthy donors, but not in those with acute ischemic stroke, transient ischemic attack, or obstructive sleep apnea syndrome. The area under the receiver operating characteristic curve for anti-PCK1 antibodies was 0.7024 for DM. The serum anti-PCK1 antibody levels were associated with age, platelet count, and blood pressure. Anti-PCK1-antibody-positive patients showed significantly lower overall survival than the negative patients. Conclusions: Serum anti-PCK1 antibody levels were found to be associated with DM. The anti-PCK1 antibody marker is useful for predicting the overall survival of patients with DM. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D) is often accompanied with an induction of retinaldehyde dehydrogenase 1 (RALDH1 or ALDH1A1) expression and a consequent decrease in hepatic retinaldehyde (Rald) levels. However, the role of hepatic Rald deficiency in T2D progression remains unclear. In this study, we demonstrated that reversing T2D-mediated hepatic Rald deficiency by Rald or citral treatments, or liver-specific Raldh1 silencing substantially lowered fasting glycemia levels, inhibited hepatic glucogenesis, and downregulated phosphoenolpyruvate carboxykinase 1 (PCK1) and glucose-6-phosphatase (G6PC) expression in diabetic db/db mice. Fasting glycemia and Pck1/G6pc mRNA expression levels were strongly negatively correlated with hepatic Rald levels, indicating the involvement of hepatic Rald depletion in T2D deterioration. A similar result that liver-specific Raldh1 silencing improved glucose metabolism was also observed in high-fat diet-fed mice. In primary human hepatocytes and oleic acid-treated HepG2 cells, Rald or Rald + RALDH1 silencing resulted in decreased glucose production and downregulated PCK1 / G6PC mRNA and protein expression. Mechanistically, Rald downregulated direct repeat 1-mediated PCK1 and G6PC expression by antagonizing retinoid X receptor α , as confirmed by luciferase reporter assays and molecular docking. These results highlight the link between hepatic Rald deficiency, glucose dyshomeostasis, and the progression of T2D, whilst also suggesting RALDH1 as a potential therapeutic target for T2D. Rald inhibits RXR/DR1-mediated PCK1/G6PC expression. Type 2 diabetes (T2D)-induced hepatic Rald deficiency enhances gluconeogenesis by attenuating the inhibitory effects on the induction of PCK1/G6PC by RXR activation, which exacerbates the progression of T2D. [Display omitted] [ABSTRACT FROM AUTHOR]

Phosphoenolpyruvate carboxykinase 1 (PCK1 or PEPCK-C) is a cytosolic enzyme converting oxaloacetate to phosphoenolpyruvate, with a potential role in gluconeogenesis, ammoniagenesis, and cataplerosis in the liver. Kidney proximal tubule cells display high expression of this enzyme, whose importance is currently not well defined. We generated PCK1 kidney-specific knockout and knockin mice under the tubular cell-specific PAX8 promoter. We studied the effect of PCK1 deletion and overexpression at the renal level on tubular physiology under normal conditions and during metabolic acidosis and proteinuric renal disease. PCK1 deletion led to hyperchloremic metabolic acidosis characterized by reduced but not abolished ammoniagenesis. PCK1 deletion also resulted in glycosuria, lactaturia, and altered systemic glucose and lactate metabolism at baseline and during metabolic acidosis. Metabolic acidosis resulted in kidney injury in PCK1-deficient animals with decreased creatinine clearance and albuminuria. PCK1 further regulated energy production by the proximal tubule, and PCK1 deletion decreased ATP generation. In proteinuric chronic kidney disease, mitigation of PCK1 downregulation led to better renal function preservation. PCK1 is essential for kidney tubular cell acid-base control, mitochondrial function, and glucose/lactate homeostasis. Loss of PCK1 increases tubular injury during acidosis. Mitigating kidney tubular PCK1 downregulation during proteinuric renal disease improves renal function. [ABSTRACT FROM AUTHOR]

Background: It has been reported that Sirtuin 2 ( SIRT2 ) prevents phosphoenolpyruvate carboxykinase 1 ( PCK1 ) degradation, which can be involved in aging-induced osteoarthritis (OA), but the molecular mechanism of SIRT2 / PCK1 in chondrocytes has not been clarified. Therefore, this study aims to explore the mechanism of SIRT2 / PCK1 in chondrocyte inflammation., Method: To establish the OA model in vitro , chondrocytes cultured with interleukin-1β (IL-1β, 10 ng/mL) and manipulation of SIRT2 and PCK1 expression in the constructed cells to elucidate the interaction between the two genes. 1,9-Dimethyl-Methylene Blue (DMMB) was used to detect cellular glycosaminoglycan (GAG) content. Inflammatory factor levels were assessed using Enzyme-linked Immunosorbent Assay (ELISA). Apoptosis was detected by osmotic dye. The expression of B-cell lymphoma-2 (Bcl-2), Bcl-2 Associated X (Bax), Wnt Family Member 1 (Wnt1), catenin Beta 1 (β-catenin), Aggrecan, Collagen II, matrix metallopeptidase 13 (MMP-13) proteins in cells were analyzed using Western blot., Results: PCK1 gained lower expressions in OA cell models. Overexpression of PCK1 or S IRT2 in the IL-1β chondrocyte model of inflammation promoted GAG content, inhibited apoptosis and Wnt/β-catenin protein expression, and lowered the levels of inflammatory factors. PCK1 silencing was proved to have the opposite effect. SIRT2 overexpression rescued the increased inflammation, MMP-13 expression, and apoptosis and the decreased Aggrecan and Collagen II expression caused by PCK1 silencing. PCK1 silencing also reversed the positive effects of SIRT2 overexpression on chondrocytes., Conclusion: SIRT2 inhibits articular chondrocyte extracellular matrix (ECM) degradation, inflammatory factor expression, and apoptosis via PCK1 .

Abstract Background In China, although buffaloes are abundant, beef is mainly obtained from cattle, and this preference is mainly attributed to the low intramuscular fat (IMF) content of buffalo. Genetic factors are an important driver that affects IMF deposition. Results To reveal the intrinsic factors responsible for the low IMF content of buffalo, mRNA expression patterns in muscle and adipose tissue between buffalo and cattle were characterized by RNA sequencing analysis. The IMF content in Nanyang cattle was higher than that in Xinyang buffalo. A total of 1566 mRNAs expressed in adipose tissue showed differential expression between the longissimus dorsi muscles of buffalo and cattle. Functional annotation suggested a difference in the glycolysis/gluconeogenesis pathway between the two species. The results of RT-qPCR analysis and gain-of-function experiments confirmed the positive association between the IMF content and phosphoenolpyruvate carboxykinase 1 (PCK1) expression in buffalo. In both mouse C2C12 cells and cultured bovine myocytes, the activity of the PCK1 promoter in buffalo is lower than that in cattle. However, in mouse 3T3-L1 adipocytes and cultured bovine adipocytes, the activity of PCK1 in buffalo promoter is higher than that in cattle. Conclusions These results indicate the important role of PCK1 in buffalo IMF deposition and illustrate the differences between buffalo and cattle promoter activity that drive PCK1 expression. This research helps to establish a foundation for further studies investigating IMF deposition in buffalo.

Abstract Background Altered glucose metabolism endows tumor cells with metabolic flexibility for biosynthesis requirements. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key enzyme in the gluconeogenesis pathway, is downregulated in hepatocellular carcinoma (HCC) and predicts poor prognosis. Overexpression of PCK1 has been shown to suppress liver tumor growth, but the underlying mechanism remains unclear. Methods mRNA and protein expression patterns of PCK1, AMPK, pAMPK, and the CDK/Rb/E2F pathway were determined using qRT-PCR and western blotting. Cell proliferation ability and cell cycle were assessed by MTS assay and flow cytometric analysis. The effect of PCK1 on tumor growth was examined in xenograft implantation models. Results Both gain and loss-of-function experiments demonstrated that PCK1 deficiency promotes hepatoma cell proliferation through inactivation of AMPK, suppression of p27Kip1 expression, and stimulation of the CDK/Rb/E2F pathway, thereby accelerating cell cycle transition from the G1 to S phase under glucose-starved conditions. Overexpression of PCK1 reduced cellular ATP levels and enhanced AMPK phosphorylation and p27Kip1 expression but decreased Rb phosphorylation, leading to cell cycle arrest at G1. AMPK knockdown significantly reversed G1-phase arrest and growth inhibition of PCK1-expressing SK-Hep1 cells. In addition, the AMPK activator metformin remarkably suppressed the growth of PCK1-knockout PLC/PRF/5 cells and inhibited tumor growth in an orthotropic HCC mouse model. Conclusion This study revealed that PCK1 negatively regulates cell cycle progression and hepatoma cell proliferation via the AMPK/p27Kip1 axis and supports a potential therapeutic and protective effect of metformin on HCC.

Background/Aims: Gluconeogenesis, a reverse process of glycolysis, is suppressed in neoplastic livers. Cytoplasmic phosphoenolpyruvate carboxykinase (PEPCK-C/PCK1, encoded by PCK1) is a step limiting enzyme of gluconeogenesis. The induced expression of the factor is reported to initiate gluconeogenesis process and antagonize hepatocellular carcinoma (HCC). In the current study, the effect of the modulation of PCK1 expression on HCC was assessed. Methods: The levels of PCK1 in clinical HCC tissues and different HCC cell lines were investigated with real time quantitative PCR, immunochemistry, and western blotting. Thereafter, the expression of PCK1 gene was induced in two HCC cell lines and the effect of the overexpression on proliferation and migration potentials of HCC cells was detected with CCK-8 assay, flow cytometry, TUNEL staining, and transwell assay. The activities of glycolysis and gluconeogenesis pathways in PCK1-overexpressed HCC cell lines were detected with specific kits to underlie the mechanism by which PCK1 exerted its function. The results of the in vitro experiments were validated with HCC xenograft rat models. Results: The expression levels of PCK1 were suppressed in HCC samples and in cells derived from HCC tissues. According to the results of the in vitro assays, the overexpression of PCK1 decreased viability, induced apoptosis, and inhibited migration in both HCC cell lines. The effect was associated with the suppressed glycolysis and the induced gluconeogenesis pathways, represented by the enhanced production of glucose and the limited production of pyruvic acid, lactate, citrate, and malate. The results of the in vitro assays were confirmed in rat models in that the growth rate of solid HCC tumors was reduced in mice transplanted with PCK1-overexpressed HCC cells. Conclusion: Findings outlined in the current study demonstrated that activating gluconeogenesis process via PCK1 overexpression was a potential treating strategy against HCC.

The present study was performed to identify the susceptible single nucleotide polymorphisms (SNPs) for the prediction of Korean type 2 diabetes mellitus (T2DM) and to clarify the matrilineal origin of Korean T2DM-specific SNPs. Fourteen SNPs from the adiponectin (ADIPOQ), hepatocyte nuclear factor 4α, phosphoenolpyruvate carboxykinase 1 and glucokinase genes in the Korean population were analyzed. Only one SNP, -11,377 C/G on the ADIPOQ gene, was finally determined to be responsible for the incidence of Korean T2DM (P=0.028). The G-T-T-A haplotype at positions -11,377, +45, +276 and +349 on the ADIPOQ gene was also associated with a high incidence of Korean T2DM (P=0.023). In addition, the susceptibility of Korean individuals to T2DM appears to be affected by their matrilineal origin. Of note, the group of Southern origin, consisting of mitochondrial DNA macrohaplogroups F and R, was predisposed to T2DM, whereas the group of Northern origin, consisting of haplogroups A and Y, was resistant to T2DM. This implied that the differential genetics between the two groups, which were formed from the initial peopling of the proto-Korean population via Southern and Northern routes to the present time, may explain their differing susceptibility to T2DM. In conclusion, from Southern Asia Northward, a matrilineal origin of Korean individuals appears to be responsible for the prevalence of Korean T2DM caused by the -11,377 G allele. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a fatal disease characterized by poor liver function with increasing morbidity and poor prognosis. Extracellular vesicles, released by different cells, have been associated with HCC development. Nevertheless, the mechanisms beyond extracellular vesicles in HCC remain uncharacterized. Therefore, the current study aimed to clarify the mechanism of pro-angiogenic microRNA-584-5p in hepatocellular carcinoma. Our results showed that miR-584-5p was highly-expressed in both cancer cells (Hep3B) and their extracellular vesicles. Hep3B and extracellular vesicles were then respectively co-cultured with human vascular endothelial cell line (Ea.hy926), and they both accelerated Ea.hy926 proliferation and migration. Ea.hy926 cells could internalize extracellular vesicles carrying microRNA-584-5p. Of note, microRNA-584-5p could bind to phosphoenolpyruvate carboxykinase 1 to promote nuclear factor E2-related factor 2. Moreover, silencing microRNA-584-5p was found to decline microvessel density, vascular endothelial growth factor A, and tumor growth in vivo and in vitro. Taken altogether, our findings demonstrated that extracellular vesicles-derived microRNA-584-5p promotes angiogenesis by inhibiting PCK1 -mediating NRF2 activation, which highlights the theoretical basis for potential treatments for HCC. [ABSTRACT FROM AUTHOR]

Background: Altered glucose metabolism endows tumor cells with metabolic flexibility for biosynthesis requirements. Phosphoenolpyruvate carboxykinase 1 (PCK1), a key enzyme in the gluconeogenesis pathway, is downregulated in hepatocellular carcinoma (HCC) and predicts poor prognosis. Overexpression of PCK1 has been shown to suppress liver tumor growth, but the underlying mechanism remains unclear. Methods: mRNA and protein expression patterns of PCK1, AMPK, pAMPK, and the CDK/Rb/E2F pathway were determined using qRT-PCR and western blotting. Cell proliferation ability and cell cycle were assessed by MTS assay and flow cytometric analysis. The effect of PCK1 on tumor growth was examined in xenograft implantation models. Results: Both gain and loss-of-function experiments demonstrated that PCK1 deficiency promotes hepatoma cell proliferation through inactivation of AMPK, suppression of p27Kip1 expression, and stimulation of the CDK/Rb/E2F pathway, thereby accelerating cell cycle transition from the G1 to S phase under glucose-starved conditions. Overexpression of PCK1 reduced cellular ATP levels and enhanced AMPK phosphorylation and p27Kip1 expression but decreased Rb phosphorylation, leading to cell cycle arrest at G1. AMPK knockdown significantly reversed G1-phase arrest and growth inhibition of PCK1-expressing SK-Hep1 cells. In addition, the AMPK activator metformin remarkably suppressed the growth of PCK1-knockout PLC/PRF/5 cells and inhibited tumor growth in an orthotropic HCC mouse model. Conclusion: This study revealed that PCK1 negatively regulates cell cycle progression and hepatoma cell proliferation via the AMPK/p27Kip1 axis and supports a potential therapeutic and protective effect of metformin on HCC. [ABSTRACT FROM AUTHOR]

Background/aims: Gluconeogenesis, a reverse process of glycolysis, is suppressed in neoplastic livers. Cytoplasmic phosphoenolpyruvate carboxykinase (PEPCK-C/PCK1, encoded by PCK1) is a step limiting enzyme of gluconeogenesis. The induced expression of the factor is reported to initiate gluconeogenesis process and antagonize hepatocellular carcinoma (HCC). In the current study, the effect of the modulation of PCK1 expression on HCC was assessed., Methods: The levels of PCK1 in clinical HCC tissues and different HCC cell lines were investigated with real time quantitative PCR, immunochemistry, and western blotting. Thereafter, the expression of PCK1 gene was induced in two HCC cell lines and the effect of the overexpression on proliferation and migration potentials of HCC cells was detected with CCK-8 assay, flow cytometry, TUNEL staining, and transwell assay. The activities of glycolysis and gluconeogenesis pathways in PCK1-overexpressed HCC cell lines were detected with specific kits to underlie the mechanism by which PCK1 exerted its function. The results of the in vitro experiments were validated with HCC xenograft rat models., Results: The expression levels of PCK1 were suppressed in HCC samples and in cells derived from HCC tissues. According to the results of the in vitro assays, the overexpression of PCK1 decreased viability, induced apoptosis, and inhibited migration in both HCC cell lines. The effect was associated with the suppressed glycolysis and the induced gluconeogenesis pathways, represented by the enhanced production of glucose and the limited production of pyruvic acid, lactate, citrate, and malate. The results of the in vitro assays were confirmed in rat models in that the growth rate of solid HCC tumors was reduced in mice transplanted with PCK1-overexpressed HCC cells., Conclusion: Findings outlined in the current study demonstrated that activating gluconeogenesis process via PCK1 overexpression was a potential treating strategy against HCC., (© 2018 The Author(s). Published by S. Karger AG, Basel.)