scholarly journals Role of PKR in the Inhibition of Proliferation and Translation by Polycystin-1

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Yan Tang ◽  
Guang Shi ◽  
JungWoo Yang ◽  
Wang Zheng ◽  
Jingfeng Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Protein Synthesis ◽  
Kinase Activity ◽  
Protein Translation ◽  
Dominant Negative ◽  
Inhibition Of Proliferation ◽  
Proliferation And Apoptosis ◽  
Autosomal Dominant Polycystic Kidney ◽  
Underlying Mechanisms

Autosomal dominant polycystic kidney disease (ADPKD) is mainly caused by mutations in the PKD1 (~85%) or PKD2 (~15%) gene which, respectively, encode polycystin-1 (PC1) and polycystin-2 (PC2). How PC1 regulates cell proliferation and apoptosis has been studied for decades but the underlying mechanisms remain controversial. Protein kinase RNA-activated (PKR) is activated by interferons or double-stranded RNAs, inhibits protein translation, and induces cell apoptosis. In a previous study, we found that PC1 reduces apoptosis through suppressing the PKR/eIF2α signaling. Whether and how PKR is involved in PC1-inhibited proliferation and protein synthesis remains unknown. Here we found that knockdown of PKR abolishes PC1-inhibited proliferation and translation. Because suppressed PKR-eIF2α signaling/activity by PC1 would stimulate, rather than inhibit, the proliferation and translation, we examined the effect of dominant negative PKR mutant K296R that has no kinase activity and found that it enhances the inhibition of proliferation and translation by PC1. Thus, our study showed that inhibition of cell proliferation and protein synthesis by PC1 is mediated by the total expression but not the kinase activity of PKR, possibly through physical association.

Centrosome cohesion is regulated by a balance of kinase and phosphatase activities

2001 ◽  
Vol 114 (20) ◽  
pp. 3749-3757 ◽  
Author(s):  
Patrick Meraldi ◽  
Erich A. Nigg
Keyword(s):  
Protein Phosphatase ◽  
Kinase Activity ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Microtubule Depolymerization ◽  
Drug Induced ◽  
Microtubule Network ◽  
Similar Phenotype ◽  
Underlying Mechanisms

Centrosome cohesion and separation are regulated throughout the cell cycle, but the underlying mechanisms are not well understood. Since overexpression of a protein kinase, Nek2, is able to trigger centrosome splitting (the separation of parental centrioles), we have surveyed a panel of centrosome-associated kinases for their ability to induce a similar phenotype. Cdk2, in association with either cyclin A or E, was as effective as Nek2, but several other kinases tested did not significantly interfere with centrosome cohesion. Centrosome splitting could also be triggered by inhibition of phosphatases, and protein phosphatase 1α (PP1α) was identified as a likely physiological antagonist of Nek2. Furthermore, we have revisited the role of the microtubule network in the control of centrosome cohesion. We could confirm that microtubule depolymerization by nocodazole causes centrosome splitting. Surprisingly, however, this drug-induced splitting also required kinase activity and could specifically be suppressed by a dominant-negative mutant of Nek2. These studies highlight the importance of protein phosphorylation in the control of centrosome cohesion, and they point to Nek2 and PP1α as critical regulators of centrosome structure.

Activation of bovine oocytes by protein synthesis inhibitors: new findings on the role of MPF/MAPKs†

2021 ◽  
Author(s):  
Cecilia Valencia ◽  
Felipe Alonso Pérez ◽  
Carola Matus ◽  
Ricardo Felmer ◽  
María Elena Arias
Keyword(s):  
Protein Synthesis ◽  
Kinase Activity ◽  
Cyclin B1 ◽  
Protein Synthesis Inhibitors ◽  
Vitro Fertilization ◽  
New Findings ◽  
Bovine Oocytes ◽  
Dependent Pathway

Abstract The present study evaluated the mechanism by which protein synthesis inhibitors activate bovine oocytes. The aim was to analyze the dynamics of MPF and MAPKs. MII oocytes were activated with ionomycin (Io), ionomycin+anisomycin (ANY) and ionomycin+cycloheximide (CHX) and by in vitro fertilization (IVF). The expression of cyclin B1, p-CDK1, p-ERK1/2, p-JNK, and p-P38 were evaluated by immunodetection and the kinase activity of ERK1/2 was measured by enzyme assay. Evaluations at 1, 4, and 15 hours postactivation (hpa) showed that the expression of cyclin B1 was not modified by the treatments. ANY inactivated MPF by p-CDK1Thr14-Tyr15 at 4 hpa (P < 0.05), CHX increased pre-MPF (p-CDK1Thr161 and p-CDK1Thr14-Tyr15) at 1 hpa and IVF increased p-CDK1Thr14-Tyr15 at 17 hours postfertilization (hpf) (P < 0.05). ANY and CHX reduced the levels of p-ERK1/2 at 4 hpa (P < 0.05) and its activity at 4 and 1 hpa, respectively (P < 0.05). Meanwhile, IVF increased p-ERK1/2 at 6 hpf (P < 0.05); however, its kinase activity decreased at 6 hpf (P < 0.05). p-JNK in ANY, CHX, and IVF oocytes decreased at 4 hpa (P < 0.05). p-P38 was only observed at 1 hpa, with no differences between treatments. In conclusion, activation of bovine oocytes by ANY, CHX, and IVF inactivates MPF by CDK1-dependent specific phosphorylation without cyclin B1 degradation. ANY or CHX promoted this inactivation, which seemed to be more delayed in the physiological activation (IVF). Both inhibitors modulated MPF activity via an ERK1/2-independent pathway, whereas IVF activated the bovine oocytes via an ERK1/2-dependent pathway. Finally, ANY does not activate the JNK and P38 kinase pathways.

scholarly journals Neuropeptide Y (NPY) promotes inflammation-induced tumorigenesis by enhancing epithelial cell proliferation

2017 ◽  
Vol 312 (2) ◽  
pp. G103-G111 ◽  
Author(s):  
Sabrina Jeppsson ◽  
Shanthi Srinivasan ◽  
Bindu Chandrasekharan
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Neuropeptide Y ◽  
Intestinal Inflammation ◽  
Enteric Neurons ◽  
Intestinal Epithelial ◽  
Epithelial Proliferation ◽  
Proliferation And Apoptosis

We have demonstrated that neuropeptide Y (NPY), abundantly produced by enteric neurons, is an important regulator of intestinal inflammation. However, the role of NPY in the progression of chronic inflammation to tumorigenesis is unknown. We investigated whether NPY could modulate epithelial cell proliferation and apoptosis, and thus regulate tumorigenesis. Repeated cycles of dextran sodium sulfate (DSS) were used to model inflammation-induced tumorigenesis in wild-type (WT) and NPY knockout ( NPY−/−) mice. Intestinal epithelial cell lines (T84) were used to assess the effects of NPY (0.1 µM) on epithelial proliferation and apoptosis in vitro. DSS-WT mice exhibited enhanced intestinal inflammation, polyp size, and polyp number (7.5 ± 0.8) compared with DSS- NPY−/− mice (4 ± 0.5, P < 0.01). Accordingly, DSS-WT mice also showed increased colonic epithelial proliferation (PCNA, Ki67) and reduced apoptosis (TUNEL) compared with DSS- NPY−/− mice. The apoptosis regulating microRNA, miR-375, was significantly downregulated in the colon of DSS-WT (2-fold, P < 0.01) compared with DSS- NPY−/−-mice. In vitro studies indicated that NPY promotes cell proliferation (increase in PCNA and β-catenin, P < 0.05) via phosphatidyl-inositol-3-kinase (PI3-K)-β-catenin signaling, suppressed miR-375 expression, and reduced apoptosis (increase in phospho-Bad). NPY-treated cells also displayed increased c-Myc and cyclin D1, and reduction in p21 ( P < 0.05). Addition of miR-375 inhibitor to cells already treated with NPY did not further enhance the effects induced by NPY alone. Our findings demonstrate a novel regulation of inflammation-induced tumorigenesis by NPY-epithelial cross talk as mediated by activation of PI3-K signaling and downregulation of miR-375. NEW & NOTEWORTHY Our work exemplifies a novel role of neuropeptide Y (NPY) in regulating inflammation-induced tumorigenesis via two modalities: first by enhanced proliferation (PI3-K/pAkt), and second by downregulation of microRNA-375 (miR-375)-dependent apoptosis in intestinal epithelial cells. Our data establish the existence of a microRNA-mediated cross talk between enteric neurons producing NPY and intestinal epithelial cells, and the potential of neuropeptide-regulated miRNAs as potential therapeutic molecules for the management of inflammation-associated tumors in the gut.

scholarly journals Modulation of Cathepsin S (CTSS) Regulates the Secretion of Progesterone and Estradiol, Proliferation, and Apoptosis of Ovarian Granulosa Cells in Rabbits

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1770
Author(s):  
Guohua Song ◽  
Yixuan Jiang ◽  
Yaling Wang ◽  
Mingkun Song ◽  
Xuanmin Niu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Granulosa Cells ◽  
Hormone Secretion ◽  
Vital Role ◽  
Regulatory Function ◽  
Cathepsin S ◽  
Related Gene ◽  
Ovarian Granulosa Cells ◽  
Proliferation And Apoptosis

Cathepsin S (CTSS) is a member of cysteine protease family. Although many studies have demonstrated the vital role of CTSS in many physiological and pathological processes including tumor growth, angiogenesis and metastasis, the function of CTSS in the development of rabbit granulosa cells (GCS) remains unknown. To address this question, we isolated rabbit GCS and explored the regulatory function of the CTSS gene in cell proliferation and apoptosis. CTSS overexpression significantly promoted the secretion of progesterone (P4) and estrogen (E2) by increasing the expression of STAR and CYP19A1 (p < 0.05). We also found that overexpression of CTSS increased GCS proliferation by up-regulating the expression of proliferation related gene (PCNA) and anti-apoptotic gene (BCL2). Cell apoptosis was markedly decreased by CTSS activation (p < 0.05). In contrast, CTSS knockdown significantly decreased the secretion of P4 and E2 and the proliferation of rabbit GCS, while increasing the apoptosis of rabbit GCS. Taken together, our results highlight the important role of CTSS in regulating hormone secretion, cell proliferation, and apoptosis in rabbit GCS. These results might provide a basis for better understanding the molecular mechanism of rabbit reproduction.

scholarly journals Cellular homeostasis, implantation window and unexplained infertility: role of phosphatase and tensin homolog deleted on chromosome 10

2019 ◽  
Vol 8 (7) ◽  
pp. 2754
Author(s):  
Annu Makker ◽  
Madhu Mati Goel ◽  
Kumari Manu ◽  
Renu Makker
Keyword(s):  
Cell Proliferation ◽  
Unexplained Infertility ◽  
Endometrial Cell ◽  
Chromosome 10 ◽  
Cellular Homeostasis ◽  
Phosphatase And Tensin Homolog ◽  
Implantation Window ◽  
Tensin Homolog ◽  
Proliferation And Apoptosis

Background: Balance between endometrial cell proliferation and apoptosis is crucial for successful embryo implantation. PTEN (phosphatase and tensin homolog deleted on chromosome 10), a pro-apoptotic factor, is proposed to be one of the signaling proteins through which estrogen and progesterone act to affect cellular homeostasis. Although reports in literature have suggested role of PTEN in regulating endometrial cell proliferation and apoptosis during window of implantation, its involvement in women with unexplained infertility is not clear. In the present study, we examined expression, cellular distribution and activation status of PTEN, cell proliferation, and apoptosis in midsecretory endometrium from women with unexplained infertility as compared to fertile controls.Methods: Endometrial biopsies from infertile (n=11) and fertile women (n=22) were used for immunohistochemical evaluation of PTEN, phospho-PTEN and Ki67. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assay was performed for detection of apoptotic cells.Results: Biopsies from infertile women as compared to fertile controls demonstrated statistically significant: i) decrease in nuclear PTEN (P < 0.001), increase in nuclear phospho-PTEN (P < 0.05), increase in nuclear and cytoplasmic phospho-PTEN/PTEN ratio (P < 0.001 and P < 0.05 respectively) in endometrial stroma, ii) increase in cytoplasmic phospho-PTEN (P < 0.001) and phospho-PTEN/PTEN ratio (P < 0.05) in glandular epithelium (GE), iii) increase in Ki67 labeling in GE (P < 0.01) and stroma (P < 0.05) and, iv) decrease in (P < 0.001) apoptosis.Conclusions: Altered PTEN expression and associated modulation in cellular homeostasis during the implantation window might contribute to mechanism underlying unexplained infertility.

scholarly journals Role of LM23 in cell proliferation and apoptosis and its expression during the testis development

2013 ◽  
Vol 15 (4) ◽  
pp. 539-544 ◽  
Author(s):  
Qing Liu ◽  
Ya-Juan Song ◽  
Li-Jun Meng ◽  
Fen Hu ◽  
Li-Xia Gou ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Testis Development ◽  
Proliferation And Apoptosis

scholarly journals Ankhd1 enhances polycystic kidney disease development via promoting proliferation and fibrosis

2020 ◽  
Author(s):  
Foteini Patera ◽  
Guillaume M Hautbergue ◽  
Patricia Wilson ◽  
Paul C Evans ◽  
Albert CM Ong ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Kidney Disease ◽  
Polycystic Kidney Disease ◽  
Therapeutic Benefit ◽  
Polycystic Kidney ◽  
Molecular Events ◽  
Proliferative Growth ◽  
Kh Domain ◽  
Autosomal Dominant Polycystic Kidney

ABSTRACTAutosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common genetic kidney disorder resulting in 10% of patients with renal failure. The molecular events responsible for the relentless growth of cysts are not defined. Thus, identification of novel drivers of ADPKD may lead to new therapies. Ankyrin Repeat and Single KH domain-1 (ANKHD1) controls cancer cell proliferation, yet its role in ADPKD is unexplored. Here, we present the first data that identify ANKHD1 as a driver of proliferative growth in cellular and mouse models of ADPKD. Using the first Ankhd1-deficient mice, we demonstrate that Ankhd1 heterozygosity potently reduces cystic growth and fibrosis, in a genetically orthologous mouse model of ADPKD. We performed transcriptome-wide profiling of patient-derived ADPKD cells with and without ANKHD1 siRNA silencing, revealing a major role for ANKHD1 in the control of cell proliferation and matrix remodelling. We validated the role of ANKHD1 in enhancing proliferation in patient-derived cells. Mechanistically ANKHD1 promotes STAT5 signalling in ADPKD mice. Hence, ANKHD1 is a novel driver of ADPKD, and its inhibition may be of therapeutic benefit.

Regulation of hemoglobin synthesis and proliferation of differentiating erythroid cells by heme-regulated eIF-2α kinase

Blood ◽  
2000 ◽  
Vol 96 (9) ◽  
pp. 3241-3248 ◽  
Author(s):  
John S. Crosby ◽  
Peter J. Chefalo ◽  
Irene Yeh ◽  
Shong Ying ◽  
Irving M. London ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Erythroid Differentiation ◽  
Dominant Negative ◽  
Erythroid Cells ◽  
3T3 Cells ◽  
Binding Domains ◽  
Inhibition Of Protein Synthesis ◽  
Nih 3T3 ◽  
Hemoglobin Production

Abstract Protein synthesis in reticulocytes depends on the availability of heme. In heme deficiency, inhibition of protein synthesis correlates with the activation of heme-regulated eIF-2α kinase (HRI), which blocks the initiation of protein synthesis by phosphorylating eIF-2α. HRI is a hemoprotein with 2 distinct heme-binding domains. Heme negatively regulates HRI activity by binding directly to HRI. To further study the physiological function of HRI, the wild-type (Wt) HRI and dominant-negative inactive mutants of HRI were expressed by retrovirus-mediated transfer in both non-erythroid NIH 3T3 and mouse erythroleukemic (MEL) cells. Expression of Wt HRI in 3T3 cells resulted in the inhibition of protein synthesis, a loss of proliferation, and eventually cell death. Expression of the inactive HRI mutants had no apparent effect on the growth characteristics or morphology of NIH 3T3 cells. In contrast, expression of 3 dominant-negative inactive mutants of HRI in MEL cells resulted in increased hemoglobin production and increased proliferative capacity of these cells upon dimethyl-sulfoxide induction of erythroid differentiation. These results directly demonstrate the importance of HRI in the regulation of protein synthesis in immature erythroid cells and suggest a role of HRI in the regulation of the numbers of matured erythroid cells.

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