scholarly journals PLRG1 Is an Essential Regulator of Cell Proliferation and Apoptosis during Vertebrate Development and Tissue Homeostasis

2009 ◽  
Vol 29 (11) ◽  
pp. 3173-3185 ◽  
Author(s):  
André Kleinridders ◽  
Hans-Martin Pogoda ◽  
Sigrid Irlenbusch ◽  
Neil Smyth ◽  
Csaba Koncz ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Tissue Homeostasis ◽  
Mrna Splicing ◽  
Vertebrate Development ◽  
Adult Tissue ◽  
Serum Stimulation ◽  
Evolutionarily Conserved ◽  
Proliferation And Apoptosis ◽  
Dependent Cell

ABSTRACT PLRG1, an evolutionarily conserved component of the spliceosome, forms a complex with Pso4/SNEV/Prp19 and the cell division and cycle 5 homolog (CDC5L) that is involved in both pre-mRNA splicing and DNA repair. Here, we show that the inactivation of PLRG1 in mice results in embryonic lethality at 1.5 days postfertilization. Studies of heart- and neuron-specific PLRG1 knockout mice further reveal an essential role of PLRG1 in adult tissue homeostasis and the suppression of apoptosis. PLRG1-deficient mouse embryonic fibroblasts (MEFs) fail to progress through S phase upon serum stimulation and exhibit increased rates of apoptosis. PLRG1 deficiency causes enhanced p53 phosphorylation and stabilization in the presence of increased γ-H2AX immunoreactivity as an indicator of an activated DNA damage response. p53 downregulation rescues lethality in both PLRG1-deficient MEFs and zebrafish in vivo, showing that apoptosis resulting from PLRG1 deficiency is p53 dependent. Moreover, the deletion of PLRG1 results in the relocation of its interaction partner CDC5L from the nucleus to the cytoplasm without general alterations in pre-mRNA splicing. Taken together, the results of this study identify PLRG1 as a critical nuclear regulator of p53-dependent cell cycle progression and apoptosis during both embryonic development and adult tissue homeostasis.

scholarly journals ATR-Mediated Checkpoint Pathways Regulate Phosphorylation and Activation of Human Chk1

2001 ◽  
Vol 21 (13) ◽  
pp. 4129-4139 ◽  
Author(s):  
Hui Zhao ◽  
Helen Piwnica-Worms
Keyword(s):  
Protein Kinase ◽  
Cell Cycle Progression ◽  
Gel Filtration ◽  
Genotoxic Stress ◽  
Protein Kinase Activity ◽  
Checkpoint Activation ◽  
Cycle Progression ◽  
Evolutionarily Conserved

ABSTRACT Chk1 is an evolutionarily conserved protein kinase that regulates cell cycle progression in response to checkpoint activation. In this study, we demonstrated that agents that block DNA replication or cause certain forms of DNA damage induce the phosphorylation of human Chk1. The phosphorylated form of Chk1 possessed higher intrinsic protein kinase activity and eluted more quickly on gel filtration columns. Serines 317 and 345 were identified as sites of phosphorylation in vivo, and ATR (the ATM- and Rad3-related protein kinase) phosphorylated both of these sites in vitro. Furthermore, phosphorylation of Chk1 on serines 317 and 345 in vivo was ATR dependent. Mutants of Chk1 containing alanine in place of serines 317 and 345 were poorly activated in response to replication blocks or genotoxic stress in vivo, were poorly phosphorylated by ATR in vitro, and were not found in faster-eluting fractions by gel filtration. These findings demonstrate that the activation of Chk1 in response to replication blocks and certain forms of genotoxic stress involves phosphorylation of serines 317 and 345. In addition, this study implicates ATR as a direct upstream activator of Chk1 in human cells.

scholarly journals OLFML2A Downregulation Inhibits Glioma Proliferation through Suppression of Wnt/β-catenin Signaling

2020 ◽  
Author(s):  
Shize Ma ◽  
Lei Duan ◽  
Huateng Dong ◽  
Xiaodong Ma ◽  
Xinyu Guo ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Underlying Mechanism ◽  
Kaplan Meier ◽  
Proliferation And Apoptosis ◽  
Spectral Computed Tomography ◽  
Dependent Cell ◽  
Apoptosis Gene ◽  
Tomography Scan ◽  
Worse Prognosis

Abstract Background: Glioma is a highly heterogeneous and lethal tumor with extremely poor prognosis. Through analysis of TCGA data, we found that OLFML2A was significantly upregulated in glioma tissues and positively correlated with glioma grade and worse prognosis. However, the molecular function of OLFML2A and its underlying mechanism in glioma remain unclear.Methods: The expression of OLFML2A in glioma was determined by immunohistochemistry (IHC). Celigo assay, MTT assay and flow cytometry were utilized to evaluate the effects of OLFML2A on glioma proliferation and apoptosis. Gene chip microarray analysis and ingenuity pathway analysis were used to investigate the potential regulatory mechanisms of OLFML2A, which were further assessed by q-PCR, western blotting and IHC. An animal transplanting glioma model and spectral computed tomography scan were used to verify OLFML2A expression in vivo.Results: In this study, we found that the expression of OLFML2A was significantly upregulated in glioma specimens and positively correlated with pathological grades in glioma patients. Moreover, Kaplan-Meier survival analysis of TCGA data revealed that glioma patients with higher expression of OLFML2A had shorter overall survival. Importantly, when we knocked down the expression of OLFML2A in glioma cells, cell proliferation was inhibited, and apoptosis was promoted. Mechanistically, downregulation of OLFML2A inhibited Wnt/β-catenin signaling by directly reducing the level of stabilized β-catenin and upregulating the expression of amyloid precursor protein (APP) to indirectly suppress β-catenin, leading to repression of MYC, CD44 and CSKN2A2 expression. Furthermore, we found that OLFML2A downregulation clearly suppressed the growth of subcutaneous glioma and intracranial transplantation of glioma by inhibiting Wnt/β-catenin pathway-dependent cell proliferation.Conclusion: Our data indicate the oncogenic effect of OLFML2A in glioma through regulation of Wnt/β-catenin signaling, which may provide a novel therapeutic target for glioma.

scholarly journals Splicing factor SRSF1 expands the regulatory logic of microRNA expression

2020 ◽  
Author(s):  
Marija Dargyte ◽  
Julia Philipp ◽  
Christina D. Palka ◽  
Michael D. Stone ◽  
Jeremy R. Sanford
Keyword(s):  
Binding Sites ◽  
Regulatory Elements ◽  
Mrna Splicing ◽  
Splicing Factor ◽  
Stem Loop ◽  
Microrna Biogenesis ◽  
Evolutionarily Conserved ◽  
Rna Interaction

AbstractThe serine and arginine-rich splicing factor SRSF1 is an evolutionarily conserved, essential pre-mRNA splicing factor. Through a global protein-RNA interaction survey we discovered SRSF1 binding sites 25-50nt upstream from hundreds of pre-miRNAs. Using primary miRNA-10b as a model we demonstrate that SRSF1 directly regulates microRNA biogenesis both in vitro and in vivo. Selective 2’ hydroxyl acylation analyzed by primer extension (SHAPE) defined a structured RNA element located upstream of the precursor miRNA-10b stem loop. Our data support a model where SRSF1 promotes initial steps of microRNA biogenesis by relieving the repressive effects of cis-regulatory elements within the leader sequence.

scholarly journals Transcript-specific determinants of pre-mRNA splicing revealed through in vivo kinetic analyses of the 1st and 2nd chemical steps

2020 ◽  
Author(s):  
Michael A. Gildea ◽  
Zachary W. Dwyer ◽  
Jeffrey A. Pleiss
Keyword(s):  
Genetic Variant ◽  
Important Determinant ◽  
Mrna Splicing ◽  
Splicing Regulation ◽  
Order Kinetic ◽  
Ribosomal Protein Genes ◽  
First Order ◽  
Rna Labeling ◽  
Evolutionarily Conserved

SummaryUnderstanding how the spliceosome processes its composite of substrates through the two chemical steps required for mRNA production will be essential to deciphering splicing regulation and mis-regulation. Here we measure the in vivo rates of these steps across the genome by coupling metabolic RNA labeling, targeted sequencing, and first order kinetic modeling. We reveal a wide variety of rates by which introns are removed, that splice site sequences are primary determinants of 1st step rates, and that the 2nd step is generally faster than the 1st step. We show that ribosomal protein genes (RPGs) are spliced faster than non-RPGs at each step, and that RPGs share evolutionarily conserved cis-features which facilitate their splicing. A genetic variant defective at the 1st step shows the expected defect in the 1st step, but an unexpected change in the 2nd step which suggests how co-transcriptional splicing functions as an important determinant of splicing rates.

scholarly journals OLFML2A Downregulation Inhibits Glioma Proliferation Through Suppression of Wnt/β-Catenin Signaling

2020 ◽  
Author(s):  
Shize Ma ◽  
Lei Duan ◽  
Huateng Dong ◽  
Xiaodong Ma ◽  
Xinyu Guo ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Underlying Mechanism ◽  
Kaplan Meier ◽  
Proliferation And Apoptosis ◽  
Spectral Computed Tomography ◽  
Dependent Cell ◽  
Apoptosis Gene ◽  
Tomography Scan ◽  
Worse Prognosis

Abstract Background: Glioma is a highly heterogeneous and lethal tumor with extremely poor prognosis. Through analysis of TCGA data, we found that OLFML2A was significantly upregulated in glioma tissues and positively correlated with glioma grade and worse prognosis. However, the molecular function of OLFML2A and its underlying mechanism in glioma remain unclear.Methods: The expression of OLFML2A in glioma was determined by immunohistochemistry (IHC). Celigo assay, MTT assay and flow cytometry were utilized to evaluate the effects of OLFML2A on glioma proliferation and apoptosis. Gene chip microarray analysis and ingenuity pathway analysis were used to investigate the potential regulatory mechanisms of OLFML2A, which were further assessed by q-PCR, western blotting and IHC. An animal transplanting glioma model and spectral computed tomography scan were used to verify OLFML2A expression in vivo.Results: In this study, we found that the expression of OLFML2A was significantly upregulated in glioma specimens and positively correlated with pathological grades in glioma patients. Moreover, Kaplan-Meier survival analysis of TCGA data revealed that glioma patients with higher expression of OLFML2A had shorter overall survival. Importantly, when we knocked down the expression of OLFML2A in glioma cells, cell proliferation was inhibited, and apoptosis was promoted. Mechanistically, downregulation of OLFML2A inhibited Wnt/β-catenin signaling by directly reducing the level of stabilized β-catenin and upregulating the expression of amyloid precursor protein (APP) to indirectly suppress β-catenin, leading to repression of MYC, CD44 and CSKN2A2 expression. Furthermore, we found that OLFML2A downregulation clearly suppressed the growth of subcutaneous glioma and intracranial transplantation of glioma by inhibiting Wnt/β-catenin pathway-dependent cell proliferation.Conclusion: Our data indicate the oncogenic effect of OLFML2A in glioma through regulation of Wnt/β-catenin signaling, which may provide a novel therapeutic target for glioma.

scholarly journals Autophagy Deficiency by Atg4B Loss Leads to Metabolomic Alterations in Mice

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 481
Author(s):  
Gemma G. Martínez-García ◽  
Raúl F. Pérez ◽  
Álvaro F. Fernández ◽  
Sylvere Durand ◽  
Guido Kroemer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Mammalian Cells ◽  
Tissue Homeostasis ◽  
In Vivo Studies ◽  
Protective Mechanism ◽  
Cardiac Damage ◽  
Wide Range ◽  
First Time

Autophagy is an essential protective mechanism that allows mammalian cells to cope with a variety of stressors and contributes to maintaining cellular and tissue homeostasis. Due to these crucial roles and also to the fact that autophagy malfunction has been described in a wide range of pathologies, an increasing number of in vivo studies involving animal models targeting autophagy genes have been developed. In mammals, total autophagy inactivation is lethal, and constitutive knockout models lacking effectors of this route are not viable, which has hindered so far the analysis of the consequences of a systemic autophagy decline. Here, we take advantage of atg4b−/− mice, an autophagy-deficient model with only partial disruption of the process, to assess the effects of systemic reduction of autophagy on the metabolome. We describe for the first time the metabolic footprint of systemic autophagy decline, showing that impaired autophagy results in highly tissue-dependent alterations that are more accentuated in the skeletal muscle and plasma. These changes, which include changes in the levels of amino-acids, lipids, or nucleosides, sometimes resemble those that are frequently described in conditions like aging, obesity, or cardiac damage. We also discuss different hypotheses on how impaired autophagy may affect the metabolism of several tissues in mammals.

scholarly journals Loss of PR55α promotes proliferation and metastasis by activating MAPK/AKT signaling in hepatocellular carcinoma

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
JiangSheng Zhao ◽  
GuoFeng Chen ◽  
Jingqi Li ◽  
Shiqi Liu ◽  
Quan Jin ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Cycle Progression ◽  
Lung Metastases ◽  
Cell Counting ◽  
Migration And Invasion ◽  
Signal Pathways ◽  
And Migration ◽  
Healthy Liver

Abstract Background PR55α plays important roles in oncogenesis and progression of numerous malignancies. However, its role in hepatocellular carcinoma (HCC) is unclear. This study aims to characterize the functions of PR55α in HCC. Methods PR55α expressions in HCC tissues and paired healthy liver samples were evaluated using Western blot and tissue microarray immunohistochemistry. We knocked down the expression of PR55α in SMMC-7721 and LM3 cell lines via small interfering and lentivirus. In vitro cell counting, colony formation, migration and invasion assays were performed along with in vivo xenograft implantation and lung metastases experiments. The potential mechanisms involving target signal pathways were investigated by RNA-sequencing. Results PR55α expression level was suppressed in HCC tissues in comparison to healthy liver samples. Decreased PR55α levels were correlated with poorer prognosis (P = 0.0059). Knockdown of PR55α significantly promoted cell proliferation and migration, induced repression of the cell cycle progression and apoptosis in vitro while accelerating in vivo HCC growth and metastasis. Mechanistic analysis indicated that PR55α silencing was involved with MAPK/AKT signal pathway activation and resulted in increased phosphorylation of both AKT and ERK1/2. Conclusions This study identifies PR55α to be a candidate novel therapeutic target in the treatment of HCC.

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