scholarly journals Loss of Mouse Ikbkap, a Subunit of Elongator, Leads to Transcriptional Deficits and Embryonic Lethality That Can Be Rescued by Human IKBKAP

2008 ◽  
Vol 29 (3) ◽  
pp. 736-744 ◽  
Author(s):  
Yei-Tsung Chen ◽  
Matthew M. Hims ◽  
Ranjit S. Shetty ◽  
James Mull ◽  
Lijuan Liu ◽  
...  
Keyword(s):  
Neural Development ◽  
Protein Function ◽  
Vascular System ◽  
Embryonic Lethality ◽  
Transcriptional Elongation ◽  
Knockout Mouse Model ◽  
Intronic Mutation ◽  
Visceral Yolk Sac ◽  
A Subunit

ABSTRACT Familial dysautonomia (FD), a devastating hereditary sensory and autonomic neuropathy, results from an intronic mutation in the IKBKAP gene that disrupts normal mRNA splicing and leads to tissue-specific reduction of IKBKAP protein (IKAP) in the nervous system. To better understand the roles of IKAP in vivo, an Ikbkap knockout mouse model was created. Results from our study show that ablating Ikbkap leads to embryonic lethality, with no homozygous Ikbkap knockout (Ikbkap − / −) embryos surviving beyond 12.5 days postcoitum. Morphological analyses of the Ikbkap − / − conceptus at different stages revealed abnormalities in both the visceral yolk sac and the embryo, including stunted extraembryonic blood vessel formation, delayed entry into midgastrulation, disoriented dorsal primitive neural alignment, and failure to establish the embryonic vascular system. Further, we demonstrate downregulation of several genes that are important for neurulation and vascular development in the Ikbkap − / − embryos and show that this correlates with a defect in transcriptional elongation-coupled histone acetylation. Finally, we show that the embryonic lethality resulting from Ikbkap ablation can be rescued by a human IKBKAP transgene. For the first time, we demonstrate that IKAP is crucial for both vascular and neural development during embryogenesis and that protein function is conserved between mouse and human.

scholarly journals Slow transcriptional elongation causes embryonic lethality and perturbs kinetic coupling of long neural genes

2018 ◽  
Author(s):  
Magdalena M. Maslon ◽  
Ulrich Braunschweig ◽  
Stuart Aitken ◽  
Abigail R. Mann ◽  
Fiona Kilanowski ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Embryonic Stem ◽  
Elongation Rate ◽  
Embryonic Lethality ◽  
Transcriptional Elongation ◽  
Neural Lineage ◽  
Kinetic Coupling ◽  
The Impact

The rate of RNA Polymerase II (RNAPII) elongation has an important role in the control of Alternative splicing (AS); however, thein vivoconsequences of an altered elongation rate are unknown. Here, we generated mouse embryonic stem cells (ESCs) knocked-in for a slow elongating form of RNAPII. We show that a reduced transcriptional elongation rate results in early embryonic lethality in mice and impairs the differentiation of ESCs into the neural lineage. This is accompanied by changes in splicing and in gene expression in ESCs and along the pathway of neuronal differentiation. In particular, we found a crucial role for RNAPII elongation rate in transcription and splicing of long neuronal genes involved in synapse signaling. The impact of the kinetic coupling of RNAPII elongation rate with AS is more predominant in ESC-differentiated neurons than in pluripotent cells. Our results demonstrate the requirement for an appropriate transcriptional elongation rate to ensure proper gene expression and to regulate AS during development.

scholarly journals PPM1G promotes the progression of hepatocellular carcinoma via phosphorylation regulation of alternative splicing protein SRSF3

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Dawei Chen ◽  
Zhenguo Zhao ◽  
Lu Chen ◽  
Qinghua Li ◽  
Jixue Zou ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Alternative Splicing ◽  
Protein Function ◽  
Vital Role ◽  
Normal Tissues ◽  
Mechanistic Analysis ◽  
Highly Correlated ◽  
Splicing Patterns

AbstractEmerging evidence has demonstrated that alternative splicing has a vital role in regulating protein function, but how alternative splicing factors can be regulated remains unclear. We showed that the PPM1G, a protein phosphatase, regulated the phosphorylation of SRSF3 in hepatocellular carcinoma (HCC) and contributed to the proliferation, invasion, and metastasis of HCC. PPM1G was highly expressed in HCC tissues compared to adjacent normal tissues, and higher levels of PPM1G were observed in adverse staged HCCs. The higher levels of PPM1G were highly correlated with poor prognosis, which was further validated in the TCGA cohort. The knockdown of PPM1G inhibited the cell growth and invasion of HCC cell lines. Further studies showed that the knockdown of PPM1G inhibited tumor growth in vivo. The mechanistic analysis showed that the PPM1G interacted with proteins related to alternative splicing, including SRSF3. Overexpression of PPM1G promoted the dephosphorylation of SRSF3 and changed the alternative splicing patterns of genes related to the cell cycle, the transcriptional regulation in HCC cells. In addition, we also demonstrated that the promoter of PPM1G was activated by multiple transcription factors and co-activators, including MYC/MAX and EP300, MED1, and ELF1. Our study highlighted the essential role of PPM1G in HCC and shed new light on unveiling the regulation of alternative splicing in malignant transformation.

scholarly journals Important Role for Phylogenetically Invariant PP2Acα Active Site and C-Terminal Residues Revealed by Mutational Analysis in Saccharomyces cerevisiae

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 21-29 ◽  
Author(s):  
David R H Evans ◽  
Brian A Hemmings
Keyword(s):  
Protein Interactions ◽  
Active Site ◽  
Protein Function ◽  
Mutational Analysis ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Active Site Residues ◽  
Catalytic Function

Abstract PP2A is a central regulator of eukaryotic signal transduction. The human catalytic subunit PP2Acα functionally replaces the endogenous yeast enzyme, Pph22p, indicating a conservation of function in vivo. Therefore, yeast cells were employed to explore the role of invariant PP2Ac residues. The PP2Acα Y127N substitution abolished essential PP2Ac function in vivo and impaired catalysis severely in vitro, consistent with the prediction from structural studies that Tyr-127 mediates substrate binding and its side chain interacts with the key active site residues His-118 and Asp-88. The V159E substitution similarly impaired PP2Acα catalysis profoundly and may cause global disruption of the active site. Two conditional mutations in the yeast Pph22p protein, F232S and P240H, were found to cause temperature-sensitive impairment of PP2Ac catalytic function in vitro. Thus, the mitotic and cell lysis defects conferred by these mutations result from a loss of PP2Ac enzyme activity. Substitution of the PP2Acα C-terminal Tyr-307 residue by phenylalanine impaired protein function, whereas the Y307D and T304D substitutions abolished essential function in vivo. Nevertheless, Y307D did not reduce PP2Acα catalytic activity significantly in vitro, consistent with an important role for the C terminus in mediating essential protein-protein interactions. Our results identify key residues important for PP2Ac function and characterize new reagents for the study of PP2A in vivo.

scholarly journals Oxidized LDLs as Signaling Molecules

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1184
Author(s):  
Jean-Marc Zingg ◽  
Adelina Vlad ◽  
Roberta Ricciarelli
Keyword(s):  
Free Radicals ◽  
Cellular Response ◽  
Vascular System ◽  
Signaling Molecules ◽  
Scavenger Receptors ◽  
Physiological Relevance ◽  
Reactive Radicals ◽  
Accumulation Of Lipids

Levels of oxidized low-density lipoproteins (oxLDLs) are usually low in vivo but can increase whenever the balance between formation and scavenging of free radicals is impaired. Under normal conditions, uptake and degradation represent the physiological cellular response to oxLDL exposure. The uptake of oxLDLs is mediated by cell surface scavenger receptors that may also act as signaling molecules. Under conditions of atherosclerosis, monocytes/macrophages and vascular smooth muscle cells highly exposed to oxLDLs tend to convert to foam cells due to the intracellular accumulation of lipids. Moreover, the atherogenic process is accelerated by the increased expression of the scavenger receptors CD36, SR-BI, LOX-1, and SRA in response to high levels of oxLDL and oxidized lipids. In some respects, the effects of oxLDLs, involving cell proliferation, inflammation, apoptosis, adhesion, migration, senescence, and gene expression, can be seen as an adaptive response to the rise of free radicals in the vascular system. Unlike highly reactive radicals, circulating oxLDLs may signal to cells at more distant sites and possibly trigger a systemic antioxidant defense, thus elevating the role of oxLDLs to that of signaling molecules with physiological relevance.

scholarly journals A study of deregulated MMR pathways and anticancer potential of curcuma derivatives using computational approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Priyanjali Bhattacharya ◽  
Trupti N. Patel
Keyword(s):  
Mismatch Repair ◽  
Protein Function ◽  
Curcuma Longa ◽  
Signaling Cascades ◽  
Altered Expression ◽  
Anticancer Properties ◽  
Medicinal Properties ◽  
Multiple Signaling

AbstractPlant derived products have steadily gained momentum in treatment of cancer over the past decades. Curcuma and its derivatives, in particular, have diverse medicinal properties including anticancer potential with proven safety as supported by numerous in vivo and in vitro studies. A defective Mis-Match Repair (MMR) is implicated in solid tumors but its role in haematologic malignancies is not keenly studied and the current literature suggests that it is limited. Nonetheless, there are multiple pathways interjecting the mismatch repair proteins in haematologic cancers that may have a direct or indirect implication in progression of the disease. Here, through computational analysis, we target proteins that are involved in rewiring of multiple signaling cascades via altered expression in cancer using various curcuma derivatives (Curcuma longa L. and Curcuma caesia Roxb.) which in turn, profoundly controls MMR protein function. These biomolecules were screened to identify their efficacy on selected targets (in blood-related cancers); aberrations of which adversely impacted mismatch repair machinery. The study revealed that of the 536 compounds screened, six of them may have the potential to regulate the expression of identified targets and thus revive the MMR function preventing genomic instability. These results reveal that there may be potential plant derived biomolecules that may have anticancer properties against the tumors driven by deregulated MMR-pathways.

scholarly journals NDUFA4L2 promotes glioblastoma progression, is associated with poor survival, and can be effectively targeted by apatinib

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Zheng Chen ◽  
Xiangyu Wei ◽  
Xueyi Wang ◽  
Xuan Zheng ◽  
Bowen Chang ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Hypoxia Inducible Factor ◽  
Mitochondrial Respiratory Chain ◽  
Metabolic Reprogramming ◽  
Tumor Cell Apoptosis ◽  
Survival Gene ◽  
A Subunit ◽  
Tumor Types

AbstractNADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2 (NDUFA4L2) is a subunit of Complex I of the mitochondrial respiratory chain, which is important in metabolic reprogramming and oxidative stress in multiple cancers. However, the biological role and molecular regulation of NDUFA4L2 in glioblastoma (GBM) are poorly understood. Here, we found that NDUFA4L2 was significantly upregulated in GBM; the elevated levels were correlated with reduced patient survival. Gene knockdown of NDUFA4L2 inhibited tumor cell proliferation and enhanced apoptosis, while tumor cells initiated protective mitophagy in vitro and in vivo. We used lentivirus to reduce expression levels of NDUFA4L2 protein in GBM cells exposed to mitophagy blockers, which led to a significant enhancement of tumor cell apoptosis in vitro and inhibited the development of xenografted tumors in vivo. In contrast to other tumor types, NDUFA4L2 expression in GBM may not be directly regulated by hypoxia-inducible factor (HIF)-1α, because HIF-1α inhibitors failed to inhibit NDUFA4L2 in GBM. Apatinib was able to effectively target NDUFA4L2 in GBM, presenting an alternative to the use of lentiviruses, which currently cannot be used in humans. Taken together, our data suggest the use of NDUFA4L2 as a potential therapeutic target in GBM and demonstrate a practical treatment approach.

scholarly journals Pilot Study: Quantitative Photoacoustic Evaluation of Peripheral Vascular Dynamics Induced by Carfilzomib In Vivo

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 836
Author(s):  
Thi Thao Mai ◽  
Manh-Cuong Vo ◽  
Tan-Huy Chu ◽  
Jin Young Kim ◽  
Chulhong Kim ◽  
...  
Keyword(s):  
Pilot Study ◽  
Side Effects ◽  
Cardiovascular Events ◽  
Evaluation Method ◽  
Vascular System ◽  
Maximum Amplitude ◽  
Peripheral Vascular ◽  
Peripheral Vasculature ◽  
Mouse Ear

Carfilzomib is mainly used to treat multiple myeloma. Several side effects have been reported in patients treated with carfilzomib, especially those associated with cardiovascular events, such as hypertension, congestive heart failure, and coronary artery disease. However, the side effects, especially the manifestation of cardiovascular events through capillaries, have not been fully investigated. Here, we performed a pilot experiment to monitor peripheral vascular dynamics in a mouse ear under the effects of carfilzomib using a quantitative photoacoustic vascular evaluation method. Before and after injecting the carfilzomib, bortezomib, and PBS solutions, we acquired high-resolution three-dimensional PAM data of the peripheral vasculature of the mouse ear during each experiment for 10 h. Then, the PAM maximum amplitude projection (MAP) images and five quantitative vascular parameters, i.e., photoacoustic (PA) signal, diameter, density, length fraction, and fractal dimension, were estimated. Quantitative results showed that carfilzomib induces a strong effect on the peripheral vascular system through a significant increase in all vascular parameters up to 50%, especially during the first 30 min after injection. Meanwhile, bortezomib and PBS do not have much impact on the peripheral vascular system. This pilot study verified PAM as a comprehensive method to investigate peripheral vasculature, along with the effects of carfilzomib. Therefore, we expect that PAM may be useful to predict cardiovascular events caused by carfilzomib.

scholarly journals Rgs4 is a regulator of mTOR activity required for motoneuron axon outgrowth and neuronal development in zebrafish

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aya Mikdache ◽  
Marie-José Boueid ◽  
Lorijn van der Spek ◽  
Emilie Lesport ◽  
Brigitte Delespierre ◽  
...  
Keyword(s):  
Nervous System ◽  
G Protein ◽  
Neural Development ◽  
Neuronal Development ◽  
Axon Outgrowth ◽  
Rgs Proteins ◽  
Protein Signaling ◽  
Loss Of Function ◽  
G Protein Coupled

AbstractThe Regulator of G protein signaling 4 (Rgs4) is a member of the RGS proteins superfamily that modulates the activity of G-protein coupled receptors. It is mainly expressed in the nervous system and is linked to several neuronal signaling pathways; however, its role in neural development in vivo remains inconclusive. Here, we generated and characterized a rgs4 loss of function model (MZrgs4) in zebrafish. MZrgs4 embryos showed motility defects and presented reduced head and eye sizes, reflecting defective motoneurons axon outgrowth and a significant decrease in the number of neurons in the central and peripheral nervous system. Forcing the expression of Rgs4 specifically within motoneurons rescued their early defective outgrowth in MZrgs4 embryos, indicating an autonomous role for Rgs4 in motoneurons. We also analyzed the role of Akt, Erk and mechanistic target of rapamycin (mTOR) signaling cascades and showed a requirement for these pathways in motoneurons axon outgrowth and neuronal development. Drawing on pharmacological and rescue experiments in MZrgs4, we provide evidence that Rgs4 facilitates signaling mediated by Akt, Erk and mTOR in order to drive axon outgrowth in motoneurons and regulate neuronal numbers.

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