Inactivation of a Frameshift TSH Receptor Variant Val711Phefs*18 is Due to Acquisition of a Hydrophobic Degron

2020 ◽  
Vol 106 (1) ◽  
pp. e265-e272
Author(s):  
Chiho Sugisawa ◽  
Makoto Ono ◽  
Kenichi Kashimada ◽  
Tomonobu Hasegawa ◽  
Satoshi Narumi
Keyword(s):  
Amino Acid ◽  
Congenital Hypothyroidism ◽  
Fluorescent Protein ◽  
Transmembrane Domain ◽  
Tsh Receptor ◽  
Hek293 Cells ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Tail Region

Abstract Context Inactivating variants of thyrotropin (thyroid-stimulating hormone; TSH) receptor (TSHR) cause congenital hypothyroidism. More than 60 such variants have been reported so far, most of which were located in the extracellular or transmembrane domain. Objective We report the identification and characterization of a frameshift TSHR variant in the intracytoplasmic C-tail region. Methods Sequencing of TSHR was performed in a patient with congenital hypothyroidism. The functionality of the identified variants was assessed by expressing TSHR in HEK293 cells and measuring TSH-dependent activation of the cAMP–response element-luciferase reporter. A series of systematic mutagenesis experiments were performed to characterize the frameshifted amino acid sequence. Results The proband was heterozygous for a known TSHR variant (p.Arg519His) and a novel frameshift TSHR variant (p.Val711Phefs*18), which removed 54 C-terminal residues and added a 17–amino acid frameshifted sequence. The loss of function of Val711Phefs*18-TSHR was confirmed in vitro, but the function of Val711*-TSHR was found to be normal. Western blotting showed the low protein expression of Val711Phefs*18-TSHR. Fusion of the frameshift sequence to green fluorescent protein or luciferase induced inactivation of them, indicating that the sequence acted as a degron. A systematic mutagenesis study revealed that the density of hydrophobic residues in the frameshift sequence determined the stability. Eight additional frameshift TSHR variants that covered all possible shifted frames in C-tail were created, and another frameshift variant (Thr748Profs*27) with similar effect was found. Conclusions We characterized a naturally occurring frameshift TSHR variant located in C-tail, and provided a unique evidence that hydrophobicity in the C-terminal region of the receptor affects protein stability.

scholarly journals The Effect of Single Nucleotide Variations in the Transmembrane Domain of OATP1B1 on in vitro Functionality

2021 ◽  
Author(s):  
Wilma Kiander ◽  
Kati-Sisko Vellonen ◽  
Melina M. Malinen ◽  
Mikko Gynther ◽  
Marja Hagström ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Cellular Localization ◽  
Transmembrane Domain ◽  
Organic Anion ◽  
Hek293 Cells ◽  
Protein Abundance ◽  
Loss Of Function ◽  
Wild Type ◽  
The Impact

Abstract Purpose Organic Anion Transporting Polypeptide 1B1 (OATP1B1) mediates hepatic influx and clearance of many drugs, including statins. The SLCO1B1 gene is highly polymorphic and its function-impairing variants can predispose patients to adverse effects. The effects of rare genetic variants of SLCO1B1 are mainly unexplored. We examined the impact of eight naturally occurring rare variants and the well-known SLCO1B1 c.521C > T (V174A) variant on in vitro transport activity, cellular localization and abundance. Methods Transport of rosuvastatin and 2,7-dichlorofluorescein (DCF) in OATP1B1 expressing HEK293 cells was measured to assess changes in activity of the variants. Immunofluorescence and confocal microscopy determined the cellular localization of OATP1B1 and LC–MS/MS based quantitative targeted absolute proteomics analysis quantified the amount of OATP1B1 in crude membrane fractions. Results All studied variants, with the exception of P336R, reduced protein abundance to varying degree. V174A reduced protein abundance the most, over 90% compared to wild type. Transport function was lost in G76E, V174A, L193R and R580Q variants. R181C decreased activity significantly, while T345M and L543W retained most of wild type OATP1B1 activity. P336R showed increased activity and H575L decreased the transport of DCF significantly, but not of rosuvastatin. Decreased activity was interrelated with lower absolute protein abundance in the studied variants. Conclusions Transmembrane helices 2, 4 and 11 appear to be crucial for proper membrane localization and function of OATP1B1. Four of the studied variants were identified as loss-of-function variants and as such could make the individual harboring these variants susceptible to altered pharmacokinetics and adverse effects of substrate drugs.

scholarly journals LINC00680 enhances hepatocellular carcinoma stemness behavior and chemoresistance by sponging miR-568 to upregulate AKT3

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Gege Shu ◽  
Huizhao Su ◽  
Zhiqian Wang ◽  
Shihui Lai ◽  
Yan Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Xenograft Model ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Mechanism Study ◽  
Downstream Signaling ◽  
Mouse Xenograft Model ◽  
High Level

Abstract Background Hepatocellular carcinoma (HCC) has an extremely poor prognosis due to the development of chemoresistance, coupled with inherently increased stemness properties. Long non-coding RNAs (LncRNAs) are key regulators for tumor cell stemness and chemosensitivity. Currently the relevance between LINC00680 and tumor progression was still largely unknown, with only one study showing its significance in glioblastoma. The study herein was aimed at identifying the role of LINC00680 in the regulation HCC stemness and chemosensitivity. Methods QRT-PCR was used to detect the expression of LINC00680, miR-568 and AKT3 in tissue specimen and cell lines. Gain- or loss-of function assays were applied to access the function of LINC00680 in HCC cells, including cell proliferation and stemness properties. HCC stemness and chemosensitivity were determined by sphere formation, cell viability and colony formation. Luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays were performed to examine the interaction between LINC00680 and miR-568 as well as that between miR-568 and AKT3. A nude mouse xenograft model was established for the in vivo study. Results We found that LINC00680 was remarkably upregulated in HCC tissues. Patients with high level of LINC00680 had poorer prognosis. LINC00680 overexpression significantly enhanced HCC cell stemness and decreased in vitro and in vivo chemosensitivity to 5-fluorouracil (5-Fu), whereas LINC00680 knockdown led to opposite results. Mechanism study revealed that LINC00680 regulated HCC stemness and chemosensitivity through sponging miR-568, thereby expediting the expression of AKT3, which further activated its downstream signaling molecules, including mTOR, elF4EBP1, and p70S6K. Conclusion LINC00680 promotes HCC stemness properties and decreases chemosensitivity through sponging miR-568 to activate AKT3, suggesting that LINC00680 might be a potentially important HCC diagnosis marker and therapeutic target.

scholarly journals p53 upregulated by HIF-1α promotes hypoxia-induced G2/M arrest and renal fibrosis in vitro and in vivo

2018 ◽  
Vol 11 (5) ◽  
pp. 371-382 ◽  
Author(s):  
Limin Liu ◽  
Peng Zhang ◽  
Ming Bai ◽  
Lijie He ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Renal Fibrosis ◽  
Intraperitoneal Administration ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
P53 Expression ◽  
Tubular Cells

Abstract Hypoxia plays an important role in the genesis and progression of renal fibrosis. The underlying mechanisms, however, have not been sufficiently elucidated. We examined the role of p53 in hypoxia-induced renal fibrosis in cell culture (human and rat renal tubular epithelial cells) and a mouse unilateral ureteral obstruction (UUO) model. Cell cycle of tubular cells was determined by flow cytometry, and the expression of profibrogenic factors was determined by RT-PCR, immunohistochemistry, and western blotting. Chromatin immunoprecipitation and luciferase reporter experiments were performed to explore the effect of HIF-1α on p53 expression. We showed that, in hypoxic tubular cells, p53 upregulation suppressed the expression of CDK1 and cyclins B1 and D1, leading to cell cycle (G2/M) arrest (or delay) and higher expression of TGF-β, CTGF, collagens, and fibronectin. p53 suppression by siRNA or by a specific p53 inhibitor (PIF-α) triggered opposite effects preventing the G2/M arrest and profibrotic changes. In vivo experiments in the UUO model revealed similar antifibrotic results following intraperitoneal administration of PIF-α (2.2 mg/kg). Using gain-of-function, loss-of-function, and luciferase assays, we further identified an HRE3 region on the p53 promoter as the HIF-1α-binding site. The HIF-1α–HRE3 binding resulted in a sharp transcriptional activation of p53. Collectively, we show the presence of a hypoxia-activated, p53-responsive profibrogenic pathway in the kidney. During hypoxia, p53 upregulation induced by HIF-1α suppresses cell cycle progression, leading to the accumulation of G2/M cells, and activates profibrotic TGF-β and CTGF-mediated signaling pathways, causing extracellular matrix production and renal fibrosis.

Silencing of hsa_circ_0000515 Inhibits Proliferation, Migration and Invasion of Gastric Cancer Cells by Sponging miR-615-5p In Vitro

2021 ◽  
Vol 11 (8) ◽  
pp. 1466-1476
Author(s):  
Xuli Wang ◽  
Aiping Wang
Keyword(s):  
Gastric Cancer ◽  
Underlying Mechanism ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Pcr Analysis ◽  
Circular Rnas ◽  
Loss Of Function ◽  
Gastric Cancer Cells ◽  
Novel Target

Circular RNAs (circRNAs) have been reported to participate in the molecular mechanism of human cancers. This study investigates the role of circRNA hsa_circ_0000515 in gastric cancer (GC) cells and the underlying mechanism associated with microRNA-615-5p (miR-615-5p). qRT-PCR analysis showed the upregulation of hsa_circ_0000515 and downregulation of miR-615-5p in GC cell lines. Loss-of-function experiments indicated that suppression of hsa_circ_0000515 inhibited cell proliferation, migration, and invasion. Dual-luciferase reporter assay highlighted that hsa_circ_0000515 was able to act as a ceRNA of miR-615-5p. Furthermore, hsa_circ_0000515 could interact with splicing factors and bind miR-615-5p to regulate progression of GC cells. Deficiency of miR-615-5p reverses the inhibitory roles of si-hsa_circ_0000515 on the proliferation, migration, and invasion of GC cells. The findings highlighted the promising uses of hsa_circ_0000515 as a likely novel target for gastric cancer treatment.

scholarly journals LncRNA GAPLINC Promotes Renal Cell Cancer Tumorigenesis by Targeting the miR-135b-5p/CSF1 Axis

2021 ◽  
Vol 11 ◽  
Author(s):  
Siyuan Wang ◽  
Xiaorong Yang ◽  
Wenjie Xie ◽  
Shengqiang Fu ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Renal Cell ◽  
Noncoding Rna ◽  
Cell Cancer ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Long Intergenic Noncoding Rna ◽  
And Migration ◽  
Molecular Therapeutic

BackgroundLong noncoding RNAs (lncRNAs) are closely related to the occurrence and development of cancer. Gastric adenocarcinoma-associated, positive CD44 regulator, long intergenic noncoding RNA (GAPLINC) is a recently identified lncRNA that can actively participate in the tumorigenesis of various cancers. Here, we investigated the functional roles and mechanism of GAPLINC in renal cell carcinoma (RCC) development.MethodsDifferentially expressed lncRNAs between RCC tissues and normal kidney tissues were detected by using a microarray technique. RNA sequencing was applied to explore the mRNA expression profile changes after GAPLINC silencing. After gain- and loss-of-function approaches were implemented, the effect of GAPLINC on RCC in vitro and in vivo was assessed by cell proliferation and migration assays. Moreover, rescue experiments and luciferase reporter assays were used to study the interactions between GAPLINC, miR-135b-5p and CSF1.ResultsGAPLINC was significantly upregulated in RCC tissues and cell lines and was associated with a poor prognosis in RCC patients. Knockdown of GAPLINC repressed RCC growth in vitro and in vivo, while overexpression of GAPLINC exhibited the opposite effect. Mechanistically, we found that GAPLINC upregulates oncogene CSF1 expression by acting as a sponge of miR-135b-5p.ConclusionTaken together, our results suggest that GAPLINC is a novel prognostic marker and molecular therapeutic target for RCC.

scholarly journals Hepatitis B Virus X-Associated Protein 2 Is a Subunit of the Unliganded Aryl Hydrocarbon Receptor Core Complex and Exhibits Transcriptional Enhancer Activity

1998 ◽  
Vol 18 (2) ◽  
pp. 978-988 ◽  
Author(s):  
Brian K. Meyer ◽  
Marilyn G. Pray-Grant ◽  
John P. Vanden Heuvel ◽  
Gary H. Perdew
Keyword(s):  
Amino Acid ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Aryl Hydrocarbon Receptor ◽  
In Vitro Translation ◽  
Luciferase Reporter ◽  
Core Complex ◽  
Aryl Hydrocarbon ◽  
B Virus

ABSTRACT Prior to ligand activation, the unactivated aryl hydrocarbon receptor (AhR) exists in a heterotetrameric 9S core complex consisting of the AhR ligand-binding subunit, a dimer of hsp90, and an unknown subunit. Here we report the purification of an ∼38-kDa protein (p38) from COS-1 cell cytosol that is a member of this complex by coprecipitation with a FLAG-tagged AhR. Internal amino acid sequence information was obtained, and p38 was identified as the hepatitis B virus X-associated protein 2 (XAP2). The simian ortholog of XAP2 was cloned from a COS-1 cDNA library; it codes for a 330-amino-acid protein containing regions of homology to the immunophilins FKBP12 and FKBP52. A tetratricopeptide repeat (TPR) domain in the carboxy-terminal region of XAP2 was similar to the third and fourth TPR domains of human FKBP52 and the Saccharomyces cerevisiae transcriptional modulator SSN6, respectively. Polyclonal antibodies raised against XAP2 recognized p38 in the unliganded AhR complex in COS-1 and Hepa 1c1c7 cells. It was ubiquitously expressed in murine tissues at the protein and mRNA levels. It was not required for the assembly of an AhR-hsp90 complex in vitro. Additionally, XAP2 did not directly associate with hsp90 upon in vitro translation, but was present in a 9S form when cotranslated in vitro with murine AhR. XAP2 enhanced the ability of endogenous murine and human AhR complexes to activate a dioxin-responsive element–luciferase reporter twofold, following transient expression of XAP2 in Hepa 1c1c7 and HeLa cells.

scholarly journals Role of SIRT2 in Regulation of Stemness of Cancer Stem-Like Cells in Renal Cell Carcinoma

2018 ◽  
Vol 49 (6) ◽  
pp. 2348-2357 ◽  
Author(s):  
Ruojing Wei ◽  
Dalin He ◽  
Xinshi Zhang
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Renal Cell ◽  
Cancer Metastasis ◽  
Fluorescent Protein ◽  
Luciferase Reporter ◽  
Tumor Sphere ◽  
Bivariate Correlation ◽  
Induced Apoptosis

Background/Aims: Cancer stem cells (CSCs) contribute to tumorgenesis, invasion and metastasis, and are typically resistant to chemotherapy. Recent reports showed that SIRT2 was upregulated in several cancers. However, whether SIRT2 may be a CSC marker in renal cell carcinoma (RCC) is not clear. Methods: The SIRT2 levels in both RCC samples and the corresponding normal kidney samples (NT) were assessed by RT-qPCR and ELISA. The association between SIRT2 levels and patient survival was examined using Bivariate correlation analysis by Spearman’s Rank Correlation Coefficients. The survival of the patients was analyzed using Kaplan-Meier curve. In vitro, 2 RCC cell lines were co-transduced with a lentivirus expressing both a green fluorescent protein and a luciferase reporter under a cytomegalovirus promoter, and another lentivirus expressing a nuclear red fluorescent protein reporter under the control of a SIRT2 promoter for differentiating SIRT2+ vs SIRT2- RCC cells by flow cytometry. The SIRT2+ vs SIRT2- RCC cells were examined for the potential of forming tumor sphere in a tumor sphere formation assay, resistance to fluorouracil-induced apoptosis by CCK-8 assay, and the frequency of forming tumor in vivo after serial adoptive transplantation by bioluminescence. Results: The levels of SIRT2 were higher in RCC samples than NT. The prognosis of RCC patients with high SIRT2 was worse than that of with low SIRT2. Compared to SIRT2- cells, SIRT2+ cells formed more tumor spheres, appeared to be more resistant towards fluorouracil-induced apoptosis, and generated bigger tumors with higher frequency after serial adoptive transplantation. Conclusion: SIRT2 may be highly expressed in the RCC stem-like cells and regulates cancer metastasis. Selective knockout of SIRT2 or elimination of SIRT2+ cells may improve the therapeutic outcome for patients with RCC.

CircRNA circ-ERBB2 elevates Warburg effect and facilitates triple-negative breast cancer growth by the miR-136-5p/PDK4 axis

2021 ◽  
Author(s):  
Yihong Huang ◽  
Shuo Zheng ◽  
Ying Lin ◽  
Liming Ke
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Warburg Effect ◽  
Triple Negative ◽  
Pyruvate Dehydrogenase Kinase ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Loss Of Function

Triple negative breast cancer (TNBC) is an aggressive histological subtype of breast cancer. It has been reported that that circRNA circ-ERBB2 (circBase ID: hsa_circ_0007766) is mainly distributed in the cytoplasm of TNBC cells and promotes the proliferation and invasion of TNBC cells. This study aimed to explore the molecular mechanism of circ-ERBB2 regulating the progression of TNBC. Expression of circ-ERBB2 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Loss-of-function experiments were performed to investigate the function of circ-ERBB2 in TNBC cells in vitro and in vivo . The regulatory mechanism of circ-ERBB2 was surveyed by bioinformatics analysis, dual-luciferase reporter and RNA immunoprecipitation (RIP) or RNA pull-down assays. We observed that Circ-ERBB2 was overexpressed in TNBC, and TNBC patients with high circ-ERBB2 expression had a poor prognosis. Functionally, circ-ERBB2 knockdown constrained TNBC growth in vivo and reduced Warburg effect, accelerated apoptosis, repressed proliferation, migration, and invasion of TNBC cell in vitro . Mechanically, circ-ERBB2 sponged miR-136-5p to elevate pyruvate dehydrogenase kinase 4 (PDK4) expression. In conclusion, circ-ERBB2 facilitated Warburg effect and malignancy of TNBC cells by the miR-136-5p/PDK4 pathway, at least in part. This study supported circ-ERBB2 as a prognostic indicator for TNBC.

scholarly journals The Receptor for Parathyroid Hormone and Parathyroid Hormone-Related Peptide Is Hydrolyzed and Its Signaling Properties Are Altered by Directly Binding the Calpain Small Subunit

Endocrinology ◽  
2005 ◽  
Vol 146 (5) ◽  
pp. 2336-2344 ◽  
Author(s):  
Masako Shimada ◽  
Matthew J. Mahon ◽  
Peter A. Greer ◽  
Gino V. Segre
Keyword(s):  
Parathyroid Hormone ◽  
Fluorescent Protein ◽  
Yellow Fluorescent Protein ◽  
Small Subunit ◽  
Hek293 Cells ◽  
Calpain Inhibitor ◽  
Dependent Manner ◽  
Intact Cells ◽  
Calcium Dependent

Abstract We show calcium-dependent, direct binding between the N-terminal portion of the PTH/PTHrP receptor (PTH1R) C-terminal intracellular tail and the calpain small subunit. Binding requires, but may not be limited to, amino acids W474, S475, and W477. The wild-type, full-length rat (r) PTH1R, but not rPTH1R with W474A/W477A substitutions, copurifies with the endogenous calpain small subunit in HEK293 cells. Calpain hydrolyzes ΔNt-rPTH1R, a receptor with a 156-amino acid N-terminal deletion, in a calcium-dependent manner in vitro and in intact cells. Most importantly, PTH stimulation increases the cleavage of ΔNt-rPTH1R and rPTH1R-yellow fluorescent protein in HEK293 cells, and of talin in HEK293 cells expressing rPTH1R-yellow fluorescent protein and in ROS17/2.8 osteoblast-like cells that express rPTH1R endogenously. The absence of calpain in Capn4-null embryonic fibroblasts and the lowered calpain activity in MC3T3-E1 osteoblastic cells due to stable expression of the calpain inhibitor, calpastatin, reduce PTH-stimulated cAMP accumulation. The calpain small subunit is the second protein, in addition to the sodium-hydrogen exchanger regulatory factor, and the first enzyme that binds the PTH1R; PTH1R bound to both of these proteins results in altered PTH signaling.

Congenital Hypothyroidism Due to Truncating PAX8 Mutations: A Case Series and Molecular Function Studies

2020 ◽  
Vol 105 (11) ◽  
Author(s):  
Megumi Iwahashi-Odano ◽  
Keisuke Nagasaki ◽  
Maki Fukami ◽  
Junko Nishioka ◽  
Shuichi Yatsuga ◽  
...  
Keyword(s):  
Western Blotting ◽  
Congenital Hypothyroidism ◽  
Cultured Cells ◽  
Mutation Screening ◽  
Intracellular Localization ◽  
Functional Characterization ◽  
Case Series ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Paired Domain

Abstract Context PAX8 is a transcription factor required for thyroid development, and its mutation causes congenital hypothyroidism (CH). More than 20 experimentally verified loss-of-function PAX8 mutations have been described, and all but one were located in the DNA-binding paired domain. Objective We report the identification and functional characterization of 3 novel truncating PAX8 mutations located outside the paired domain. Methods Three CH probands, diagnosed in the frame of newborn screening, had thyroid hypoplasia and were treated with levothyroxine. Next-generation sequencing-based mutation screening was performed. Functionality of the identified mutations were verified with Western blotting, intracellular localization assays, and transactivation assays with use of HeLa cells. Luciferase complementation assays were used to evaluate the effect of mutations on the interaction between PAX8 and its partner, NKX2-1. Results Each proband had novel truncating PAX8 mutations that were I160Sfs*52, Q213Efs*27, and F342Rfs*85. Western blotting showed destabilization of the I160fs-PAX8 protein. Q213fs-PAX8 and F342fs-PAX8 showed normal protein expression levels and normal nuclear localization, but showed loss of transactivation of the luciferase reporter. By luciferase complementation assays, we showed that PAX8-NKX2-1 interaction was defective in Q213fs-PAX8. We also characterized the recombinant PAX8 proteins, and found that the protein sequence corresponding to exon 10 (363-400 aa residues) was essential for the PAX8-NKX2-1 interaction. Conclusions Clinical and molecular findings of 3 novel truncating PAX8 mutations located outside the paired domain were reported. Experiments using cultured cells and recombinant proteins showed that the C-terminal portion (ie, 363-400 aa) of PAX8 is required for the PAX8-NKX2-1 interaction.

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