scholarly journals IQD proteins integrate auxin and calcium signaling to regulate microtubule dynamics during Arabidopsis development

2018 ◽  
Author(s):  
Jos R. Wendrich ◽  
Bao-Jun Yang ◽  
Pieter Mijnhout ◽  
Hong-Wei Xue ◽  
Bert De Rybel ◽  
...  
Keyword(s):  
Calcium Signaling ◽  
Binding Proteins ◽  
Preprophase Band ◽  
Auxin Signaling ◽  
Dependent Manner ◽  
Regulatory Pathways ◽  
Calcium Dependent ◽  
Specific Effects

AbstractGeometry and growth and division direction of individual cells are major contributors to plant organ shape and these processes are dependent on dynamics of microtubules (MT). Different MT structures, like the cortical microtubules, preprophase band and mitotic spindle, are characterized by diverse architectural dynamics (Hashimoto, 2015). While several MT binding proteins have been identified that have various effects on MT stability and architecture, they do not discriminate between the different MT structures. It is therefore likely that specific MT binding proteins exist that differentiate between MT structures in order to allow for the differences in architectural dynamics. Although evidence for the effect of specific cues, such as light and auxin, on MT dynamics has been shown in recent years (Lindeboom et al., 2013; Chen et al., 2014), it remains unknown how such cues are integrated and lead to specific effects. Here we provide evidence for how auxin and calcium signaling can be integrated to modulate MT dynamics, by means of IQD proteins. We show that the Arabidopsis IQD15-18 subclade of this family is regulated by auxin signaling, can bind calmodulins in a calcium-dependent manner and are evolutionarily conserved. Furthermore, AtIQD15-18 directly bind SPIRAL2 protein in vitro and in vivo and modulate its function, likely in a calmodulin-dependent way, thereby providing a missing link between two important regulatory pathways of MT dynamics.One sentence summaryIQD proteins integrate auxin and calcium signaling, two major signaling pathways, to control the cytoskeleton dynamics and cell shape of Arabidopsis.

Reticulon 3-mediated Chk2/p53 activation suppresses hepatocellular carcinogenesis and is blocked by hepatitis B virus

Gut ◽  
2020 ◽  
pp. gutjnl-2020-321386
Author(s):  
Shushu Song ◽  
Yinghong Shi ◽  
Weicheng Wu ◽  
Hao Wu ◽  
Lei Chang ◽  
...  
Keyword(s):  
Cellular Proliferation ◽  
Dependent Manner ◽  
Mice Model ◽  
Calcium Dependent ◽  
B Virus ◽  
P53 Activation ◽  
Underlying Mechanisms ◽  
Induced Apoptosis

ObjectiveDysfunction of endoplasmic reticulum (ER) proteins is closely related to homeostasis disturbance and malignant transformation of hepatocellular carcinoma (HCC). Reticulons (RTN) are a family of ER-resident proteins critical for maintaining ER function. Nevertheless, the precise roles of RTN in HCC remain largely unclear. The aim of the study is to examine the effect of reticulon family member RTN3 on HCC development and explore the underlying mechanisms.DesignClinical HCC samples were collected to assess the relationship between RTN3 expression and patients’ outcome. HCC cell lines were employed to examine the effects of RTN3 on cellular proliferation, apoptosis and signal transduction in vitro. Nude mice model was used to detect the role of RTN3 in modulating tumour growth in vivo.ResultsWe found that RTN3 was highly expressed in normal hepatocytes but frequently downregulated in HCC. Low RTN3 expression predicted poor outcome in patients with HCC in TP53 gene mutation and HBV infection status-dependent manner. RTN3 restrained HCC growth and induced apoptosis by activating p53. Mechanism studies indicated that RTN3 facilitated p53 Ser392 phosphorylation via Chk2 and enhanced subsequent p53 nuclear localisation. RTN3 interacted with Chk2, recruited it to ER and promoted its activation in an ER calcium-dependent manner. Nevertheless, the tumour suppressive effects of RTN3 were abrogated in HBV-positive cells. HBV surface antigen competed with Chk2 for RTN3 binding and blocked RTN3-mediated Chk2/p53 activation.ConclusionThe findings suggest that RTN3 functions as a novel suppressor of HCC by activating Chk2/p53 pathway and provide more clues to better understand the oncogenic effects of HBV.

scholarly journals Annexin VI: an intracellular target for ATP.

1999 ◽  
Vol 46 (3) ◽  
pp. 801-812 ◽  
Author(s):  
J Bandorowicz-Pikuła ◽  
M Danieluk ◽  
A Wrzosek ◽  
R Buś ◽  
R Buchet ◽  
...  
Keyword(s):  
Nucleotide Binding ◽  
Dependent Manner ◽  
Amino Acid Residues ◽  
Binding Motifs ◽  
Calcium Dependent ◽  
Annexin Vi ◽  
Self Association ◽  
Nucleotide Binding Proteins

Annexin VI (AnxVI), an Ca2+- and phospholipid-binding protein, interacts in vitro with ATP in a calcium-dependent manner. Experimental evidence indicates that its nucleotide-binding domain which is localized in the C-terminal half of the protein differs structurally from ATP/GTP-binding motifs found in other nucleotide-binding proteins. The amino-acid residues of AnxVI directly involved in ATP binding have not been yet defined. Binding of ATP to AnxVI induces changes in the secondary and tertiary structures of protein, affecting the affinity of AnxVI for Ca2+ and, in consequence, influencing the Ca2+-dependent activities of AnxVI: binding to F-actin and to membranous phospholipids, and self-association of the annexin molecules. These observations suggest that ATP is a functional ligand for AnxVI in vivo, and ATP-sensitive AnxVI may play the role of a factor coupling vesicular transport and calcium homeostasis to cellular metabolism.

scholarly journals Apigenin Inhibits the Growth of Hepatocellular Carcinoma Cells by Affecting the Expression of microRNA Transcriptome

2021 ◽  
Vol 11 ◽  
Author(s):  
Shou-Mei Wang ◽  
Pei-Wei Yang ◽  
Xiao-Jun Feng ◽  
Yi-Wei Zhu ◽  
Feng-Jun Qiu ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Dependent Manner ◽  
Regulatory Pathways ◽  
The Core ◽  
Huh7 Cells

BackgroundApigenin, as a natural flavonoid, has low intrinsic toxicity and has potential pharmacological effects against hepatocellular carcinoma (HCC). However, the molecular mechanisms involving microRNAs (miRNAs) and their target genes regulated by apigenin in the treatment of HCC have not been addressed.ObjectiveIn this study, the molecular mechanisms of apigenin involved in the prevention and treatment of HCC were explored in vivo and in vitro using miRNA transcriptomic sequencing to determine the basis for the clinical applications of apigenin in the treatment of HCC.MethodsThe effects of apigenin on the proliferation, cell cycle progression, apoptosis, and invasion of human hepatoma cell line Huh7 and Hep3B were studied in vitro, and the effects on the tumorigenicity of Huh7 cells were assessed in vivo. Then, a differential expression analysis of miRNAs regulated by apigenin in Huh7 cells was performed using next-generation RNA sequencing and further validated by qRT-PCR. The potential genes targeted by the differentially expressed miRNAs were identified using a curated miRTarBase miRNA database and their molecular functions were predicted using Gene Ontology and KEGG signaling pathway analysis.ResultsCompared with the control treatment group, apigenin significantly inhibited Huh7 cell proliferation, cell cycle, colony formation, and cell invasion in a concentration-dependent manner. Moreover, apigenin reduced tumor growth, promoted tumor cell necrosis, reduced the expression of Ki67, and increased the expression of Bax and Bcl-2 in the xenograft tumors of Huh7 cells. Bioinformatics analysis of the miRNA transcriptome showed that hsa-miR-24, hsa-miR-6769b-3p, hsa-miR-6836-3p, hsa-miR-199a-3p, hsa-miR-663a, hsa-miR-4739, hsa-miR-6892-3p, hsa-miR-7107-5p, hsa-miR-1273g-3p, hsa-miR-1343, and hsa-miR-6089 were the most significantly up-regulated miRNAs, and their key gene targets were MAPK1, PIK3CD, HRAS, CCND1, CDKN1A, E2F2, etc. The core regulatory pathways of the up-regulated miRNAs were associated with the hepatocellular carcinoma pathway. The down-regulated miRNAs were hsa-miR-181a-5p and hsa-miR-148a-3p, and the key target genes were MAPK1, HRAS, STAT3, FOS, BCL2, SMAD2, PPP3CA, IFNG, MET, and VAV2, with the core regulatory pathways identified as proteoglycans in cancer pathway.ConclusionApigenin can inhibit the growth of HCC cells, which may be mediated by up-regulation or down-regulation of miRNA molecules and their related target genes.

scholarly journals miR-17~92 exerts stage-specific effects in adult V-SVZ neural stem cell lineages

2021 ◽  
Author(s):  
Fabrizio Favaloro ◽  
Annina DeLeo ◽  
Ana Delgado ◽  
Fiona Doetsch
Keyword(s):  
Stem Cell ◽  
Neural Stem Cell ◽  
Oligodendrocyte Progenitor Cells ◽  
Dependent Manner ◽  
Cell Lineages ◽  
Conditional Deletion ◽  
Specific Effects ◽  
Cell Type Specific

In the adult mouse brain, neural stem cells (NSCs) in the ventricular-subventricular zone (V-SVZ) generate neurons and glia throughout life. microRNAs are important regulators of cell states, frequently acting in a stage- or context-dependent manner. Here, miRNA profiling of FACS-purified populations identified miR-17~92 as highly upregulated in activated NSCs and transit amplifying cells (TACs) in comparison to quiescent NSCs. Conditional deletion of miR-17~92 in NSCs reduced stem cell proliferation both in vitro and in vivo. In contrast, in TACs, miR-17~92 deletion caused a selective shift from neurogenic DLX2+ TACs towards oligodendrogenic OLIG2+ TACs, resulting in increased oligodendrogenesis to the corpus callosum. miR-17~92 deletion also decreased proliferation and maturation of intraventricular oligodendrocyte progenitor cells. Together, these findings reveal stage- and cell-type- specific functions of the miR-17~92 cluster within adult V-SVZ neural stem cell lineages.

scholarly journals Collectin Kidney 1 Plays an Important Role in Innate Immunity against Streptococcus pneumoniae Infection

2017 ◽  
Vol 9 (2) ◽  
pp. 217-228 ◽  
Author(s):  
Insu Hwang ◽  
Kenichiro Mori ◽  
Katsuki Ohtani ◽  
Yasuyuki Matsuda ◽  
Nitai Roy ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Streptococcus Pneumoniae ◽  
Pulmonary Inflammation ◽  
Dependent Manner ◽  
Complement Pathway ◽  
Calcium Dependent ◽  
Host Protection ◽  
In The Wild

Collectins are C-type lectins that are involved in innate immunity as pattern recognition molecules. Recently, collectin kidney 1 (CL-K1) has been discovered, and in vitro studies have shown that CL-K1 binds to microbes and activates the lectin complement pathway. However, in vivo functions of CL-K1 against microbes have not been elucidated. To investigate the biological functions of CL-K1, we generated CL-K1 knockout (CL-K1-/-) mice and then performed a Streptococcus pneumoniae infection analysis. First, we found that recombinant human CL-K1 bound to S. pneumoniae in a calcium-dependent manner, and induced complement activation. CL-K1-/- mice sera formed less C3 deposition on S. pneumoniae. Furthermore, immunofluorescence analysis in the wild-type (WT) mice demonstrated that CL-K1 and C3 were localized on S. pneumoniae in infected lungs. CL-K1-/- mice revealed decreased phagocytosis of S. pneumoniae. Consequently, less S. pneumoniae clearance was observed in their lungs. CL-K1-/- mice showed severe pulmonary inflammation and weight loss in comparison with WT mice. Finally, the decreased clearance and severe pulmonary inflammation caused by S. pneumoniae infection might cause higher CL-K1-/- mice lethality. Our results suggest that CL-K1 might play an important role in host protection against S. pneumoniae infection through the activation of the lectin complement pathway.

scholarly journals Essential role of CIB1 in regulating PAK1 activation and cell migration

2005 ◽  
Vol 170 (3) ◽  
pp. 465-476 ◽  
Author(s):  
Tina M. Leisner ◽  
Mingjuan Liu ◽  
Zahara M. Jaffer ◽  
Jonathan Chernoff ◽  
Leslie V. Parise
Keyword(s):  
Cell Migration ◽  
Specific Interaction ◽  
Dependent Manner ◽  
Lim Kinase ◽  
Calcium Dependent ◽  
Cellular Processes ◽  
Cofilin Phosphorylation ◽  
Pak1 Activation

p21-activated kinases (PAKs) regulate many cellular processes, including cytoskeletal rearrangement and cell migration. In this study, we report a direct and specific interaction of PAK1 with a 22-kD Ca2+-binding protein, CIB1, which results in PAK1 activation both in vitro and in vivo. CIB1 binds to PAK1 within discrete regions surrounding the inhibitory switch domain in a calcium-dependent manner, providing a potential mechanism of CIB1-induced PAK1 activation. CIB1 overexpression significantly decreases cell migration on fibronectin as a result of a PAK1-and LIM kinase–dependent increase in cofilin phosphorylation. Conversely, the RNA interference–mediated depletion of CIB1 increases cell migration and reduces normal adhesion-induced PAK1 activation and cofilin phosphorylation. Together, these results demonstrate that endogenous CIB1 is required for regulated adhesion-induced PAK1 activation and preferentially induces a PAK1-dependent pathway that can negatively regulate cell migration. These results point to CIB1 as a key regulator of PAK1 activation and signaling.

scholarly journals Flagellar Radial Spoke Protein 2 Is a Calmodulin Binding Protein Required for Motility in Chlamydomonas reinhardtii

2004 ◽  
Vol 3 (1) ◽  
pp. 72-81 ◽  
Author(s):  
Pinfen Yang ◽  
Chun Yang ◽  
Winfield S. Sale
Keyword(s):  
Calcium Binding ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Radial Spoke ◽  
Calcium Dependent ◽  
Calmodulin Binding ◽  
Morphological Studies ◽  
Radial Spokes

ABSTRACT Genetic and morphological studies have revealed that the radial spokes regulate ciliary and flagellar bending. Functional and biochemical analysis and the discovery of calmodulin in the radial spokes suggest that the regulatory mechanism involves control of axonemal protein phosphorylation and calcium binding to spoke proteins. To identify potential regulatory proteins in the radial spoke, in-gel kinase assays were performed on isolated axonemes and radial spoke fractions. The results indicated that radial spoke protein 2 (RSP2) can bind ATP and transfer phosphate in vitro. RSP2 was cloned and mapped to the PF24 locus, a gene required for motility. Sequencing revealed that pf24 contains a point mutation converting the first ATG to ATA, resulting in only trace amounts of RSP2 and confirming the RSP2 mapping. Surprisingly, the sequence does not include signature domains for conventional kinases, indicating that RSP2 may not perform as a protein kinase in vivo. However, the predicted RSP2 protein sequence contains Ca2+-dependent calmodulin binding motifs and a GAF domain, a domain found in diverse signaling proteins for binding small ligands including cyclic nucleotides. As predicted from the sequence, recombinant RSP2 binds calmodulin in a calcium-dependent manner. We postulate that RSP2 is a regulatory subunit of the radial spoke involved in localization of calmodulin for control of motility.

scholarly journals Adenosine 5'-triphosphate--a new regulator of annexin function. A hypothesis.

1998 ◽  
Vol 45 (3) ◽  
pp. 735-744
Author(s):  
J Bandorowicz-Pikuła ◽  
S Pikuła
Keyword(s):  
Binding Motif ◽  
Dependent Manner ◽  
In Vitro Activity ◽  
Consensus Sequences ◽  
Calcium Dependent ◽  
Gtp Binding ◽  
Integral Proteins

The paradigm of annexins as phospholipid-binding proteins interacting with membranes in a calcium-dependent manner has been recently questioned in light of observations that some annexin isoforms may behave like membrane integral proteins or remain associated with their target membranes at low, resting, concentrations of Ca2+ in the cytoplasm. In addition, an evidence has been presented that some annexins (annexins I, VI and VII) bind in vitro ATP and GTP, and upon binding the nucleotide the in vitro activity of these proteins is modified. However, annexins do not contain Walker A and B consensus sequences for ATP/GTP binding. This review presents the hypothesis that a new ATP-binding motif exists within the annexin molecules and that ATP may play a role of functional ligand for annexins also in vivo.

scholarly journals Annexin A5 Is Not Essential for Skeletal Development

2003 ◽  
Vol 23 (8) ◽  
pp. 2907-2913 ◽  
Author(s):  
Bent Brachvogel ◽  
Jörg Dikschas ◽  
Helga Moch ◽  
Heike Welzel ◽  
Klaus von der Mark ◽  
...  
Keyword(s):  
Skeletal Development ◽  
Structural Similarity ◽  
Annexin A5 ◽  
Dependent Manner ◽  
Calcium Dependent ◽  
Expression Studies ◽  
Compensatory Effect

ABSTRACT Annexins are highly conserved proteins that are characterized by their ability to interact with phospholipids in a calcium-dependent manner. Although diverse functions have been ascribed to annexins based on in vitro analyses, their in vivo functions still remain unclear. The intensively studied annexin A5 has been identified by its effects on blood coagulation, and subsequently, its function as a calcium-specific ion channel was described. In vitro experiments and expression studies suggested a potential role of annexin A5 during calcification processes in vivo, especially in endochondral ossification. To gain insights into the relevance of annexin A5 in this process, we generated an annexin A5-deficient mouse mutant. Mice lacking annexin A5 are viable, are fertile, and reveal no significant alterations in the biochemical parameters characteristic for metabolic or functional defects. Neither the development of skeletal elements nor the in vitro calcification properties of isolated chondrocytes is significantly impaired by the absence of annexin A5. Therefore, annexin A5 is dispensable for the formation and maintenance of skeletal elements in the mouse and may possibly be pointing to a compensatory effect of other members from the annexin family due to their high functional and structural similarity.

Calbindin-D28K acts as a calcium-dependent chaperone suppressing α-synuclein fibrillation in vitro

2010 ◽  
Vol 5 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Wenbo Zhou ◽  
Chunmei Long ◽  
Anthony Fink ◽  
Vladimir Uversky
Keyword(s):  
Neuronal Membrane ◽  
Dependent Manner ◽  
Calcium Dependent ◽  
Unfolded Protein ◽  
Natively Unfolded Protein ◽  
Calbindin D28k ◽  
Natively Unfolded ◽  
Membrane Pumps

Abstractα-Synuclein, a natively unfolded protein aggregation which is implicated in the pathogenesis of Parkinson’s disease and several other neurodegenerative diseases, is known to interact with a great number of unrelated proteins. Some of these proteins, such as β-synuclein and DJ-1, were shown to inhibit α-synuclein aggregation in vitro and in vivo therefore acting as chaperones. Since calbindin-D28K is co-localized with Ca2+ neuronal membrane pumps, and since α-synuclein is also found in the membrane proximity, these two proteins can potentially interact in vivo. Here we show that calbindin-D28K interacts with α-synuclein and inhibits its fibrillation in a calcium-dependent manner, therefore potentially acting as a calcium-dependent chaperone.

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