scholarly journals The role of the linker between the SH2 domain and catalytic domain in the regulation and function of Src

1997 ◽  
Vol 16 (24) ◽  
pp. 7261-7271 ◽  
Author(s):  
S. Gonfloni
Keyword(s):  
Catalytic Domain ◽  
Sh2 Domain ◽  
And Function

Abnormal Expression and Function of the Lnk Adaptor Protein in Myeloproliferative Neoplasms (MPN).

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2897-2897
Author(s):  
Jean-Jacques Kiladjian ◽  
Fanny Baran-Marszak ◽  
Christophe Desterke ◽  
Bruno Cassinat ◽  
Hajer Magdoud ◽  
...  
Keyword(s):  
Cell Lines ◽  
Adaptor Protein ◽  
Sh2 Domain ◽  
Terminal Region ◽  
Interaction Site ◽  
Cd34 Cells ◽  
And Function ◽  
Mutant Forms ◽  
Jak2v617f Allele Burden

Abstract Abstract 2897 Poster Board II-873 Introduction: We have shown in a deficient mouse model that the adaptor protein Lnk had an important role as negative regulator of cytokine signaling during hematopoiesis (Velazquez et al., J. Exp Med 2002). Lnk-/- animals display abnormal megakaryopoiesis sharing many features with that found in MPN patients. This phenotype is due to loss of Lnk inhibition of thrombopoietin (TPO)-mediated JAK2 activation (Tong et al., J Exp Med 2004). Recent studies have shown that Lnk, when expressed in hematopoietic cell lines, could bind and regulate two mutant proteins found in MPNs, JAK2V617F and MPLW515L. However, the role of Lnk in MPN pathogenesis is still unclear. In the present study, we studied in detail both Lnk expression and function in MPNs. Patients and methods: The study included a total of 82 MPN patients (pts), including 41 essential thrombocytemia (ET), 29 polycythemia vera (PV) and 12 primary myelofibrosis (PMF). Lnk expression was assessed by quantitative RT-PCR. Biochemical and cellular analyses of Lnk and JAK2 interaction were carried out using co-immunoprecipitation, GST pull-down and proliferation assays on primary hematopoietic cells and cell lines expressing either wild-type (WT) or mutant forms of both Lnk and JAK2. Results: Lnk mRNA was clearly overexpressed in platelets and CD34+ cells of most MPN pts compared to controls (P=0.005 and P=0.03, respectively). Moreover, this increased Lnk expression strongly correlated with JAK2V617F allele burden (P=0.02). In contrast, Lnk mRNA levels were reduced in the 18 pts treated with interferon-α compared to the 34 pts treated with hydroxyurea (P=0.04). TPO specifically upregulated Lnk expression at both mRNA and protein levels in both primary and UT7/Mpl megakaryocytic (MK) cells. Analysis of TPO-stimulated platelets from ET patients revealed the existence of a new interaction site between Lnk and JAK2 located in the N-terminal region of Lnk, in addition to the previously known interaction mediated by Lnk SH2 domain. This interaction resulted in Lnk phosphorylation. In JAK2V617F expressing platelets or cell lines, we observed both increased phosphorylation of Lnk, and stronger binding of JAK2 to the N-terminal region of Lnk compared to WT-JAK2 cells. Overexpression of Lnk in JAK2V617F cells showed a dose dependent growth inhibition, as seen in JAK2 WT cells. In addition, overexpression of various mutant forms of Lnk showed that this inhibition required a fully functional SH2 domain. Finally, expression of either WT or mutant forms of Lnk also demonstrated the crucial role of Lnk SH2 domain in growth inhibition of myeloid and MK progenitors in Lnk-/- hematopoietic cells. Conclusion: This first study of a large cohort of 82 patients allowed us to investigate the role of Lnk in MPN: (1) Lnk mRNA was found to be significantly overexpressed in MPN derived platelets and CD34+ cells, and correlated with JAK2V617F allele burden. (2) Lnk expression is upregulated by TPO, an effect likely mediated by JAK2 activation. (3) The Lnk SH2 domain plays a major role in the down-regulation of both normal and MPN-derived hematopoiesis. (4) We describe here a novel interaction site between the N-terminal region of Lnk and JAK2. Stronger interaction of the JAK2V617F mutant form with this N-terminal binding site may account for the dysregulated hematopoiesis observed in MPN patients despite Lnk overexpression. Disclosures: No relevant conflicts of interest to declare.

Abstract P108: Circulating Matrix Metalloproteinase-2 Invades the Heart and Causes Heart Failure

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Alejandro F Prado ◽  
Aline Azevedo ◽  
Cibele M Prado ◽  
Larissa Pernomian ◽  
Laena Pernomian ◽  
...  
Keyword(s):  
Heart Failure ◽  
Catalytic Domain ◽  
Heart Function ◽  
Matrix Metalloproteinase 2 ◽  
Saline Control ◽  
Function Loss ◽  
And Function ◽  
Tgf Β1

Background: An increase in MMP-2 levels is reported in heart failure (HF). However the role of MMP-2 in the pathogenesis of HF remains unclear. The aim of the present study was to determine the effect of increased circulating levels of MMP-2 on heart morphology and function. Methods and Results: Purified MMP-2 catalytic domain fused to GFP (catMMP-2/GFP) or saline (control) was injected into 11-wk-old male C57BL/6 mice for four weeks. The fluorescent active protein was tracked in vivo and homed in the heart. Cardiomyocyte diameter not changed between groups (catMMP-2/GFP: 11.37 ± 0.25 μm, n=7; Control: 11.38 ± 0.13 μm, n=7; P =0.97). On the other hand, fibrosis increased in the hearts of catMMP-2/GFP mice (0.82 ± 0.05% area/field, n=7 vs Control: 0.58 ± 0.02% area/field, n=7; P< 0.05). Apoptotic stained nuclei in the left ventricle (LV) of catMMP-2/GFP injected-mice amounted to 7.24%, n=4, P<0,05, whilst the LV of control animals only exhibited 0.27%, n=4. catMMP-2/GFP localized in the heart interstitium, where increased proteolytic activity (15.13 ± 1.33 U, n=5 vs Control: 9.70 ± 0.42 U, n=5; P <0.05). Hearts of catMMP-2/GFP mice showed 25% decrease in cardiac output (13 ± 1 mL/min, n=9 vs Control: 17 ± 1 mL/min, n=9), 30% decrease in ejection fraction (40 ± 2 %, n=9 vs Control: 56 ± 2 %, n=9) and stroke volume (28 ± 2 μL, n=9 vs Control: 40 ± 2 μL, n=9), and 34% decrease in fractional shortening (18 ± 1 %, n=9 vs Control: 28 ± 1 %, n=9) ( P <0.05 for all data).Western blotting showed 40% decrease in N-cadherin in animals that received catMMP-2/GFP (0.53 ± 0.08 U, n=6 vs control: 0.89 ± 0.11 U, n=6; P <0.05). Expression of signaling proteins also changed in LV of catMMP-2/GFP mice: TGF-β1 expression increased by 30% (0.60 ± 0.07 U, n=7 vs control: 0.40 ± 0.05 U, n=7, P<0,05), pAkt/Akt decreased by 40% (0.46 ± 0.05 U, n=7 vs control: 0.76 ± 0.11 U, n=7; P <0.05), pSMAD2/total SMAD2 ratio increased (1.88 ± 0.22 U, n=6 vs control: 0.93±0.12 U, n=6, P<0,05), and pSMAD3/total SMAD3 ratio increased (1.24 ± 0.22 U, n=7 vs control: 0.33 ± 0.07 U, n=7; P <0.05). Conclusions: Circulating active MMP-2 homing to the heart interstitium degrades N-cadherin and induces TGF-β1 overexpression, leading to apoptosis, and fibrosis. This mechanism may account for heart function loss when plasma levels of MMP-2 increase.

scholarly journals Structure of Mycobacterium tuberculosis Cya, an evolutionary ancestor of the mammalian membrane adenylyl cyclases

2021 ◽  
Author(s):  
Ved Mehta ◽  
Basavraj Khanppnavar ◽  
Dina Schuster ◽  
Irene Vercellino ◽  
Angela Kosturanova ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Catalytic Activity ◽  
Adenylyl Cyclase ◽  
Catalytic Domain ◽  
Transmembrane Domain ◽  
Vital Role ◽  
Cytosolic Side ◽  
Tm Domain ◽  
And Function

AbstractMycobacterium tuberculosis adenylyl cyclase (AC) Cya is an evolutionary ancestor of the mammalian membrane ACs and a model system for studies of their structure and function. Although the vital role of ACs in cellular signaling is well established, the function of their transmembrane (TM) regions remains unknown. Here we describe the cryo-EM structure of Cya bound to a stabilizing nanobody at 3.6 Å resolution. The TM helices 1-5 form a structurally conserved domain that facilitates the assembly of the helical and catalytic domains. The TM region contains discrete pockets accessible from the extracellular and cytosolic side of the membrane. Neutralization of the negatively charged extracellular pocket Ex1 destabilizes the cytosolic helical domain and reduces the catalytic activity of the enzyme. The TM domain acts as a functional component of Cya, guiding the assembly of the catalytic domain and providing the means for direct regulation of catalytic activity in response to extracellular ligands.One-Sentence SummaryCryo-EM structure of M. tuberculosis adenylyl cyclase Cya provides clues to the role of its transmembrane domain

scholarly journals Role of tryptophan residues of Erv1: Trp95 and Trp183 are important for its folding and oxidase function

2015 ◽  
Vol 35 (4) ◽  
Author(s):  
Qi Wang ◽  
Swee Kim Ang ◽  
Efrain Ceh-Pavia ◽  
Jiayun Pang ◽  
Hui Lu
Keyword(s):  
Catalytic Domain ◽  
Tryptophan Residues ◽  
And Function ◽  
Fad Binding

Erv1 (essential for respiration and viability 1) is a FAD-dependent sulphydryl oxidase with a tryptophan-rich catalytic domain. We show that Trp95 and Trp183 are important for stabilizing the folding, FAD-binding, and function of Erv1, whilst other four tryptophan residues are not functionally important.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

POPDC proteins and cardiac function

2019 ◽  
Vol 47 (5) ◽  
pp. 1393-1404 ◽  
Author(s):  
Thomas Brand
Keyword(s):  
Potential Role ◽  
Striated Muscle ◽  
Short Review ◽  
Effector Proteins ◽  
Muscle Disease ◽  
Disease Genes ◽  
Protein Protein Interaction ◽  
Interaction Partners ◽  
And Function

Abstract The Popeye domain-containing gene family encodes a novel class of cAMP effector proteins in striated muscle tissue. In this short review, we first introduce the protein family and discuss their structure and function with an emphasis on their role in cyclic AMP signalling. Another focus of this review is the recently discovered role of POPDC genes as striated muscle disease genes, which have been associated with cardiac arrhythmia and muscular dystrophy. The pathological phenotypes observed in patients will be compared with phenotypes present in null and knockin mutations in zebrafish and mouse. A number of protein–protein interaction partners have been discovered and the potential role of POPDC proteins to control the subcellular localization and function of these interacting proteins will be discussed. Finally, we outline several areas, where research is urgently needed.

Role of the 807 C/T Polymorphism of the α2 Gene in Platelet GP Ia Collagen Receptor Expression and Function

1999 ◽  
Vol 81 (06) ◽  
pp. 951-956 ◽  
Author(s):  
J. Corral ◽  
R. González-Conejero ◽  
J. Rivera ◽  
F. Ortuño ◽  
P. Aparicio ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Cell Types ◽  
Receptor Expression ◽  
Case Control Studies ◽  
Platelet Surface ◽  
Vitro Analysis ◽  
And Function ◽  
In Vitro Analysis

SummaryThe variability of the platelet GP Ia/IIa density has been associated with the 807 C/T polymorphism (Phe 224) of the GP Ia gene in American Caucasian population. We have investigated the genotype and allelic frequencies of this polymorphism in Spanish Caucasians. The T allele was found in 35% of the 284 blood donors analyzed. We confirmed in 159 healthy subjects a significant association between the 807 C/T polymorphism and the platelet GP Ia density. The T allele correlated with high number of GP Ia molecules on platelet surface. In addition, we observed a similar association of this polymorphism with the expression of this protein in other blood cell types. The platelet responsiveness to collagen was determined by “in vitro” analysis of the platelet activation and aggregation response. We found no significant differences in these functional platelet parameters according to the 807 C/T genotype. Finally, results from 3 case/control studies involving 302 consecutive patients (101 with coronary heart disease, 104 with cerebrovascular disease and 97 with deep venous thrombosis) determined that the 807 C/T polymorphism of the GP Ia gene does not represent a risk factor for arterial or venous thrombosis.

Von Willebrand disease and Weibel-Palade bodies

2010 ◽  
Vol 30 (03) ◽  
pp. 150-155 ◽  
Author(s):  
J. W. Wang ◽  
J. Eikenboom
Keyword(s):  
Platelet Adhesion ◽  
Coagulation Factor ◽  
Von Willebrand Disease ◽  
Inflammatory Factors ◽  
Limited Data ◽  
Storage Organelle ◽  
And Function ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryVon Willebrand factor (VWF) is a pivotal haemostatic protein mediating platelet adhesion to injured endothelium and carrying coagulation factor VIII (FVIII) in the circulation to protect it from premature clearance. Apart from the roles in haemostasis, VWF drives the formation of the endothelial cell specific Weibel-Palade bodies (WPBs), which serve as a regulated storage of VWF and other thrombotic and inflammatory factors. Defects in VWF could lead to the bleeding disorder von Willebrand disease (VWD).Extensive studies have shown that several mutations identified in VWD patients cause an intracellular retention of VWF. However, the effects of such mutations on the formation and function of its storage organelle are largely unknown. This review gives an overview on the role of VWF in WPB biogenesis and summarizes the limited data on the WPBs formed by VWD-causing mutant VWF.

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