Physical and functional characterization of the genetic locus of IBtk, an inhibitor of Bruton's tyrosine kinase: evidence for three protein isoforms of IBtk

Spatuzza, Carmen; Schiavone, Marco; Salle, Emanuela Di; Janda, Elżbieta; Sardiello, Marco; Fiume, Giuseppe; Fierro, Olga; Simonetta, Marco; Argiriou, Anagnostis; Faraonio, Raffaella; Capparelli, Rosanna; Quinto, Ileana; Scala, Giuseppe

doi:10.1093/nar/gkn413

Cited by 28 publications

(37 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…GST-IBtk␥ and His-IBtk␥ were produced in bacteria and purified as previously described 28,29 ; further details are reported in supplemental Data.…”

Section: Production Of Ibtk␥ Recombinant Proteinsmentioning

confidence: 99%

“…28 We have recently reported the physical and functional analysis of the IBTK locus, which encodes for the IBtk isoforms ␣, ␤, and ␥. 29 IBtk␣ (150.53 kDa) and IBtk␤ (133.87 kDa) are ubiquitous and might exert regulatory functions beyond the Btk regulation by associating with other proteins. 29 IBtk␥ (26.31 kDa), which was the first identified isoform, 28 arises from an independent promoter included within the intron 24 of the IBTK gene, resulting in a 240-amino acid protein.…”

Section: Introductionmentioning

confidence: 99%

“…29 IBtk␥ (26.31 kDa), which was the first identified isoform, 28 arises from an independent promoter included within the intron 24 of the IBTK gene, resulting in a 240-amino acid protein. 29 IBtk␥ is mainly expressed in hematopoietic cells 28,29 and might play a major role in Btk-mediated regulation of B cells by competing for the binding of Btk-PH-SH2 domain to other signaling molecules, such as BLNK, PIP 3 , and PIP5K.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ

Janda

Palmieri

Pisano

et al. 2011

Blood

Self Cite

View full text Add to dashboard Cite

The inhibitor of Bruton tyrosine kinase ␥ (IBtk␥) is a negative regulator of the Bruton tyrosine kinase (Btk), which plays a major role in B-cell differentiation; however, the mechanisms of IBtk␥-mediated regulation of Btk are unknown. Here we report that B-cell receptor (BCR) triggering caused serine-phosphorylation of IBtk␥ at protein kinase C consensus sites and dissociation from Btk. By liquid chromatography and mass-mass spectrometry and functional analysis, we identified IBtk␥-S87 and -S90 as the critical amino acid residues that regulate the IBtk␥ binding affinity to Btk. Consistently, the mutants IBtk␥ carrying S87A and S90A mutations bound constitutively to Btk and down-regulated Ca 2؉ IntroductionBruton tyrosine kinase (Btk) is a member of the Tec family of nonreceptor protein tyrosine kinases and is expressed in B cells, macrophages, and neutrophils. 1 Btk sustains the developmental program of pre-B cells by limiting the pre-B cell expansion and by promoting B-cell differentiation. 1,2 Consistently, mutations of BTK cause the human X-linked agammaglobulinemia and the murine X-linked immunodeficiency syndromes, which are characterized by increased susceptibility to recurrent bacterial infections as a consequence of the impaired generation of mature B cells and low production of immunoglobulin. 3,4 Btk is a crucial component of the immunoglobulin B-cell receptor (BCR) signaling pathway. Evidence from 5 indicates that Btk is required for a proper tyrosine phosphorylation of phospholipase C-␥ (PLC-␥), which in turn leads to inositol-3,4,5-triphosphate, a major mediator of [Ca 2ϩ ]i mobilization, and to diacylglycerol, an activator of protein kinase C (PKC). 6 These pathways activate specific transcription factors, including NF-B, 7,8 which regulate the gene transcription program required for B-cell survival and cell-cycle progression. Accordingly, DT40 Btk Ϫ/Ϫ chicken B cells show a drastic decrease in Ca 2ϩ signaling and NF-B activation on antigen stimulation, 9 and Btk Ϫ/Ϫ mice have a significant reduction of B cells. 10,11 Btk harbors the Pleckstrin homology domain (PH) and the Src homology domain 2 (SH2) and SH3, suggesting that its regulation occurs through protein-protein interaction. 12 The PH domain mediates the binding of Btk to phosphatidylinositol-(3,4,5)-trisphosphate (PIP 3 ) resulting in the recruitment of Btk to the plasma membrane. 13 The kinase activity of Btk is up-regulated by the Src-mediated phosphorylation of Y551 at the activation loop of the Btk kinase domain and by autophosphorylation of Y223 in the Src homology domain 3, 14,15 whereas it is inactivated by the PKC␤-mediated phosphorylation of S180. 16 Genetic evidence indicates that Syk, BLNK, and Btk are all required for the full activation of PLC␥ and Ca 2ϩ signaling on BCR triggering, [17][18][19][20] which suggests the occurrence of a multimolecular complex for PLC␥ activation. 21,22 In this scenario, it was proposed that the BCR triggering causes the Syk-mediated tyrosine phosphorylation of the signaling adaptor BLNK, w...

show abstract

“…GST-IBtk␥ and His-IBtk␥ were produced in bacteria and purified as previously described 28,29 ; further details are reported in supplemental Data.…”

Section: Production Of Ibtk␥ Recombinant Proteinsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ

Janda

Palmieri

Pisano

et al. 2011

Blood

Self Cite

View full text Add to dashboard Cite

show abstract

“…Total RNA extraction and qRT-PCR were performed as previously described. 35 Briefly, RNA aliquots (1 µg) were reverse transcribed using Random Examers and Superscript IV Reverse Transcriptase (Thermo Fisher Scientific), according to the manufacturer's protocol. qRT-PCR was carried out with the Quantstudio 7 Flex RealTime PCR system (Thermo Fisher Scientific) and PowerUp SYBR Green Master Mix (Thermo Fisher Scientific) under the following conditions: 50°C, 2 min; 95°C, 2 min; (95°C, 15 s; 60°C, 60 s) ×40.…”

mentioning

confidence: 99%

Nanoparticle-based strategy for personalized B-cell lymphoma therapy

Martucci¹,

Migliaccio²,

Ruggiero³

et al. 2016

IJN

View full text Add to dashboard Cite

B-cell lymphoma is associated with incomplete response to treatment, and the development of effective strategies targeting this disease remains challenging. A new personalized B-cell lymphoma therapy, based on a site-specific receptor-mediated drug delivery system, was developed in this study. Specifically, natural silica-based nanoparticles (diatomite) were modified to actively target the antiapoptotic factor B-cell lymphoma/leukemia 2 (Bcl2) with small interfering RNA (siRNA). An idiotype-specific peptide (Id-peptide) specifically recognized by the hypervariable region of surface immunoglobulin B-cell receptor was exploited as a homing device to ensure specific targeting of lymphoma cells. Specific nanoparticle uptake, driven by the Id-peptide, was evaluated by flow cytometry and confocal microscopy and was increased by approximately threefold in target cells compared with nonspecific myeloma cells and when a random control peptide was used instead of Id-peptide. The specific internalization efficiency was increased by fourfold when siRNA was also added to the modified nanoparticles. The modified diatomite particles were not cytotoxic and their effectiveness in downregulation of gene expression was explored using siRNA targeting Bcl2 and evaluated by quantitative real-time polymerase chain reaction and Western blot analyses. The resulting gene silencing observed is of significant biological importance and opens new possibilities for the personalized treatment of lymphomas

show abstract

“…IBTK regulates the activity of Bruton's tyrosine kinase (BTK), which is required for B-cell development in humans and mice (Spatuzza et al, 2008). Progenitor B cells transform into mature B cells and lead to the production of different immunoglobulins: IgG, IgM, IgA, IgD, and IgE.…”

Section: Genome-wide Association Studymentioning

confidence: 99%

Genetics of equine insect bite hypersensitivity and genetic diversity in horses

Shrestha¹

View full text Add to dashboard Cite

Genetic variation contributing to the phenotypic variation was utilized in this thesis to understand the genetic background of a complex trait IBH, and to understand genetic diversity and relationships between various horse populations.IBH is the most common skin allergic disorder in horses, caused by bites of midges, predominantly Culicoides species. It affects various horse breeds worldwide. With no effective treatment, IBH degrades horse health and causes economic loss. In this thesis, we used genome-wide SNPs to identify regions contributing to genetic variance of IBH susceptibility. We also investigated influence of increased number of horses and dense SNPs on identification of genomic regions associated to IBH susceptibility. Multiple genomic regions with small effects were observed in Studies I-III. Interesting genomic regions in the Icelandic horse population across the studies I and II, was observed on chromosomes 1, 7, 10, 15 and 17. The percentage of the genetic variance explained by top ten windows increased from 3.07% (Study I) to 6.56% (Study II). Novel genomic regions were identified when number of Icelandic horses was increased in Study II. Using dense SNPs on the Exmoor pony population we identified novel genomic regions, on chr 8, associated to IBH susceptibility, though with borderline significance.In Study IV, pre-conceived understanding about evolutionary history of horse populations matched obtained results from investigation of genetic relationships within Dutch warmblood populations (pairwise mean FST ≤ 0.070), and within pony-like populations (pairwise mean FST ≤ 0.078). Horse populations with similar genetic background might share similar genetic components for IBH susceptibility. The Friesian horse population had lowest diversity (mean inbreeding coefficients: fi: 30.4%, fiROH= 22.2%) in Study IV and was genetically distinct (FST ranged from 0.13 to 0.17). This might be a result of a history of several population bottlenecks and selection on a closed breeding scheme. Low diversity in immunity related genes, observed in the Friesian horse population, might have led to increased prevalence of IBH. Similarly, low susceptibility of IBH in a warmblood population, KWPN sport horse population might be due to high genetic diversity ( i f =-6.9%). High genetic diversity in KWPN sport horse population might be a result of an open breeding scheme and interbreeding with other warmblood populations.

show abstract

Physical and functional characterization of the genetic locus of IBtk, an inhibitor of Bruton's tyrosine kinase: evidence for three protein isoforms of IBtk

Cited by 28 publications

References 68 publications

Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ

Btk regulation in human and mouse B cells via protein kinase C phosphorylation of IBtkγ

Nanoparticle-based strategy for personalized B-cell lymphoma therapy

Genetics of equine insect bite hypersensitivity and genetic diversity in horses

Contact Info

Product

Resources

About