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The ubiquitous transcription factor SP1 binds to a GC rich consensus sequence. Here we describe an adaptor molecule that mediates binding of SP1 to a non-cognate DNA site rich in AT. The adaptor is comprised of a Dervan-type hairpin polyamide with high affinity to an AT rich hexamer duplex. It also carries a 27mer DNA that contains the SP1 consensus sequence. The synthesis and purification of the polyamide-DNA conjugate is reported. Pulldown experiments and western blot analysis demonstrate adaptor mediated binding of SP1 to the hexamer duplex TTGTTA.

Caspase Recruitment Domain Family Member 9 (CARD9) is an adaptor molecule that drives antifungal activity of macrophages and neutrophils in the skin. Autosomal recessive loss-of-function mutations in CARD9 confer increased susceptibility to invasive disease with select fungi in non-immunosuppressed patients. We report on a patient with X-linked ichthyosis complicated by chronic cutaneous invasive dermatophyte infection. We identified a previously reported c.271T>C (p.Y91H) mutation and a novel intronic c.1269+18G>A mutation in CARD9 underlying recurrent deep dermatophytosis in this patient despite various antifungals for over three decades. Our case highlights susceptibility to invasive dermatophytosis related to autosomal recessive CARD9 deficiency and illustrates the range of CARD9 mutations to be pursued in immunocompetent patients with unexplained deep dermatophyte infections. Further studies are needed to define the best therapeutic regimen.

TRAF1 is a pro-survival adaptor molecule in TNFR superfamily (TNFRSF) signaling. TRAF1 is overexpressed in many B cell cancers including refractory chronic lymphocytic leukemia (CLL). Little has been done to assess the role of TRAF1 in human cancer. Here we show that the protein kinase C related kinase Protein Kinase N1 (PKN1) is required to protect TRAF1 from cIAP-mediated degradation during constitutive CD40 signaling in lymphoma. We show that the active phospho-Thr774 form of PKN1 is constitutively expressed in CLL but minimally detected in unstimulated healthy donor B cells. Through a screen of 700 kinase inhibitors, we identified two inhibitors, OTSSP167, and XL-228, that inhibited PKN1 in the nanomolar range and induced dose-dependent loss of TRAF1 in RAJI cells. OTSSP167 or XL-228 treatment of primary patient CLL samples led to a reduction in TRAF1, pNF-κB p65, pS6, pERK, Mcl-1 and Bcl-2 proteins, and induction of activated caspase-3. OTSSP167 synergized with venetoclax in inducing CLL death, correlating with loss of TRAF1, Mcl-1, and Bcl-2. Although correlative, these findings suggest the PKN1-TRAF1 signaling axis as a potential new target for CLL. These findings also suggest the use of the orally available inhibitor OTSSP167 in combination treatment with venetoclax for TRAF1 overexpressing CLL.

The success of conventional chimeric antigen receptor (CAR) therapy in the treatment of refractory hematologic malignancies has triggered the development of novel exciting experimental CAR technologies. Among them, adaptor CAR platforms have received much attention. They combine the flexibility and controllability of recombinant antibodies with the power of CARs. Due to their modular design, adaptor CAR systems propose answers to the central problems of conventional CAR therapy, such as safety and antigen escape. This review provides an overview on the different adaptor CAR platforms available, discusses the possibilities and challenges of adaptor CAR therapy, and summarizes the first clinical experiences.

Among the innate and adaptative immune cells recruited to the tumour site, tumour associated macrophages (TAMs) are particularly abundant and by simplified classification can be classified into (M1) and (M2) TAMs. In the present study, we quantified by immunohistochemistry ionized calcium binding adaptor molecule 1 (Iba1)-positive total and CD204-positive M2-polarized TAMs in 60 canine malignant mammary tumours (CMMTs) to analyze the relationship between M1 or M2 response and the histopathologic features of examined CMMTs, the dogs' body condition score (BCS) and the progression of the neoplastic disease. The mean number of total and CD204+ TAMS were significantly higher in solid and in grade III than in grades I and II carcinomas. Moreover, the mean number of CD204-positive TAMs was significantly higher in CMMTs with lymphatic invasion and necrosis rather than CMMTs without. The presence of higher number of CD204-positive M2-polarized TAMs was associated with a worst outcome of the neoplastic disease: bitches bearing CMMTs with a prevalent M2-polarized TAM response had a median cancer-specific survival time of 449 days, while in animals with a M1-polarized TAM response the median cancer-specific survival time was 1209 days. The results of our study confirm that in CMMTs the presence of a M2-polarized TAMs response might affect the tumour development and behaviour. Finally, it strongly suggests the potential of CD204 expression as a prognostic factor.

The success of conventional chimeric antigen receptor (CAR) therapy in the treatment of refractory hematologic malignancies has triggered the development of novel exciting experimental CAR technologies. Among them, adaptor CAR platforms have received much attention. They combine the flexibility and controllability of recombinant antibodies with the power of CARs. Due to their modular design, adaptor CAR systems propose answers to central problems of conventional CAR therapy such as safety and antigen escape. This review provides an overview on the different adaptor CAR platforms available, discusses the possibilities and challenges of adaptor CAR therapy and summarizes first clinical experiences.

Restimulation-induced cell death (RICD) is an apoptotic program that regulates effector T cell expansion, triggered by repeated stimulation through the T cell receptor (TCR) in the presence of interleukin-2 (IL-2). Although CD4(+) regulatory T cells (Tregs) consume IL-2 and experience frequent TCR stimulation, they are highly resistant to RICD. Resistance in Tregs is dependent on the forkhead box P3 (FOXP3) transcription factor, although the mechanism remains unclear. T cells from patients with X-linked lymphoproliferative disease (XLP-1), that lack the adaptor molecule SLAM-associated protein (SAP), are also resistant to RICD. Here we demonstrate that normal Tregs express very low levels of SAP compared to conventional T cells. FOXP3 reduces SAP expression by directly binding to and repressing the SH2D1A (SAP) promoter. Indeed, ectopic SAP expression restores RICD sensitivity in human FOXP3(+) Tregs. Our findings illuminate the mechanism behind FOXP3-mediated RICD resistance in Tregs, providing new insight into their long-term persistence.

Chimeric antigen receptor (CAR)-engineered T cells have a proven efficacy for the treatment of refractory hematological B cell malignancies. While often accompanied by side effects, CAR-T technology is getting more mature and will become an important treatment option for various tumor indications. In this review, we summarize emerging approaches that aim to further evolve CAR-T cell therapy based on combinations of so-called universal or modular CAR-(modCAR-)T cells, and their respective adaptor molecules (CAR-adaptors), which mediate the crosslinking between target and effector cells. The activity of such modCAR-T cells is entirely dependent on binding of the respective CAR-adaptor to both a tumor antigen and to the CAR-expressing T cell. Contrary to conventional CAR-T cells, where the immunological synapse is established by direct interaction of CAR and membrane-bound target, modCAR-T cells provide a highly flexible and customizable development of the CAR-T cell concept and offer an additional possibility to control T cell activity.

Background TRIF is a key protein in antiviral innate immunity, operating downstream of TLRs. TRIF activation leads to the production of interferon-β and pro-inflammatory cytokines. There is evidence from experiments to suggest that the N-terminal domain of TRIF binds to its TIR domain to avoid constitutive activation. However, no structure of a complex between the N-terminal domain and the TIR domain exists till date. The disordered nature of the region connecting the N-terminal domain and the TIR domain compounds the issue of elucidating the mechanism of autoinhibition of TRIF. In this study, we have employed an integrative approach consisting of mutual information analysis, docking, molecular dynamics simulations and residue network analysis, in combination with existing experimental data to provide a glimpse of TRIF in its autoinhibited state. Results Our extensive docking approach reveals that the N-terminal domain binds to the BB loop-B helix region of the TIR domain, consistent with experimental observations. Long length molecular dynamics simulations of 1 microsecond performed on the docked model highlights residues participating in hydrogen bonding and hydrophobic interactions at the interface. A pair of residues present in the vicinity of the interface is also predicted by mutual information analysis, to co-evolve. Residues mediating long-range interactions within the TIR domain of TRIF were identified using residue network analysis. Conclusions Based on the results of the modelling and residue network analysis, we propose that the N-terminal domain binds to the BB loop region of the TIR domain, thereby preventing its homodimersation. The binding of TRIF to TLR3 or TRAM could induce a slight conformational change, causing the interactions between the N-terminal domain and TIR domain to disrupt, thereby exposing the BB loop and rendering it amenable for higher-order oligomerisation. Reviewers This article was reviewed by Michael Gromiha, Srikrishna Subramaniam and Peter Bond (nominated by Chandra Verma). Electronic supplementary material The online version of this article (doi:10.1186/s13062-017-0179-0) contains supplementary material, which is available to authorized users.

We appreciate the comments by Jiang et al 1 on our study showing that IL-38 overexpression has anti-inflammatory effects in experimental arthritis presumably through decreased production of proinflammatory cytokines by macrophages.2 Jiang et al point out that the Iba1 marker used in our immunohistochemistry analysis is also expressed by dendritic cells (DCs) and that IL-23, whose expression is reduced by IL-38, is also highly expressed by DCs. Therefore, IL-38 could target DCs in addition to macrophages. Ionised calcium-binding adaptor molecule 1 (Iba1) also known as allograft inflammatory factor 1 (AIF-1) is widely accepted as a pan-macrophage marker expressed in …

RIG-I activates interferon signaling pathways by promoting filament formation of the adaptor molecule, MAVS. Assembly of the MAVS filament is mediated by its CARD domain (CARD(MAVS)), and requires its interaction with the tandem CARDs of RIG-I (2CARD(RIG-I)). However, the precise nature of the interaction between 2CARD(RIG-I) and CARD(MAVS), and how this interaction leads to CARD(MAVS) filament assembly, has been unclear. Here we report a 3.6 Å electron microscopy structure of the CARD(MAVS) filament and a 3.4 Å crystal structure of the 2CARD(RIG-I):CARD(MAVS) complex, representing 2CARD(RIG-I) "caught in the act" of nucleating the CARD(MAVS) filament. These structures, together with functional analyses, show that 2CARD(RIG-I) acts as a template for the CARD(MAVS) filament assembly, by forming a helical tetrameric structure and recruiting CARD(MAVS) along its helical trajectory. Our work thus reveals that signal activation by RIG-I occurs by imprinting its helical assembly architecture on MAVS, a previously uncharacterized mechanism of signal transmission.

The tumor suppressor kinase LKB1 and germinal center kinases (GCKs) are key regulators of various cellular functions. The adaptor molecule MO25 not only recruits and activates LKB1 through the pseudokinase STRAD, but also may directly activate GCKs like MST3, MST4, STK25, OSR1 and SPAK. Targeting MO25 in a pathological setting has been recently studied in mouse. Yet the regulatory mechanism of MO25-mediated kinase activation is not fully understood. Here, our structural studies of MO25-related kinases reveal that MO25 binds to and activates GCK kinases or pseudokinase through a unified structural mechanism, featuring an active conformation of the αC helix and A-loop stabilized by MO25. Compared to GCKs that are directly activated by MO25-binding, activation of LKB1 has evolved additional layer of regulatory machinery, i.e., MO25 "activates" the pseudokinase STRAD, which in turn activates LKB1. Importantly, the structures of MO25α-STK25 and MO25α-MST3 determined in this work represent a transition/intermediate state and a fully activated state, respectively during the MO25-mediated kinase activating process.

Inflammation is emerging as a new hallmark of cancer, and the toll-like receptor and interleukin-1 receptor adaptor molecule MyD88 has been linked to tumorigenesis. The purpose of this review is to give a brief overview of the latest advances in understanding the complexity of MyD88 implication in tumorigenesis.MyD88 is shown to play a protumorigenic role through two mechanisms. First, it activates the nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway in the hematopoietic compartment and in tumor cells, inducing an inflammatory environment favorable to carcinogenesis. Second, it plays a cell-autonomous role in Ras signaling and transformation, independently of its role in inflammatory signaling. MyD88 mediates the optimal activation of the Ras/extracellular signal-regulated kinase (ERK) pathway by binding to ERK and protecting it from dephosphorylation. This optimal activation of the Ras pathway is essential for the expression of important DNA repair enzymes, allowing cancer cells to efficiently repair damaged DNA. MyD88 is also shown in certain cases to play an antitumoral role through modulation of the immune responseThese findings present a new dual function model for MyD88 implication in carcinogenesis making it a potential therapeutic target in cancer.

The removal of afferent activity has been reported to modify neuronal activity in the cochlear nucleus of adult rats. After cell damage, microglial cells are rapidly activated, initiating a series of cellular responses that influences neuronal function and survival. To investigate how this glial response occurs and how it might influence injured neurons, bilateral cochlear ablations were performed on adult rats to examine the short-term (16 and 24 hours and 4 and 7 days) and long-term (15, 30, and 100 days) changes in the distribution and morphology of microglial cells (immunostained with the ionized calcium-binding adaptor molecule 1; Iba-1) and the interaction of microglial cells with deafferented neurons in the ventral cochlear nucleus. A significant increase in the mean cross-sectional area and Iba-1 immunostaining of microglial cells in the cochlear nucleus was observed at all survival times after the ablation compared with control animals. These increases were concomitant with an increase in the area of Iba-1 immunostaining at 24 hours and 4, 7, and 15 days postablation. Additionally, microglial cells were frequently seen apposing the cell bodies and dendrites of auditory neurons at 7, 15, and 30 days postablation. In summary, these results provide evidence for persistent glial activation in the ventral cochlear nucleus and suggest that long-term interaction occurs between microglial cells and deafferented cochlear nucleus neurons following bilateral cochlear ablation, which could facilitate the remodeling of the affected neuronal circuits. J. Comp. Neurol. 520:2974–2990, 2012. © 2012 Wiley Periodicals, Inc.

Summary Aim To determine whether acute or long-term exposure of the brain to mobile telephone radiofrequency (RF) fields produces activation of microglia, which normally respond rapidly to any change in their microenvironment. Methods Using a purpose designed exposure system at 900 MHz, mice were given a single, far-field whole body exposure at a specific absorption rate (SAR) of 4 W/kg for 60 min (acute) or on five successive days per week for 104 weeks (long-term). Control mice were sham-exposed or freely mobile in a cage to control for any stress caused by immobilisation in the exposure module. Positive control brains subjected to a stab wound were also included to confirm the ability of microglia to react to any neural stress. Brains were perfusion-fixed with 4% paraformaldehyde and representative regions of the cerebral cortex and hippocampus immunostained for ionised calcium binding adaptor molecule (Iba1), a specific microglial marker. Results There was no increase in microglial Iba1 expression in brains short or long-term exposed to mobile telephony microwaves compared to control (sham-exposed or freely moving caged mice) brains, while substantial microglial activation occurred in damaged positive control neural tissue. Conclusions Acute (60 minutes) or longer duration (2 years) exposure of murine brains to mobile telephone RF fields did not produce any microglial activation detectable by Iba1 immunostaining.

Microglia are classically considered to be immune cells in the brain, but have now been proven to be involved in neuronal activity as well. Here we stereologically analyzed the spatial arrangement of microglia in the mouse hippocampus. First, we estimated the numerical densities (NDs) of microglia identified by ionized calcium-binding adaptor molecule 1 (Iba1). Despite that microglia appeared to be evenly distributed throughout the hippocampal area, the NDs demonstrated significant dorsoventral, interregional, and interlaminar differences. Briefly, the NDs in the ventral hippocampus were significantly lower in the CA3 region than in the CA1 region and dentate gyrus, although no interregional differences were detectable in the dorsal hippocampus. Both in the CA1 and CA3 regions, the NDs were significantly higher in the stratum lacunosum-moleculare than in the remaining layers. Next, we investigated the spatial patterns of distribution of Iba1-labeled microglia and S100b-labeled astrocytes. So far as we examined, the somato–somatic contacts were not seen among microglia or among astrocytes, whereas the close apposition between microglia and astrocytes were occasionally detected. The 3D point process analysis showed that the spatial distribution of microglia was significantly repulsive. Because the statistical territory of single microglia was larger than that estimated from process tracing, they are not likely to touch each other with their processes. Astrocytes were distributed slightly repulsively with overlapping areas. The 3D point process analysis also revealed a significant spatial attraction between microglia and astrocytes. The present findings provide a novel anatomical basis for glial research. V C 2007 Wiley-Liss, Inc.

Porcine melanomas have proven interesting in a wider biological perspective due to a common phenomenon of spontaneous regression, which is characterized by infiltration of macrophages, among others. Separation of neoplastic melanocytes from pigment-laden macrophages may, however, be challenging as the morphology of melanocytes varies considerably and sometimes resembles macrophages. The aim of this study was correspondingly to characterize and differentiate the cells in 20 porcine melanocytomas and regional lymph nodes by histologic examination and immunohistochemistry for melan A, PNL2, S100, lysozyme, alpha-1-antitrypsin, and ionized calcium binding adaptor molecule 1 (Iba1). Grossly, the melanocytomas were divided into 2 distinct types: pigmented maculae ( n = 7) and raised tumors ( n = 13). In the maculae, the pigmented cells were mainly melanocytes reactive for melan A, PNL2 and S100. In contrast, the majority of the cells in the raised tumors were melanophages, which expressed Iba1, alpha-1-antitrypsin, and lysozyme. Yet, cells histomorphologically indistinguishable from the melanophages expressed melan A and PNL2. These cells were Iba1 and S100 negative, and ultrastructurally, they were devoid of lysosomal bodies and filled with stage III and IV melanosomes. In the regional lymph nodes, melanocytes were present in the trabecular sinuses. In focally or diffusely black lymph nodes, pigmentation was, however, mainly due to aggregates of melanophages, which were confined to the trabeculae, deep cortex, and peripheral lymphoreticular tissue. Normal and neoplastic porcine melanocytes express melan A and PNL2, and immunohistochemical staining for melan A, PNL2, and Iba1 was found useful to identify and distinguish melanocytes and melanophages in porcine melanotic lesions.

The present invention relates to a method of producing single-stranded nucleic acid molecules from oligo- or polynucleotides wherein each of said oligo- or polynucleotides has a predefined 5' or 3' terminus, comprising the steps of (a) annealing an adaptor oligonucleotide simultaneously or step by step to (aa) a first oligo- or polynucleotide; and (ab) a second oligo- or polynucleotide wherein the 5'-terminus of said adaptor oligonucleotide is complementary in sequence to the 5' terminus of said first oligo- or polynucleotide and the 3'terminus of said adaptor molecule is complementary in sequence to the 3' terminus of said second oligo- or polynucleotide; and optionally (a') simultaneously with or subsequently to step (a) annealing at least one further adaptor oligonucleotide to free termini of said first or second oligonucleotides and to free termini of further oligo- or polynucleotides; (b) optionally filling in gaps between the neighbouring ends of said oligo- or polynucleotides; (c) ligating said oligo- or polynucleotides; and (d) removing said at least one adaptor oligonucleotide. In a preferred embodiment of the method of the invention, said single-stranded nucleic acid molecules represent a collection of nucleic acid molecules wherein either said first or said second oligo- or polynucleotide is invariable in sequence between all members of said collection of nucleic acid molecules.

γ-Aminobutyric acid type A and glycine receptors (GABA(A)Rs, GlyRs) are the major inhibitory neurotransmitter receptors and contribute to many synaptic functions, dysfunctions and human diseases. GABA(A)Rs are important drug targets regulated by direct interactions with the scaffolding protein gephyrin. Here we deduce the molecular basis of this interaction by chemical, biophysical and structural studies of the gephyrin-GABA(A)R α3 complex, revealing that the N-terminal region of the α3 peptide occupies the same binding site as the GlyR β subunit, whereas the C-terminal moiety, which is conserved among all synaptic GABA(A)R α subunits, engages in unique interactions. Thermodynamic dissections of the gephyrin-receptor interactions identify two residues as primary determinants for gephyrin's subunit preference. This first structural evidence for the gephyrin-mediated synaptic accumulation of GABA(A)Rs offers a framework for future investigations into the regulation of inhibitory synaptic strength and for the development of mechanistically and therapeutically relevant compounds targeting the gephyrin-GABA(A)R interaction.

Mutations in KLHL3 and CUL3, components of an E3 ligase complex, cause a familial disease of hyperkalemia and hypertension (PHAII). Here, we explore how KLHL3/CUL3 normally regulates the ROMK channel for potassium balance. We previously reported that ROMK is targeted for endocytosis by a specific clathrin adaptor molecule, ARH (Fang et al, JCI ’09). Because KLHL3/CUL3 targets ARH for proteasomal degradation (Fang et al, EB ’13), we wondered if ARH is a direct substrate of KLHL3/CUL3 ubiquitination. In vitro protein-protein interaction studies with purified ARH, KLHL3, CUL3 revealed that ARH directly interacts with KLHL3. We found separate interaction domains allow KLHL3 to simultaneously recruit CUL3 and the E3 ligase, ROC1, into a complex. As measured in ubiquitination assays in vitro with purified components, the direct interaction results in an increase in ARH ubiquitination, indicating that ARH is a direct substrate of KLHL3/CUL3. Importantly, KLHL3 localizes to the late DCT and CNT, overlapping with ...

ik3-1/Cables is associated with and phosphorylated by cdk3 in self-replicating cells. In postmitotic neurons, it may serve as an adaptor molecule, functionally connecting c-abl and cdk5, and supporting neurite growth. Here, we cloned cDNAs coding for mouse Trap (tudor repeat associator with Pctaire 2) to interact with ik3-1. ik3-1 interacts with a region of mouse Trap containing the C-terminal tudor repeat domains 4 and 5 (corresponding to amino acids 881–1086 of mouse Trap). Furthermore, the N-terminal 93-amino-acid domain of ik3-1 is essential for ik3-1 interaction with Trap. Moreover, ik3-1 is coimmunoprecipitated with Pctaire 2 from COS7 cells, although we could not clarify whether ik3-1 is directly associated with Pctaire 2 or indirectly associated with Pctaire 2 through Trap. In vitro kinase assay indicated that ik3-1 does not activate phosphorylation of myelin basic protein or histione H 1 by the Pctaire 2-mediated kinase. These findings led us to speculate that through ik3-1, the Pctaire family and Trap may be functionally connected with cdk3 or cdk5.

ASC was first identified as a caspase recruitment domain (CARD)-containing proapoptotic molecule that forms insoluble aggregates during apoptosis. Here, we report both the pyrin N-terminal homology domain (PYD) and CARD domains are involved in the aggregation of ASC. Preliminary experiments indicated that overexpression of ASC formed filament-like aggregates in COS-7 cells. Expression experiments using green fluorescent protein (GFP) constructs showed that not only the GFP-ASC-CARD but also the GFP-ASC-PYD formed filament-like aggregates in COS-7 cells. We confirmed these filament-like aggregates of both the ASC-PYD and the ASC-CARD due to homophilic interaction by immunoprecipitation method. We also demonstrated that the ASC-PYD associated with the ASC-CARD by heterophilic interaction. These observations suggest that the dimerization of the PYD as well as the CARD plays an important role in the oligomerization of ASC as an adaptor molecule.

Myeloid differentiating factor 88 (MyD88) is one of a critical adaptor molecule in the Toll-like receptor (TLR) signaling pathway. The TIR domain of MyD88 serves as a protein-protein interaction module and interacts with other TIR-containing proteins such as Mal (MyD88 adaptor-like) and Toll-like receptor 4 to form signal initiation complexes. Here we report the (15)N, (13)C, and (1)H chemical shift assignments of the TIR domain of MyD88. The resonance assignments obtained in this work will contribute to the study of heteromeric TIR-TIR interactions between MyD88 and TIR-containing receptors or adaptors.

Accumulating evidence indicates that the Cbl protein plays a negative role in immune receptor signaling; however, the mode of Cbl action in B cell receptor (BCR) signaling still remains unclear. DT40 B cells deficient in Cbl showed enhanced BCR-mediated phospholipase C (PLC)-gamma2 activation, thereby leading to increased apoptosis. A possible explanation for the involvement of Cbl in PLC-gamma2 activation was provided by findings that Cbl interacts via its Src homology 2 (SH2) domain with B cell linker protein (BLNK) after BCR ligation. BLNK is a critical adaptor molecule for PLC-gamma2 tyrosine phosphorylation through its binding to the PLC-gamma2 SH2 domains. As a consequence of the interaction between Cbl and BLNK, the BCR-induced recruitment of PLC-gamma2 to BLNK and the subsequent PLC-gamma2 tyrosine phosphorylation were inhibited. Thus, our data suggest that Cbl negatively regulates the PLC-gamma2 pathway by inhibiting the association of PLC-gamma2 with BLNK.

In this issue of Blood , Stritt et al show that platelet functions dependent on integrin activation are unimpaired in mice lacking the Rap1-GTP-interacting adaptor molecule (RIAM).[1][1] ![Figure][2] Pathways for talin-mediated activation of integrins. In the unstimulated platelet, integrin