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Project description:Response of human iPSCs-derived macrophages to apoptotic cells, role of ACK1 and BRK tyrosine kinases
| PRJNA486609 | ENA
Project description:Activation of androgen receptor (AR) may have a role in the development of castration-resistant prostate cancer. Two intracellular tyrosine kinases, Ack1 (activated cdc42-associated kinase) and Src, phosphorylate and enhance AR activity and promote prostate xenograft tumor growth in castrated animals. However, the upstream signals that activate these kinases and lead to AR activation are incompletely characterized. In this study, we investigated AR phosphorylation in response to non-androgen ligand stimulation using phospho-specific antibodies. Treatment of LNCaP and LAPC-4 cells with epidermal growth factor (EGF), heregulin, Gas6 (ligand binding to the Mer receptor tyrosine kinase and activating Ack1 downstream), interleukin (IL)-6 or bombesin stimulated cell proliferation in the absence of androgen. Treatment of LNCaP and LAPC-4 cells with EGF, heregulin or Gas6 induced AR phosphorylation at Tyr-267, whereas IL-6 or bombesin treatment did not. AR phosphorylation at Tyr-534 was induced by treatment with EGF, IL-6 or bombesin, but not by heregulin or Gas6. Small interfering RNA-mediated knockdown of Ack1 or Src showed that Ack1 mediates heregulin- and Gas6-induced AR Tyr-267 phosphorylation, whereas Src mediates Tyr-534 phosphorylation induced by EGF, IL-6 and bombesin. Dasatinib, a Src inhibitor, blocked EGF-induced Tyr-534 phosphorylation. In addition, we showed that dasatinib also inhibited Ack1 kinase. Dasatinib inhibited heregulin-induced Ack1 kinase activity and AR Tyr-267 phosphorylation. In addition, dasatinib inhibited heregulin-induced AR-dependent reporter activity. Dasatinib also inhibited heregulin-induced expression of endogenous AR target genes. Dasatinib inhibited Ack1-dependent colony formation and prostate xenograft tumor growth in castrated mice. Interestingly, Ack1 or Src knockdown or dasatinib did not inhibit EGF-induced AR Tyr-267 phosphorylation or EGF-stimulated AR activity, suggesting the existence of an additional tyrosine kinase that phosphorylates AR at Tyr-267. These data suggest that specific tyrosine kinases phosphorylate AR at distinct sites and that dasatinib may exert antitumor activity in prostate cancer through inhibition of Ack1.
| S-EPMC2880659 | biostudies-literature
Project description:Tyrosine kinases (TKs) play essential roles in signaling processes that regulate cell survival, migration, and proliferation. Dysregulation of tyrosine kinases underlies many disorders, including cancer, cardiovascular and developmental diseases, as well as pathologies of the immune system. Ack1 and Brk are nonreceptor tyrosine kinases (NRTKs) best known for their roles in cancer. Here, we have biochemically characterized novel Ack1 and Brk mutations identified in patients with systemic lupus erythematosus (SLE). These mutations are the first SLE-linked polymorphisms found among NRTKs. We show that two of the mutants are catalytically inactive, while the other three have reduced activity. To understand the structural changes associated with the loss-of-function phenotype, we solved the crystal structure of one of the Ack1 kinase mutants, K161Q. Furthermore, two of the mutated residues (Ack1 A156 and K161) critical for catalytic activity are highly conserved among other TKs, and their substitution in other members of the kinase family could have implications in cancer. In contrast to canonical gain-of-function mutations in TKs observed in many cancers, we report loss-of-function mutations in Ack1 and Brk, highlighting the complexity of TK involvement in human diseases.
| S-EPMC10052838 | biostudies-literature
Project description:Mononuclear phagocytes comprise a mobile, broadly dispersed and highly adaptable system that lies at the very epicenter of host defense against pathogens and the interplay of the innate and adaptive arms of immunity. Understanding the molecular mechanisms that control the response of mononuclear phagocytes to apoptotic cells and the anti-inflammatory consequences of that response is an important goal with implications for multiple areas of biomedical sciences. This review details current understanding of the heterogeneity of apoptotic cell uptake by different members of the mononuclear phagocyte family in humans and mice. It also recounts the unique role of the Tyro3 family of receptor tyrosine kinases, best characterized for Mertk, in the signal transduction leading both to apoptotic cell ingestion and the anti-inflammatory effects that result.
| S-EPMC4191832 | biostudies-literature
Project description:Neurotrophins are involved in many crucial cellular functions, including neurite outgrowth, synapse formation, and plasticity. Although these events have long been known, the molecular determinants underlying neuritogenesis have not been fully characterized. Ack1 (activated Cdc42-associated tyrosine kinase) is a non-receptor tyrosine kinase that is highly expressed in the brain. Here, we demonstrate that Ack1 is a molecular constituent of neurotrophin signaling cascades in neurons and PC12 cells. We report that Ack1 interacts with Trk receptors and becomes tyrosine phosphorylated and its kinase activity is increased in response to neurotrophins. Moreover, our data indicate that Ack1 acts upstream of the Akt and MAPK pathways. We show that Ack1 overexpression induces neuritic outgrowth and promotes branching in neurotrophin-treated neuronal cells, whereas the expression of Ack1 dominant negatives or short-hairpin RNAs counteract neurotrophin-stimulated differentiation. Our results identify Ack1 as a novel regulator of neurotrophin-mediated events in primary neurons and in PC12 cells.
| S-EPMC3668633 | biostudies-literature
Project description:The nonreceptor tyrosine kinase (NRTK) Ack1 comprises a distinct arrangement of non-catalytic modules. Its SH3 domain has a C-terminal to the kinase domain (SH1), in contrast to the typical SH3-SH2-SH1 layout in NRTKs. The Ack1 is the only protein that shares a region of high homology to the tumor suppressor protein Mig6, a modulator of EGFR. The vertebrate Acks make up the only tyrosine kinase (TK) family known to carry a UBA domain. The GTPase binding and SAM domains are also uncommon in the NRTKs. In addition to being a downstream effector of receptor tyrosine kinases (RTKs) and integrins, Ack1 can act as an epigenetic regulator, modulate the degradation of the epidermal growth factor receptor (EGFR), confer drug resistance, and mediate the progression of hormone-sensitive tumors. In this review, we discuss the domain architecture of Ack1 in relation to other protein kinases that possess such defined regulatory domains.
| S-EPMC10047419 | biostudies-literature
Project description:Pancreatic cancer is a significant cause of cancer mortality worldwide as the disease has advanced significantly in patients before symptoms are evident. The signal transduction pathways that promote this rapid progression are not well understood. Ack1 or TNK2, an ubiquitously expressed oncogenic non-receptor tyrosine kinase, integrates signals from ligand-activated receptor tyrosine kinases to modulate intracellular signaling cascades. In the present study, we investigated the Ack1 activation profile in a pancreatic cancer tumor microarray, and observed that expression levels of activated Ack1 and pTyr284-Ack1 positively correlated with the severity of disease progression and inversely correlated with the survival of patients with pancreatic cancer. To explore the mechanisms by which Ack1 promotes tumor progression, we investigated the role of AKT/PKB, an oncogene and Ack1-interacting protein. Ack1 activates AKT directly in pancreatic and other cancer cell lines by phosphorylating AKT at Tyr176 to promote cell survival. In addition, the Ack1 inhibitor AIM-100 not only inhibited Ack1 activation but also suppressed AKT tyrosine phosphorylation, leading to cell cycle arrest in the G1 phase. This effect resulted in a significant decrease in the proliferation of pancreatic cancer cells and induction of apoptosis. Collectively, our data indicate that activated Ack1 could be a prognostic marker for ascertaining early or advanced pancreatic cancer. Thus, Ack1 inhibitors hold promise for therapeutic intervention to inhibit pancreatic tumor growth.
| S-EPMC3349895 | biostudies-literature
Project description:Ack1 is a nonreceptor tyrosine kinase that participates in tumorigenesis, cell survival, and migration. Relatively little is known about the mechanisms that regulate Ack1 activity. Recently, four somatic missense mutations of Ack1 were identified in cancer tissue samples, but the effects on Ack1 activity, and function have not been described. These mutations occur in the N-terminal region, the C-lobe of the kinase domain, and the SH3 domain. Here, we show that the cancer-associated mutations increase Ack1 autophosphorylation in mammalian cells without affecting localization and increase Ack1 activity in immune complex kinase assays. The cancer-associated mutations potentiate the ability of Ack1 to promote proliferation and migration, suggesting that point mutation is a mechanism for Ack1 deregulation. We propose that the C-terminal Mig6 homology region (MHR) (residues 802-990) participates in inhibitory intramolecular interactions. The isolated kinase domain of Ack1 interacts directly with the MHR, and the cancer-associated E346K mutation prevents binding. Likewise, mutation of a key hydrophobic residue in the MHR (Phe(820)) prevents the MHR-kinase interaction, activates Ack1, and increases cell migration. Thus, the cancer-associated mutation E346K appears to destabilize an autoinhibited conformation of Ack1, leading to constitutively high Ack1 activity.
| S-EPMC2856269 | biostudies-literature
Project description:Ack1 is a nonreceptor tyrosine kinase that is associated with cellular proliferation and survival. The receptor tyrosine kinase Mer, a member of the TAM family of receptors, has previously been reported to be an upstream activator of Ack1 kinase. The mechanism linking the two kinases, however, has not been investigated. We confirmed that Ack1 and Mer interact by co-immunoprecipitation experiments and found that Mer expression led to increased Ack1 activity. The effect on Ack1 was dependent on the kinase activity of Mer, whereas mutation of the Mer C-terminal tyrosines Y867 and Y924 did not significantly decrease the ability of Mer to activate Ack1. Ack1 possesses a Mig6 Homology Region (MHR) that contains adjacent regulatory tyrosines (Y859 and Y860). Using synthetic peptides, we showed that Mer preferentially binds and phosphorylates the MHR sequence containing phosphorylated pY860, as compared to the pY859 sequence. This suggested the possibility of sequential phosphorylation within the MHR of Ack1, as has been observed previously for other kinases. In cells co-expressing Mer and Ack1 MHR mutants, the Y859F mutant had higher activity than the Y860F mutant, consistent with this model. The interaction between Mer and Ack1 could play a role in immune cell signaling in normal physiology and could also contribute to the hyperactivation of Ack1 in prostate cancer and other tumors.
| S-EPMC10473914 | biostudies-literature
Project description:Inappropriate clearance of apoptotic remnants is considered to be the primary cause of systemic autoimmune diseases, like systemic lupus erythematosus. Here we demonstrate that apoptotic cells release distinct types of subcellular membranous particles (scMP) derived from the endoplasmic reticulum (ER) or the plasma membrane. Both types of scMP exhibit desialylated glycotopes resulting from surface exposure of immature ER-derived glycoproteins or from surface-borne sialidase activity, respectively. Sialidase activity is activated by caspase-dependent mechanisms during apoptosis. Cleavage of sialidase Neu1 by caspase 3 was shown to be directly involved in apoptosis-related increase of surface sialidase activity. ER-derived blebs possess immature mannosidic glycoepitopes and are prioritized by macrophages during clearance. Plasma membrane-derived blebs contain nuclear chromatin (DNA and histones) but not components of the nuclear envelope. Existence of two immunologically distinct types of apoptotic blebs may provide new insights into clearance-related diseases.
| S-EPMC3249103 | biostudies-literature