Proteomic profiling of colorectal cancer cell culture samples treated with apoptosis- and mTOR inhibitors under normoxia and hypoxia
ABSTRACT: To examine changes in tyrosine kinase activity in colorectal cancer cell culture samples treated with apoptosis inhibitors or/and mTOR inhibitors, under normoxic or/and hypoxic experimental conditions.
BACKGROUND:The use of targeted agents to impel dual inhibition of anti-apoptotic mechanisms and mTOR-mediated pro-survival signaling in colorectal carcinoma (CRC) cell lines with KRAS or BRAF mutation has been shown to induce apoptosis, a timely result given CRC entities harboring such mutations are in need of new therapies. Since CRC comprises heterogeneous tumors with predominant hypoxic components, we investigated effects of an inhibitor of anti-apoptotic Bcl-2 family proteins (ABT-737) in co ...[more]
Project description:Meningococcal sepsis is an overwhelming form of the sepsis syndrome which may cause mortality within 12-24 hours in previously healthy children and adults, where the causative infectious agent is N. meningitidis, an obligate human pathogen. The genomic changes induced by N. meningitidis are modulated by the anti-inflammatory cytokine interleukin-10 (IL-10), which is present in large quantities in plasma from patients with meningococcal sepsis. This present study investigated kinase activities in human monocytes stimulated by N. meningitidis and IL-10. The first aim was to identify array peptides that could indicate which signaling pathways were activated or inhibited by the host response to the meningococci. The second aim was to detect whether IL-10 affected N. meningitidis-nduced phosphorylation of array peptides, in order to identify potential targets of the IL-10 anti-inflammatory response. We approached this using a strategy where elutriation-purified human monocytes are stimulated in vitro with N. meningitidis and IL-10, with concentrations corresponding to previously measured levels in patients with fulminant meningococcal septicemia. This work examined activation or inhibition of signaling pathways mediated by tyrosine kinases when purified human monocytes are in vitro incubated with N. meningitidis in the presence or absence of IL-10.
Project description:Tyrosine kinase activity profiling of metatstatic malignant melanoma and normal skin tissue samples was performed using peptide kinase arrays. All samples were run in triplicates with and withouth inhbitor PLX4032 and Sutent Malate in order to identify how tyrosine kinases responds to kinase inhibitor treatment, ex vivo.
Project description:To examine changes in tyrosine kinase activity in prostate cancer tumors developing resistance to androgen deprivation therapy and to compare these to changes in tyrosine kinase activity occuring in cell lines exposed to oxygen deficiency (hypoxia)
Project description:Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, the leading cause of death among all infectious diseases. There are 11 eukaryotic-like serine/threonine protein kinases (STPKs) in Mtb, which are thought to play pivotal roles in cell growth, signal transduction and pathogenesis. However, their underlying mechanisms of action remain largely uncharacterized. In this study, using a Mtb proteome microarray, we have globally identified the binding proteins in Mtb for all of the STPKs, and constructed the first STPK protein interaction (KPI) map that includes 492 binding proteins and 1,027 interactions. Bioinformatics analysis showed that the interacting proteins reflect diverse functions, including roles in two-component system, transcription, protein degradation, and cell wall integrity. Functional investigations confirmed that PknG regulates cell wall integrity through key components of peptidoglycan (PG) biosynthesis, e.g., MurC. The global STPK-KPIs network constructed here is expected to serve as a rich resource for understanding the key signaling pathways in Mtb, thus facilitating drug development and effective control of Mtb.
Project description:AMP-activated protein kinase (AMPK) is a central energy gauge that regulates metabolism and has been increasingly involved in non-metabolic processes and diseases. However, AMPK’s direct substrates in non-metabolic contexts are largely unknown. To better understand the AMPK network, we use a chemical genetics screen coupled to a peptide capture approach in whole cells, resulting in identification of direct AMPK phosphorylation sites. Interestingly, the high-confidence AMPK substrates contain many proteins involved in cell motility, adhesion, and invasion. AMPK phosphorylation of the RHOA guanine nucleotide exchange factor NET1A inhibits extracellular matrix degradation, an early step in cell invasion. The identification of direct AMPK phosphorylation sites also facilitates large-scale prediction of AMPK substrates. We provide an AMPK motif matrix and a pipeline to predict additional AMPK substrates from quantitative phosphoproteomics datasets. As AMPK is emerging as a critical node in aging and pathological processes, our study identifies potential targets for therapeutic strategies.
Project description:The present study reports an unbiased analysis of the cytotoxic T cell serine-threonine phosphoproteome using high resolution mass spectrometry. Approximately 2,000 phosphorylations were identified in CTLs of which approximately 450 were controlled by TCR signaling. A significantly overrepresented group of molecules identified in the phosphoproteomic screen were transcription activators, co-repressors and chromatin regulators. A focus on the chromatin regulators revealed that CTLs have high expression of the histone deacetylase HDAC7 but continually phosphorylate and export this transcriptional repressor from the nucleus. HDAC7 dephosphorylation results in its nuclear accumulation and suppressed expression of genes encoding key cytokines, cytokine receptors and adhesion molecules that determine CTL function. The screening of the CTL phosphoproteome thus reveals intrinsic pathways of serine-threonine phosphorylation that target chromatin regulators in CTLs and determine the CTL functional program. We used Affymetrix microarray analysis to explore the molecular basis for the role of HDAC7 in CTLs and the impact of GFP-HDAC7 phosphorylation deficient mutant expression on the CTL transcriptional profile. In vitro generated P14 TCR cytotoxic T cells were retrovirally infected with a construct encoding GFP-HDAC7 phosphorylation deficient mutant, sorted in base of GFP expression (GFP positive and GFP negative) and processed for microarray analysis in three biological replicas.
Project description:TGF-β Activated Kinase 1 (TAK1) is a critical signaling hub responsible for translating antigen binding signals to immune receptors for the activation of the AP-1 and NF-κB master transcriptional programs. Despite its importance, known substrates of TAK1 are limited to kinases of the MAPK and IKK families and include no direct effectors of biochemical processes. Here, we identify over 200 novel substrates of TAK1 using a chemical genetic kinase strategy. We validate phosphorylation of the dynamic switch II region of GTPase Rab1 at T75 to be regulated by TAK1 in vivo. TAK1 preferentially phosphorylates the inactive (GDP-bound) state of Rab1. Phosphorylation of Rab1 disrupts interaction with GDP Dissociation Inhibitor 1 (GDI1), but not GEF or GAP proteins, and is exclusive to membrane localized Rab1, suggesting phosphorylation may stimulate Rab1 activation and membrane association. We found phosphorylation of Rab1 at T75 to be necessary for normal Rab1 mediated ER to Golgi vesicular transport. Previous studies established that the pathogen Legionella pneumophila is capable of hijacking Rab1 function through post-translational modifications of the switch II region. Here, we present the first evidence that Rab1 is regulated by the host in a similar fashion; and that the innate immunity kinase TAK1 and Legionella effectors compete directly to regulate Rab1 by switch II modifications during infection.