BCR-ABL residues interacting with ponatinib are critical to preserve the tumorigenic potential of the oncoprotein

Patients with chronic myeloid leukemia in whom tyrosine kinase inhibitors (TKIs) fail often present mutations in the BCR-ABL catalytic domain. We noticed a lack of substitutions involving 4 amino acids (E286, M318, I360, and D381) that form hydrogen bonds with ponatinib. We therefore introduced mutations in each of these residues, either preserving or altering their physicochemical properties. We found that E286, M318, I360, and D381 are dispensable for ABL and BCR-ABL protein stability but are critical for preserving catalytic activity. Indeed, only a "conservative" I360T substitution retained kinase proficiency and transforming potential. Molecular dynamics simulations of BCR-ABLI360T revealed differences in both helix αC dynamics and protein-correlated motions, consistent with a modified ATP-binding pocket. Nevertheless, this mutant remained sensitive to ponatinib, imatinib, and dasatinib. These results suggest that changes in the 4 BCR-ABL residues described here would be selected against by a lack of kinase activity or by maintained responsiveness to TKIs. Notably, amino acids equivalent to those identified in BCR-ABL are conserved in 51% of human tyrosine kinases. Hence, these residues may represent an appealing target for the design of pharmacological compounds that would inhibit additional oncogenic tyrosine kinases while avoiding the emergence of resistance due to point mutations.This work was supported by an investigator grant to P.V. from Associazione Italiana per la Ricerca sul Cancro (AIRC) and by funding from the Biotechnology and Biological Sciences Research Council (BB/I023291/1 and BB/H018409/1 to AP and FF). P.B. is the recipient of an AIRC - Marie Curie fellowship

Nondestructive Evaluation Techniques for Silicon Carbide Heat-Exchanger Tubing

The adequacy of various nondestructive evaluation (NDE) techniques for inspecting silicon carbide heat-exchanger tubing is discussed. These methods include conventional ultrasonics, acoustic microscopy, conventional and dye-enhanced radiography, holographic interferometry and infrared scanning techniques. On the basis of current test results and an examination of the discussions in available literature, these techniques were compared with respect to (a) effectiveness in detecting cracks, pitting, inclusions, and voids, (b) effectiveness in characterizing detected flaws, (c) adaptability to tube geometry, (d) adaptability to in-service inspection, (e) reliability, and (f) extent of development required for commercialization

Zika Virus: Infectious Process and Public Health Response

The Zika virus has become a growing concern as a global pandemic. Since being identified in Uganda in 1947, the virus has spread around the world, recently emerging in South America with a great impact on Brazil. As of 2016, Zika has made its appearance in the United States and is now actively being transmitted in Florida. The virus is a mosquito-vectored flavivirus primarily transmitted by the Aedes mosquito which infects a human through biting. Transmission through sexual intercourse is also possible as well as transmission from a pregnant woman to her fetus. This latter form of transmission presents the primary problem with the Zika virus; transmission to the fetus can cause microcephaly as well as other brain and developmental problems. Proper precautions should be taken based on these identified modes of transmission. Symptoms of Zika are similar to flu-like symptoms, such as low-grade fever, muscle pain and headache. About 20 percent of patients that come in contact with the Zika virus will originally present as asymptomatic and will not display symptoms until almost two weeks after initial contact with the virus. Zika virus can remain in the blood for about a week, but can remain in the semen for months. There are a number of methods used to detect the Zika virus—urine, blood or semen samples may be used to assess if a patient is infected

Characteristics of transposable element exonization within human and mouse

Insertion of transposed elements within mammalian genes is thought to be an important contributor to mammalian evolution and speciation. Insertion of transposed elements into introns can lead to their activation as alternatively spliced cassette exons, an event called exonization. Elucidation of the evolutionary constraints that have shaped fixation of transposed elements within human and mouse protein coding genes and subsequent exonization is important for understanding of how the exonization process has affected transcriptome and proteome complexities. Here we show that exonization of transposed elements is biased towards the beginning of the coding sequence in both human and mouse genes. Analysis of single nucleotide polymorphisms (SNPs) revealed that exonization of transposed elements can be population-specific, implying that exonizations may enhance divergence and lead to speciation. SNP density analysis revealed differences between Alu and other transposed elements. Finally, we identified cases of primate-specific Alu elements that depend on RNA editing for their exonization. These results shed light on TE fixation and the exonization process within human and mouse genes.Comment: 11 pages, 4 figure

Distinct roles for FOXP3(+) and FOXP3(-) CD4(+) T cells in regulating cellular immunity to uncomplicated and severe plasmodium falciparum Malaria

Failure to establish an appropriate balance between pro- and anti-inflammatory immune responses is believed to contribute to pathogenesis of severe malaria. To determine whether this balance is maintained by classical regulatory T cells (CD4+ FOXP3+ CD127−/low; Tregs) we compared cellular responses between Gambian children (n = 124) with severe Plasmodium falciparum malaria or uncomplicated malaria infections. Although no significant differences in Treg numbers or function were observed between the groups, Treg activity during acute disease was inversely correlated with malaria-specific memory responses detectable 28 days later. Thus, while Tregs may not regulate acute malarial inflammation, they may limit memory responses to levels that subsequently facilitate parasite clearance without causing immunopathology. Importantly, we identified a population of FOXP3−, CD45RO+ CD4+ T cells which coproduce IL-10 and IFN-γ. These cells are more prevalent in children with uncomplicated malaria than in those with severe disease, suggesting that they may be the regulators of acute malarial inflammation

CCN3: a key growth regulator in Chronic Myeloid Leukaemia

Chronic Myeloid Leukaemia (CML) is characterized by expression of the constitutively active Bcr-Abl tyrosine kinase. We have shown previously that the negative growth regulator, CCN3, is down-regulated as a result of Bcr-Abl kinase activity and that CCN3 has a reciprocal relationship of expression with BCR-ABL. We now show that CCN3 confers growth regulation in CML cells by causing growth inhibition and regaining sensitivity to the induction of apoptosis. The mode of CCN3 induced growth regulation was investigated in K562 CML cells using gene transfection and treatment with recombinant CCN3. Both strategies showed CCN3 regulated CML cell growth by reducing colony formation capacity, increasing apoptosis and reducing ERK phosphorylation. K562 cells stably transfected to express CCN3 showed enhanced apoptosis in response to treatment with the tyrosine kinase inhibitor, imatinib. Whilst CCN3 expression was low or undetectable in CML stem cells, primary CD34+ CML progenitors were responsive to treatment with recombinant CCN3. This study shows that CCN3 is an important growth regulator in haematopoiesis, abrogation of CCN3 expression enhances BCR-ABL dependent leukaemogenesis. CCN3 restores growth regulation, regains sensitivity to the induction of apoptosis and enhances imatinib cell kill in CML cells. CCN3 may provide an additional therapeutic strategy in the management of CML

Ponatinib in patients with refractory acute myeloid leukaemia: findings from a phase 1 study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99099/1/bjh12382.pd