DNA end sequestration by DNA-dependent protein kinase and end joining of sterically constrained substrates in whole-cell extracts

2003 ◽  
Vol 42 (4) ◽  
pp. 279-287 ◽  
Author(s):  
Jae Wan Lee ◽  
Kedar V. Inamdar ◽  
Michele F. Hannah ◽  
Susan P. Lees-Miller ◽  
Lawrence F. Povirk
Keyword(s):  
Protein Kinase ◽  
End Joining ◽  
Dependent Protein Kinase ◽  
Whole Cell ◽  
Cell Extracts ◽  
Dependent Protein

scholarly journals Nonhomologous end-joining deficiency of L5178Y-S cells is not associated with mutation in the ABCDE autophosphorylation cluster.

2006 ◽  
Vol 53 (1) ◽  
pp. 233-236 ◽  
Author(s):  
Kamil Brzóska ◽  
Marcin Kruszewski ◽  
Irena Szumiel
Keyword(s):  
Protein Kinase ◽  
Cell Line ◽  
In Vitro Test ◽  
End Joining ◽  
Dependent Protein Kinase ◽  
Cell Extracts ◽  
Dependent Protein ◽  
Phenotypic Features ◽  
Repair Defect

Cells with mutated autophosphorylation sites in the ABCDE cluster of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are defective in the repair of ionising radiation-induced DSB, but show in an in vitro test the same DNA-PK activity as the cells possessing wild type enzyme. Nevertheless, the mutated DNA-PK is able to undergo ATP-dependent autophosphorylation and inactivation. This characteristics correspond well with the phenotypic features of the L5178Y-S (LY-S) cell line that is defective in DSB repair, shows a pronounced G1 phase radiosensitivity, but in which the level of DNA-PK activity present in total cell extracts is similar to that of its radioresistant counterpart L5178Y-R (LY-R) cell line. The purpose of this work was to examine the possible alterations in the sequence encoding the cluster of autophosphorylation sites in the DNA-dependent protein kinase in LY-S cells. Despite the presence of phenotypic features indicating the possibility of such alterations, no differences were found between the sequences coding for the autophosphorylation sites in L5178Y-R and L5178Y-S cells. In conclusion, the repair defect in LY-S cells is not related to the structure of the DNA-PK autophosphorylation sites (ABCDE casette).

Revertants of an S49 cell mutant that expresses altered cyclic AMP-dependent protein kinase

1982 ◽  
Vol 2 (10) ◽  
pp. 1229-1237
Author(s):  
T van Daalen Wetters ◽  
P Coffino
Keyword(s):  
Protein Kinase ◽  
Regulatory Subunit ◽  
Mutational Event ◽  
Wild Type ◽  
Cell Mutant ◽  
Dependent Protein Kinase ◽  
Cell Extracts ◽  
Counter Selection ◽  
Dependent Protein ◽  
Gene Lesion

Dibutyryl adenosine 3',5'-phosphate (Bt2cAMP)-sensitive (Bt2cAMPS) revertants were isolated from a resistant S49 cell mutant carrying a structural gene lesion in the regulatory subunit of cAMP-dependent protein kinase (cA-PK). This was accomplished with a counter-selection in which, first, Bt2cAMP was used to reversibly arrest revertants, and then a sequence of treatments with bromodeoxyuridine, 33258 Hoechst dye, and white light was used to kill cycling mutant cells. Reversion rates in nonmutagenized cultures could not be accurately measured, but spontaneous revertants do occur and with frequencies of less than 10(-7) to 10(-5). The mutagens ethyl methane sulfonate (EMS), N-methyl-N'-nitro-N-nitro-soguanidine (MNNG), and ICR191 increased the reversion frequency. In all cases, reversion to Bt2cAMP sensitivity was associated with restoration of wild-type levels and apparent activation constant for cAMP of cA-PK. MNNG induced revertants whose cell extracts contained cA-PK activity distinguishable from that of wild type by thermal liability. EMS did not. The counter-selection effectively isolates rare phenotypes and is therefore a useful tool in further somatic genetic experiments. The association of reversion with alterations in cA-PK function supports all previous data from this and other laboratories implicating cA-PK as the intracellular mediator of cAMP effects. Reversion is probably the result of a mutational event. Induction of reversion by ICR191 suggests the existence of a novel mechanism for generating revertants in somatic cells.

scholarly journals Activation of DNA-PK by hairpinned DNA ends reveals a stepwise mechanism of kinase activation

2020 ◽  
Vol 48 (16) ◽  
pp. 9098-9108 ◽  
Author(s):  
Katheryn Meek
Keyword(s):  
Protein Kinase ◽  
End Joining ◽  
Dependent Protein Kinase ◽  
Kinase Activation ◽  
Stepwise Mechanism ◽  
Dependent Protein ◽  
Enzymatic Activation ◽  
Non Homologous End Joining ◽  
Dna Ends ◽  
Step Mechanism

Abstract As its name implies, the DNA dependent protein kinase (DNA-PK) requires DNA double-stranded ends for enzymatic activation. Here, I demonstrate that hairpinned DNA ends are ineffective for activating the kinase toward many of its well-studied substrates (p53, XRCC4, XLF, HSP90). However, hairpinned DNA ends robustly stimulate certain DNA-PK autophosphorylations. Specifically, autophosphorylation sites within the ABCDE cluster are robustly phosphorylated when DNA-PK is activated by hairpinned DNA ends. Of note, phosphorylation of the ABCDE sites is requisite for activation of the Artemis nuclease that associates with DNA-PK to mediate hairpin opening. This finding suggests a multi-step mechanism of kinase activation. Finally, I find that all non-homologous end joining (NHEJ) defective cells (whether deficient in components of the DNA-PK complex or components of the ligase complex) are similarly deficient in joining DNA double-stranded breaks (DSBs) with hairpinned termini.

scholarly journals Somatic Hypermutation in the Absence of DNA-Dependent Protein Kinase Catalytic Subunit (DNA-Pkcs) or Recombination-Activating Gene (Rag)1 Activity

2000 ◽  
Vol 192 (10) ◽  
pp. 1509-1514 ◽  
Author(s):  
Mats Bemark ◽  
Julian E. Sale ◽  
Hye-Jung Kim ◽  
Claudia Berek ◽  
Ruth A. Cosgrove ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Somatic Hypermutation ◽  
Cell Receptor ◽  
Catalytic Subunit ◽  
Antigen Receptors ◽  
End Joining ◽  
Dependent Protein Kinase ◽  
Recombination Activating Gene ◽  
Dependent Protein ◽  
Rag 1

Somatic hypermutation and isotype switch recombination occur in germinal center B cells, are linked to transcription, and are similarly affected by deficiency in MutS homologue (MSH)2. Class-switch recombination is abrogated by disruption of genes encoding components of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs)/Ku complex and likely involves nonhomologous end joining (NHEJ). That somatic hypermutation might also be associated with end joining is suggested by its association with the creation of deletions, duplications, and sites accessible to terminal transferase. However, a requirement for NHEJ in the mutation process has not been demonstrated. Here we show that somatic mutation in mice deficient in NHEJ can be tested by introduction of rearranged immunoglobulin and T cell receptor transgenes: the transgene combination not only permits reconstitution of peripheral lymphoid compartments but also allows formation of germinal centers, despite the wholly monoclonal nature of the lymphocyte antigen receptors in these animals. Using this strategy, we confirm that somatic hypermutation like class-switching can occur in the absence of recombination-activating gene (RAG)1 but show that the two processes differ in that hypermutation can proceed essentially unaffected by deficiency in DNA-PKcs activity.

Ca2+/calmodulin-dependent protein kinase II activation and regulation of adrenal glomerulosa Ca2+ signaling

1995 ◽  
Vol 269 (6) ◽  
pp. F751-F760 ◽  
Author(s):  
R. J. Fern ◽  
M. S. Hahm ◽  
H. K. Lu ◽  
L. P. Liu ◽  
F. S. Gorelick ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Low Voltage ◽  
Extracellular Potassium ◽  
Dependent Protein Kinase ◽  
Calmodulin Antagonist ◽  
Cell Extracts ◽  
Protein Kinase Ii ◽  
Dependent Protein ◽  
A Cell

We recently reported that elevations in the intracellular Ca2+ concentration ([Ca2+]i) enhance low-voltage-activated, T-type, Ca2+ channel activity via Ca2+/calmodulin-dependent protein kinase II (CaMKII). Here, we document CaMKII activity in bovine adrenal glomerulosa (AG) cells and assess the importance of CaMKII in depolarization-induced Ca2+ signaling. AG cell extracts exhibited kinase activity toward a CaMKII-selective peptide substrate that was dependent on both Ca2+ [half-maximal concentration for Ca2+ activation (K0.5) = 1.5 microM] and calmodulin (K0.5 = 46 nM) and was sensitive to a calmodulin antagonist and a CaMKII peptide inhibitor. On cell treatment with elevated extracellular potassium (10-60 mM) or angiotensin II, Ca(2+)-independent CaMKII activity increased to 133-205% of basal activity. Ca(2+)-independent kinase activity in agonist-stimulated extracts was inhibited by the CaMKII inhibitor peptide, 1(-)[N,O-bis(1,5- isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62), a cell-permeable inhibitor of CaMKII, reduced the agonist-induced stimulation of Ca(2+)-independent CaMKII activity. KN-62 also diminished depolarization-induced increases in [Ca2+]i without affecting the membrane potential. These observations suggest that CaMKII is activated in situ by aldosterone secretagogues and augments Ca2+ signaling through voltage-gated Ca2+ channels.

scholarly journals scid cells are deficient in Ku and replication protein A phosphorylation by the DNA-dependent protein kinase.

1995 ◽  
Vol 15 (10) ◽  
pp. 5700-5706 ◽  
Author(s):  
N V Boubnov ◽  
D T Weaver
Keyword(s):  
Protein Kinase ◽  
Nuclear Dna ◽  
Protein A ◽  
Catalytic Subunit ◽  
Chromosome 8 ◽  
Dependent Protein Kinase ◽  
Cell Extracts ◽  
Dependent Protein ◽  
Radiation Induced ◽  
Scid Cells

Cell mutants of the Ku nuclear DNA-binding complex are ionizing radiation sensitive and show V(D)J recombination defects. Ku binds and activates a catalytic subunit of DNA-dependent protein kinase (DNA-PK), although the substrates for DNA-PK are unknown. We found that scid cell extracts were deficient in Ku phosphorylation by DNA-PK. Human chromosome 8-complemented scid cells, containing the human DNA-PK catalytic subunit, restored Ku phosphorylation. Likewise, radiation-induced RPA hyperphosphorylation was not completed in scid cells compared with control or chromosome 8-reconstituted cells. Thus, the inactivity of DNA-PK is likely responsible for the repair and recombination defects in scid cells.

Sign in / Sign up

Export Citation Format

Share Document