HIPK2 modulates p53 activity towards pro-apoptotic transcription

<p>Abstract</p> <p>Background</p> <p>Activation of p53-mediated gene transcription is a critical cellular response to DNA damage and involves a phosphorylation-acetylation cascade of p53. The discovery of differences in the response to different agents raises the question whether some of the p53 oncosuppressor functions might be exerted by different posttranslational modifications. Stress-induced homeodomain-interacting protein kinase-2 (HIPK2) phosphorylates p53 at serine-46 (Ser46) for p53 apoptotic activity; p53 acetylation at different C-terminus lysines including p300-mediated lysine-382 (Lys382) is also required for full activation of p53 transcriptional activity. The purpose of the current study was to evaluate the interplay among HIPK2, p300, and p53 in p53 acetylation and apoptotic transcriptional activity in response to drug by using siRNA interference, p300 overexpression or deacetylase inhibitors, in cancer cells.</p> <p>Results</p> <p>Knockdown of HIPK2 inhibited both adriamycin-induced Ser46 phosphorylation and Lys382 acetylation in p53 protein; however, while combination of ADR and zinc restored Ser46 phosphorylation it did not recover Lys382 acetylation. Chromatin immunoprecipitation studies showed that HIPK2 was required <it>in vivo </it>for efficient p300/p53 co-recruitment onto apoptotic promoters and that both p53 modifications at Ser46 and Lys382 were necessary for p53 apoptotic transcription. Thus, p53Lys382 acetylation in HIPK2 knockdown as well as p53 apoptotic activity in response to drug could be rescued by p300 overexpression. Similar effect was obtained with the Sirt1-inhibitor nicotinamide. Interestingly trichostatin A (TSA), the inhibitor of histone deacetylase complexes (HDAC) did not have effect, suggesting that Sirt1 was the deacetylase involved in p53 deacetylation in HIPK2 knockdown.</p> <p>Conclusion</p> <p>These results reveal a novel role for HIPK2 in activating p53 apoptotic transcription. Our results indicate that HIPK2 may regulate the balance between p53 acetylation and deacetylation, by stimulating on one hand co-recruitment of p300 and p53Lys382 on apoptotic promoters and on the other hand by inhibiting Sirt1 deacetylase activity. We attempted to reactivate p53 apoptotic transcriptional activity by rescuing both Ser46 and Lys382 modification in response to drug. Our data propose combination strategies for the treatment of tumors with dysfunctional p53 and/or HIPK2 that include classical chemotherapy with pharmacological or natural agents such as Sirt1-deacetylase inhibitors or zinc, respectively.</p

Cauliflower ear - a minimally invasive treatment method in a wrestling athlete: a case report

Acute auricular hematoma can be caused by direct blunt trauma or other injury to the external ear. It is typically seen in those who practice full contact sports such as boxing, wrestling, and rugby. “Cauliflower ear” deformity, fibrocartilage formation during scarring, is a common complication of auricular hematomas. Therefore, acute drainage of the hematoma and postprocedural techniques for preventing recurrence are necessary for preventing the deformity. There are many techniques although no superior method of treatment has been found. In this case report, we describe a novel method using needle aspiration followed by the application of a magnet and an adapted disc to the affected area of the auricular. This minimally invasive, simple, and accessible method could potentially facilitate the treatment of cauliflower ear among full contact sports athletes

Cross-sectional analysis of the mandibular lingual concavity using cone beam computed tomography

To study the prevalence and the degree of lingual concavity in the edentulous first molar region from cone beam computed tomography (CBCT) scans of the mandibles.Qualified cross-sectional images in mandibular first molar edentulous region taken from CBCT were selected. The mandible morphology 2 mm above the inferior alveolar canal (IAC) was classified into the convex (C), parallel (P) and undercut (U) type, based on the presence of lingual concavity and the shape of alveolar ridge. The prevalence of each group was determined. Subsequently, the lingual concavity characters, including the depth, the angulation and the vertical location were determined by the measurements of selected anatomic landmarks.One hundred and three subjects (mean age 51 with a range of 23.7–70.4 years) were studied. The U type was the most prevalent, accounting for 66% of the study population. The mean undercut depth and angulation at the level 2 mm above IAC were on average 2.4 mm and 57.7°. The mean vertical distances from the most prominent point (P) of the lingual concavity to the cemento-enamel junction of second premolar and the inferior border of the mandible were 11.7 and 14.9 mm, respectively.The anatomic location and the degree of the lingual concavity presented in this article add more information in implant treatment planning in the mandibular first molar edentulous region. To cite this article: Chan H-L, Brooks SL, Fu J-H, Yeh C-Y, Rudek I, Wang H-L. Cross-sectional analysis of the mandibular lingual concavity using cone beam computed tomography. Clin. Oral Impl. Res . 22 , 2011; 201–206. doi: 10.1111/j.1600-0501.2010.02018.xPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79062/1/j.1600-0501.2010.02018.x.pd

A new approach for the isolation of biologically active compounds by affinity chromatography: Isolation of trypsin

Digitalitzat per Artypla

Properties of yeast pyruvate decarboxylase and their modification by proteolytic enzymes : II. Selective alteration by yeast proteases

Pyruvate decarboxylase has been shown to be more heat labile in extracts of a mutant strain than in extracts of the parent yeast strain. Mutant extracts were found to contain higher levels of proteolytic enzymes than wild-type extracts, although aging of the latter preparations resulted in the activation of inactive proteases. A partially purified protease preparation was shown to degrade pyruvate decarboxylase in a selective manner such that the ability to form free acetaldehyde was destroyed while the acetylmethylcarbinol-forming activity was increased 60%. Pyruvate, or a mixture of pyruvate and acetaldehyde, was partly successful in protecting pyruvate decarboxylase from the action of the protease. Stabilization of pyruvate decarboxylase by high concentrations of phosphate, sulfate, or glycerol has been shown to be due to the inhibitory action of these compounds on yeast proteases. Pyruvate decarboxylase which was partially degraded by the protease had different relative activities on a series of [alpha]-keto acids from the corresponding activities of a nondegraded decarboxylase preparation. The data presented are in accord with a two-site mechanism postulated for pyruvate decarboxylase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33236/1/0000626.pd

Alternative splicing of the mouse embryonic poly(A) binding protein (Epab) mRNA is regulated by an exonic splicing enhancer: a model for post-transcriptional control of gene expression in the oocyte

Embryonic poly(A) binding protein (EPAB), expressed in oocytes and early embryos, binds and stabilizes maternal mRNAs, and mediates initiation of their translation. We identified an alternatively spliced form of Epab lacking exon 10 (c.Ex10del) and investigated the regulation of Epab mRNA alternative splicing as a model for alternative splicing in oocytes and early preimplantation embryos. Specifically, we evaluated the following mechanisms: imprinting; RNA editing and exonic splicing enhancers (ESEs). Sequence analysis led to the identification of two single nucleotide polymorphisms (SNPs): one was detected in exon 9 (rs55858A/G), and served as a marker for the parental origin of the alternatively spliced form, and the other was found in exon 10 (rs56574G/C), and co-segregated with the exon 9 SNP. We found that the presence of rs56574G in exon 10 led to the formation of an ESE, leading to efficient exclusion of exon 10. Real-time RT–PCR results revealed a 5-fold increase in the expression of the c.Ex10del alternative splicing variant in animals carrying rs56574G/G in exon 10 compared with rs56574C/C at the same locus. Our findings suggest that SNPs may alter the ratio between alternative splicing variants of oocyte-specific proteins. The role that these subtle differences play in determining individual reproductive outcome remains to be determined