ABSTRACT
The p53 tumour suppressor protein is one of the major factors responsible for cell cycle regulation and protection against cancer development. This is why it is often referred to as "the guardian of the genome". On the other hand, mutations in the p53 gene are connected with more than 50% of tumours of various types. The thirty-six years of extensive research on the p53 gene and its protein products have shown how sophisticated the p53-based cell system control is. An additional level of complexity of the p53 research is connected with at least twelve p53 isoforms which have been identified in the cell. Importantly, disturbance of the p53 isoforms' expression seems to play a key role in tumorigenesis, cell differentiation and cell response to pathogenic bacteria, and RNA and DNA viruses. Expression of various p53 isoforms results from the usage of different transcription promoters, alternative splicing events and translation initiation from alternative AUG codons. The importance of the 5'-terminal regions of different p53 mRNA transcripts in the multi-level regulation of the p53 gene has recently been documented. In this review we focus on the structural features of these regions and their specific role in the p53 translation initiation process.
Subject(s)
RNA, Messenger/genetics , Tumor Suppressor Protein p53/genetics , 5' Untranslated Regions , Gene Expression , Gene Expression Regulation, Neoplastic , Genes, p53 , Humans , Neoplasms/genetics , Neoplasms/metabolism , Peptide Chain Initiation, Translational , Promoter Regions, Genetic , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Tumor Suppressor Protein p53/metabolismABSTRACT
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystemic disorder caused by expansion of CTG triplet repeats in 3'-untranslated region of DMPK gene. The pathomechanism of DM1 is driven by accumulation of toxic transcripts containing expanded CUG repeats (CUG(exp)) in nuclear foci which sequester several factors regulating RNA metabolism, such as Muscleblind-like proteins (MBNLs). In this work, we utilized very short chemically modified antisense oligonucleotides composed exclusively of locked nucleic acids (all-LNAs) complementary to CUG repeats, as potential therapeutic agents against DM1. Our in vitro data demonstrated that very short, 8- or 10-unit all-LNAs effectively bound the CUG repeat RNA and prevented the formation of CUG(exp)/MBNL complexes. In proliferating DM1 cells as well as in skeletal muscles of DM1 mouse model the all-LNAs induced the reduction of the number and size of CUG(exp) foci and corrected MBNL-sensitive alternative splicing defects with high efficacy and specificity. The all-LNAs had low impact on the cellular level of CUG(exp)-containing transcripts and did not affect the expression of other transcripts with short CUG repeats. Our data strongly indicate that short all-LNAs complementary to CUG repeats are a promising therapeutic tool against DM1.
Subject(s)
Alternative Splicing , Myotonic Dystrophy/therapy , Oligonucleotides, Antisense/therapeutic use , Oligonucleotides/therapeutic use , 3' Untranslated Regions , Animals , Base Sequence , Cell Line , Disease Models, Animal , HEK293 Cells , HeLa Cells , Humans , Mice , Mice, Transgenic , Mutant Proteins/genetics , Myotonic Dystrophy/genetics , Myotonic Dystrophy/metabolism , Myotonin-Protein Kinase/genetics , Oligonucleotides/genetics , Oligonucleotides, Antisense/genetics , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Trinucleotide Repeat ExpansionABSTRACT
INTRODUCTION: Recent reports have confirmed an increase in plasma immunoglobulin E (IgE), which had been previously observed in clinical situations associated with tissue injury. Studies on the regulation of IgE levels have pointed to the role of low-affinity IgE receptor, i.e., sFcεRII (soluble CD23 [sCD23]). OBJECTIVES: The aim of the study was to assess the changes in the levels of this receptor in response to surgical injury during coronary artery bypass grafting. PATIENTS AND METHODS: The study group consisted of 33 patients (28 men and 5 women, aged 45-75 years). Blood samples were obtained from all patients before surgery and 24, 48, 72, and 120 hours after the surgery. The expression of FcεRII on B cells was measured using flow cytometry and plasma levels of sCD23 were determined by an enzyme-linked immunosorbent assay. RESULTS: We observed a significant increase in the total number of leukocytes and a significant decrease in the total number of lymphocytes with a simultaneous increase in the proportion of B cells (P <0.001). At the same time, the percentage of CD23-positive B cells (CD19/23+) decreased significantly (P <0.001) at 24 hours after surgery and remained low over the period of 72 hours. The plasma levels of sCD23 increased significantly (P <0.05) at 24 hours after surgery and remained elevated until the end of follow-up. All the above changes in the immune status preceded an increase in plasma IgE levels (P <0.001), which reached peak values on the fifth day after surgery (120 h). CONCLUSIONS: Surgical procedures are associated with a transient increase in plasma IgE levels, which is preceded by an increase in the level of sCD23 and a simultaneous decrease in the expression of CD23 on B cells. FcεRII (CD23) and sFcεRII (sCD23) may be involved in the regulation of IgE levels after trauma.
