ABSTRACT
MicroRNAs (miRNAs) are short single-stranded RNAs that have a potentially important role in gene regulation. Using a quantitative real-time polymerase chain reaction assay specific to the mature miRNA, the expression level of a selected group of haematopoietic tissue-specific miRNAs was measured across a set of 30 primary adult acute myeloid leukaemia (AML) with a normal karyotype. The expression levels of each miRNA were correlated with the genome-wide mRNA expression profiles in the same leukaemias. This revealed that miR-181a correlated strongly with the AML morphological sub-type and with the expression of genes previously identified through sequence analysis as potential interaction targets. Three other miRNAs, miR-10a, miR-10b and miR-196a-1, showed a clear correlation with HOX gene expression.
Subject(s)
Gene Expression Profiling , Leukemia, Myeloid, Acute/genetics , MicroRNAs/analysis , Adult , Aged , Aged, 80 and over , Female , Genes, Homeobox , Humans , Leukemia, Myeloid, Acute/classification , Leukemia, Myeloid, Acute/pathology , Male , Middle AgedABSTRACT
The chromosomal translocation t(8;21) is associated with 10-15% of all cases of acute myeloid leukaemia (AML). The resultant fusion protein AML1/MTG8 interferes with haematopoietic gene expression and is an important regulator of leukaemogenesis. We studied the effects of small interfering RNA (siRNA)-mediated AML1/MTG8 depletion on global gene expression in t(8;21)-positive leukaemic cell lines and in primary AML blasts using cDNA arrays, oligonucleotide arrays and real-time reverse transcription-polymerase chain reaction (RT-PCR). Suppression of AML1/MTG8 results in the increased expression of genes associated with myeloid differentiation, such as AZU1, BPI, CTSG, LYZ and RNASE2 as well as of antiproliferative genes such as IGFBP7, MS4A3 and SLA both in blasts and in cell lines. Furthermore, expression levels of several genes affiliated with drug resistance or indicative of poor prognosis AML (BAALC, CD34, PRG2, TSPAN7) are affected by AML1/MTG8 depletion. In conclusion, siRNA-mediated suppression of AML1/MTG8 cause very similar changes in gene expression pattern in t(8;21)-positive cell lines and in primary AML blasts. Furthermore, the results suggest that the specific targeting of AML1/MTG8 function may be a promising approach for complementing existing treatment strategies.
Subject(s)
Cell Differentiation/genetics , Cell Proliferation , Chromosomes, Human, Pair 21 , Chromosomes, Human, Pair 8 , Core Binding Factor Alpha 2 Subunit/physiology , DNA-Binding Proteins/physiology , Gene Expression Regulation, Neoplastic/physiology , Leukemia, Myeloid/genetics , Proto-Oncogene Proteins/physiology , RNA, Small Interfering/physiology , Transcription Factors/physiology , Translocation, Genetic , Acute Disease , Base Sequence , Cell Line, Tumor , Core Binding Factor Alpha 2 Subunit/genetics , DNA Primers , DNA-Binding Proteins/genetics , Gene Expression Profiling , Humans , Leukemia, Myeloid/pathology , Male , Middle Aged , Oligonucleotide Array Sequence Analysis , Proto-Oncogene Proteins/genetics , RUNX1 Translocation Partner 1 Protein , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors/geneticsABSTRACT
A reduction in pH is known to induce the disassociation of the tetrameric form of transthyretin and favor the formation of amyloid fibers. Using continuum electrostatic techniques, we calculate the titration curves and the stability of dimer and tetramer formation of transthyretin as a function of pH. We find that the tetramer and the dimer become less stable than the monomer as the pH is lowered. The free energy difference is 13.8 kcal/mol for dimer formation and 27 kcal/mol for tetramer formation, from the monomers, when the pH is lowered from 7 to 3.9. Similar behavior is observed for both the wild-type and the mutant protein. Certain residues (namely Glu-72, His-88, His-90, Glu-92, and Tyr-116), play an important role in the binding process, as seen by the considerable pK(1/2) change of these residues upon dimer formation.