MCL-1V, a novel mouse antiapoptotic MCL-1 variant, generated by RNA splicing at a non-canonical splicing pair.

Myeloid cell leukemia-1 (MCL-1) that belongs to BCL-2 family is essential for survival of hematopoietic stem cells. It is upregulated in various types of cancer and promotes cancer cell metastasis. It is known that human MCL-1 gene undergoes differential splicing and yields three mRNAs encoding antiapoptotic MCL-1L and proapoptotic MCL-1S and MCL-1ES. However, no MCL-1 variants have been reported in mouse cells. We report here a new splicing variant of mouse Mcl-1, Mcl-1V, that is expressed in a variety of mouse normal and tumor cell lines and tissues. Comparative sequence analysis of the full-length Mcl-1 and Mcl-1V cDNAs suggested that Mcl-1V mRNA results from splicing within the first coding exon of Mcl-1 gene at a non-canonical donor-acceptor pair. MCL-1V lacks 46 amino acid residues within the N-terminal region of MCL-1. It localizes in mitochondria and inhibits anoxia- and anticancer drug-induced apoptosis as potent as MCL-1, and decayed less rapidly than MCL-1 in the cells undergoing apoptosis. Collectively, our results show that mouse cells ubiquitously express antiapoptotic MCL-1V that may play a role in mitochondrial cell death.

[Optimization of histogram analysis for pediatric digital chest radiography using flat panel detector system].

Optical density of the lung area in pediatric digital chest radiography using an indirect flat panel detector (FPD) system were changed enormously by the influence of such factors as the size of lung area, gas of retroperitoneum, and so on. Our purpose in this study was to improve the stability of lung density on output images by means of optimizing histogram analysis. Chest images of a lung phantom were taken at various X-ray tube voltages and processed using a half-type region of interest (ROI) for the lung area. The shape of the histogram obtained by two different calculation methods including frequency distribution and cumulative relative frequency were compared, and digital chest images of 110 clinical cases in our hospital were classified into three age-groups (under 6 years old, over 6 years old and under 13 years old, and over 13 years old) and their histograms were analyzed. In conclusion, it was important that to analyze the histograms of age-groups, a cumulative relative frequency histogram should be used because the influence of X-ray tube voltage was lower than the frequency distribution histogram, and stabilized lung density under 6 years old could be obtained if the value of the imaging parameter for lung density from default was 90% to 85% or 80% because the distribution of lung area and its center value were significantly lower than in those over 13 years old.