Ubr3 E3 ligase regulates apoptosis by controlling the activity of DIAP1 in Drosophila

Apoptosis has essential roles in a variety of cellular and developmental processes. Although the pathway is well studied, how the activities of individual components in the pathway are regulated is less understood. In Drosophila, a key component in apoptosis is Drosophila inhibitor of apoptosis protein 1 (DIAP1), which is required to prevent caspase activation. Here, we demonstrate that Drosophila CG42593 (ubr3), encoding the homolog of mammalian UBR3, has an essential role in regulating the apoptosis pathway. We show that loss of ubr3 activity causes caspase-dependent apoptosis in Drosophila eye and wing discs. Our genetic epistasis analyses show that the apoptosis induced by loss of ubr3 can be suppressed by loss of initiator caspase Drosophila Nedd2-like caspase (Dronc), or by ectopic expression of the apoptosis inhibitor p35, but cannot be rescued by overexpression of DIAP1. Importantly, we show that the activity of Ubr3 in the apoptosis pathway is not dependent on its Ring-domain, which is required for its E3 ligase activity. Furthermore, we find that through the UBR-box domain, Ubr3 physically interacts with the neo-epitope of DIAP1 that is exposed after caspase-mediated cleavage. This interaction promotes the recruitment and ubiquitination of substrate caspases by DIAP1. Together, our data indicate that Ubr3 interacts with DIAP1 and positively regulates DIAP1 activity, possibly by maintaining its active conformation in the apoptosis pathway

Metabolomics on CMOS for personalised medicine

The emergence of personalised and precision healthcare requires detailed knowledge of human molecular pathology. Genomics has been transformed by sequencing technologies that can unravel the human genome in 1 day for less than a thousand dollars. Recently, metabolomics, the quantitative measurement of small molecules, has emerged as a field to study an individual’s molecular profile. This is very important because a genome can only give a prediction of an individual’s propensity to a disease – genotyping, while a metabolome can provide immediate diagnosis of biochemical activity in human body – phenotyping. However, the present approach of measuring metabolites depends on large and expensive equipment such as NMR spectroscopy and mass spectroscopy. More importantly, this equipment does not provide a single analytical platform to measure the entire metabolome. CMOS technology has made a major impact in personal mobile computing, digital imaging and communications as part of everyday life. CMOS provides a single integrated platform for sensing technologies, low-cost manufacturing and miniaturisation of microelectronic systems. CMOS has been used successfully to create an all-electronic sequencing technology. We anticipate that CMOS has the potential to allow multiple biomarkers to be monitored in parallel, thus paving the way for metabolome profiling. This review will provide a background to personalised medicine, in terms of genomics and metabolomics, to show the importance for future healthcare delivery. A theoretical background of enzymes for metabolite quantification will also be discussed. A description of DNA microarray technologies will be provided. A background of CMOS chemical sensor systems will be presented for DNA sequencing and metabolite quantification. Finally, a discussion of future CMOS sensor systems, microelectronics and integration technologies that could lead to new “omics” technologies, will be given