Insights into RNA Biology from an Atlas of Mammalian mRNA-Binding Proteins.
Castello, A., Fischer, B., Eichelbaum, K., Horos, R., Beckmann, B.M., Strein, C., Davey, N.E., Humphreys, D.T., Preiss, T., Steinmetz, L.M., Krijgsveld, J. & Hentze, M.W.
Cell. 2012 Jun 8;149(6):1393-406. Epub 2012 May 31.
RNA-binding proteins (RBPs) determine RNA fate from synthesis to decay. Employing two complementary protocols for covalent UV crosslinking of RBPs to RNA, we describe a systematic, unbiased, and comprehensive approach, termed "interactome capture," to define the mRNA interactome of proliferating human HeLa cells. We identify 860 proteins that qualify as RBPs by biochemical and statistical criteria, adding more than 300 RBPs to those previously known and shedding light on RBPs in disease, RNA-binding enzymes of intermediary metabolism, RNA-binding kinases, and RNA-binding architectures. Unexpectedly, we find that many proteins of the HeLa mRNA interactome are highly intrinsically disordered and enriched in short repetitive amino acid motifs. Interactome capture is broadly applicable to study mRNA interactome composition and dynamics in varied biological settings.
Iron regulatory proteins secure mitochondrial iron sufficiency and function.
Galy, B., Ferring-Appel, D., Sauer, S.W., Kaden, S., Lyoumi, S., Puy, H., Kolker, S., Grone, H.J. & Hentze, M.W.
Cell Metab. 2010 Aug 4;12(2):194-201.
Mitochondria supply cells with ATP, heme, and iron sulfur clusters (ISC), and mitochondrial energy metabolism involves both heme- and ISC-dependent enzymes. Here, we show that mitochondrial iron supply and function require iron regulatory proteins (IRP), cytosolic RNA-binding proteins that control mRNA translation and stability. Mice lacking both IRP1 and IRP2 in their hepatocytes suffer from mitochondrial iron deficiency and dysfunction associated with alterations of the ISC and heme biosynthetic pathways, leading to liver failure and death. These results uncover a major role of the IRPs in cell biology: to ensure adequate iron supply to the mitochondrion for proper function of this critical organelle.
The REM phase of gene regulation.
Hentze, M.W. & Preiss, T.
Trends Biochem Sci. 2010 Aug;35(8):423-6. Epub 2010 Jun 16.
'Classic' enzymes carry out the housekeeping functions of intermediary metabolism. The past decades have seen a steady trickle of reports of several of these enzymes 'moonlighting' as RNA-binding proteins. Although evidence for a physiological role for RNA binding is strong in a few individual examples, no systematic concept has been proposed for the overall phenomenon. We suggest that these diverse observations might herald the existence of currently hidden post-transcriptional regulatory networks between intermediary metabolism and gene expression based on RNA, enzyme and metabolite interactions. We briefly summarize the evidence in support of such networks and discuss how current approaches can be employed for systematic analyses and integration into our understanding of cellular biology, given the technical and conceptual advances of the 'omics' age.
Two to tango: regulation of Mammalian iron metabolism.
Hentze, M.W., Muckenthaler, M.U., Galy, B. & Camaschella, C.
Cell. 2010 Jul 9;142(1):24-38.
Disruptions in iron homeostasis from both iron deficiency and overload account for some of the most common human diseases. Iron metabolism is balanced by two regulatory systems, one that functions systemically and relies on the hormone hepcidin and the iron exporter ferroportin, and another that predominantly controls cellular iron metabolism through iron-regulatory proteins that bind iron-responsive elements in regulated messenger RNAs. We describe how the two distinct systems function and how they "tango" together in a coordinated manner. We also highlight some of the current questions in mammalian iron metabolism and discuss therapeutic opportunities arising from a better understanding of the underlying biological principles.
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