An EU-funded study led by researchers in Austria has found that lamins are responsible for producing new 'tissue-specific' cells in adult organisms, and thereby play a key role in the maintenance and regeneration of high-turnover tissues such as skin and muscle. The findings have major implications for inherited disorders such as muscular dystrophy, cardiomyopathy, diabetes and premature aging. The results, published in the journal Nature Cell Biology, have come out of the three-year EURO-Laminopathies project, received EUR 2.5 million from the EU's Sixth Framework Programme (FP6) under the Thematic area 'Life sciences, genomics and biotechnology for health'. Professor Roland Foisner of the Medical University of Vienna in Austria worked with a team of researchers in Austria, Singapore and the US examining the molecular properties of lamin complexes and how these properties impact both disease and normal ageing. Lamins are major structural component proteins of the nucleus in vertebrate cells. Laminopathies are inherited human disorders, including muscular dystrophy, cardiomyopathy, lipodystrophy, insulin resistance, diabetes, and premature aging, which are linked to mutations in genes that encode 'nuclear envelope proteins', for example A-type lamins and lamin-binding proteins. The EURO-Laminopathies project sought to identify the molecular mechanisms underlying these mutations in order to understand how their effect on lamins might reduce a cell's stress resistance. The outermost part of a cell's nucleus is called the 'nuclear envelope'. The inner layer of this envelope is called the 'peripheral nuclear lamina', and contains the protein lamin A. Lamin A was until recently considered to be an exclusively structural component of vertebrate cells; the study by Professor Foisner's team showed that it is actually involved in other processes. The researchers studied cells in culture and in mice and confirmed that lamin A is essential for the regulation of the cell cycle. They observed that lamin A was responsible for regulating the proliferation and differentiation of progenitor cells, which are similar to stem cells, in highly regenerative tissues such as skin and muscle. The biochemists deleted a specific lamin A 'binding partner', which determines where the protein will be located within the nucleus. This caused the lamin A to be produced in the wrong place, which in turn impaired the cell's ability to stop the cell-division cycle, which then caused an overproduction of progenitor cells and tissue hyperplasia (wherein the cells constantly divide). 'We consider our findings to be highly relevant for laminopathic diseases in humans,' the study concluded, 'suggesting that mutations in LMNA or LAP2 may impair early progenitor cells in tissue regeneration.' One of the goals of the EURO-Laminopathies project is to apply their new knowledge to identifying drug targets for potential therapeutic intervention. 'We are just beginning to understand some of the functions of lamins in adult stem cells,' said Dr Foisner. 'The role of lamins in the natural ageing process is highly interesting and has a great scientific and social potential, and we are very eager to continue our research in this field.'