Physiological and evolutionary origin of the eukaryotic microtubule system – Alliegro Lab

All eukaryotic cells (cells with nuclei, such as human and plant cells) have a skeletal system made of microtubules. This microtubule-based “cytoskeleton” requires an organizing center to function effectively. In animal cells, the microtubule organizing center, or MTOC, is the centrosome. The centrosome and the structures that arise from it are essential for normal cell division. They are also essential for the formation and function of tiny hair-like structures on the cell surface known as cilia. An almost uncountable number of human maladies are directly or indirectly related to the cytoskeleton, abnormal cell division, and malfunctioning cilia. Moreover, since the microtubule-based cytoskeleton is a signature structure of all eukaryotic cells, its evolutionary history holds clues to the origins of all animals and plants.

The Alliegro lab is interested in the genesis of the centrosome and related structures during the living cell cycle, as well as their original development in eukaryotic cells approximately two billion years ago. To this end, the laboratory has isolated a unique group of nucleic acids (RNAs) from centrosomes and uses them to study both aspects of centrosome genesis, the physiological and the evolutionary. In the former case, these RNAs have been used to discover a link between the centrosome and a poorly understood subcompartment of the nucleus known as the nucleolinus. The Alliegros have shown that the nucleolinus gives rise to centrosomal precursors (see microscopic image, below) and is essential for formation of the cell division apparatus. From the evolutionary standpoint, the laboratory is providing evidence that these RNAs (and by inference, MTOCs) have origins that stretch back further than the beginnings of the eukaryotic cell line and perhaps originated with prokaryotic cells (such as bacteria) or viruses.

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