CNR - Institute of Neuroscience CNR
Institute of Neuroscience
 

Project

Cellular mechanisms controlling fate choice in developing neurons

In multicellular organisms, cells choose their fate (to divide, differentiate or die) by converting extracellular signals in intracellular messages. My research is focused on the early intracellular signaling underlying the processes of mitotic cycle exit and differentiation onset in developing neurons. Particular attention is dedicated to the role of the sphingolipid metabolites, a class of bioactive lipids, in transducing the extracellular signals which control neuronal proliferation, differentiation and death.

The Sphingolipid metabolites

The sphingolipids, besides playing a structural role in plasma membranes, are bioactive signaling molecules involved in the regulation of many different cell functions such as growth, differentiation, adhesion, migration, intracellular trafficking, senescence, and apoptosis. The rapidly expanding field of bioactive lipids is exemplified by ceramide, sphingosine, sphingosine-1-phosphate (S1P), ceramide-1-phosphate and lyso-sphingomyelin. The first of these to be identified was sphingosine, which exerts various effects in regulating the actin cytoskeleton, endocytosis, the cell cycle and apoptosis. Even more emphasis has been placed on the sphingolipids ceramide and sphingosine-1-phosphate (S1P). Ceramide mediates many cell-stress responses, including the cell senescence, whereas S1P has crucial roles in cell survival, cell migration and inflammation. Recent additions to the family of bioactive sphingolipids include ceramide-1-phosphate, which has roles in inflammation and vesicular trafficking, and glucosylceramide, which is involved in post-Golgi trafficking and in drug resistance. The enzymes of lipid metabolism are intimately related to each other, generating an interconnected network that regulates both the levels of specific bioactive lipids and their metabolic interconversion. Unlike other second messengers such as cAMP or cGMP, the sphingolipids exhibit hydrophobic properties, therefore, their physiological environment is restricted to the biological membranes.

The use of live-cell imaging to identify the mechanisms of action of bioactive sphingolipids

 

Understanding what bioactive sphingolipids do and how they transmit signals requires the elucidation of their intracellular targets. In my laboratory a combination of cell biology and imaging techniques, such as Ca++ imaging, time-lapse video microscopy, fluorescence and confocal imaging on living neurons are used to study the sphingolipid second messengers as well as the early phases of neuronal differentiation. The use of vital fluorescent synthetic dyes and genetically encoded fluorescent proteins with fluorescence and confocal microscopy allows the visualization of a broad range of dynamic features in living cells. In particular, using these approaches, the role of Ca++ signaling in mediating the sphingolipid effects is currently evaluated, as well as the function of the intracellular relocation of proteins and transcription factors following the activation of specific sphingolipid signaling pathways. The perturbation of the mitochondrial function by bioactive lipids is also evaluated. This is an important point since an altered mitochondrial function is often the basis of neurodegenerative diseases. Additionally, many neurodegenerative diseases share common aspects that are associated with changes in the dynamic behaviour of definite cell compartments, including missorting and aggregation of proteins or disturbances of protein or lipid turnover and transport.

 

Recently a neuronal model of Niemann-Pick type C disease has been developed in my laboratory. This is a rare genetic disease determined by the alteration of the intracellular transport of cholesterol and sphingolipids. The proper control of this transport is essential for normal cell function and its deregulation is characterized by an over accumulation of free sterols and sphingolipids in endosomes and in Endoplasmic Reticulum. The molecular mechanisms that lead to neuronal dysfunction and death in Niemann-Pick type C disease, at the present, are poorly understood. The use of live-cell-imaging approaches allows a precise characterization of the cellular functions altered by the defective lipid trafficking and provides useful information to develop new therapies for the treatment of this fatal disease.

Publications

  • Voccoli V, Colombaioni L (2009) Mitochondrial remodeling in differentiating neuroblasts. Brain Res. 1252:15-29.
  • Voccoli V, Mazzoni F, Garcia-Gil M, Colombaioni L (2007) Serum-withdrawal-dependent apoptosis of hippocampal neuroblasts involves Ca++ release by endoplasmic reticulum and caspase-12 activation. Brain Res. 1147:1-11.
  • Colombaioni L, Garcia-Gil M (2004) Sphingolipid metabolites in neural signalling and function. Brain Res. Brain Res. Rev. 46:328-55.
  • Colombaioni L, Colombini L, Garcia-Gil M (2002) Role of mitochondria in serum withdrawal-induced apoptosis of immortalized neuronal precursors. Brain Res. Dev. Brain Res. 134:93-102.
  • Colombaioni L, Frago LM, Varela-Nieto I, Pesi R, Garcia-Gil M (2002) Serum deprivation increases ceramide levels and induces apoptosis in undifferentiated HN9.10e cells. Neurochem. Int. 40:327-36.
  • Cellerino A, Galli-Resta L, Colombaioni L (2000) The dynamics of neuronal death: a time-lapse study in the retina. J. Neurosci. 20:RC92.

Grants

2008 to 2010: Coordinator, Associazione Italiana Niemann-Pick

Collaborations

  • D.S. Ory, Washington University School of Medicine, USA.
  • R. Sabbadini, L-Path Biotech, San Diego, USA.
  • S. Pyne, Institute of Pharmacy and Biomedical Sciences, Glasgow, UK.
  • E. Pitzinos, Institute of Physical Chemistry, Athens, Greece.

 

no PI photo

Laura Colombaioni

Contact information

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Participating staff
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