|Professor of Biology
Development of neuronal connections
My lab is studying the problem of growth cone guidance during the development and regeneration of the nervous system. There are two main projects in my lab, one studying the dynamic behavior of growth cones in the nematode C. elegans and the other using an RNAi based screen to identify genes regulating neural regeneration.
In the first project the simple, well-characterized nervous system of the nematode C. elegans provides us with an opportunity to study the behavior of growth cones in vivo. Distinct cellular landmarks are known and can be easily visualized in the transparent worm. C. elegans is a powerful genetic system; as a result many molecules required for axonal outgrowth have been identified. The ultimate goal of our research is to observe the behavior of growth cones in vivo and correlate changes in behavior with specific molecular mutations. Our preliminary results show that time-lapse laser-scanning confocal microscopy can be used to visualize growth cones as they migrate in vivo. We have found that distinct behavioral changes are exhibited by growth cones as they interact with different cellular substrates. These changes and the nature of these modifications to growth cone behavior can be analyzed using a variety of approaches. As a result we have developed an assay for observing the behavior of growth cones as they migrate in the complex molecular environment of the living animal. Now the function of any molecule regulating growth cone behavior can be determined by disrupting the function of that molecule genetically and observing the resultant behavioral changes that growth cones exhibit in the mutant environment.
Neuronal regeneration after axotomy has been studied in humans and other vertebrate model systems for over 100 years and yet we still do not have a comprehensive molecular model nor an effective treatment to induce regeneration. Surprisingly, the powerful genetic model systems used so successfully to study body pattern formation, programmed cell death, neural development and many other important biological problems have not been used to study neuronal regeneration. This was obviously not an oversight by scientists. Rather, it has been difficult to devise a robust screening assay for neural regeneration in either D. melanogaster or C. elegans. Recently, Hammarlund, Jorgensen, and myself made an observation that now makes it possible to screen for genes required for regeneration in C. elegans. We discovered that embryonic neurons lacking B-spectrin develop normally (normal growth cone motility, pathfinding, and target recognition), but after hatching undergo movement-induced axotomy followed by regeneration. This is a robust phenotype, with most commissural axons in each animal breaking and regenerating before the animal reaches adulthood. There is a progressive failure of regeneration as each cycle of axotomy and regeneration takes place so that the adult displays a severely abnormal nervous system. This well-characterized regeneration phenotype in C. elegans mimics the phenotype of mammalian neurons in response to axotomy. We are using RNAi knockdown to assay the function of every gene in the worm genome in the process of neuronal regeneration.
Nix, P., Hisamoto, N., Matsumoto, K., and Bastiani, M. (2011) Axon regeneration requires coordinate activation of p38 and JNK MAPK pathways. Proc Natl Acad Sci U S A, Jun 13. [Epub ahead of print]
Frøkjaer-Jensen, C., Davis, M.W., Hollopeter, G., Taylor, J., Harris, T.W., Nix, P., Lofgren, R., Prestgard-Duke, M., Bastiani, M., Moerman, D.G., and Jorgensen, E.M. (2010) Targeted gene deletions in C. elegans using transposon excision. Nat Methods, Jun;7(6):451-3. Epub 2010 Apr 25.
Hammarlund, M., Nix, P., Hauth, L., Jorgensen, E.M., and Bastiani, M. (2009) Axon regeneration requires a conserved MAP kinase pathway. Science, 323(5915):802-806.
Commentary on Science Paper: O'Brien, G. S. and A. Sagasti (2009) Fragile axons forge the path to gene discovery: a MAP kinase pathway regulates axon regeneration. Sci Signal, 2(69):pe30.
Weinkove, D., Bastiani, M., Chessa, T.A., Joshi, D., Hauth, L., Cooke, F.T., Divecha, N., and Schuske, K. (2008) Overexpression of PPK-1, the Caenorhabditis elegans Type I PIP kinase, inhibits growth cone collapse in the developing nervous system and causes axonal degeneration in adults. Dev Biol, 313(1):384-397.
Hammarlund, M., Jorgensen, E.M., and Bastiani, M.J. (2007) Axons break in animals lacking B-spectrin. J. Cell Biology, 176:269-275.
Strigini, M., Cantera R., Morin, X., Dunlop, J., Bastiani, M.J., Bate, M., and Karagogeos, D. (2006) The IgLON protein Lachesin is required for the blood-brain barrier in Drosophila. Molecular and Cellular Neuroscience, May 6 (available online), in press.
Sanchez, D., López-Arias, B., Torroja, L., Canal, I., Wang, X., Bastiani, M.J., and Ganfornina, M.D. (2006) Glial Lazarillo, a homolog of Apolipoprotein D in flies, confers protection in situations of oxidative stress. Current Biology, 16(7):680-686.
Rong, Y. S., Titen, S. W., Xie, H. B., Golic, M. M., Bastiani, M., Bandyopadhyay, P., Olivera, B. M., Brodsky, M., Rubin, G. M., and Golic, K. G. (2002) Targeted mutagenesis by homologous recombination in D. melanogaster. Genes Dev., Jun 15; 16(12):1568-1581.
Knobel, K., Davis, W. S., Jorgensen, E. M., and Bastiani, M. J. (2001) UNC-119 suppresses axon branching in C. elegans. Development, 128:4079-4092.
Sanchez, D., Ganfornina, M. D., Torres-Schumann, S., Speese, S. D., Lora, J. M., and Bastiani, M. J. (2000) Characterization of two novel lipocalins expressed in the Drosophila embryonic nervous system. Int. J. Dev. Biol., Jun;44(4):349-359.
Ganfornina, M. D., Sánchez, D., and Bastiani, M. J. (1999) Developmental expression and molecular characterization of two gap junction channel proteins expressed during embryogenesis in the grasshopper Schistocerca americana. Developmental Genetics 24:137-150.
Knobel, K., Jorgensen, E. M., and Bastiani, M. J. (1999) Growth cones stall and collapse during axon outgrowth in C. elegans. Development 126:4489-4498.
Ganfornina, M. D., and Bastiani, M. J. (1998) Growth cones. In: Encyclopedia of Neuroscience (2nd Edition), Ed.: G. Adelman. Birkhäuser, Boston.
Sánchez, D., Ganfornina, M. D., Gutierrez, G., and Bastiani, M. J. (1998) Molecular characterization and phylogenetic relationships of a protein with oxygen-binding capabilities in the grasshopper embryo. A hemocyanin in insects? Molecular Biology and Evolution 15:415-426.