I. An Introduction to Paracrine Signaling
II. Cytoneme Directed Transport and Direct Transfer Model
Part I: An Introduction to Paracrine Signaling
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|Resources: Related ArticlesTranscript (.txt)(.xls)Recorded: 2014|
It has been known since 1908 that tissue transplanted from one Hydra to another can influence development in the recipient hydra. Later in the 1920s, Spemann and colleagues found that transplantation of tissue from the dorsal to the ventral side of an amphibian embryo induced the growth of a second embryonic axis. Kornberg describes the experiments that implicated “inducers” that are responsible for such effects and reports recent findings that show that inducers are proteins that move across tissues to affect nearby cells. Inducers are proteins such as FGF, TGF-beta, Hedgehog, and Wnt. Although diffusion initially seemed to be the simplest explanation for their dispersion, experimental data now reveals that their transport is directed and that the inducers are targeted to recipient cells. Kornberg presents evidence that their transport occurs via a system of signaling filipodia called cytonemes.
In Part 2 of his talk, Kornberg focuses on the signals that regulate development of the dorsal air sacs in Drosophila. Dorsal air sacs are multi-lobed structures that distribute oxygen to the flight muscles of the adult fly. They develop from an organ in Drosophila larvae called the air sac primordium, which nestles up against the wing imaginal disc; the wing imaginal disc gives rise to numerous structures of the adult fly, including wings, the thorax and the dorsal air sacs. The protein inducers that activate signal transduction in the air sac primordium are produced many microns away in the wing disc. How do these signals travel across this distance? Using labeled proteins and fluorescence microscopy, Kornberg shows us that the inducers are transferred directly from producer cells to recipient cells via cytonemes. This transfer requires direct cell-to-cell contact in a manner similar to a neuronal synapse.
Tom Kornberg received his BA in Biology and his PhD in Biochemistry both from Columbia University. As a graduate student, Kornberg identified and purified E. coli DNA polymerase II and III for the first time. Kornberg went on to do post-doctoral studies at Princeton and the MRC labs at Cambridge.
In 1978, Kornberg joined the faculty at the University of California, San Francisco where he is now Professor of Biochemistry and Biophysics in the Cardiovascular Research Institute. His lab uses the development of the Drosophila wing disc as a model system to study the mechanisms by which cells communicate over long distances.
While Kornberg was a undergraduate biology student, he also studied cello at the renowned Juilliard School. Kornberg continues to play cello and you can hear him in his iBioMagazine video in this video.
- Eric Wieschaus iBioSeminar: Developmental Patterning in the Early Embryo
- Trudi Schupbach iBioSeminar: Control of Embryonic Axis Formation in Drosophila
- Thomas Kornberg iBioMagazine: Beethoven’s Cello Sonata No. 3 in A major, 1st movement.
Roy, S., Hsiung, F. and T.B. Kornberg (2011) Specificity of Drosophila Cytonemes for Distinct Signaling Pathways. Science, 332, 354-358. PMID: 21493861; PMC3109072
Roy, S., Huang, H., Liu, SM and T.B. Kornberg (2014) Cytoneme-mediated contact-dependent transport of the Drosophila Decapentaplegic signaling protein. Science, 343, 1244624 PMID: 24385607; PMC43361497
Kornberg, T.B. and S. Roy (2014) Communicating by touch – neurons are not alone. Trends Cell Bio., 24, 370-376. PMID: 24560610; PMC4037336