Manojkumar A. Puthenveedu
202 Mellon Institute
Department of Biological Sciences
Carnegie Mellon University
4400 Fifth Avenue
Pittsburgh, PA 15213
M.B.,B.S., Calicut Medical College, India
Ph.D., Carnegie Mellon
Postdoctoral Appointment, University of California, San Francisco
How does membrane trafficking control and co-ordinate the complex signaling pathways in the brain? Normal signaling depends on accurate localization of signaling receptors in specific regions of the cell, and trafficking plays a critical role in controlling this localization. Despite this obvious significance, we still know very little about the protein machineries that mediate trafficking of signaling receptors, the regulatory events that control these protein machineries, and the functional consequences of these regulatory events. Research in the lab addresses fundamental questions in these areas using G protein-coupled signaling receptors (GPCRs) important in drug addiction as model signaling receptors.
- Regulation of Endocytosis of Opioid Receptors by Addictive Drugs
Activation of signaling receptors, including opioid receptors and related GPCRs, results in removal of activated receptors from the cell surface via endocytosis through clathrin-coated pits. Receptors were long thought to be passive ‘cargo’ in the endocytic pathway. Our recent data, however, suggest that receptors play a more active role in controlling their own destiny, by specifically regulating the kinetics of the subset of clathrin-coated pits that they use. We are investigating the mechanisms by which opioid receptors, activated by drugs, regulate endocytic kinetics. These mechanisms likely play a key role in drug addiction, as the amount of receptor endocytosis induced by drugs seem to be linked to their addictive potential.
- Sorting of Signaling Receptors in the Endosome
Endocytosed receptors may be returned (or recycled) to the cell surface, thus allowing the cell to respond to the signal again (i.e., be ‘re-sensitized’ to the signal), or may be targeted to the lysosome to be destroyed, leading to prolonged ‘de-sensitization’ of the cell. Despite this clear significance to signaling, how different receptors are sorted into distinct trafficking pathways in the endosome is not known. We have identified a novel role for an actin-based machinery in selectively directing specific receptors to the recycling pathway, and are investigating the biochemical mechanism, regulation, and functional relevance of this machinery.
- Regulated Surface Insertion of Receptors from the Biosynthetic Pathway
In the case of receptors that are sorted into the lysosome and destroyed, the cell is re-sensitized only when newly synthesized receptors are inserted on the plasma membrane from the biosynthetic pathway. While there is evidence that biosynthetic insertion of receptors is highly regulated in neurons, we know very little about the signaling mechanisms that regulate this insertion and their functional significance. We use the delta-opioid receptor, whose biosynthetic trafficking is regulated, as a model receptor to study the general principles, mechanisms, and functional consequences of regulated insertion of signaling receptors on the plasma membrane.
Puthenveedu MA, et al. Sequence-dependent sorting of recycling proteins by actin-stabilized endosomal microdomains. Cell. 143(5):761-73, 2010 Nov 24.
Yudowski GA*, Puthenveedu MA*, Henry AG, von Zastrow M. Cargo-mediated regulation of a rapid Rab4-dependent recycling pathway. Mol Biol Cell. 20(11):2774-84, 2009 Jun.
*denotes equal authorship
Yudowski GA*, Puthenveedu MA*, Leonoudakis D, Panicker S, Thorn KS, Beattie EC, von Zastrow M. Real-time imaging of discrete exocytic events mediating surface delivery of AMPA receptors. Journal of Neuroscience. 27(41):11112-21, 2007.
*denotes equal authorship
Puthenveedu MA, Yudowski GA, von Zastrow M. Endocytosis of neurotransmitter receptors: location matters. Cell. 130(6):988-9, 2007.
Shaw RM, Fay AJ, Puthenveedu MA, von Zastrow M, Jan YN, Jan LY. Microtubule plus-end-tracking proteins target gap junctions directly from the cell interior to adherens junctions. Cell. 128(3):547-60, 2007 Feb 9.
Puthenveedu MA, von Zastrow M. Cargo regulates clathrin-coated pit dynamics. Cell. 127(1):113-24, 2006.
Yudowski GA, Puthenveedu MA, von Zastrow M. Distinct modes of regulated receptor insertion to the somatodendritic plasma membrane. Nature Neuroscience. 9(5):622-7, 2006.