The Porter lab focuses on identifying the genes and gene products that regulate the ciliary assembly and motility using Chlamydomonas as the experimental model for gene discovery. Given that cilia and flagella are highly conserved structures, more than 80% of the genes identified have obvious vertebrate orthologues, and many have been implicated in human disorders such as infertility, chronic respiratory disease, polycystic kidney disease, and a variety of developmental defects. Current projects in the lab are focused on two major topics:
1) Regulation of motility. We use both classical genetics and insertional mutagenesis to identify novel gene products involved in the regulation of dynein motor activity. Biochemical characterization of the encoded polypeptides indicates that many serve as structural scaffolds that interconnect microtubules and limit dynein-driven sliding. Others mediate that attachment of regulatory enzymes that modify dynein activity. Several of these gene products have recently been linked to chronic respiratory disease and infertility.
2) Characterization of motor proteins involved in ciliary assembly. Assembly and maintenance of cilia and flagella requires constant, intraflagellar transport (IFT) of ciliary proteins, similar to the bidirectional transport that occurs in neurons. Our lab identified a novel dynein isoform (Dhc1b/DHC2) that is required for retrograde IFT. We are using genetics, biochemistry, and high-resolution light microscopy to identify and characterize other subunits of the retrograde motor. We are also characterizing mutations in other genes that regulate motor activity.
Viswanadha R, Sale WS, Porter ME. (2017) Ciliary Motility: Regulation of Axonemal Dynein Motors. Cold Spring Harb Perspect Biol. 9(8). pii: a018325. doi: 10.1101/cshperspect.a018325.
Lewis WR, Malarkey EB, Tritschler D, Bower R, Pasek RC, Porath JD, Birket SE, Saunier S, Antignac C, Knowles MR, Leigh MW, Zariwala MA, Challa AK, Kesterson RA, Rowe SM, Drummond IA, Parant JM, Hildebrandt F, Porter ME, Yoder BK, Berbari NF. (2016) Mutation of Growth Arrest Specific 8 Reveals a Role in Motile Cilia Function and Human Disease. PLoS Genet. 2016 Jul 29;12(7):e1006220. doi: 10.1371/journal.pgen.1006220.
Reck J, Schauer AM, VanderWaal Mills K, Bower R, Tritschler D, Perrone CA, Porter ME. (2016) The role of the dynein light intermediate chain in retrograde IFT and flagellar function in Chlamydomonas. Mol Biol Cell. 27(15):2404-22. doi: 10.1091/mbc.E16-03-0191. Epub 2016 Jun 1.
Alford LM, Stoddard D, Li JH, Hunter EL, Tritschler D, Bower R, Nicastro D, Porter ME, Sale WS. (2016) The nexin link and B-tubule glutamylation maintain the alignment of outer doublets in the ciliary axoneme. Cytoskeleton (Hoboken). Jun;73(7):331-40. doi: 10.1002/cm.21301. Epub 2016 Jun 13.
Song K, Awata J, Tritschler D, Bower R, Witman GB, Porter ME, Nicastro D (2015) In situ localization of N and C termini of subunits of the flagellar nexin-dynein regulatory complex (N-DRC) using SNAP tag and cryo-electron tomography. J Biol Chem. 290:5341-5353.
Blaby IK, Blaby-Haas CE, Tourasse N, Hom EF, Lopez D, Aksoy M, Grossman A, Umen J, Dutcher S, Porter M, King S, Witman GB, Stanke M, Harris EH, Goodstein D, Grimwood J, Schmutz J, Vallon O, Merchant SS, Prochnik S. (2014) The Chlamydomonas genome project: a decade on. Trends Plant Sci. 19:672-680
Wren KN, Craft JM, Tritschler D, Schauer A, Patel DK, Smith EF, Porter, ME, Kner P, and Lechtreck, KF (2013) A differential cargo-loading model of ciliary length regulation by IFT. Current Biol. 23:2463-2471.
Austin-Tse C, Halbritter J, Zariwala MA, Gilberti RM,. Gee HY, Hellman N, Pathak N, Liu Y, Panizzi JR, Patel-King RS, Tritschler D, Bower R, O’Toole E, Portath JD, Hurd TW, Chaki M, Diaz KA, Kohl, S, Lovric S, Hwang DY, Braun DA, Schueler M, Airik R, Otto EA, Leigh MW, Noone PG, Carson JL, Davis SD, Pittman JE, Ferkol TW, Atkinson, JJ, Olivier, KN, Sagel, SD, Dell SD, Rosenfeld M, Milla CE, Loges NT, Omran H, Porter ME, King SM, Knowles MR, Drummond IA, Hildebrandt, F. (2013) Zebrafish ciliopathy screen plus human mutational analysis identifies C21orf59 and CCDC65 defects as causing primary ciliary dyskinesis. Am J. Hum Genet. 93:672-686.
Bower R., Tritschler D, VanderWaal K., Perrone CA, Mueller J, Fox L, Sale WS, and Porter ME (2013) The N-DRC forms a conserved biochemical complex that maintains outer doublet alignment and limits microtubule sliding in motile axonemes. Mol. Biol Cell 24:1134-1152.
Wirschell M, Olbrich H, Werner C, Tritschler D, Bower R, Sale WS, Loges NT, Pennekamp P, Lindberg S, Stenram U, Carlén B, Horak E, Köhler G, Nürnberg P, Nürnberg G, Porter ME, Omran H. (2013) The nexin-dynein regulatory complex subunit DRC1 is essential for motile cilia function in algae and humans. Nature Genetics 45:262-268.
Heuser T, Barber CF, Lin J, Krell J, Rebesco M, Porter ME, Nicastro D. (2012) Cryoelectron tomography reveals doublet-specific structures and unique interactions in the I1 dynein. Proc. Natl. Acad. Sci. USA 109:2067-2076.
VanderWaal KE, Yamamoto R, Wakabayashi K, Fox L, Kamiya R, Dutcher SK, Bayly PV, Sale WS, and M.E. Porter (2011) bop5 Mutations reveal new roles for the IC138 phosphoprotein in the regulation of flagellar motility and asymmetric waveforms. Mol. Biol. Cell 22:2862-2874.
Porter, M.E. (2011) Flagellar motility and the dynein regulatory complex. In: Dyneins: Structure, Biology, and Disease, ed. S. King, 1st edition, Elsevier Press.