|2017 -||Associate Professor, University of Georgia, Cellular Biology|
|2011 - 2017||Assistant Professor, University of Georgia, Cellular Biology|
|2006 - 2011||Research Assistant Professor, University of Massachusetts Medical School, Department of Cell Biology|
|2004 - 2006||Postdoctoral Fellow in the laboratory of Dr. George Witman, University of Massachusetts Medical School, Department of Cell Biology|
|2000 - 2004||Heisenberg Scholar, Department of Botany, University of Cologne|
|1999 - 2000||Visiting scientist at the Institut Curie, CNRS, Paris, France, in the laboratory of Dr. Michel Bornens|
|1995 - 1996||Visiting scientist at the Department of Cell Biology and Genetics, University of Minnesota, U.S.A., in the laboratory of Dr. Carolyn Silflow|
|1992 - 1999||Junior faculty position, fixed term, Botanical Institute, in the laboratory of Dr.Michael Melkonian, University of Cologne, Cologne, Germany|
|1988 - 1991||Research Associate, Botanical Institute, in the laboratory of Dr.Michael Melkonian, University of Cologne, Cologne, Germany|
Cilia and cilia-related diseases
Office: 635C Biological Science Building
Phone: 706-542 0167
Airway cilia (in mouse trachea; real time and 8x slow motion)
Chlamydomonas reinhardtii Cilium with 9+2 axoneme
(~100x, high-speed video) (TEM cross section)
Cilia and cilia-related disease - An introduction
Cilia and flagella are microtubule-based cell organelles that protrude from the cell surface; the terms cilia and flagella are used interchangeably. Cilia have motile and sensory functions. We known examples for motile cilia are spermatozoa, which move by the means of a motile flagellum, and ciliated epithelia of the airways, which generate a mucociliary flow to keep the airway clean. In humans, defects in cilia motility cause primary ciliary dyskinesia (PCD), which is characterized by chronic airway infections, male infretility, and situs anomalies including congentital heart defects. The molecular machinery that powers ciliary bending is the axoneme with the associated dynein motors. The ultrastructure, composition and function of motile cilia is well conserved over a broad range of species including in Chlamydomonas reinhardtii, a unicellular organism that we use in the lab to study cilia assembly and function. Chlamydomonas possess two typical 9+2 cilia and allows for 1) the isolation of cilia for biochemical analysis, 2) the genetic and molecular genetic manipulation of cilia, and 3) in vivo of protein flux inside cilia with single molecule sensitivity. This unique combination of features makes Chlamydomonas an ideal model to study cilia biology.
The second type of cilia in the mammalian body are non-motile cilia or primary cilia. They typically lack the structures required for motility such as dynein arms but retain a ring of 9 doublet microtubules. Primary cilia possess sensory functions. Our senses of smell and vision are generated in neuronal primary cilia and signaling by cilia-based G-protein coupled receptors in the central nervous system control appetite and other behavioral responses. In fact, many cells in out body in virtually all tissues and organs possess primary cilia, which sense a variety of environmental cues ranging mechanical tension to hormones including hedgehog. Defects in ciliary sensing cause a plethora of developmental disorders and diseases referred to as ciliopathies including blindness, anosmia (loss of the sense of smell), polydactyly (extra fingers and toes) and severe skeletal malformations, obesity, diabetes, certain cancers and cystic kidney diseases. The latter includes polycystic kidney disease(PKD), one of the most common inherited disorders in humans affecting approximately 1 in 1,500 individuals. Many of the genes that when defective cause ciliopathies in mammals are conserved in the genome of Chlamydomonas and other protists. It is widely assumes that the last common ancestor of all eukaryoyes possessed a motile 9+2 cilium with sensory functions.
The goal of our research is to understand how cells assemble and maintain cilia and to identify the molecular mechanisms underlying ciliary diseases. Because cilia lack ribosomes all its proteins are synthesized in the cell body and post-translationally transferred into cilia. Toward this end, cilia possess a dedicated protein shuttle called intraflagellar transport or IFT. Using direct analysis of protein transport inside cilia, we determine which proteins are cargoes of IFT, how the proteins destined from the cilium are selected and how the cells ensure that proteins are transported at right time and in correct amounts to ensure the assembly of a functional cilium.
In IFT, multimegadalton protein arrays (= IFT trains) travel from the cell body along the microtubules of the axoneme and back; the motion is driven by the molecular motors kinesin-2 (to the tip, = anterograde IFT) and IFT dynein (to the base, = retrograde IFT). The trains functions as carriers to move proteins from the cell body into cilium as well as exporting proteins from the cilium back to the cell body. We use a combination of biochemistry, genetics & molecular biology, and in vivo imaging to study protein transport in cilia. Using total internal reflection fluorescence microscopy (TIRFM), we showed that many axonemal proteins (tubulin etc.) are cargoes of IFT. The frequency of these transports is highly increased during cilia assembly; the upregulation is triggered by cilia that are too short. We try to find out how cells measure the length of their cilia and how they regulate the amount of cargo present on the IFT trains. A second focus of our research is to identify the sites on the IFT train to which the cargoes adhere and to analyze how cargo loading is regulated. Our focus is on tubulin, the main structural component of cilia.
Green Fluorescent Protein (GFP)-tagged KAP
(KAP is a subunit of the anterograde IFT motor.
The movie the movie switches between DIC mic-
roscopy showing the cells and TIRF microscopy
The strain is a gift from Mary Porter
IFT of outer dynein arms
(IC2-NG is an essential subunit of the outer arm dynein
and can be used to visualize outer arm transport with
single particle sensitivity. Note loss of the signal in one
step indicating the presence of a single GFP/NG)
see related article by Jin et al. 2018.
Assembly of the ciliary membrane
Sensing of the cell's environment and cilia-based signaling critically depend on proteins in the ciliary membrane. The signaling machinery involves transmembrane proteins such as receptors and ion channels and membrane-associated proteins such as small GTPases. Defects in ciliary signaling underlie many ciliopathies. We use Chlamydomonas to analyze the function of disease-related proteins and to answer question such as how the loss of these proteins affects the composition and function of cilia. Current projects focus on Chlamydomonas PKD2, Arl13b and BBS proteins. In humans, mutations in these proteins cause polycystic kidney disease (PKD), Joubert syndrome, and Bardet-Biedl syndrome (BBS), respectively. Using direct imaging, we showed that the BBSome (a complex of 8 BBS proteins) is an IFT adapter. The BBSome allows signaling proteins such as phospholipase D (PLD, see below), which is unable to bind to IFT trains on its own to be exported from cilia via IFT (Liu et al. 2018). Additional goals are to understand how subdomains within the ciliary membrane are established.
BBSome-dependent IFT of PLD
Top: Phospholipase D (PLD) tagged with mNeonGreen (mNG) moves by IFT in wild-type cilia. The transport of PLD is abolished in bbs mutant causing PLD to abnormally accumulate in the ciliary membrane. PLD accumulation impairs phototaxis in Chlamydomonas.
Bottom: TIRF movie showing PLD export from cilia by BBSome-dependent IFT. A PLD-mNG particle diffuses inside the cilium. Then, a BBSome (BBS4-mC = mCherry) enters the cilium by IFT and on its way back to the cilium base, picks up PLD-mNG and carries it along for removal from the cilium.
Lechtreck, K. (2019) Dynein in Intraflagellar Transport. In: Handbook of Dynein (Second Edition). Editor: Keiko Hirose, ISBN 9789814800013. pp 251-275.
Jiang, Y-Y., Maier, W., Baumeister, R., Minevich, G., Wloga, D., Ruan, Z., Kannan, N., Bocarro, S., Bahraini, A., Vasudevan, K.K., Lechtreck, K., Orias, E., and Gaertig, J. (2019) A CDK-related kinase activates LF4/MOK to regulate cilium length in Tetrahymena. (PLoS Genetics accepted).
Picariello T, Brown JM, Hou Y, Swank G, Cochran DA, King OD, Lechtreck K, Pazour GJ, Witman GB.(2019) A global analysis of IFT-A function reveals specialization for transport of membrane-associated proteins into cilia. J. Cell Sci. 132. doi: 10.1242/jcs.220749. PMID:30659111
Dai, J., Barbieri, F., Mitchell, D.R., and Lechtreck, K.-F. (2018). In vivo analysis of outer arm dynein transport reveals cargo-specific IFT properties. Mol. Biol. Cell 22 Aug 2018. E18-05-0291.
Wingfield, J.L. and Lechtreck, K.-F. (2018) Chlamydomonas basal bodies as flagella organizing centers. Invitated review to Special Issue "Comparative Biology of Centrosomal Structures in Eukaryotes". Cells 7(7), 79; doi: 10.3390/cells7070079.
Louka, P., Vasudevan, K.K., Guha, M., Joachimiak, E., Wloga, D., Tomasi, R., Baroud, C., Dupuis-Williams, P., Galati, D., Pearson,C., Rice, L., Moresco, J., Yates III, J., Jiang, Y.-Y., Lechtreck, K., Dentler, W. and Gaertig, J. (2018) Proteins that control the geometry of ciliary ends. J. Cell Biol. Sep 14. DOI: 10.1083/jcb.201804141.
Lechtreck, K.-F., Mengoni, I., Okivie, B., and Hilderhoff, K.B. (2018). In vivo analyses of radial spoke transport, assembly, repair and maintenance. Cytoskeleton (in press).
Hunter, E.L., Lechtreck, K., Hwang, J., Fu, G., Alford L.M., Gokhale, A., Yamamoto, R, Kamiya, R., Lin, H., Yang, F., Nicastro, D., Dutcher, S.K., Wirschell, M., and Sale, W.S. (2018). The IDA3 adapter, required for IFT transport of I1 dynein, is regulated by ciliary length. MBoC 29:886-896.
Liu P. and Lechtreck, K.-F. (2018). The Bardet-Biedl syndrome protein complex is an adapter expanding the cargo range of intraflagellar transport trains for ciliary export. PNAS 01.15.2017. doi: 10.1073/pnas.1713226115
Liu, Y., Visetsouk, M., Mynlieff, M.,Qin, H., Lechtreck, K.-F., and Yang, P. (2017). H+- and Na+- elicited swift distinct changes of the microtubule system in heterotrophic Chlamydomonas. Elife Sep 6; doi: 10.7554/eLife.26002.
Snouffer, A., Brown, D., Le, H., Walsh, J., Lupu, F., Norman, R., Lechtreck, K.-F., Ko, H.W., and Eggenschwiler, J. (2017). Cell Cycle-Related Kinase (CCRK) regulates ciliogenesis and Hedgehog signaling in mice. PLOS Genetics 13:e1006912
Wingfield, J.L., Mengoni, I., Bomberger, H., Jiang, Y.-Y., Walsh, J.D., Brown, J.M., Picariello, T., Cochran, C.A., Zhu, B., Pan, J., Eggenschwiler, J., Gaertig, J., Witman, G.B., Kner, P., and Lechtreck, K.-F. (2017). IFT trains in different stages of assembly queue at the ciliary base for consecutive release into the cilium. Elife May 31. doi: 10.7554/eLife.26609.
Lechtreck K.-.F, Van De Weghe J.C., Harris J.A., Liu P. (2017). Protein transport in growing and steady-state cilia. Traffic 18: 277-286.
Lechtreck, K.-F. (2016). Methods for Studying Movement of Molecules Within Cilia. Methods of Molecular Biology: Cilia. Eds.: S.T. Christensen & P. Satir. Volume 1454:83-96
Harris, J.A., Liu, Y., Yang, P., Kner, P., and Lechtreck, K.-F. (2016). Single particle imaging reveals IFT-independent transport and accumulation of EB1 in Chlamydomonas flagella. Molecular Biology of the Cell 27: 295-307.
Kubo T, Brown JM, Bellve K, Craige B, Craft JM, Fogarty K, Lechtreck KF, Witman GB. (2016). Together, the IFT81 and IFT74 N-termini form the main module for intraflagellar transport of tubulin. Journal of Cell Science 129:2106-19.
Tran, P.V. and Lechtreck, K.-F. (2016). An age of enlightenment for cilia: The FASEB Summer Research Conference on the “Biology of Cilia and Flagella”. Meeting Report. Developmental Biology 409:319-28
Lechtreck, K.-F. (2015) IFT-cargo interactions and protein transport in cilia. Trends in Biochemical Science 40:765-778.
Jiang, Y.-Y., Lechtreck, K.-F. and Gaertig, J. (2015). Total Internal Reflection Fluorescence Microscopy of Intraflagellar Transport in Tetrahymena thermophila. In: Methods in Cilia & Flagella, W.F. Marshall (Ed.) Elsevier Science and Technology. Vol 127; p. 223-237.
Vasudevan, K.K., Jiang Y.-Y., Lechtreck, K.-F., Kushida, Y., Alford, L.M., Sale, W.S., Hennessey, T. and Gaertig, J. (2015). Kinesin-13 regulates the quantity and quality of tubulin inside cilia. Mol. Biol Cell 26:478-94
Craft, J.M., Harris, J.A., Hyman, S., Kner, P., and Lechtreck, K.-F. (2015). Tubulin Transport by IFT is Upregulated during Ciliary Growth by a Cilium-autonomous Mechanism. J. Cell Biol. 208:223-237. (see also JCB biosights video)
Awata, J.,Takada, S., Standley, C., Lechtreck, K.-F., Bellvé, K.D., Pazour, G.J., Fogarty, K.E., and Witman, G.B. (2014). Nephrocystin-4 controls ciliary trafficking of membrane and large soluble proteins at the transition zone. J. Cell Sci. 127:4714–4727.
Bhogaraju, S., Weber, K., Engel, B.D., Lechtreck, K.-F. and Lorentzen, E. (2014) Getting tubulin to the tip of the cilium: One IFT train, many different tubulin cargo-binding sites? Bioassays.
Lechtreck, K.F. (2014) Chlamydomonas reinhardtii as a model for flagellar assembly. Perspectives in Phycology 1: 41 - 51 (Invited review for inaugural issue). (Request reprint)
Wren, K., Craft, J.M., Tritschler, D., Schauer, A., Patel,, D.K., Smith E.F., Porter, M.E., Kner, P., and Lechtreck, K.-F. (2013). A differential cargo loading model of ciliary length regulation by IFT. Current Biology 23, 2463–2471.
Lechtreck, K.-F., Gould, T.J., and Witman, G.B. (2013). Repair of the Flagellar Central Pair in Chlamydomonas reinhardtii. Cilia 2,15.
Lechtreck, K.-F., Brown, J.M., Sampaio, J.L., Shevchenko, A., Evans, J.E. and Witman, G.B. (2013). Cycling of the signaling protein Phospholipase D through cilia requires the BBSome only for the export phase. Journal of Cell Biology 201, 249-61.
Ludington, W.B., Wemmer, K.A., Lechtreck, K.-F., Witman, G.B., and Marshall, W.F. (2013). Avalanche-like behavior in ciliary import. PNAS 110, 3925-3930.
Lechtreck, K.-F. (2013). Visualizing IFT in Chlamydomonas flagella. Methods in Enzymology, 524, 265-284.
Cilia in mouse brain (slow motion)
Craige, B., Tsao, C.-C., Diener, D.R., Hou, Y., Lechtreck, K.-F., Rosenbaum J.L., and Witman, G.B. (2010). CEP290 tethers flagellar transition zone microtubules to the membrane and regulates flagellar protein content. Journal of Cell Biology 190, 927-940.
Lechtreck, K.-F., Johnson, E.C., Sakai, T., Cochran, D., Ballif, B.A., Rush, J., Pazour, G.J., Ikebe, M., Witman, G.B. (2009). The Chlamydomonas BBSome is an IFT cargo required for export of specific signaling proteins from flagella. Journal of Cell Biology 187, 1117-1132.
Lechtreck , K.-F., Luro, S., and Witman, G.B. (2009). HA-tagging of putative flagellar proteins in Chlamydomonas reinhardtii identifies a novel protein of intraflagellar transport complex B. Cell Motil Cytoskel. 66, 469-82.
Lechtreck, K.-F., Delmotte, P., Robinson, M.L., Sanderson, M.J., and Witman, G.B. (2008). Mutations in Hydin impair ciliary motility in mice. Journal of Cell Biology 180, 633-643.
Lechtreck, K.-F. and Witman, G.B. (2007). Chlamydomonas reinhardtii hydin is a central pair protein required for flagellar motility. Journal of Cell Biology 176, 473-482.
Habilitation (in Botany), University of Cologne, Germany, April 1998
Dr. rer. nat. (Ph.D.), University of Cologne, Germany, June 1991
University-Diploma (equivalent to M.S. degree) in Biology, Westfalian Wilhelms University Münster, February 1988