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RNAi of the receptor tyrosine phosphatase Hm LAR2 in a single cell of an intact leech embryo leads to growth-cone collapse

2000; Elsevier BV; Volume: 10; Issue: 17 Linguagem: Inglês

10.1016/s0960-9822(00)00674-6

1879-0445

Michael W. Baker, Eduardo R. Macagno,

Zebrafish Biomedical Research Applications

Receptor protein tyrosine phosphatases (RPTPs) are important for growth-cone migration [1Desai C.J. Gindhart Jr., J.G. Goldstein L.S. Zinn K. Receptor tyrosine phosphatases are required for motor axon guidance in the Drosophila embryo.Cell. 1996; 84: 599-609Abstract Full Text Full Text PDF PubMed Scopus (255) Google Scholar, 2Krueger N.X. Van Vactor D. Wan H.I. Gelbart W.M. Goodman C.S. Saito H. The transmembrane tyrosine phosphatase DLAR controls motor axon guidance in Drosophila.Cell. 1996; 84: 611-622Abstract Full Text Full Text PDF PubMed Scopus (294) Google Scholar, 3den Hertog J. Protein-tyrosine phosphatases in development.Mech Dev. 1999; 85: 3-14Crossref PubMed Scopus (58) Google Scholar, 4Burden-Gulley S.M. Brady-Kalnay S.M. PTPmu regulates N-cadherin-dependent neurite outgrowth.J Cell Biol. 1999; 144: 1323-1336Crossref PubMed Scopus (114) Google Scholar, 5Ledig M.M. Haj F. Bixby J.L. Stoker A.W. Mueller B.K. The receptor tyrosine phosphatase CRYPalpha promotes intraretinal axon growth.J Cell Biol. 1999; 147: 375-388Crossref PubMed Scopus (68) Google Scholar], but their specific roles have yet to be defined. Previously, we showed that the growth cones of the Comb cell, an embryonic cell in the leech, express high levels of an RPTP called HmLAR2 [6Gershon T.R. Baker M.W. Nitabach M. Macagno E.R. The leech receptor protein tyrosine phosphatase HmLAR2 is concentrated in growth cones and is involved in process outgrowth.Development. 1998; 125: 1183-1190PubMed Google Scholar, 7Gershon T.R. Baker M.W. Nitabach M. Wu P. Macagno E.R. Two receptor tyrosine phosphatases of the LAR family are expressed in the developing leech by specific central neurons as well as select peripheral neurons, muscles, and other cells.J Neurosci. 1998; 18: 2991-3002PubMed Google Scholar]. Here, we report the use of RNA interference (RNAi) to block expression of HmLAR2 in individual Comb cells in the developing embryo. HmLAR2 mRNA levels were reduced in the soma, processes and growth cones of Comb cells injected with double-stranded RNA (dsRNA) for HmLAR2, but no decrease was detected when control dsRNAs were injected. Consistent with this observation, the level of phosphotyrosine increased significantly in the growth cones of Comb cells injected with HmLAR2 dsRNA. Within 24 hours, the growth cones of treated cells showed a distinct collapsed phenotype, with sharp reductions in lamellipodial surface area and in numbers of filopodia. These experiments indicate a key role for LAR-like RPTPs in maintaining the integrity of the growth cone.