QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 26 October 2005
doi: 10.1242/dev.02103

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Itoh, B. Articles by Okada, M. Search for Related Content PubMed PubMed Citation Articles by Itoh, B. Articles by Okada, M.

SRC-1, a non-receptor type of protein tyrosine kinase, controls the direction of cell and growth cone migration in C. elegans

Bunsho Itoh^1,*, Takashi Hirose^1,*, Nozomu Takata¹, Kiyoji Nishiwaki², Makoto Koga³, Yasumi Ohshima³ and Masato Okada^1,

¹ Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan
² RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan
³ Department of Biology, Faculty of Sciences, Kyushu University Graduate School, Hakozaki, Fukuoka 812-8581, Japan

View larger version (18K): [in a new window]   Fig. 1. (A) Schematic representation of the gonad structure of a wild-type hermaphrodite. The U-shaped gonad lobes are rotationally symmetrical around the dorsoventral axis at the center of the body. DTC, distal tip cell. The dorsal side is upwards. (B) Schematic illustration of the time course and pattern of gonad lobe extensions in wild-type hermaphrodites (lateral view). The DTCs lead the extension of the gonad lobes in three migration phases. First, the DTCs are generated at the ventral mid-body during the L2 stage and migrate in opposite directions along the ventral body wall muscle (phase I). They then turn orthogonally and migrate over the lateral hypodermis towards the dorsal muscles during the L3 stage (phase II). After reaching the dorsal side, the DTCs turn again and migrate towards the midbody along the dorsal body wall muscles during the L4 stage (phase III). The ventral midbody is marked with an asterisk.

View larger version (62K): [in a new window]   Fig. 2. Defective DTC migration in the src-1(cj293) mutant. The position of DTC was monitored by analyzing the expression of lag-2::gfp in wild-type (A,C,E,G) and src-1(cj293) mutant (B,D,F,H) worms. The DTCs migrate in opposite directions along the ventral body wall muscle during the L2 stage in both the wild-type and mutant (A,B). However, the DTCs fail to turn dorsally in the src-1(cj293) mutant (D) during the L3 stage and continue their centrifugal migration in the anterior and posterior directions (F). By contrast, in the wild-type worm at the adult stage, the DTCs migrate centripetally along the dorsal muscle bands back toward the midbody (E). In the adult src-1(cj293) mutant, the extended gonads are randomly bent and accordionated (H). The arrowheads indicate the DTCs. Arrows show the migration pattern of the DTCs. Scale bar: 100 µm.

View larger version (79K): [in a new window]   Fig. 3. The DTC migration defect in the src-1(cj293) mutant is phenocopied in src-1(RNAi), but neither the src-2 mutation nor the src-2 RNAi impairs DTC migration. (A-H) Shown are Nomarski images of the posterior gonad lobe at the young adult stage in the wild-type N2 (A), the control gfp (RNAi) worm (B), the src-1 (cj293) mutant (C), the src-1(RNAi) worm (D), the src-2(ok819) mutant (E) and the src-2(RNAi) worm (F). Also shown are the male gonads of the wild-type N2 (G) and the src-1(cj293) mutant (H). Arrows show the migration pattern of the DTCs. Scale bar: 20 µm. (I) Percentages of the various worm types that have a DTC migration defect in their anterior or posterior lobe. The total numbers of worms observed (n) are also indicated.

View larger version (89K): [in a new window]   Fig. 4. Rescue of the DTC migration defect by the DTC-specific expression of active SRC-1. (A-F) Shown are Nomarski images of the posterior gonad lobe at the young adult stage in the src-1(cj293) mutant (A), the src-1(cj293) mutant expressing src-1 (B) or src-1K290M (C) under the src-1 promoter, the src-1(cj293) mutant expressing src-1 (D) or src-1K290M (E) under the lag-2 promoter, and the src-1(cj293) mutant expressing src-1 under the myo-3 promoter (F). Arrows show the migration pattern of the DTCs. Scale bar: 20 µm. (G) Percentages of worms with DTC migration defects in their anterior or posterior lobe are indicated. For each transgene, two independent lines were scored; similar results were obtained. The total numbers of worm observed (n) are also indicated.

View larger version (103K): [in a new window]   Fig. 5. DTC expression of SRC-1 in the wild-type DTCs, and limited tyrosine phosphorylation in the DTCs of the src-1(cj293) mutant. (A.B) The expression of SRC-1 in wild-type DTCs was determined by detecting the expression of a reporter gene expressed under the src-1 promoter (Psrc-1::gfp). The DIC image is shown in B. (C,D) The dissected gonads of a wild-type worm (C) and the src-1(cj293) mutant (D) were stained with the anti-phosphotyrosine antibody 4G10. The arrowheads indicate the DTCs. Scale bar: 40 µm.

View larger version (90K): [in a new window]   Fig. 6. (A,B) The expression of unc-5 is not affected by the src-1(cj293) mutation. The expression of unc-5::lacZ in wild-type worms (A) and the src-1(cj293) mutant (B) at around L3 stage was detected by staining for ß-galactosidase activity. The arrowheads indicate the DTCs. Scale bar: 100 µm. (C,D) The precocious turning of DTCs induced by the precocious expression of UNC-5 is not observed in the src-1(cj293) homozygote background. The expression vector for UNC-5 under the emb-9 promoter (emb-9::unc-5) was injected into the src-1/hT2 worm, and the gonad morphology of the resulting heterozygote (src-1/+; C) and homozygote (src-1/src-1; D) was analyzed. The arrows show the migration pattern of the DTCs. Scale bar: 40 µm.

View larger version (25K): [in a new window]   Fig. 7. Defects in the migration of the QR neuroblast and its descendants in the src-1(cj293) mutant. (A) Schematic representation of the AVM and ALM neuronal cells that originate from the QR neuroblast and the PVM descendant of the QL neuroblast. (B-E) The GFP signals produced from mec-7::gfp in wild-type worms (B) and the src-1(cj293) mutant (D) were visualized by epifluorescence. The merged GFP and DIC images are shown in C and E. Scale bar: 20 µm. (F) The genetic interaction of the aberrant AVM phenotype in the src-1(cj293) mutant with the ced-5/-12 mutations. The final positions of AVM and PVM in the wild-type and indicated mutant worms were scored according to their relative distance from the stationary Vn.a and Vn.p cells shown on the x-axis.

View larger version (58K): [in a new window]   Fig. 8. Defective axon guidance in the src-1(cj293) mutant. (A-F) The typical axon trajectories of the AVM (A,B), ALM (C,D) and CAN (E,F) neurons in the wild-type (A,C,E) and src-1(cj293) mutant were visualized as described in the materials and methods. Defects in the nerve ring branch of the AVM trajectory (B), the ALM cell body and its trajectory (D) and the CAN cell body and posterior axon trajectory (D) were observed. The percentages of worms with defective axon guidance and the total numbers of worm observed (n) are indicated in each panel. Scale bar: 20 µm. (G) Schematic representation of the PVM axon trajectory in a wild-type worm. (H-K) The defective PVM axon trajectory in the src-1(cj293) mutant. The defects were classified into two patterns as indicated schematically at the bottom of the panels. Some of the PVM axons in the src-1(cj293) mutant turn in the posterior direction on the ventral cord and then makes a reverse turn in the anterior direction (J), while others turn in the posterior direction on the ventral cord and continues in that direction (K). The percentages of worms with the various PVM axon trajectory patterns are shown. Scale bar: 20 µm.