spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

doi: 10.1242/10.1242/dev.00517

This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Related articles in Development
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Klinedinst, S. L.
Right arrow Articles by Bodmer, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Klinedinst, S. L.
Right arrow Articles by Bodmer, R.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

Gata factor Pannier is required to establish competence for heart progenitor formation

Susan L. Klinedinst and Rolf Bodmer*

Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA



View larger version (80K):

[in a new window]
  		Fig. 1. Expression patterns of pnr and ush in stage 11 embryos. (A-C) Confocal optical section (2 µm) through the mesoderm of two abdominal segments double labeled for Mef2 (A,C) protein and pnr RNA (B,C). Note that pnr RNA is present at high levels in the cardiac mesoderm surrounding Mef2 labeled nuclei. (D) A wild-type embryo cross-section showing the relative patterns of tin, pnr, ush and dpp expression.

 


View larger version (75K):

[in a new window]
  		Fig. 2. pnr and ush are required for myocardial and pericardial cell formation. (A-L) tin expression. (A-D) Mid-stage 11. (A) Wild-type embryo expressing tin segmentally in two clusters of cells. The dorsal clusters (arrow) correspond to the cardiac precursors and the lateral clusters (arrowhead) correspond to visceral mesoderm. (B) pnr mutant embryo exhibiting normal tin expression only in the lateral clusters (arrowhead), but not in dorsal clusters (arrow). (C) ush mutant expressing tin normally. (D) Histogram of tin expression in the heart progenitors of pnr and ush mutants at mid-stage 11. (E-H) Late-stage 11. (E) Wild-type embryos expressing tin in the cardiac mesoderm. (F) pnr and (G) ush mutants exhibiting a reduction in tin expression (arrow). (H) Histogram of tin expression in the heart progenitors of pnr and ush mutants at late-stage 11. (I-L) Stage 13 embryos. (J) pnr and (K) ush mutants exhibiting reduced tin expression (arrow). (L) Histogram of tin expression in the heart progenitors of pnr and ush mutants at stage 13. (M-P) Late stage 11 embryos stained for Eve. (M) Wild-type embryo expressing Eve in 11 clusters of cells. (N) In pnr mutants, the number of Eve cells is reduced (arrow). (O) In ush mutants, Eve stained cardiac clusters are indistinguishable from wild type. (P) Histogram of Eve expression in late stage 11 pnr and ush mutants. (Q-T) Stage 13 embryos stained for Eve (red) and Lbe (green). (Q) Wild-type embryo. (R) pnr mutant embryo exhibiting dramatically reduced Lbe staining and moderately reduced Eve staining (arrow). (S) ush mutant embryo exhibiting near normal amounts of Lbe and Eve staining, although the segmental pattern is perturbed (compounded by defects in germ band retraction). (T) Histogram of Lbe expression in stage 13 pnr and ush mutants. (U-X) Stage 13 embryos expressing svp RNA in the cardiac mesoderm (indicated by arrows). (U) Wild type. (V) pnr and (W) ush mutant embryos exhibiting severely reduced svp expression in the heart. (X) Histogram of svp expression in stage 13 pnr and ush mutants. (Y1-Z) Dorsal view of stage 16 embryos stained for the late pericardial cell marker Pericardin (Yarnitzky and Volk, 1995Go; Chartier et al., 2002Go). pnr, ush and raw mutants do not complete dorsal closure. (Y1) Wild type. (Y2) pnr and (Y3) ush mutants exhibiting a severe decrease in pericardial cells (arrowheads). (Y4) Histogram of Pericardin expression in stage 16 pnr and ush mutants. (Z) Dorsal open raw mutant exhibiting an excess in pericardial cell staining.

 


View larger version (133K):

[in a new window]
  		Fig. 3. Pan-mesodermal expression in progeny of the cross between twi-Gal4;24B-Gal4 driver and UAS-cDNA containing transgenic flies. (A-F) tin expression in late-stage 11 embryos. (A) Wild type. (B) UAS-pnr embryo shows ectopic expression in the ventrolateral mesoderm (arrow). (C) UAS-ush embryo shows unaltered or slightly reduced tin expression (arrows). (D) UAS-ush,UAS-pnr embryo shows a moderate reduction in tin expression (arrow). (E) UAS-pnrD4 shows an increase in tin expression in the ventrolateral mesoderm, similar to UAS-pnr embryos (B). (F) UAS-ush;UAS-pnrD4 embryo shows an increase in tin expression in the ventrolateral mesoderm, similar to UAS-pnrD4 embryos (E). (G-L) tin expression in stage 13 embryos. (G) Wild type. (H) UAS-pnr embryo shows moderate ectopic expression in the ventrolateral mesoderm (arrows). (I) UAS-ush embryo shows a moderate reduction in tin expression. (J) UAS-ush,UAS-pnr embryo shows a similar decrease in tin expression as in UAS-ush embryos (I). (K) UAS-pnrD4 embryo shows dramatic ectopic expression in the ventrolateral mesoderm. (L) UAS-ush;UAS-pnrD4 embryo shows a similar increase in ectopic tin expression as in UAS-pnrD4 embryos (K). (M-O) Hand expression in stage 13 embryos. (M) Wild type. (N) UAS-pnr embryo shows moderate ectopic expression in the ventrolateral mesoderm, as with tin (H). (O) UAS-tin;UAS-pnr embryo shows an increase in ectopic Hand expression in the ventrolateral mesoderm that is comparable with tin expression in embryos with mesodermal overexpression of UAS-pnrD4 (K).

 


View larger version (75K):

[in a new window]
  		Fig. 4. Germ layer-specific requirement of pnr and ush for heart formation. (A,B) Histograms of tin expression in stage 13 pnr and ush mutants with (`rescue') or without mesodermal overexpression of wild-type cDNA for pnr and ush, respectively (see Materials and Methods). (A) Mesodermal (yellow) and ubiquitous (blue) pnr restores tin expression when compared with pnr mutants (red); however, ectodermal rescue (orange) moderately restores tin expression in a small percentage of embryos. (B) Mesodermal (blue) ush rescue also restores tin expression in a large proportion of embryos when compared with ush mutants (red). (C) pnr mesodermal rescued embryo shows restored tin expression, when compared with wild type (Fig. 2E). (D) pnr ectodermal rescued embryo exhibits moderately decreased tin expression (brackets indicate the embryonic domain affected with the ZKr-Gal4 driver). (E-L) Overexpression of UAS-pnrEnR (see Materials and Methods) in either the mesoderm or the ectoderm. tin (E,F) and Eve (G-L) expression. (E,G-I) Late stage 11. (F,J-L) Stage 13. (E) Mesodermal overexpression of pnrEnR causes a dramatic reduction in tin expression already at late stage 11. (F) Ectodermal overexpression causes a moderate reduction in tin expression that occurs only in later stage embryos. (G,J) Wild type. (H,K) Mesodermal overexpression of pnrEnR causes a decrease in mesodermal Eve, similar to pnr mutants (Fig. 2N). (I,L) Ectodermal overexpression causes a moderate reduction of Eve only in later stage embryos (L).

 


View larger version (55K):

[in a new window]
  		Fig. 5. pnr and ush mutants exhibit reduced dpp expression. (A-C) Stage 11. (D-F) Stage 13. (A,D) Wild-type dpp expression. dpp is expressed in two stripes, one along the dorsal edge of the ectoderm and the other more laterally. pnr and ush mutants exhibit normal dpp expression at stage 11 (B,C), but reduced expression at later stages (E,F). Note gaps in dpp expression (arrows).

 


View larger version (103K):

[in a new window]
  		Fig. 6. Mesodermal or ectodermal overexpression of brk causes a decrease in tin (A,B,E,F), Eve (C,D) and dpp (G,H) expression. (A,C) Late stage 11 wild-type embryos. (B,D) Late stage 11 twi-Gal4;24B-Gal4>UAS-brk embryos exhibiting a severe reduction in tin expression (B) and in the number of Eve clusters (D). (E) Mid-stage 11 ZKr-Gal4>UAS-brk embryo exhibiting a selective reduction of cardiac (arrow), but not visceral (arrowhead) tin expression in the domain affected by the ZKr-Gal4 driver (brackets). (F) 69B-Gal4>UAS-brk embryo showing a slight reduction in cardiac tin expression (arrow) at stage 13, but not at earlier stages (data not shown). (G) Mid-stage 11 ZKr-Gal4>UAS-brk embryo exhibiting a selective reduction of dorsal ectodermal dpp expression (arrow) in the Kr domain (brackets). (H) 69B-Gal4>UAS-brk embryo showing a moderate reduction in dorsal ectodermal dpp expression (arrow) at stage 13, but not at earlier stages (data not shown).

 


View larger version (47K):

[in a new window]
  		Fig. 7. The genetic network involved in Drosophila heart development. In the early embryo (stage 6), both pnr and ush are induced by dpp in the early ectoderm. Twist, a bHLH factor, induces tin expression in the early mesoderm. By stage 9/10 tin expression is restricted to the dorsal mesoderm (DM) via dpp signaling from the ectoderm. By stage 11, when dpp is expressed in a thinner dorsal stripe (DS), pnr expression is initiated in the presumptive cardiac mesoderm (CM) at the dorsal mesodermal margin, presumably by dpp and wg signaling from the ectoderm in the context of tin (DM). By late stage 11, we propose that pnr (in conjunction with ectodermal dpp and wg signaling) initiates the expression of tin in the cardiac mesoderm. By late stage 11 and stage 12, ush is needed to help maintain the expression of tin in the cardiac precursors. By stage 12/13, pnr and ush are also needed to maintain ectodermal dpp expression in the dorsal stripe and are also mediating the ectodermal signal of dpp in the mesoderm. In these later stages, ush may also be needed to limit the ability of pnr to activate tin expression in the ventrolateral mesoderm. Based on the data presented here, we propose the model that during the spatial convergence of dpp, wg and tin during cardiogenesis, the crucial mediator and executioner of the dpp signal is likely to be pnr.

 

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?



© The Company of Biologists Ltd 2003