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L Grotewold

Publications and source records attributed to L Grotewold.

5 recordsLinked to original sources
PubMed2005

Comparative proteomic analysis identifies protein disulfide isomerase and peroxiredoxin 1 as new players involved in embryonic interdigital cell death.

In this study, we used comparative proteomics to identify proteins that were involved in the regulation of interdigital cell death. The protein profiles of embryonic day (E) 12.5 and 13.5 mouse hindlimb interdigital tissues were compared to identify proteins that were differentially expressed. The interdigital cells are irreversibly committed to programmed cell death (PCD) at E13.5, whereas they are developmentally plastic at E12.5. We established that protein disulfide isomerase (PDI) expression was up-regulated at E13.5, while peroxiredoxin 1 (Prdx1) expression was down-regulated at this time point. Semiquantitative reverse transcriptase-polymerase chain reaction and Western blot analyses confirmed the data obtained from the two-dimensional electrophoresis gels. Furthermore, we were able to up-regulate PDI expression by manipulating the E12.5 interdigital tissues to die during culture, although this up-regulation was not possible when cell survival was promoted. In addition, we could inhibit interdigital cell death and expression of proapoptotic genes (Bmp-4 and Bambi) by treating interdigital tissues with PDI antibodies and bacitracin (a PDI enzyme inhibitor). These findings suggested that PDI was involved in the activation and maintenance of interdigital cell death. Conversely, we determined that Prdx1 expression was maintained when interdigital cultures were manipulated to survive but down-regulated when the cultures were permitted to die. The result suggested that Prdx1 was involved in maintaining interdigital cell survival. However, we were unable to induce interdigital cell death by means of RNA interference-mediated silencing of Prdx1 expression, indicating that Prdx1 down-regulation is not sufficient for PCD to occur. Proteomic analysis of the Prdx1 knock-down cells revealed that the level of NF-kappaB inhibitor epsilon (IkappaBepsilon) was dramatically reduced. Furthermore, we found an increase in NFkappaB activation and reactive oxygen species (ROS) levels in the cytoplasm as a result of Prdx1 knockdown. We also found that silencing Prdx1 made the interdigital cells more susceptible to ROS-induced cell death. Taken together, our study identifies two new players in interdigital cell death and highlights that PCD is regulated by a delicate balance of proapoptotic and survival-promoting activities.

Animals↗
PubMed2001

Bambi is coexpressed with Bmp-4 during mouse embryogenesis.

Signaling of TGF-beta superfamily members is tightly controlled by an elaborate network of regulators (for recent review see Trends Genet. 15 (1999) 3; Genes Dev. 14 (2000) 627). Recently, the transmembrane protein BAMBI (BMP and activin membrane-bound inhibitor) has been shown to interfere with Bmp and activin-like signaling by inhibiting Tgf-beta type I receptor activation (Nature 401 (1999) 480). In striking contrast to other Bmp antagonists like noggin (Cell 86 (1996) 599) or chordin (Cell 86 (1996) 589), BAMBI is strictly coexpressed with Bmp-4 during early Xenopus embryogenesis. The grouping of genes according to their shared complex spatial expression pattern and their involvement in the same biological signaling pathway has been referred to as synexpression group. This concept facilitates prognoses about the roles of a group member with unknown function. Apparently, only a minority of genes is organized in synexpression groups and up to now they have mainly been described in yeast and Xenopus (for review see Nature 402 (1999) 483). In the frog, BAMBI is a member of the Bmp-4 synexpression group (Nature 401 (1999) 480). We identified two murine homologues of BAMBI one of which, named Bambi-psi, is a pseudogene. We show that the spatiotemporal expression pattern of Bambi closely matches that of Bmp-4 during mouse embryonic development. Moreover, we show that Bambi expression is induced in mouse embryonic fibroblasts by Bmp-4. Hence, we provide first evidence for the existence of an evolutionarily conserved Bmp-4 synexpression group in mammals.

Amino Acid Sequence↗
PubMed1999

Gli genes and limb development.

During development of the limb Shh plays a key role as a mediator of zone of polarizing activity (ZPA). However, the molecular mechanisms by which Shh directs anterior/posterior patterning in the limb remain unknown. Members of the Gli gene family encode zinc-finger transcription factors and represent likely candidates for being regulators of Shh target genes. In this review we would like to summarize the current knowledge on expression and function of Gli genes in limb development.

Animals↗
PubMed1999

Expression pattern of Dkk-1 during mouse limb development.

dkk-1 has recently been identified as a secreted protein in Xenopus laevis which is sufficient and necessary to cause head induction by antagonizing Wnt signalling (Glinka et al., 1998, Nature 391, 357-362). Consistent with such a role dkk-1 is expressed in the Spemann organizer of the early frog gastrula. Later, expression can be observed in an endomesodermal domain corresponding to the prospective prechordal plate, in two longitudinal stripes flanking the anterior chordamesoderm and in the precursors of the liver. At late neurula stage expression occurs in the prechordal plate adjacent to the prospective forebrain and eyes and in a stripe corresponding to the forming somites. dkk-1 is part of a gene family with at least three family members which is conserved between species. Its mouse homologue, Dkk-1, is first expressed at embryonic day (E) 6.5 in mesodermal cells adjacent to the embryonic/extraembryonic junction. Starting at E7.5 transcripts can be detected in the head mesoderm and at E8.5 additionally in developing somites (Glinka et al., 1998, Nature 391, 357-362). In this study we focus on the highly dynamic pattern of Dkk-1 mRNA distribution during mouse limb development from E9.0-E14.5. The other currently known family members, Dkk-2 and -3, are not expressed in the limb bud before E11.5 (C. Niehrs, pers. commun.) while the limb pattern is established. We show that Dkk-1 expression starts with the first sign of forelimb budding, whereas in the presumptive hindlimb region transcription becomes already apparent before the limb starts to bud out. Expression then becomes confined to two mesenchymal domains at E10.5 and E11.5. Using double-whole mount in situ hybridization we show that the posterior Dkk-1 expression domain initially overlaps with that of Shh, one of the key signalling molecules in limb development. Later, the two expression domains become separated. At E12.5-E14.5 Dkk-1 transcripts are restricted to the interdigital mesenchyme.

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