| 1. |
- Dudas, Marek, et al.
(author)
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Epithelial and ectomesenchymal role of the type I TGF-beta receptor ALK5 during facial morphogenesis and palatal fusion
- 2006
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In: Developmental Biology. - : Elsevier BV. - 1095-564X .- 0012-1606. ; 296:2, s. 298-314
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Journal article (peer-reviewed)abstract
- Transforming growth factor beta (TGF-beta) proteins play important roles in morphogenesis of many cramofacial tissues; however, detailed biological mechanisms of TGF-beta action, particularly in vivo, are still poorly understood. Here, we deleted the TGF-beta type I receptor gene Alk5 specifically in the embryonic ectodermal and neural crest cell lineages. Failure in signaling via this receptor, either in the epithelium or in the mesenchyme, caused severe craniofacial defects including cleft palate. Moreover, the facial phenotypes of neural crest-specific Alk5 mutants included devastating facial cleft and appeared significantly more severe than the defects seen in corresponding mutants lacking the TGF-beta type II receptor (TGF beta II), a prototypical binding partner of ALK5. Our data indicate that ALK5 plays unique, non-redundant cell-autonomous roles during facial development. Remarkable divergence between Tgfbr2 and A1k5 phenotypes, together with our biochemical in vitro data, imply that (1) ALK5 mediates signaling of a diverse set of ligands not limited to the three isoforms of TGF-beta, and (2) ALK5 acts also in conjunction with type II receptors other than TGF beta RII. (c) 2006 Elsevier Inc. All rights reserved.
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| 2. |
- Dudas, Marek, et al.
(author)
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Tgf-beta3-induced palatal fusion is mediated by Alk-5/Smad pathway.
- 2004
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In: Dev Biol. - 0012-1606. ; 266:1, s. 96-108
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Journal article (peer-reviewed)abstract
- Cleft palate is among the most common birth defects in humans, caused by a failure in the complex multistep developmental process of palatogenesis. It has been recently shown that transforming growth factor beta3 (Tgf-beta3) is an absolute requirement for successful palatal fusion, both in mice and humans. However, very little is known about the mechanisms of Tgf-beta3 signaling during this process. Here we show that putative Tgf-beta type I receptors, Alk-1, Alk-2, and Alk-5, are all endogenously expressed in the palatal epithelium. Activation of Alk-5 in the Tgf-beta3 (-/-) palatal epithelium is able to rescue palatal fusion, whereas inactivation of Alk-5 in the wild-type palatal epithelium prevents palatal fusion. The effect of Alk-2 is similar, but less pronounced. The induction of fusion by activation of Alk-5 or Alk-2 is stronger in the posterior parts of the palates at the embryonic day 14 (E14), while their activation at E13.5 also restores anterior fusion, reflecting the natural anterior-posterior direction of palate maturation in vivo. We also show that Smad2 is endogenously activated in the palatal midline epithelial seam (MES) during the fusion process. By using a mutant Alk-5 receptor that is an active kinase but is unable to activate Smads, we show that activation of Smad-independent Tgf-beta responses is not sufficient to induce fusion of shelves deficient in Tgf-beta3. Based on these observations, we conclude that the Smad2-dependent Alk-5 signaling pathway is dominant in palatal fusion driven by Tgf-beta3.
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| 3. |
- Israelsson, Charlotte, et al.
(author)
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Genetically modified bone morphogenetic protein signalling alters traumatic brain injury-induced gene expression responses in the adult mouse
- 2006
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In: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 84:1, s. 47-57
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Journal article (peer-reviewed)abstract
- Three genetic mouse models were examined to define effects of bone morphogenetic protein (BMP) signalling on gene expression in normal and injured adult brain. CaMKII-Cre eliminated the BMP receptor Acvr1 (Alk2) and the common TGF beta superfamily signal mediator Smad4 or activated a constitutively active Acvr1 in postnatal forebrain neurons. All mutants followed mendelian ratios, with no overt phenotypic changes. In situ hybridization demonstrated normal patterns of the dendritic marker MAP2 (Mtap2) throughout cortex despite neuron-specific losses of Acvr1 or Smad4. However, strong up-regulation of Mtap2 transcript in these mice was found by quantitative RT-PCR (qRT-PCR), indicating that Mtap2 is normally suppressed by BMR Traumatic brain injury (TBI) resulted in increases of histone-associated DNA fragments in both control and Smad4-deficient cortex. Several cell-type-specific transcripts known to be involved in injury-related responses were measured by qRT-PCR. Gfap mRNA was strongly upregulated in controls as well as in the loss-of-BMP-signalling mutants. Notably, activated Acvr1 signalling gave significantly lower TBI-induced up-regulations of Gfap and Phox2a mRNA levels, indicating reductions in astroglial and neuronal reactions to injury. Strong impairment in injury-induced Timp1 transcript up-regulation was also seen in these mice. In contrast, osteopontin (Spp1) transcript levels in activated microglia were not reduced by Acvr1 signalling. Altogether, the data suggest that BMP signalling is dispensable in adult cortical neurons but that augmented BMP signalling affects molecular changes associated with neuronal lesions.
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| 4. |
- Sridurongrit, Somyoth, et al.
(author)
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Signaling via the Tgf-beta type I receptor Alk5 in heart development
- 2008
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In: Developmental Biology. - : Elsevier BV. - 1095-564X .- 0012-1606. ; 322:1, s. 208-218
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Journal article (peer-reviewed)abstract
- Trophic factors secreted both from the endocardium and epicardium regulate appropriate growth of the myocardium during cardiac development. Epicardially-derived cells play also a key role in development of the coronary vasculature. This process involves transformation of epithelia] (epicardial) cells to mesenchymal cells (EMT). Similarly, a subset of endocardial cells undergoes EMT to form the mesenchyme of endocardial cushions, which function as primordia for developing valves and septa. While it has been suggested that transforming growth factor-beta s (Tgf-beta) play an important role in induction of EMT in the avian epi- and endocardium, the function of Tgf-beta s in corresponding mammalian tissues is still poorly understood. In this study, we have ablated the Tgf-beta type I receptor Alk5 in endo-, myo- and epicardial lineages using the Tie2-Cre, Nkx2.5-Cre, and Gata5-Cre driver lines, respectively. We show that while Alk5-mediated signaling does not play a major role in the myocardium during mouse cardiac development, it is critically important in the endocardium for induction of EMT both in vitro and fit vivo. Moreover, loss of epicardial Alk5-mediated signaling leads to disruption of cell-cell interactions between the epicardium and myocardium resulting in a thinned myocardium. Furthermore, epicardial cells lacking Alk5 fail to undergo Tgf-beta-inducecl EMT in vitro, Late term mutant embryos lacking epicardial Alk5 display defective formation of a smooth Muscle cell layer around coronary arteries, and aberrant formation of capillary vessels in the myocardium suggesting that AIk5 is controlling vascular homeostasis during cardiogenesis. To conclude, Tgf-beta signaling via AIk5 is not required in myocardial cells during mammalian cardiac development, but plays an irreplaceable cell-autonomous role regulating cellular communication, differentiation and proliferation in endocardial and epicardial cells. (c) 2008 Elsevier Inc, All rights reserved.
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| 5. |
- Vazirisani, Forugh, 1967, et al.
(author)
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Developmental changes in cellular and extracellular structural macromolecules in the secondary palate and nasal cavity of the mouse
- 2010
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In: European Journal of Oral Sciences. - 1600-0722. ; 118:3, s. 221-236
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Journal article (peer-reviewed)abstract
- The aim of this study was to analyse the hitherto largely unknown expression patterns of some specific cellular and extracellular molecules during palate and nasal cavity development. We show that epithelia of the developing palate and the vomerine epithelium express similar sets of structural proteins. With the exception of keratin 15, which becomes barely detectable in the elevated palatal shelves, nearly all of these become upregulated at the presumptive areas of fusion and in the adhering epithelia of the palate and nasal septum. In vivo and in vitro analyses indicated that keratin 15 protein reduction is independent of Tgfβ-Alk5 signaling. Foxa1 expression also highlighted the regionalization of the palatal and nasal epithelia. Due to lack of reliable markers of the palatal periderm, the fate of peridermal cells has been controversial. We identified LewisX/SSEA1 as a specific peridermal marker, and showed that numerous peridermal cells remain trapped in the medial epithelial seam (MES). The fate of these cells is likely apoptosis together with the rest of MES cells, as we provided further strong evidence for this event. Heparan sulphate, chondroitin-6-sulphate and versican displayed dynamically changing distribution patterns. The hitherto unknown innervation pattern of the developing palate was revealed. These findings may be of value for unravelling the pathogenesis of palatal clefting.
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| 6. |
- Wang, Jikui, et al.
(author)
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Defective ALK5 signaling in the neural crest leads to increased postmigratory neural crest cell apoptosis and severe outflow tract defects
- 2006
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In: BMC Developmental Biology. - 1471-213X. ; 6:51
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Journal article (peer-reviewed)abstract
- Background: Congenital cardiovascular diseases are the most common form of birth defects in humans. A substantial portion of these defects has been associated with inappropriate induction, migration, differentiation and patterning of pluripotent cardiac neural crest stem cells. While TGF-beta superfamily signaling has been strongly implicated in neural crest cell development, the detailed molecular signaling mechanisms in vivo are still poorly understood. Results: We deleted the TGF-beta type I receptor Alk5 specifically in the mouse neural crest cell lineage. Failure in signaling via ALK5 leads to severe cardiovascular and pharyngeal defects, including inappropriate remodeling of pharyngeal arch arteries, abnormal aortic sac development, failure in pharyngeal organ migration and persistent truncus arteriosus. While ALK5 is not required for neural crest cell migration, our results demonstrate that it plays an important role in the survival of post-migratory cardiac neural crest cells. Conclusion: Our results demonstrate that ALK5-mediated signaling in neural crest cells plays an essential cell-autonomous role in the pharyngeal and cardiac outflow tract development.
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