Transforming growth factor-β1 (TGF-

Mice lacking TGF-β3 exhibit an incompletely penetrant failure of the palatal shelves to fuse leading to cleft palate. The defect appears to result from impaired adhesion of the apposing medial edge epithelia of the palatal shelves and subsequent elimination of the mid-line epithelial seam. No craniofacial abnormalities were observed. This result demonstrates that TGF-β3 affects palatal shelf fusion by an intrinsic, primary mechanism rather than by effects secondary to craniofacial defects.Members of the transforming growth factor-β (TGF-β) gene family have biological activities that control cell proliferation, migration and differentiation, regulation of extracellular matrix deposition and epithelial-mesenchymal transformation [1][2][3] . Mammals contain three highly conserved isoforms of TGF-β, termed TGF-β1, TGF-β2 and TGF-β3, which display distinctive, although at times overlapping, spatial and temporal expression patterns [4][5][6] . Previous studies suggested that TGF-β3 may play a crucial role during palatogenesis 7-9 , Meckel's cartilage formation 10 , cardiac morphogenesis 11 , mammary gland development 12 and wound healing 13 . Other tissues expressing TGF-β3 in significant levels are cartilage, bone, brain and lung [4][5][6]14 .In mammalian palatogenesis apposition of the palatal shelves, adhesion of the medial edge epithelia (MEE) and subsequent elimination of the epithelial seam lead to a seamless mesenchymal shelf separating the oral and nasal cavities 15 . In vitro organ culture studies indicate that TGF-β1 and TGF-β2 accelerate palatal shelf fusion 16,17 and that antisense oligodeoxynucleotides or neutralizing antibodies to TGF-β3, but not to TGF-β1 or TGF-β2, block the fusion process 9 . We have now created mice deficient in TGF-β3, and show that this factor has a role in palatal shelf fusion by means of an intrinsic, primary mechanism and not by effects secondary to craniofacial morphometrics. A comparison of this defect to the inflammatory disorder of TGF-β1-deficient mice [18][19][20][21] Mutation of TGF-β3 in ES cellsThe TGF-β3 gene was mutated in ES cells (Fig. 1a) by replacing exon 6, the first full exon encoding sequences of the active domain of the protein, with the neomycin-resistance gene from pMC1neo 22 . Diagnostic Southern blots of the clone I98 indicated that the locus was successfully targeted; the proper genomic regions flanking both sides of the target site remained intact (Fig. 1b). Probing with a neo-gene probe indicated that there was only one integration site (not shown). Consequently, only the TGF-β3 locus has been disrupted. RT-PCR analysis of whole 11.5- (Fig. 1c) and 15.5-day embryos (not shown) indicated no TGF-β3 expression in homozygous mutant embryos, and revealed no significant change in the expression of TGF-β1 or TGF-β2 in the absence of TGF-β3. Cleft palate in TGF-β3 null mutantsThe targeted ES cell clone I98 was used to produce chi-maeric mice, which were mated with CF-1, C57BL/6 or 129/Sv mice. Heterozygous offspring showed no apparent phenotype. Interc...

Vascular tone control is essential in blood pressure regulation, shock, ischemia-reperfusion, inflammation, vessel injury/repair, wound healing, temperature regulation, digestion, exercise physiology, and metabolism. Here we show that a well-known growth factor, FGF2, long thought to be involved in many developmental and homeostatic processes, including growth of the tissue layers of vessel walls, functions in vascular tone control. Fgf2 knockout mice are morphologically normal and display decreased vascular smooth muscle contractility, low blood pressure and thrombocytosis. Following intra-arterial mechanical injury, FGF2-deficient vessels undergo a normal hyperplastic response. These results force us to reconsider the function of FGF2 in vascular development and homeostasis in terms of vascular tone control.

Transforming growth factor 31 (TGFj81) -

TGF-β1 plays an important role in the maintenance of immune homeostasis and self-tolerance. To determine the mechanism by which TGF-β1 prevents autoimmunity we have analyzed T cell activation in splenic lymphocytes from TGF-β1-deficient mice. Here we demonstrate that unlike wild-type splenic lymphocytes, those from Tgfb1−/− mice are hyporesponsive to receptor-mediated mitogenic stimulation, as evidenced by diminished proliferation and reduced IL-2 production. However, they have elevated levels of IFN-γ and eventually undergo apoptosis. Receptor-independent stimulation of Tgfb1−/− T cells by PMA plus ionomycin induces IL-2 production and mitogenic response, and it rescues them from anergy. Tgfb1−/− T cells display decreased CD3 expression; increased expression of the activation markers LFA-1, CD69, and CD122; and increased cell size, all of which indicate prior activation. Consistently, mutant CD4+ T cells have elevated intracellular Ca2+ levels. However, upon subsequent stimulation in vitro, increases in Ca2+ levels are less than those in wild-type cells. This is also consistent with the anergic phenotype. Together, these results demonstrate that the ex vivo proliferative hyporesponsiveness of Tgfb1−/− splenic lymphocytes is due to prior in vivo activation of T cells resulting from deregulated intracellular Ca2+ levels.