SummaryWound healing crucially relies on the mechanical activity of fibroblasts responding to TGFb1 and to forces transmitted across focal adhesions. Integrin-linked kinase (ILK) is a central adapter recruited to integrin b1 tails in focal adhesions mediating the communication between cells and extracellular matrix. Here, we show that fibroblast-restricted inactivation of ILK in mice leads to impaired healing due to a severe reduction in the number of myofibroblasts, whereas inflammatory infiltrate and vascularization of the granulation tissue are unaffected. Primary ILK-deficient fibroblasts exhibit severely reduced levels of extracellular TGFb1, a-smooth muscle actin (aSMA) production and myofibroblast conversion, which are rescued by exogenous TGFb1. They are further characterized by elevated RhoA and low Rac1 activities, resulting in abnormal shape and reduced directional migration. Interference with RhoA-ROCK signaling largely restores morphology, migration and TGFb1 levels. We conclude that, in fibroblasts, ILK is crucial for limiting RhoA activity, thus promoting TGFb1 production, which is essential for dermal repair following injury.

ADAM-9 belongs to a family of transmembrane, disintegrincontaining metalloproteinases involved in protein ectodomain shedding and cell-cell and cell-matrix interactions. The aim of this study was to analyze the expression of ADAM-9 in skin and to assess the role of this proteolytic/adhesive protein in skin physiology. In normal skin, ADAM-9 expression was detected in both the epidermis and dermis and in vitro in keratinocytes and fibroblasts. Here we report that ADAM-9 functions as a cell adhesion molecule via its disintegrin-cysteine-rich domain. Using solid phase binding assays and antibody inhibition experiments, we demonstrated that the recombinant disintegrin-cysteine-rich domain of ADAM-9 specifically interacts with the ␤1 integrin subunit on keratinocytes. This was corroborated by co-immunoprecipitation. In addition, engagement of integrin receptors by the disintegrin-cysteine-rich domain resulted in ERK phosphorylation and increased MMP-9 synthesis. Treatment with the ERK inhibitor PD98059 inhibited MMP-9 induction. Furthermore, the presence of the soluble disintegrin-cysteine-rich domain did not interfere with cell migration on different substrates. However, keratinocytes adhering to the immobilized disintegrin-cysteine-rich domain showed increased motility, which was partially due to the induction of MMP-9 secretion. In summary, our results indicate that the ADAM-9 adhesive domain plays a role in regulating the motility of cells by interaction with ␤1 integrins and modulates MMP synthesis.Degradation of the extracellular matrix is a prerequisite for tissue repair but also for cell migration and for release of bound factors and bioactive peptides. Different proteases have been implicated in these processes, such as the matrix metalloproteinase (MMP), 2 serine, cysteine, and aspartic protease families. In recent years, the family of proteases (a disintegrin and metalloproteinase (ADAM)) has drawn attention because the manifold proteolytic and adhesive activities of the different ADAM family members were attributed a pivotal role in physiological and pathological situations.The ADAM family includes ϳ30 members of proteins containing disintegrin-and metalloprotease-like domains. Most of the family members share a common well conserved domain structure, including a prodomain, metalloprotease, disintegrinlike, cysteine-rich, EGF-like, and a short cytoplasmic domain (reviewed in Refs. 1 and 2).Structurally, the ADAMs are most closely related to the P-III snake venom metalloproteases. However, in contrast to snake venom metalloproteases, most ADAMs possess EGF-like, transmembrane, and cytoplasmic domains. Half of the ADAM proteins are predicted to be active metalloproteinases, although the identification of specific substrates is still lacking for most of them. Various cell surface proteins are shed by ADAMs, such as IL-6 receptor, FAS-ligand, transforming growth factor-␣, tumor necrosis factor-␣, heparin-binding EGF, and L-selectin. The release of soluble forms of these proteins might lead to autocrine and di...

By screening genome databases, 12 genes encoding membrane proteins homologous to nucleobase-ascorbate transporters (NATs) were identified in Arabidopsis thaliana. A similar number of genes was found in the rice genome. The plant NAT proteins split into five clades (I-V) based on protein multisequence alignments. This classification nicely correlates with the patterns of organ- and tissue-specific expression during the whole life cycle of A. thaliana. Interestingly, expression of two members of clade III, AtNAT7 and AtNAT8, was found to be up-regulated in undifferentiated tissues such as callus or tumors produced by Agrobacterium tumefaciens. Clade V comprises AtNAT12 possessing a hydrophilic N-terminal extension. Transient expression of green fluorescent protein (GFP) fusions in different systems showed that AtNAT12 along with AtNAT7 and -8 are located in the plasma membrane. Mutations in any of the AtNAT genes do not induce phenotypic alterations. The absence of obvious mutant phenotypes in single but also in double and triple mutants suggests a high degree of functional redundancy between AtNAT genes, but might also point to redundant functions provided by genes or pathways unrelated to the AtNATs.

The germination of Physcomitrella patens spores only occurs when wet spores are exposed to light. Depending on their ripeness, spores require from 44 to 64 h illumination to bring about maximum germination. There is a lag period of about 15 h between the reception of sufficient light to elicit germination before germination can be observed. Wavelengths in the range 640–64080 nm are much more effective in inducing germination than longer or shorter wavelengths, but far‐red reversal of red light induction of germination has not been demonstrated. Light also has very marked effects on protonemal and gametophore development. In darkness, only caulonemata are produced, and these grow negatively geotropically. No new gametophores develop but existing gametophores grow negatively geotropically, etiolate and bear only scale leaves. In light, chloronemata, as well as caulonemata are produced, the former grow positively phototropically, while the latter grow at right angles to the direction of light, and neither cell type is sensitive to gravity. In the light, gametophores grow positively phototropically, are indifferent to gravity, produce large leaves and do not etiolate. All these responses to light by protonemata and gametophores are shown by cultures growing in a 23 h dark/l h red light cycle, but if this red light treatment is followed by 15min far‐red light, the effect of the red light is reversed, indicating an involvement of phytochrome in the mediation of these responses. Mutants showing abnormal growth in the dark have been isolated, as well as mutants having abnormal phototropic responses. The latter type has lost the phototropic response of both the protonemal cell types, as well as of gametophores, indicating that these different responses may share a common component.