Evidence for the role of fibronectin in amphibian gastrulation

Development ◽  
1985 ◽  
Vol 89 (Supplement) ◽  
pp. 211-227
Author(s):  
J. C. Boucaut ◽  
T. Darribere ◽  
Shi De Li ◽  
H. Boulekbache ◽  
K. M. Yamada ◽  
...  

In amphibian embryos, fibronectin (FN) assembles as a fibrillar network on the roof of the blastocoel cavity, preceding mesodermal cell migration. Local inversion of the ectoderm to produce a site where no FN is available prevents mesodermal cell migration. Microinjection of monovalent antibodies to FN arrests gastrulation. A complete inhibition of mesodermal cell migration is obtained after microinjection of a synthetic peptide containing the cell binding site sequence of FN. Prevention of interactions between receptors and FN appears to be the primary cause for blockage of gastrulation.

Genetics ◽  
1999 ◽  
Vol 153 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Eugenia Y Xu ◽  
Susan Kim ◽  
Kirstin Replogle ◽  
Jasper Rine ◽  
David H Rivier

Abstract In Saccharomyces cerevisiae, chromatin-mediated silencing inactivates transcription of the genes at the HML and HMR cryptic mating-type loci and genes near telomeres. Mutations in the Rap1p and Abf1p binding sites of the HMR-E silencer (HMRa-e**) result in a loss of silencing at HMR. We characterized a collection of 15 mutations that restore the α-mating phenotype to MATα HMRa-e** strains. These mutations defined three complementation groups, two new groups and one group that corresponded to the previously identified SAS2 gene. We cloned the genes that complemented members of the new groups and identified two previously uncharacterized genes, which we named SAS4 and SAS5. Neither SAS4 nor SAS5 was required for viability. Null alleles of SAS4 and SAS5 restored SIR4-dependent silencing at HMR, establishing that each is a regulator of silencing. Null alleles of SAS4 and SAS5 bypassed the role of the Abf1p binding site of the HMR-E silencer but not the role of the ACS or Rap1p binding site. Previous analysis indicated that SAS2 is homologous to a human gene that is a site of recurring translocations involved in acute myeloid leukemia. Similarly, SAS5 is a member of a gene family that included two human genes that are the sites of recurring translocations involved in acute myeloid leukemia.


2018 ◽  
Vol 475 (6) ◽  
pp. 1141-1158 ◽  
Author(s):  
Erika Artukka ◽  
Heidi H. Luoto ◽  
Alexander A. Baykov ◽  
Reijo Lahti ◽  
Anssi M. Malinen

Membrane-bound pyrophosphatases (mPPases), which couple pyrophosphate hydrolysis to transmembrane transport of H+ and/or Na+ ions, are divided into K+,Na+-independent, Na+-regulated, and K+-dependent families. The first two families include H+-transporting mPPases (H+-PPases), whereas the last family comprises one Na+-transporting, two Na+- and H+-transporting subfamilies (Na+-PPases and Na+,H+-PPases, respectively), and three H+-transporting subfamilies. Earlier studies of the few available model mPPases suggested that K+ binds to a site located adjacent to the pyrophosphate-binding site, but is substituted by the ε-amino group of an evolutionarily acquired lysine residue in the K+-independent mPPases. Here, we performed a systematic analysis of the K+/Lys cationic center across all mPPase subfamilies. An Ala → Lys replacement in K+-dependent mPPases abolished the K+ dependence of hydrolysis and transport activities and decreased these activities close to the level (4–7%) observed for wild-type enzymes in the absence of monovalent cations. In contrast, a Lys → Ala replacement in K+,Na+-independent mPPases conferred partial K+ dependence on the enzyme by unmasking an otherwise conserved K+-binding site. Na+ could partially replace K+ as an activator of K+-dependent mPPases and the Lys → Ala variants of K+,Na+-independent mPPases. Finally, we found that all mPPases were inhibited by excess substrate, suggesting strong negative co-operativity of active site functioning in these homodimeric enzymes; moreover, the K+/Lys center was identified as part of the mechanism underlying this effect. These findings suggest that the mPPase homodimer possesses an asymmetry of active site performance that may be an ancient prototype of the rotational binding-change mechanism of F-type ATPases.


2007 ◽  
Vol 48 (3) ◽  
pp. 1110 ◽  
Author(s):  
Kazuhiro Kimura ◽  
Atsushi Hattori ◽  
Yumiko Usui ◽  
Kayo Kitazawa ◽  
Masumi Naganuma ◽  
...  

2019 ◽  
Vol 63 (5) ◽  
pp. 579-594 ◽  
Author(s):  
Guillem Lambies ◽  
Antonio García de Herreros ◽  
Víctor M. Díaz

Abstract Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.


Diabetes ◽  
1997 ◽  
Vol 46 (3) ◽  
pp. 354-362 ◽  
Author(s):  
K. Matsuda ◽  
E. Araki ◽  
R. Yoshimura ◽  
K. Tsuruzoe ◽  
N. Furukawa ◽  
...  

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