Epidermal growth factor-induced epithelio-mesenchymal transition in human breast carcinoma cells

PMC42-LA cells display an epithelial phenotype: the cells congregate into pavement epithelial sheets in which E-cadherin and beta-catenin are localized at cell-cell borders. They abundantly express cytokeratins, although 5% to 10% of the cells also express the mesenchymal marker vimentin. Stimulation of PMC42-LA cells with epidermal growth factor (EGF) leads to epithelio-mesenchymal transition-like changes including up-regulation of vimentin and down-regulation of E-cadherin. Vimentin expression is seen in virtually all cells, and this increase is abrogated by treatment of cells with an EGF receptor antagonist. The expression of the mesenchyme-associated extracellular matrix molecules fibronectin and chondroitin sulfate proteoglycan also increase in the presence of EGF. PMC42-LA cells adhere rapidly to collagen I, collagen IV, and laminin-1 substrates and markedly more slowly to fibronectin and vitronectin. EGF increases the speed of cell adhesion to most of these extracellular matrix molecules without altering the order of adhesive preference. EGF also caused a time-dependent increase in the motility of PMC42-LA cells, commensurate with the degree of vimentin staining. The increase in motility was at least partly chemokinetic, because it was evident both with and without chemoattractive stimuli. Although E-cadherin staining at cell-cell junctions disappeared in response to EGF, beta-catenin persisted at the cell periphery. Further analysis revealed that N-cadherin was present at the cell-cell junctions of untreated cells and that expression was increased after EGF treatment. N- and E-cadherin are not usually coexpressed in human carcinoma cell lines but can be coexpressed in embryonic tissues, and this may signify an epithelial cell population prone to epithelio-mesenchymal-like responses.     

Essential role of Src-family protein tyrosine kinases in NF-kappaB activation during B cell development

The nature of signals that govern the development of immunoglobulin heavy chain-dependent B cells is largely unknown. Using mice deficient for the B cell-expressed Src-family protein tyrosine kinases (SFKs) Blk, Fyn and Lyn, we show an essential role of these kinases in pre-B cell receptor (pre-BCR)- mediated NF-kappaB activation and B cell development. This signaling defect is SFK specific, as a deficiency in Syk, which controls pre-B cell development, does not affect NF-kappaB induction. Impaired NF-kappaB induction was overcome by the activation of protein kinase C (PKC)-lambda, thus suggesting the involvement of PKC-lambda in pre-BCR-mediated SFK-dependent activation of NF-kappaB. Our data show the existence of a functionally distinct SFK signaling module responsible for pre-BCR-mediated NF-kappaB activation and B cell development.     

Head circumference of children with Williams-Beuren syndrome

Head circumference is considered an important parameter of brain growth and development. Syndrome-specific standards for head circumference in Williams-Beuren syndrome (WBS) are not available to date, although mental retardation is a leading manifestation in the syndrome. Therefore, we investigated head growth in 63 girls (251 measurements) and 88 boys (298 measurements) with WBS between birth and adulthood. Most measurements in both sexes were from the first 4 years of life (n = 162 in girls and n = 189 in boys). Mean (±SD) head circumference at birth was 33.39 ± 1.38 cm and 34.02 ± 1.44 cm for term girls and boys, respectively. Although head growth in WBS girls and boys was at a slower velocity, the pattern of head circumference was similar to that in the normal population. After the age of 3 months, head circumference started to fall below the normal mean in girls (0.5–2 cm). In boys, mean head circumference was below the normal mean already at 1 month of age (2 cm). The deficit increased to 3 cm from 6 months to 4 years. Adult OFC was 52.85 ± 1.75 cm (n = 16) compared to 55.70 ± 1.83 cm (n = 46; P < 0.00001) in WBS women and 55.51 ± 1.68 cm (n = 30) compared to 57.87 ± 1.29 cm (n = 31; P < 0.00001) in WBS men. During development, microcephaly is only seen in about one third of WBS patients. © 1994 Wiley-Liss, Inc.     

Blockade of acid sensing ion channels attenuates the exercise pressor reflex in cats

Although thin fibre muscle afferents possess acid sensing ion channels (ASICs), their contribution to the exercise pressor reflex is not known. This lack of information is partly attributable to the fact that there is no known selective in vivo antagonist for ASICs. Although amiloride has been shown to antagonize ASICs, it also has been shown to antagonize voltage-gated sodium channels, thereby impairing impulse conduction in sensory nerves. Our aim was to test the hypothesis that lactic acid accumulation in exercising muscle acted on ASICs located on thin fibre muscle afferents to evoke the metabolic component of the exercise pressor reflex. To test this hypothesis, we determined in decerebrate cats if amiloride attenuated the pressor and cardioaccelerator responses to static contraction, to tendon stretch and to arterial injections of lactic acid and capsaicin. We found a dose of amiloride (0.5 μg kg⁻¹; i.a .) that attenuated the pressor and cardioaccelerator responses to both contraction and lactic acid injection, but had no effect on the responses to stretch and capsaicin. A higher dose of amiloride (5 μg kg⁻¹, i.a. ) not only blocked the pressor and cardioaccelerator responses to lactic acid and contraction, but also attenuated the responses to stretch and to capsaicin, manoeuvers in which ASICs probably play no significant role. In addition, we found that the low dose of amiloride (0.5 μg kg⁻¹) had no effect on the responses of muscle spindles to tendon stretch and to succinylcholine, whereas the high dose (5 μg kg⁻¹) attenuated the responses to both. Our data suggest the low dose of amiloride used in our experiments selectively blocked ASICs, whereas the high dose blocked ASICs and impulse conduction in muscle afferents. We conclude that ASICs play a role in the metabolic component of the exercise pressor reflex.     

Homozygous microdeletion of chromosome 4q11-q12 causes severe limb-girdle muscular dystrophy type 2E with joint hyperlaxity and contractures

Microdeletion syndromes are commonly transmitted as dominant traits and are frequently associated with variably expressed pleiotropic phenotypes. Nonlethal homozygous microdeletions, on the other hand, are very rare. Here, we delineate the fifth and so far largest homozygous microdeletion in nonmalignancies of approximately 400 kb on chromosome 4q11-q12 in a large consanguineous East-Anatolian family with six affected patients. The deleted region contains the beta-sarcoglycan gene (SGCB), the predicted gene SPATA18 (spermatogenesis associated 18 homolog) and several expressed sequence tags. Patients presented with a severe and progressive Duchenne-like muscular dystrophy phenotype, a combination of hyperlaxity and joint contractures, chest pain, palpitations, and dyspnea.     

Preaxial acrofacial dysostosis (Nager syndrome) associated with an inherited and apparently balanced X;9 translocation: Prenatal and postnatal late replication studies

We report on an infant with preaxial acrofacial dysostosis (Nager syndrome) who was diagnosed prenatally as having an apparently balanced X/autosome translocation [46,X,t(X;9)(p22.1;q32)mat] inherited from a previously diagnosed mosaic translocation carrier mother [46,XX/46,X,t(X;9)(p22.1;q32)]. Replication studies on amniocytes showed the normal X chromosome to be late replicating while the same studies repeated on the infant's lymphocytes showed the translocated X chromosome to be late replicating in most cells. Late replication studies of the mother's lymphocytes demonstrated that the normal X chromosome was late replicating in most cells. The presence of Nager syndrome in this infant may be the result of critical break-points and/or position effects on chromosome 9, inducing expression of a gene responsible for the syndrome. © 1993 Wiley-Liss, Inc.     

Killer DNA plasmids of the yeast Kluyveromyces lactis

Summary We have studied the structure of the two linear DNA plasmids, kl and k2, present in killer strains of Kluyveromyces lactis. Two killer strains of different origins, CBS 2359 and IFO 1267 were examined. For both strains, identical restriction maps of kl and k2 DNA were obtained. Several restriction sites previously reported for the kl DNA of the strain IFO 1267 have been confirmed. The molecular weights of these double-stranded DNAs were 8.8 kilobase pairs for kl and 13.4 for k2, as determined by electrophoresis of restriction fragments. The plasmid DNA from a nonkiller mutant, NK2/1, was also examined. In this mutant, the kl DNA was replaced by a smaller DNA (5.9 kilobase pairs), the k2 DNA being normal. Restriction enzyme analysis showed that the new plasmid DNA was also linear. Hybridization experiments demonstrated that it was derived from the kl DNA by deletion of a 2.9 kilobase pair segment from the central part of the kl DNA. The deleted segment carries a gene involved in toxin production, but is not related to immunity since the mutant is resistant to killers. The plasmid DNA of K. lactis showed no detectable sequence homology with the double stranded RNA of the killer system of Saccharomyces cerevisiae. Neither was any homology found with nuclear and mitochondria) DNA.