Partial trisomy 10p and familial translocation t(7;10)(p22;p12)

Summary A girl with partial trisomy for the short arm of chromosome 10(p12pter) due to mal chromosome segregation in the father 46,XY,t(7;10)(p22;p12) is described. The major abnormalities in this case are: mottled skin, mid-facial hypoplasia, low percentiles for weight, length, and head circumference, and club feet.To whom offprint requests should be sent     

Chromosome regions associated with the activity of lipoxygenase in the genome D of <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. under water deficit

Quantitative trait loci (QTLs) associated with the phenotypic expression of the activity of different forms of lipoxygenase (LOX) under water deficit were detected in the chromosomes of the D-genome using intogression lines of common wheat Triticum aestivum L. Chinese Spring (Synthetic 6x). QTL associated with the activity of seed soluble LOX was identified on the short arm of chromosome 4D. The activity of membranebound form of enzyme in the seedlings was mapped to the short arm, while that of a soluble form was on the long arm of chromosome 5D. Two regions responsible for the activity of soluble LOX in the leaves were found on the short arm of chromosome 2D. Three QTLs associated with the activities of chloroplast LOXs were found on the same chromosome: the activity of the soluble form was linked to Xgwm261 and Xgwm539 markers, and the membrane form to Xgdm93 marker. QTLs for the activities of both soluble and membrane-bound LOX in the leaves were identified in the centromeric region of chromosome 7D. The activities of two membrane enzymes in the leaves were linked to Xgdm130 marker on the short arm of this chromosome. Loci associated with the activity of different LOX forms colocalized with QTLs for the shoot mass, gas exchange parameters, chlorophyll fluorescence, content of photosynthetic pigments, and grain productivity of wheat. A correlation between these parameters and the LOX activity was detected and it was shown that various forms of the enzyme were differentially involved in the adaptation of wheat plants to water deficit. The current paper discusses their presumed physiological role.     

Regulation of norepinephrine-induced proliferation in cardiac fibroblasts by interleukin-6 and p42/p44 mitogen activated protein kinase

Norepinephrine (NE) is involved in many cardiovascular diseases such as congestive heart failure. We have recently reported that NE had a comitogenic effect in isolated cardiac fibroblasts, and that it activated p42/p44 mitogen activated protein kinase (MAPK). This study was designed to characterize a possible mechanism involved in the proliferative effect of NE. Isolated rat cardiac fibroblasts were exposed to NE (10M) for up to 8 h, and interleukin-6 (IL-6) expression was measured by Ribonuclease Protection Assay and Western blotting. The activity of p42/p44^MAPK was analyzed by Western blotting. Cell number was assessed by use of a Coulter Counter. IL-6/GAPDH mRNA was increased by NE in a time-dependent manner reaching 23 fold stimulation after 1 h compared to untreated samples. Immunoreactivity to IL-6 was not found in controls. After 16h of exposure to NE, IL-6 protein was detected. It further increased up to 48 h. The effect of NE on IL-6 mRNA was abolished by the -adrenoceptor blockers propranolol, metoprolol (₁) and ICI 118.551 (₂), but not by the -adrenoceptor blockers prazosin (₁) and yohimbine (₂). The MAPK-inhibitor PD98059 suppressed the NE-induced MAPK activation in a concentration-dependent fashion after 5 min, attenuated the NE-induced IL-6 expression after 2 h, and suppressed the proliferative effect of NE from 53 to 18% after 48 h. Recombinant IL-6 caused an increase in proliferation by 31% after 48 h. Simultaneous application of the IL-6 antibody reduced the NE-induced proliferation to 34%, and completely prevented the IL-6 induced effect. These results suggest that NE induces proliferation of rat cardiac fibroblasts in part by increasing the expression of IL-6 through regulation of MAPK.     

The biochemical genetics of permethrin resistance in the Learn-PyR strain of house fly

Permethrin resistance in the Learn-PyR strain of house fly was examined in four genetically derived substrains, each being homozygous for a different resistant autosome of the Learn-PyR strain. The resistance of these derivative strains was characterized toxicologically and biochemically. The relative levels of resistance to permethrin conferred by each autosome were 5>3>1>2. Three factors were associated with resistance: (1) increased mixed-function oxidase (MFO) activity associated with elevated levels of cytochrome P-450, cytochrome b₅, and NADPH-cytochrome c reductase (P-450 reductase) activity; (2) target-site insensitivity (kdr); and (3) decreased cuticular penetration. Permethrin resistance factors on chromosome 1 consisted of a piperonyl butoxide (PB)-suppressible mechanism correlated with increased levels of cytochromes P-450 and b₅; on chromosome 2, a PB-suppressible mechanism associated with elevated amounts of cytochrome P-450; on chromosome 3, decreased cuticular penetration, kdr, and increased amounts of P-450 reductase activity; and on chromosome 5, a largely PB-suppressible mechanism correlated with elevated levels of cytochrome P-450 and P-450 reductase activity.     

Translocation(X;Y)(p22.33;p11.2) in XX males: Etiology of male phenotype

Summary Analysis of G-banded prometaphase chromosomes from three XX males revealed extra bands on the distal end of one X short arm. These bands were similar both in size and staining properties to the distal Y short arm of their fathers (in the two cases examined) and also to other chromosomally normal males. The extra material on the abnormal X chromosomes was not C-or G-11 positive in the two cases examined, suggesting that the proximal Y long arm was not present.Previous karyotype-phenotype correlations with structurally altered Y chromosomes provided evidence for localization of male determinants on the Y short arm. The present findings in XX males provide support for more precise localization, to bands p11.2pter of Y short arm.     

A de novo case of trisomy 10p: Gene dosage studies of hexokinase,inorganic pyrophosphatase and adenosine kinase

Summary A female infant with multiple congenital anomalies is presented. Cytogenetic study revealed the presence of a de novo, supernumerary, small telocentric chromosome exhibiting the banding pattern of the short arm of chromosome no. 10 [47,XX,+10p(ptercen)]. Her clinical features were compatible with the 10p trisomy syndrome. Hexokinase (HK-1) activity was elevated in the patient's erythrocytes, which is consistent with an assignment of HK-1 to 10ptercen10. The absence of a gene dosage effect for inorganic pyrophosphatase (PP) in this study indicates exclusion of PP from 10pter cen10, and therefore implies a regional assignment of cen1010q24 for PP. Adenosine kinase (ADK) activity was within control limits, which is consistent with exclusion of ADK from 10ptercen10.     

Molecular cytogenetic analysis of Agropyron elongatum chromatin in wheat germplasm specifying resistance to wheat streak mosaic virus

Summary Three lines derived from wheat (6x) x Agropyron elongatum (10x) that are resistant to wheat streak mosaic virus (WSMV) were analyzed by chromosome pairing, banding, and in situ hybridization. Line CI15321 was identified as a disomic substitution line where wheat chromosome 1D is replaced by Ag. elongatum chromosome 1Ae-1. Line 87-94-1 is a wheat-Ag. elongatum ditelosomic addition 1Ae-1L. Line CI15322 contains an Ag. elongatum chromosome, 1Ae-2, that substitutes for chromosome 1D. The short arm of 1Ae-2 paired with the short arm of 1Ae-1 at metaphase I (MI) in 82% of the pollen mother cells (PMCs). However, the long arms of these two chromosomes did not pair with each other. In CI15322, the long arm of chromosome 4D has an Agropyron chromosome segment which was derived from the distal part of 1Ae-1L. This translocation chromosome is designated as T4DS·4DL-1L. T4DS·4DL-1Ae-1L has a 0.73 m distal part of the long arm of 4D replaced by a 1.31 m distal segment from 1Ae-1L. The major WSMV resistance gene(s) in these lines is located on the distal part of 1Ae-1L.Contribution No. 92-599-J from the Kansas Agricutural Experiment Station, Kansas State University, Manhattan, Kansas, USA     

Sequential Loading of Saccharomyces cerevisiae Ku and Cdc13p to Telomeres

Ku is a heterodimeric protein involved in nonhomologous end-joining of the DNA double-stranded break repair pathway. It binds to the double-stranded DNA ends and then activates a series of repair enzymes that join the broken DNA. In addition to its function in DNA repair, the yeast Saccharomyces cerevisiae Ku (Yku) is also a component of telomere protein-DNA complexes that affect telomere function. The yeast telomeres are composed of duplex C_1–3(A/T)G_1–3 telomeric DNA repeats plus single-stranded TG_1–3 telomeric DNA tails. Here we show that Yku is capable of binding to a tailed-duplex DNA formed by telomeric DNA that mimics the structure of telomeres. Addition of Cdc13p, a single-stranded telomeric DNA-binding protein, to the Yku-DNA complex enables the formation of a ternary complex with Cdc13p binding to the single-stranded tail of the DNA substrate. Because pre-loading of Cdc13p to the single-stranded telomeric tail inhibits the binding of Yku, the results suggested that loading of Yku and Cdc13p to telomeres is sequential. Through generating a double-stranded break near telomeric DNA sequences, we found that Ku protein appears to bind to the de novo synthesized telomeres earlier than that of Cdc13p in vivo. Thus, our results indicated that Yku interacts directly with telomeres and that sequential loading of Yku followed by Cdc13p to telomeres is required for both proteins to form a ternary complex on telomeres. Our results also offer a mechanism that the binding of Cdc13p to telomeres might prevent Yku from initiating DNA double-stranded break repair pathway on telomeres.DNA damages in the form of double-stranded breaks (DSBs)⁴ compromise the integrity of genomes. Failure in repairing or mis-repairing double-stranded breaks can lead to chromosome instability and eventually cell death or cancer (1). Double-stranded breaks are repaired by two main pathways, the homologous recombination and nonhomologous DNA end-joining. In nonhomologous DNA end-joining, Ku is the first protein to bind to the DNA ends to initiate the repair pathway (2). Upon binding, Ku then recruits a series of repair enzymes to join the broken ends (2). Ku is a heterodimeric protein composed of 70- and ∼80-kDa subunits. In Saccharomyces cerevisiae, Ku includes Yku70 and Yku80 subunits. Because the biochemical configuration of the broken ends could be very diverse on DSBs, Ku binds to double-stranded ends in a sequence- and energy-independent manner. It is capable of binding to DNA ends with blunt 3′-overhangs or 5′-overhangs as well as double-stranded DNA with nicks, gaps, or internal loops (3–7). However, Ku does not have high affinity to single-stranded DNA. The crystal structure of human Ku heterodimer indicates that it forms a ring structure that encircles duplex DNA (7). This unique structure feature enables Ku to recognize DNA ends and achieves its high affinity binding.In additional to the role in double-stranded break repair, Ku was shown to be a component of telomeric protein-DNA complex in yeast and mammals (8–10). Telomeres are terminal structures of chromosomes composed of short tandem repeated sequences (11, 12). Mutation of YKU70 or YKU80 causes defects in telomere structure (13–15), telomere silencing (16–19), and replication timing of telomeres (20). The function of yeast Ku (Yku) on telomeres could mediate through protein-protein interaction with Sir4p or protein-RNA interaction with Tlc1 RNA (21, 22). For example, through the interaction with Sir4p, Yku selectively affects telomeres silencing but not the silent mating type loci (17). Yku could also bind to telomerase Tlc1 RNA for telomere length maintenance (22). Judged by the DNA binding activity of Yku, it is reasonable to suggest that it may bind directly to telomeric DNA. Indeed, it was shown that human Ku is capable of binding directly to telomeric DNA in vitro (15). Moreover, because the deletion of SIR4 in budding yeast (23) or Taz1 in fission yeast (24) does not abolish the association of Ku with chromosomal ends, this suggests that Ku might bind directly to telomeric DNA in cells. However, because yeast telomeres have a short 12–14-mer single-stranded tail (25), it is uncertain whether Yku could pass the single-stranded region to reach its binding site. The direct binding of Yku to telomeric DNA has not been experimentally determined.In contrast to double-stranded breaks, the ends of linear chromosomes are not recognized by repair enzymes as DNA damage. In S. cerevisiae, Cdc13p is the single-stranded TG_1–3 DNA-binding protein that enables cells to differentiate whether the ends of a linear DNA are telomeres or broken ends (26–29). Thus, although the mechanism of how cells prevent the activation of DSB repair pathway in telomere is unclear, it is likely that binding of Cdc13p to telomeres might inhibit the initiation of DNA damage response by the Ku protein. Here, using a tailed-duplex DNA synthesized by telomeric DNA sequences to mimic telomere structure, we showed that Yku binds directly to this tailed-duplex DNA substrate and forms a ternary complex with Cdc13p. Our results also showed that Yku loaded to a de novo synthesized telomere earlier than Cdc13p in vivo. These results support the direct binding of Yku to telomeric DNA and that the spatial orientation of Cdc13p might block the activation of DSB repair pathway on telomeres.     

The X-autosome translocation in the common shrew (Sorex araneus L.): late replication in female somatic cells and pairing in male meiosis

Common shrews have an XX/XY₁Y₂ sex chromosome system, with the X chromosome being a translocation (tandem fusion) between the original X and an autosome; in males this autosome is represented by the Y₂ chromosome. From G-banded chromosomes, the Y₂ is homologous to the long arm and centromeric part of the short arm of the X. The region of the X that is homologous to the Y₂ and also the telomeric region of the short arm of the X were found to be early replicating in somatic cells from a female shrew after 5-bromo-2-deoxyuridine (BrdU) treatment in vitro. The remainder of the short arm of the X was shown to be late replicating. Electron microscopic examination of synaptonemal complexes in males at pachytene revealed pairing of the Y₂ axis with the long arm of the X, and Y₁ with the short arm. At early stages of pachytene, there is apparently extensive nonhomologous pairing between the X and Y₁. In essence, the short arm of the shrew X chromosome behaves like a typical eutherian X chromosome (it is inactivated in female somatic cells and is paried with the Y₁ during male meiosis) while the long arm behaves like an autosome (escapes the inactivation and pairs with the Y₂).     

Roles of Protein-disulfide Isomerase-mediated Disulfide Bond Formation of Yeast Mnl1p in Endoplasmic Reticulum-associated Degradation

The endoplasmic reticulum (ER) has a strict protein quality control system. Misfolded proteins generated in the ER are degraded by the ER-associated degradation (ERAD). Yeast Mnl1p consists of an N-terminal mannosidase homology domain and a less conserved C-terminal domain and facilitates the ERAD of glycoproteins. We found that Mnl1p is an ER luminal protein with a cleavable signal sequence and stably interacts with a protein-disulfide isomerase (PDI). Analyses of a series of Mnl1p mutants revealed that interactions between the C-terminal domain of Mnl1p and PDI, which include an intermolecular disulfide bond, are essential for subsequent introduction of a disulfide bond into the mannosidase homology domain of Mnl1p by PDI. This disulfide bond is essential for the ERAD activity of Mnl1p and in turn stabilizes the prolonged association of PDI with Mnl1p. Close interdependence between Mnl1p and PDI suggests that these two proteins form a functional unit in the ERAD pathway.The endoplasmic reticulum (ER)² is the first organelle in the secretory pathway of eukaryotic cells and provides an optimum environment for maturation of newly synthesized secretory and membrane proteins. Protein folding/assembly in the ER is aided by molecular chaperones and folding enzymes. Molecular chaperones in the ER assist folding of newly synthesized proteins and prevent them from premature misfolding and/or aggregate formation (1, 2). Protein folding in the ER is often associated with formation of disulfide bonds, which contribute to stabilization of native, functional states of proteins. Disulfide bond formation could be a rate-limiting step of protein folding both in vitro and in vivo (3, 4), and the ER has a set of folding enzymes including protein-disulfide isomerase (PDI) and its homologs that catalyze disulfide bond formation (5, 6).In parallel, protein folding/assembly in the ER relies on the inherent failsafe mechanism, i.e. the ER quality control system, to ensure that only correctly folded and/or assembled proteins can exit the ER. Misfolded or aberrant proteins are retained in the ER for refolding by ER-resident chaperones, whereas terminally misfolded proteins are degraded by the mechanism known as ER-associated degradation (ERAD). The ERAD consists of recognition and processing of aberrant substrate proteins, retrotranslocation across the ER membrane, and subsequent proteasome-dependent degradation in the cytosol. More than 20 different components have been identified to be involved in this process in yeast and mammals (7).The majority of proteins synthesized in the ER are glycoproteins, in which N-linked glycans are not only important for folding but also crucial for their ERAD if they fail in folding. Specifically, trimming of one or more mannose residues of Man₉GlcNAc₂ oligosaccharide and recognition of the modified mannose moiety represent a key step for selection of terminally misfolded proteins for disposal (8). A mannosidase I-like protein, Mnl1p/Htm1p (yeast), and EDEM (mammals, ER degradation enhancing α-mannosidase-like protein) were identified as candidates for lectins that recognize ERAD substrates with modified mannose moieties (9–11). Both Mnl1p and EDEM contain an N-terminal mannosidase homology domain (MHD), which lacks cysteine residues conserved among α1,2-mannosidase family members and is proposed to function in recognition of mannose-trimmed carbohydrate chains (supplemental Fig. S1). However, whether Mnl1p or EDEM indeed functions as an ERAD-substrate-binding lectin or has a mannosidase activity is still in debate (11–15), and Yos9p was suggested to take the role of ERAD-substrate binding lectin (14, 16–18). Mnl1p, but not EDEM, has a large C-terminal extension, which does not show any homology to known functional domains and is conserved only among fungal Mnl1p homologs (supplemental Fig. S1).After recognition of the modified mannose signal for degradation, aberrant proteins are maintained or converted to be retrotranslocation competent by ER chaperones including BiP (19). PDI was also indicated to be involved in these steps in the ERAD by, for example, its possible chaperone-like functions (20–23). The yeast PDI, Pdi1p, contains four thioredoxin-like domains, two of which have a CGHC motif as active sites, followed by a C-terminal extension containing the ER retention signal. During its catalytic cycle, PDI transiently forms a mixed disulfide intermediate with its substrate through an intermolecular disulfide bond between the cysteine residues of the active site of PDI and the substrate molecule.Here we report identification of PDI as an Mnl1p-interacting protein. Stable interactions between the C-terminal domain of Mnl1p and PDI involve intermolecular disulfide bonds. Stably interacting PDI is required for formation of the functionally essential intramolecular disulfide bond in the MHD of Mnl1p, which in turn stabilizes and prolongs the Mnl1p-PDI interactions. Possible roles for those stable interactions between Mnl1p and PDI in the ERAD will be discussed.     

12pter → 12p 12.2: Possible assignment of human triose phosphate isomerase

Summary Red cell triose-phosphate isomerase (TPI) was determined, together with other enzymes, in three patients with chromosome 12 abnormalities.In patient No. 1 (trisomy of the segment 12pter 12q12) and in patient No. 2 (trisomy of the segment 12pter 12p12.1), the TPI activity was significantly increased. In patient No. 3 (deletion of the segment 12p11 12p12.2), the TPI activity was in the normal range. These results suggest that the human TPI locus is located on the chromosome 12 short arm, between 12pter and 12p12.2.Directeur de Recherches à l'I.N.S.E.R.M.     

In vitro construction of the tufB-lacZ fusion: analysis of the regulatory mechanism of tufB promoter

Summary Genetic studies suggest that the so-called phosphorus-family of enzymes inN. crassa are controlled by a complex system of regulatory genes which are responsive to the level of phosphorus in the growth medium. The intracellular metabolite(s) that interact with this system to signal changes in the external phosphorus concentration has not been identified. In this study the pools of acid-soluble, phosphorus-containing, compounds are measured in wild-type and phosphorus-family enzyme regulatory mutant strains ofN. crassa before and during phosphorus starvation.Prolonged phosphorus starvation of wild-typeN. crassa failed to alter significantly the pre-starvation level of intracellular orthophosphate, suggesting that intracellular P_i would be a poor effector signal for the control of the phosphorus family enzymes. However, inorganic pyrophosphate (PP_i) decreased 15-fold, and tri- and tetrapolyphosphate (PPP_i and PPPP_i) increased 3- to 5-fold within 15 minutes after transfer of the wild-type strain to phosphorus-free medium. Phosphate starvation of seven different regulatory gene mutant strains resulted in a rapid decrease in the PP_i pool similar to that which occurred in the wild-type. However, only two of these seven strains showed increased PPP_i and PPPP_i pools following phosphate starvation. Additional experiments demonstrated that PP_i pools, but not PPP_i and PPPP_i pools, were unaffected by several starvation regimens other than phosphorus starvation. Metabolic studies employing H₃ ³²PO₄ showed that the pool of PP_i was labeled to steady-state levels after two minutes of continuous labeling of a phosphate-sufficient culture. Furthermore, long-term steady-state labeling showed that the intracellular PP_i pool was directly responsive to the decrease in the extracellular P_i concentration of the medium resulting from cell growth. Growth on phosphoethanolamine, a phosphorus source that allows a modest degree of derepression even in growing cells, resulted in lower levels of PP_i than were seen in phosphate-grown cells. These observations suggest that PP_i may be involved in the mechanism responsible for the control of phosphorus-family enzyme regulatory gene product activity.     

The Lysyl Oxidase Pro-peptide Attenuates Fibronectin-mediated Activation of Focal Adhesion Kinase and p130Cas in Breast Cancer Cells

The lysyl oxidase (LOX) gene encodes an enzyme (LOX) critical for extracellular matrix maturation. The LOX gene has also been shown to inhibit the transforming activity of Ras oncogene signaling. In particular, the pro-peptide domain (LOX-PP) released from the secreted precursor protein (Pro-LOX) was found to inhibit the transformed phenotype of breast, lung, and pancreatic cancer cells. However, the mechanisms of action of LOX-PP remained to be determined. Here, the ability of LOX-PP to attenuate the integrin signaling pathway, which leads to phosphorylation of focal adhesion kinase (FAK), and the activation of its downstream target p130^Cas, was determined. In NF639 breast cancer cells driven by Her-2/neu, which signals via Ras, ectopic Pro-LOX and LOX-PP expression inhibited fibronectin-stimulated protein tyrosine phosphorylation. Importantly, phosphorylation of FAK on Tyr-397 and Tyr-576, and p130^Cas were substantially reduced. The amount of endogenous p130^Cas in the Triton X-100-insoluble protein fraction, and fibronectin-activated haptotaxis were decreased. Interestingly, expression of mature LOX enzyme enhanced fibronectin-stimulated integrin signaling. Of note, treatment with recombinant LOX-PP selectively reduced fibronectin-mediated haptotaxis of NF639, MDA-MB-231, and Hs578T breast cancer cells. Thus, evidence is provided that one mechanism of action of LOX-PP tumor suppression is to block fibronectin-stimulated signaling and cell migration.The lysyl oxidase (LOX)² gene family is comprised of five members LOX, LOXL1, LOXL2, LOXL3, and LOXL4, which encode enzymes that modify extracellular matrix (ECM) proteins to promote their cross-linking and deposition (1). The LOX gene is the best characterized and codes for the synthesis of a secreted 50-kDa glycosylated pro-enzyme (Pro-LOX). Pro-LOX is extracellularly processed by proteolytic cleavage to a mature active 32-kDa enzyme (LOX) and an 18-kDa pro-peptide (LOX-PP) by the procollagen C proteinases bone morphogenic protein-1 (BMP-1), and the related tolloid-like proteins TLL1 and TLL2 (2–4). In murine Pro-LOX, proteolytic processing occurs between amino acids Gly-162 and Asp-163, generating LOX-PP containing 141 amino acids (5). LOX-PP contains two consensus N-glycosylation sites, Asn-91 and Asn-138 (murine sequence) (2) and several O-glycosylation sites.³ LOX-PP does not contain any known protein domains, and structural prediction analysis indicates that LOX-PP assembles as an intrinsically disordered protein (6). Among the LOX family members, the C-terminal ends encode the enzyme domain and are highly conserved, whereas the N-terminal ends that encode the pro-peptide region have variable sequences. Based on structural and sequence similarities of the pro-peptide regions, the LOX family members can be divided into two subgroups: LOXL2, LOXL3, and LOXL4 as one group whose propeptide regions contain four scavenger receptor cysteine-rich domains, and LOX and LOXL1 as a separate group with much simpler and smaller pro-peptide region containing no cysteine residues (reviewed in Ref. 1). In contrast to Pro-LOX, the exact maturation site of Pro-LOXL1 is still unidentified.LOX is essential in the formation of blood vessels and in maintaining their normal characteristics (7–9). Up-regulation of LOX expression has been described in stromal cells that surround ductal breast and broncho-pulmonary carcinomas (10).Expression of the LOX gene was found to inhibit the transforming activity of the Ras oncogene in NIH 3T3 fibroblasts and hence was named the “ras recision” gene (rrg) (11, 12). The LOX gene was shown to inhibit growth in soft agar of NIH 3T3 fibroblasts and to attenuate Ras-mediated activation of phosphatidylinositol 3-kinase (PI3K), Akt, and Erk1/2 kinases and NF-κB activation (13). More recently, the rrg activity was mapped to the 18-kDa LOX-PP. Specifically, LOX-PP was shown to inhibit Ras-mediated transformation of fibroblasts as determined by reduced growth in soft agar, localization of PDK1 to the membrane, and activation of NF-κB (14). Furthermore, the inhibitory effects of LOX-PP on Ras signaling were extended to breast, pancreatic, and lung cancer cells (6, 14, 15). LOX-PP expression in these carcinoma cells reverted Her-2/neu- and Ras-mediated epithelial to mesenchymal transition (EMT), leading to increased expression of E-cadherin and γ-catenin, and reduced levels of Snail, vimentin, and/or BCL-2 (7, 15). Furthermore, LOX-PP expression reduced tumor formation in a xenograft model by Her-2/neu-overexpressing NF639 cells (6).Acquisition of the ability to invade the ECM is essential to EMT. The ECM has multiple mechanical and signaling functions. The ECM defines interfaces between tissues, provides a scaffold for cell traction, and a substrate for cell migration and adhesion. It is composed of a complex of proteins such as collagens, fibronectin, and laminin, which can interact and bind various growth factors (16). Fibronectin is of particular interest because it was recently shown to interact with the C terminus of Pro-LOX (17). Binding of fibronectin to its receptors (e.g. integrins α₅β₁ or α_vβ₁) stimulates the tyrosine phosphorylation of cellular proteins, in particular that of focal adhesion kinase (FAK) (18). Little is known about the mechanism of action of LOX-PP. Here, we have asked whether the tumor suppressor activity of LOX-PP attenuates the activation of the integrin signaling pathway in breast cancer cells. We report that LOX-PP attenuates FAK signaling and activation of its downstream target p130^Cas and is a robust inhibitor of fibronectin-stimulated cell migration.     

Regional mapping of the gene for human lysosomal acid phosphatase (ACP2) using a hybrid clone panel containing segments of human chromosome 11

Summary A clone panel containing various segments of human chromosome 11 has been selected and used for regional assignment of the gene for human lysosomal acid phosphatase (ACP₂) to the short arm of chromosome 11, in the region 11p11 11p12. Further evidence has also been presented to update the regional assignment of the gene for lactate dehydrogenase A (LDH_A) to 11p12 11p13, and to support a previous assignment of the genes for the two components of the human cell-surface antigens of the SA11 (previously designated A_L) group, SA11-1 and SA11-3 (previously designated A_L-a₁ and A_L-a₃), to 11pter 11p13. This regional clone panel will be useful for rapid regional mapping of other genes assigned to chromosome 11.