Synthesis of gill Na+-K+-ATPase in Atlantic salmon smolts: differences in α-mRNA and α-protein levels

2000 ◽  
Vol 278 (1) ◽  
pp. R101-R110 ◽  
Author(s):  
Helena D'Cotta ◽  
Claudiane Valotaire ◽  
Florence le Gac ◽  
Patrick Prunet
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Early Stage ◽  
Polyclonal Antibodies ◽  
Mrna Abundance ◽  
Activity Measurement ◽  
Mrna Levels ◽  
Western Blots ◽  
Α Subunit ◽  
Protein Levels

Several parameters were analyzed to determine the mechanisms responsible for the enhancement of the gill Na+-K+-ATPase activity of Atlantic salmon smolts. A major α-subunit transcript of 3.7 kb was revealed by Northern blot in both parr and smolt gills when hybridized with two distinct cDNA probes. The α-mRNA abundance demonstrated an increase to maximal levels in smolts at an early stage of the parr-smolt transformation. This was followed by a gradual rise in α-protein levels, revealed by Western blots with specific antibodies and by an increase in gill Na+-K+-ATPase hydrolytic activity, both only reaching maximum levels a month later, at the peak of the transformation process. Parr fish experienced a decrease in α-mRNA abundance and had basal levels of α-protein and enzyme activity. Measurement of the binding of [3H]ouabain to Na+-K+-ATPase was characterized in smolts and parr gill membranes showing more than a twofold elevation in smolts and was of high affinity in both groups (dissociation constant = 20–23 nM). Modulation of the enzyme due to increased salinity was also observed in seawater-transferred smolts, as demonstrated by an increase in α-mRNA levels after 24 h with a rise in Na+-K+-ATPase activity occurring only after 11 days. No qualitative change in α-expression was revealed at either the mRNA or protein level. Immunological identification of the α-protein was performed with polyclonal antibodies directed against the rat α-specific isoforms, revealing that parr, freshwater, and seawater smolts have an α3-like isoform. This study shows that the increase in Na+-K+-ATPase activity in smolt gills depends first on an increase in the α-mRNA expression and is followed by a slower rise in α-protein abundance that eventually leads to a higher synthesis of Na+-K+pumps.

Seawater tolerance and gene expression in two strains of Atlantic salmon smolts

2002 ◽  
Vol 59 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Thomas D Singer ◽  
Koreen M Clements ◽  
Jeffrey W Semple ◽  
Patricia M Schulte ◽  
Jason S Bystriansky ◽  
...  
Keyword(s):  
Gene Expression ◽  
Atlantic Salmon ◽  
Atpase Activity ◽  
Mrna Levels ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Α Subunit ◽  
Seawater Tolerance ◽  
Mrna And Protein Expression ◽  
Or Gene

The seawater tolerance of Atlantic salmon (Salmo salar) smolts reared under identical hatchery conditions was assessed in two Norwegian strains: AquaGen and Imsa. Plasma ion levels were disrupted in both strains following seawater exposure, but these disruptions were more profound in the AquaGen fish. To investigate the mechanisms underlying these differences, we measured gill Na+,K+-adenosine triphosphatase (ATPase) activity and mRNA levels of Na+,K+-ATPase α-subunit and two isoforms of the cystic fibrosis transmembrane conductance regulator (CFTR). Gill Na+,K+-ATPase activity rose significantly in both strains following seawater exposure. Both Na+,K+-ATPase α-subunit and CFTR I mRNA levels were significantly elevated for the entire 2-week period following seawater exposure, whereas CFTR II levels were transiently elevated during the first 24 h only. There were no differences in enzyme activity or gene expression between strains, with the exception of CFTR II, which was significantly lower in the Imsa strain 2 weeks following seawater exposure. This suggests that although changes in mRNA and protein expression for these genes are associated with seawater transfer, they are not the basis of observed physiological differences between strains.

FXYD-11 associates with Na+-K+-ATPase in the gill of Atlantic salmon: regulation and localization in relation to changed ion-regulatory status

2010 ◽  
Vol 299 (5) ◽  
pp. R1212-R1223 ◽  
Author(s):  
Christian K. Tipsmark ◽  
Yasser A. Mahmmoud ◽  
Russell J. Borski ◽  
Steffen S. Madsen
Keyword(s):  
Growth Hormone ◽  
Atlantic Salmon ◽  
Protein A ◽  
Regulatory Subunit ◽  
Kinetic Properties ◽  
Mrna Levels ◽  
Α Subunit ◽  
Protein Levels ◽  
Parallel Increase

The Na+-K+-ATPase is the primary electrogenic component driving transepithelial ion transport in the teleost gill; thus regulation of its level of activity is of critical importance for osmotic homeostasis. In the present study, we examined the dynamics of the gill-specific FXYD-11 protein, a putative regulatory subunit of the pump, in Atlantic salmon during seawater (SW) acclimation, smoltification, and treatment with cortisol, growth hormone, and prolactin. Dual-labeling immunohistochemistry showed that branchial FXYD-11 is localized in Na+-K+-ATPase immunoreactive cells, and coimmunoprecipitation experiments confirmed a direct association between FXYD-11 and the Na+-K+-ATPase α-subunit. Transfer of freshwater (FW)-acclimated salmon to SW induced a parallel increase in total α-subunit and FXYD-11 protein expression. A similar concurrent increase was seen during smoltification in FW. In FW fish, cortisol induced an increase in both α-subunit and FXYD-11 abundance, and growth hormone further stimulated FXYD-11 levels. In SW fish, prolactin induced a decrease in FXYD-11 and α-subunit protein levels. In vitro cortisol (18 h, 10 μg/ml) stimulated FXYD-11, but not FXYD-9, mRNA levels in gills from FW and SW salmon. The data show that Na+-K+-ATPase expressed in branchial mitochondrion-rich cells is accompanied by FXYD-11, and that regulation of the two proteins is highly coordinated. The demonstrated association of FXYD-11 and α-subunit strengthens our hypothesis that FXYD-11 has a role in modulating the pump's kinetic properties. The presence of putative phosphorylation sites on the intracellular domain of FXYD-11 suggests the possibility that this protein also may transmit external signals that regulate Na+-K+-ATPase activity.

Functional and molecular characterization of NHE3 expression during ontogeny in rat jejunal epithelium

1997 ◽  
Vol 273 (6) ◽  
pp. C1937-C1946 ◽  
Author(s):  
James F. Collins ◽  
Hua Xu ◽  
Pawel R. Kiela ◽  
Jiamin Zeng ◽  
Fayez K. Ghishan
Keyword(s):  
Northern Blot ◽  
Polyclonal Antibodies ◽  
Membrane Vesicle ◽  
Age Groups ◽  
Fold Increase ◽  
Jejunal Mucosa ◽  
Mrna Levels ◽  
Adult Rats ◽  
Intestinal Brush Border Membrane ◽  
Protein Levels

Ontogenic changes occur in intestinal brush-border membrane vesicle (BBMV) Na+/H+exchange activity. The present studies were designed to investigate ontogenic changes in Na+/H+exchanger (NHE) isoform 3 in rat jejunum. pH-dependent Na+ uptake was assayed in four age groups of rats in the presence of 0, 50, or 800 μM HOE-694, a specific NHE inhibitor with differential sensitivities for NHE2 [inhibition constant ( K i) = 5 μM in PS120 fibroblasts] and NHE3 ( K i = 650 μM). Results showed that NHE2 and NHE3 contribute to basal BBMV uptake at all ages. Uptake levels were highest in 6-wk-old rats, lower in adult rats, and lowest in 2-wk-old (suckling) and 3-wk-old (weanling) rats. NHE3 contribution ranged from 92% at 6 wk of age to 59% at 2 and 3 wk of age. NHE3 inhibition by 800 μM HOE-694 was 38–45%. Statistical analysis showed that HOE-694 had a significant effect at both concentrations at all ages and that differences were present between all ages except 2- and 3-wk rats (at all HOE-694 concentrations). Northern blot analyses of jejunal mucosa showed lowest NHE3 mRNA levels in 2-wk animals and higher levels in all other age groups. Polyclonal antibodies were developed against an NHE3 COOH-terminal fusion protein, and antiserum was characterized with NHE3-transfected PS120 cells and by immunohistochemistry. Western blot analyses showed lowest protein levels in 2-wk animals and higher levels in the other ages. Suckling rats were subcutaneously injected with methylprednisone (MP) for 2 days and killed 1 day later. Northern blot analyses showed a twofold increase in NHE3 mRNA expression with MP treatment. Immunoblot analyses showed a 2.5-fold increase in NHE3 immunoreactive protein levels with MP injection. Overall, these data suggest that NHE3 is regulated during ontogeny and that ontogenic changes are most apparent around the time of weaning. Furthermore, the data suggest that NHE3 is regulated at transcriptional and posttranscriptional levels during mammalian intestinal development.

scholarly journals ZO-1 mRNA and protein expression during tight junction assembly in Caco-2 cells.

1989 ◽  
Vol 109 (3) ◽  
pp. 1047-1056 ◽  
Author(s):  
J M Anderson ◽  
C M Van Itallie ◽  
M D Peterson ◽  
B R Stevenson ◽  
E A Carew ◽  
...  
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Polyclonal Antibodies ◽  
Epithelial Cell Line ◽  
Cell Contact ◽  
Mrna Levels ◽  
Expression Library ◽  
Cell Contacts ◽  
Protein Levels ◽  
Cell Cell

We previously identified and characterized ZO-1 as a peripheral membrane protein specifically associated with the cytoplasmic surface of tight junctions. Here we describe the identification of partial cDNA sequences encoding rat and human ZO-1 and their use to study the assembly of tight junctions in the Caco-2 human intestinal epithelial cell line. A rat cDNA was isolated from a lambda-gtll expression library by screening with mAbs. Polyclonal antibodies were raised to cDNA-encoded fusion protein; several properties of these antibodies support this cDNA as encoding ZO-1. Expression of ZO-1 mRNA occurs in the rat and Caco-2 cells with a major transcript of approximately 7.5 kb. To disrupt tight junctions and study the subsequent process of assembly, Caco-2 cells were grown in suspension for 48 h in Ca++/Mg++-free spinner medium during which time they lose cell-cell contacts, become round, and by immunofluorescence microscopy show diffuse and speckled localization of ZO-1. Within hours of replating at confluent density in Ca++/Mg++-containing media, attached cells show discrete localization of ZO-1 at cell-cell contacts. Within 2 d, fully confluent monolayers form, and ZO-1 localizes in a continuous gasket-like fashion circumscribing all cells. ZO-1 mRNA levels are highest in cells in spinner culture, and upon replating rapidly fall and plateau at approximately 10% of initial levels after 2-3 wk in culture. ZO-1 protein levels are lowest in contact-free cells and rise five- to eightfold over the same period. In contrast, mRNA levels for sucrase-isomaltase, an apical membrane hydrolase, increase only after a confluent monolayer forms. Thus, in this model of contact-dependent assembly of the tight junction, there is both a rapid assembly beginning upon cell-cell contact, as well as a long-term modulation involving changes in expression of ZO-1 mRNA and protein levels.

scholarly journals Transgenic Overexpression of the Extra-Large Gsα Variant XLαs Enhances Gsα-Mediated Responses in the Mouse Renal Proximal Tubule in Vivo

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1222-1233 ◽  
Author(s):  
Zun Liu ◽  
Hiroko Segawa ◽  
Cumhur Aydin ◽  
Monica Reyes ◽  
Reinhold G. Erben ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Immunohistochemical Analysis ◽  
Renal Proximal Tubule ◽  
Mrna Levels ◽  
Wild Type ◽  
Western Blots ◽  
Α Subunit ◽  
Exon 1 ◽  
Serum Pth

Abstract XLαs, a variant of the stimulatory G protein α-subunit (Gsα), can mediate receptor-activated cAMP generation and, thus, mimic the actions of Gsα in transfected cells. However, it remains unknown whether XLαs can act in a similar manner in vivo. We have now generated mice with ectopic transgenic expression of rat XLαs in the renal proximal tubule (rptXLαs mice), where Gsα mediates most actions of PTH. Western blots and quantitative RT-PCR showed that, while Gsα and type-1 PTH receptor levels were unaltered, protein kinase A activity and 25-hydroxyvitamin D 1-α-hydroxylase (Cyp27b1) mRNA levels were significantly higher in renal proximal tubules of rptXLαs mice than wild-type littermates. Immunohistochemical analysis of kidney sections showed that the sodium-phosphate cotransporter type 2a was modestly reduced in brush border membranes of male rptXLαs mice compared to gender-matched controls. Serum calcium, phosphorus, and 1,25 dihydroxyvitamin D were within the normal range, but serum PTH was ∼30% lower in rptXLαs mice than in controls (152 ± 16 vs. 222 ± 41 pg/ml; P < 0.05). After crossing the rptXLαs mice to mice with ablation of maternal Gnas exon 1 (E1m−/+), male offspring carrying both the XLαs transgene and maternal Gnas exon 1 ablation (rptXLαs/E1m−/+) were significantly less hypocalcemic than gender-matched E1m−/+ littermates. Both E1m−/+ and rptXLαs/E1m−/+ offspring had higher serum PTH than wild-type littermates, but the degree of secondary hyperparathyroidism tended to be lower in rptXLαs/E1m−/+ mice. Hence, transgenic XLαs expression in the proximal tubule enhanced Gsα-mediated responses, indicating that XLαs can mimic Gsα in vivo.

Mechanisms through which bradykinin promotes glomerular injury in diabetes

2005 ◽  
Vol 288 (3) ◽  
pp. F483-F492 ◽  
Author(s):  
Yan Tan ◽  
Bing Wang ◽  
Joo-Seob Keum ◽  
Ayad A. Jaffa
Keyword(s):  
Diabetic Nephropathy ◽  
Growth Factor ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Tissue Growth ◽  
Collagen I ◽  
Mrna Levels ◽  
Glomerular Injury ◽  
Western Blots ◽  
Protein Levels

In diabetes, mesangial cell proliferation and extracellular matrix expansion are critical components in the development of glomerulosclerosis. We reported that diabetes alters the activity of the kallikrein-kinin system and that these alterations contribute to the development of diabetic nephropathy. The present study examined the influence of streptozotocin-induced diabetes on the renal expression of bradykinin (BK) B2 receptors (B2KR), connective tissue growth factor (CTGF), transforming growth factor-β (TGF-β), and TGF-β type II receptor (TGF-βRII) and assessed the signaling mechanisms through which B2KR activation may promote glomerular injury. Eight weeks after the induction of diabetes, renal mRNA levels of B2KR, CTGF, and TGF-β as well as protein levels of CTGF and TGF-βRII were measured in control (C), diabetic (D), and insulin-treated diabetic (D+I) rats. Renal B2KR and TGF-β mRNA levels expressed relative to β-actin mRNA levels and CTGF and TGF-βRII protein levels were significantly increased in D and D+I rats compared with C rats ( P < 0.03, n = 5). To assess the contribution of B2KR activation on modulating the expression of CTGF, TGF-βRII, and collagen I, mesangial cells (MC) were treated with BK (10−8 M) for 24 h and CTGF and TGF-βRII protein levels were measured by Western blots and collagen I mRNA levels were measured by RT-PCR. A two- to threefold increase in CTGF and TGF-βRII protein levels was observed in response to BK stimulation ( P < 0.001, n = 6). In addition, a marked increase in collagen I mRNA levels was observed in response to BK stimulation. Treatment of MC with BK (10−8 M) for 5 min significantly increased the tyrosine phosphorylation of p60src kinase and of p42/p44 MAPK ( P < 0.05, n = 4). Inhibition of src kinase by PP1 (10 μM) inhibited the increase in p42/p44 MAPK activation in response to BK. Finally, to determine whether BK stimulates CTGF, TGF-βRII, and collagen I expression via activation of MAPK pathways, MC were pretreated with an inhibitor of p42/p44 MAPK (PD-98059) for 45 min, followed by BK (10−8 M) stimulation for 24 h. Selective inhibition of p42/p44 MAPK significantly inhibited the BK-induced increase in CTGF, TGF-βRII, and collagen I levels. These findings are the first to demonstrate that BK regulates the expression of CTGF, TGF-βRII, and collagen I in MC and provide a mechanistic pathway through which B2KR activation may contribute to the development of diabetic nephropathy.

scholarly journals Mechanisms of angiotensin II-induced expression of B2 kinin receptors

2004 ◽  
Vol 286 (3) ◽  
pp. H926-H932 ◽  
Author(s):  
Yan Tan ◽  
Florence N. Hutchison ◽  
Ayad A. Jaffa
Keyword(s):  
Receptor Antagonist ◽  
Mapk Pathway ◽  
Renin Angiotensin System ◽  
Receptor Subtype ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Ang Ii ◽  
Western Blots ◽  
Protein Levels ◽  
Kinin Receptors

Although the primary roles of the kallikreinkinin system and the renin-angiotensin system are quite divergent, they are often intertwined under pathophysiological conditions. We examined the effect of ANG II on regulation of B2 kinin receptors (B2KR) in vascular cells. Vascular smooth muscle cells (VSMC) were treated with ANG II in a concentration (10—9-10—6 M)- and time (0–24 h)-dependent manner, and B2KR protein and mRNA levels were measured by Western blots and PCR, respectively. A threefold increase in B2KR protein levels was observed as early as 6 h, with a peak response at 10—7 M. ANG II (10—7 M) also increased B2KR mRNA levels twofold 4 h after stimulation. Actinomycin D suppressed the increase in B2KR mRNA and protein levels induced by ANG II. To elucidate the receptor subtype involved in mediating this regulation, VSMC were pretreated with losartan (AT1 receptor antagonist) and/or PD-123319 (AT2 receptor antagonist) at 10 μM for 30 min, followed by ANG II (10—7 M) stimulation. Losartan completely blocked the ANG II-induced B2KR increase, whereas PD-123319 had no effect. In addition, expression of B2KR mRNA levels was decreased in AT1A receptor knockout mice. Finally, to determine whether ANG II stimulates B2KR expression via activation of the MAPK pathway, VSMC were pretreated with an inhibitor of p42/p44mapk (PD-98059) and/or an inhibitor of p38mapk (SB-202190), followed by ANG II (10—7 M) for 24 h. Selective inhibition of the p42/p44mapk pathway significantly blocked the ANG II-induced increase in B2KR expression. These findings demonstrate that ANG II regulates expression of B2KR in VSMC and provide a rationale for studying the interaction between ANG II and bradykinin in the pathogenesis of vascular dysfunction.

scholarly journals Localisation and temporal changes in prostaglandin G/H synthase-1 and -2 content in ovine intrauterine tissues in relation to glucocorticoid-induced and spontaneous labour

2000 ◽  
Vol 165 (2) ◽  
pp. 399-410 ◽  
Author(s):  
WJ McLaren ◽  
IR Young ◽  
GE Rice
Keyword(s):  
Time Course ◽  
Polyclonal Antibodies ◽  
Placental Tissue ◽  
Fold Increase ◽  
Fetal Membranes ◽  
Western Blots ◽  
Protein Levels ◽  
Tissue Extracts ◽  
Term Labour ◽  
Labour Onset

Parturition in the ewe is preceded by an increase in the synthesis of prostaglandins (PGs) by gestational tissues. To establish the uterine source of these PGs, placental cotyledons, fetal membranes and maternal uterine tissues were collected from ewes (n=6) at spontaneous parturition. Solubilised tissue extracts were prepared and analysed by Western blots using polyclonal antibodies to PG G/H synthase-1 and -2 (PGHS-1 and PGHS-2). PGHS-1 was expressed by all intrauterine tissues at term labour. Densitometric analysis of Western blot autoradiographs showed that the fetal membranes and maternal cervix contained the largest amounts of PGHS-1. PGHS-1 enzyme content of ovine amnion was significantly greater than that of either chorion or allantois (P<0.05). PGHS-1 protein content of myometrial, endometrial and cotyledonary tissue extracts was minimal. Formation of the PGHS-2 isozyme was confined to placental tissue at term labour. PGHS-2 protein levels in sheep placenta were significantly higher than those of PGHS-1 in all intrauterine tissues examined. This result supports the hypothesis that PGHS-2 is a major contributor to PG formation at term labour. To elucidate the developmental changes in PGHS-1 and PGHS-2 relative to labour onset, an experimental paradigm of glucocorticoid-induced delivery was used. Previous characterisation and validation of this labour model demonstrated that direct, transabdominal, intrafetal injection of the synthetic glucocorticoid betamethasone (5.7 mg in 1 ml aqueous vehicle) on day 131 of gestation induced labour onset in 56.6+/-0.8 h (mean+/-s.e.m.). As the latent period to induced-labour was known, the time course of enzyme formation could be ascertained. Sheep (n=20) were killed by barbiturate injection at various time intervals post-injection (0, 14, 28, 42 and 56 h). Tissue extracts collected at post-mortem examination were prepared and analysed by Western blots. PGHS-2 was induced in ovine cotyledon in a time-dependent fashion following glucocorticoid injection (P<0.05). There was a 12-fold increase in abundance between the time of betamethasone administration (0 h) and established labour (56 h). The PGHS-2 isozyme was not detected in any of the other tissues examined. In contrast, formation of the PGHS-1 isozyme did not change in relation to induced-labour in any of the intrauterine tissues. This finding is consistent with constitutive formation of PGHS-1. Previous studies have demonstrated a rise in PG production in association with glucocorticoid-induced labour and spontaneous delivery. The results of the present study indicate that this rise in PG production is due to increased formation of the PGHS-2 isozyme in ovine cotyledon. PGHS-2 appears to be induced by exogenous glucocorticoid administration and/or the mechanisms controlling ovine parturition. The role of PG formation by the fetal membranes is yet to be elucidated.

Role of the TNF pathway in the progression of diabetic nephropathy in KK-Ay mice

2014 ◽  
Vol 306 (11) ◽  
pp. F1335-F1347 ◽  
Author(s):  
Keisuke Omote ◽  
Tomohito Gohda ◽  
Maki Murakoshi ◽  
Yu Sasaki ◽  
Saiko Kazuno ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Early Stage ◽  
Mrna Levels ◽  
Monocyte Chemoattractant Protein 1 ◽  
Protein Levels ◽  
Tnf Α ◽  
Soluble Tnf Receptor

Chronic inflammation promotes the progression of diabetic nephropathy (DN). However, the role of TNF-α remains unclear. The objectives of the present study were to examine whether TNF-α inhibition with a soluble TNF receptor (TNFR)2 fusion protein, i.e., etanercept (ETN), improves the early stage of DN in the type 2 diabetic model of the KK-Ay mouse and to also investigate which TNF pathway, TNFR1 or TNFR2, is predominantly involved in the progression of this disease. ETN was injected intraperitoneally into mice for 8 wk. Renal damage was evaluated by immunohistochemistry, Western blot analysis, and/or real-time PCR. In vitro, mouse tubular proximal cells were stimulated by TNF-α and/or high glucose (HG) and treated with ETN. ETN dramatically improved not only albuminuria but also glycemic control. Renal mRNA and/or protein levels of TNFR2, but not TNF-α and TNFR1, in ETN-treated KK-Ay mice were significantly decreased compared with untreated KK-Ay mice. mRNA levels of ICAM-1, VCAM-1, and monocyte chemoattractant protein-1 and the number of F4/80-positive cells were all decreased after treatment. Numbers of cleaved caspase-3- and TUNEL-positive cells in untreated mice were very few and were not different from ETN-treated mice. In vitro, stimulation with TNF-α or HG markedly increased both mRNA levels of TNFRs, unlike in the in vivo case. Furthermore, ETN partly recovered TNF-α-induced but not HG-induced TNFR mRNA levels. In conclusion, it appears that ETN may improve the progression of the early stage of DN predominantly through inhibition of the anti-inflammatory action of the TNF-α-TNFR2 pathway.

scholarly journals TGF-β Repressors SnoN and Ski Are Implicated in Human Colorectal Carcinogenesis

2009 ◽  
Vol 31 (1) ◽  
pp. 41-51
Author(s):  
Vasiliki Bravou ◽  
Anna Antonacopoulou ◽  
Helen Papadaki ◽  
Konstantina Floratou ◽  
Michalis Stavropoulos ◽  
...  
Keyword(s):  
Protein Expression ◽  
Human Cancer ◽  
Early Stage ◽  
Colorectal Adenomas ◽  
Colorectal Carcinogenesis ◽  
Severe Dysplasia ◽  
Mrna Levels ◽  
Colorectal Carcinomas ◽  
Early Stage Disease ◽  
Protein Levels

Background: The TGF-β signaling repressors SnoN and Ski have been critically implicated in human cancer.Methods: To explore the role of SnoN and Ski in the development and progression of colorectal cancer we examined their protein expression profile by immunohistochemistry in a series of human colorectal adenomas, carcinomas and lymph node metastases. The mRNA expression of SnoN was also quantified by Real-Time RT-PCR.Results: SnoN and Ski were overexpressed both in adenomas with severe dysplasia and colorectal carcinomas. Protein expression was cytoplasmic and nuclear with predominant cytoplasmic localization. The subcellular localization was related differently to pathologic variables of colorectal carcinomas. Although there was no significant association of protein levels with tumor invasion and metastasis, a significant correlation of nuclear SnoN and Ski with β-catenin pathway was observed. Moreover, SnoN mRNA did not differ in carcinomas as compared to normal control and there was no correlation between SnoN protein and mRNA levels.Conclusion: Our findings suggest that SnoN and Ski exert oncogenic effects in human colorectal carcinogenesis and their overexpression is implicated in early stage disease.

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