Kim, Nam Hee | Kim, Hyun Sil | Kim, Nam-Gyun | Lee, Inhan | Choi, Hyung-Seok | Li, Xiao-Yan | Kang, Shi Eun | Cha, So Young | Ryu, Joo Kyung | Na, Jung Min | Park, Changbum | Kim, Kunhong | Lee, Sanghyuk | Gumbiner, Barry M. | Yook, Jong In | Weiss, Stephen J.
Although loss of p53 function and activation of canonical Wnt signaling cascades are frequently coupled in cancer, the links between these two pathways remain unclear. We report here that p53 transactivates miRNA-34 (miR-34), which suppresses the transcriptional activity of β-catenin-T-cell factor/lymphoid enhancer factor (TCF/LEF) complexes by targeting the untranslated regions (UTRs) of a set of highly-conserved targets in a network of Wnt pathway-regulated genes. Loss of p53 function increases canonical Wnt signaling through miR-34-specific interactions with target UTRs, whereas miR-34 depletion relieves p53-mediated Wnt repression. Further, gene expression signatures reflecting the status of β-catenin-TCF/LEF transcriptional activity in breast cancer and pediatric neuroblastoma patients are closely associated with p53 and miR-34 functional status. Loss of p53 or miR-34 contributed to neoplastic progression by triggering the Wnt-dependent, tissue-invasive activity of colorectal cancer cells. Further, during development, miR-34 interactions with the β-catenin UTR determine Xenopus body axis polarity and Wnt-dependent gene patterning. These data provide insight into the mechanisms by which a p53-miR-34 network restrains canonical Wnt signaling cascades in developing organisms and human cancer.
doi:10.1126/scisignal.2001744
PMCID: PMC3447368
PMID: 22045851
Chen, Huan | Wang, Fa-Wei | Dong, Yuan-Yuan | Wang, Nan | Sun, Ye-Peng | Li, Xiao-Yan | Liu, Liang | Fan, Xiu-Duo | Yin, Hai-Long | Jing, Yuan-Yuan | Zhang, Xin-Yue | Li, Yu-Lin | Chen, Guang | Li, Hai-Yan
Background
Soybean (Glycine max L.) is one of the most important oil crops in the world. It is desirable to increase oil yields from soybean, and so this has been a major goal of oilseed engineering. However, it is still uncertain how many genes and which genes are involved in lipid biosynthesis.
Results
Here, we evaluated changes in gene expression over the course of seed development using Illumina (formerly Solexa) RNA-sequencing. Tissues at 15 days after flowering (DAF) served as the control, and a total of 11592, 16594, and 16255 differentially expressed unigenes were identified at 35, 55, and 65 DAF, respectively. Gene Ontology analyses detected 113 co-expressed unigenes associated with lipid biosynthesis. Of these, 15 showed significant changes in expression levels (log2fold values ≥ 1) during seed development. Pathway analysis revealed 24 co-expressed transcripts involved in lipid biosynthesis and fatty acid biosynthesis pathways. We selected 12 differentially expressed genes and analyzed their expressions using qRT-PCR. The results were consistent with those obtained from Solexa sequencing.
Conclusion
These results provide a comprehensive molecular biology background for research on soybean seed development, particularly with respect to the process of oil accumulation. All of the genes identified in our research have significance for breeding soybeans with increased oil contents.
doi:10.1186/1471-2229-12-122
PMCID: PMC3490753
PMID: 22849561
Gene expression; Lipid; RNA-sequencing; Soybean; Unigene
A novel metabolomic method based on gas chromatography/mass spectrometry (GC-MS) was applied to determine the metabolites in the serum of piglets in response to weaning and dietary L-glutamine (Gln) supplementation. Thirty-six 21-d-old piglets were randomly assigned into three groups. One group continued to suckle from the sows (suckling group), whereas the other two groups were weaned and their diets were supplemented with 1% (w/w) Gln or isonitrogenous L-alanine, respectively, representing Gln group or control group. Serum samples were collected to characterize metabolites after a 7-d treatment. Results showed that twenty metabolites were down-regulated significantly (P<0.05) in control piglets compared with suckling ones. These data demonstrated that early weaning causes a wide range of metabolic changes across arginine and proline metabolism, aminosugar and nucleotide metabolism, galactose metabolism, glycerophospholipid metabolism, biosynthesis of unsaturated fatty acid, and fatty acid metabolism. Dietary Gln supplementation increased the levels of creatinine,D-xylose, 2-hydroxybutyric acid, palmitelaidic acid, and α-L-galactofuranose (P<0.05) in early weaned piglets, and were involved in the arginine and proline metabolism, carbohydrate metabolism, and fatty acid metabolism. A leave-one-out cross-validation of random forest analysis indicated that creatinine was the most important metabolite among the three groups. Notably, the concentration of creatinine in control piglets was decreased (P=0.00001) compared to the suckling piglets, and increased (P=0.0003) in Gln-supplemented piglets. A correlation network for weaned and suckling piglets revealed that early weaning changed the metabolic pathways, leading to the abnormality of carbohydrate metabolism, amino acid metabolism, and lipid metabolism, which could be partially improved by dietary Gln supplementation. These findings provide fresh insight into the complex metabolic changes in response to early weaning and dietary Gln supplementation in piglets.
doi:10.1631/jzus.B1100343
PMCID: PMC3390714
PMID: 22761248
Piglet; Metabolomics; Weaning; Glutamine; Gas chromatography/mass spectrometry
Li, Xiao-Yan | Zhou, Xiaoming | Rowe, R. Grant | Hu, Yuexian | Schlaepfer, David D. | Ilić, Dusko | Dressler, Gregory | Park, Ann | Guan, Jun-Lin | Weiss, Stephen J.
FAK promotes the epithelial–mesenchymal transition in mouse embryonic cells by regulating the transcription factor Snail1.
Mouse embryonic cells isolated from focal adhesion kinase (FAK)–null animals at embryonic day 7.5 display multiple defects in focal adhesion remodeling, microtubule dynamics, mechanotransduction, proliferation, directional motility, and invasion. To date, the ability of FAK to modulate cell function has been ascribed largely to its control of posttranscriptional signaling cascades in this embryonic cell population. In this paper, we demonstrate that FAK unexpectedly exerts control over an epithelial–mesenchymal transition (EMT) program that commits embryonic FAK-null cells to an epithelial status highlighted by the expression of E-cadherin, desmoplakin, and cytokeratins. FAK rescue reestablished the mesenchymal characteristics of FAK-null embryonic cells to generate committed mouse embryonic fibroblasts via an extracellular signal–related kinase– and Akt-dependent signaling cascade that triggered Snail1 gene expression and Snail1 protein stabilization. These findings indentify FAK as a novel regulator of Snail1-dependent EMT in embryonic cells and suggest that multiple defects in FAK−/− cell behavior can be attributed to an inappropriate commitment of these cells to an epithelial, rather than fibroblastic, phenotype.
doi:10.1083/jcb.201105103
PMCID: PMC3257570
PMID: 22105351
Kim, Nam Hee | Kim, Hyun Sil | Li, Xiao-Yan | Lee, Inhan | Choi, Hyung-Seok | Kang, Shi Eun | Cha, So Young | Ryu, Joo Kyung | Yoon, Dojun | Fearon, Eric R. | Rowe, R. Grant | Lee, Sanghyuk | Maher, Christopher A. | Weiss, Stephen J. | Yook, Jong In
Expression of the essential EMT inducer Snail1 is inhibited by miR-34 through a p53-dependent regulatory pathway.
Snail1 is a zinc finger transcriptional repressor whose pathological expression has been linked to cancer cell epithelial–mesenchymal transition (EMT) programs and the induction of tissue-invasive activity, but pro-oncogenic events capable of regulating Snail1 activity remain largely uncharacterized. Herein, we demonstrate that p53 loss-of-function or mutation promotes cancer cell EMT by de-repressing Snail1 protein expression and activity. In the absence of wild-type p53 function, Snail1-dependent EMT is activated in colon, breast, and lung carcinoma cells as a consequence of a decrease in miRNA-34 levels, which suppress Snail1 activity by binding to highly conserved 3′ untranslated regions in Snail1 itself as well as those of key Snail1 regulatory molecules, including β-catenin, LEF1, and Axin2. Although p53 activity can impact cell cycle regulation, apoptosis, and DNA repair pathways, the EMT and invasion programs initiated by p53 loss of function or mutation are completely dependent on Snail1 expression. These results identify a new link between p53, miR-34, and Snail1 in the regulation of cancer cell EMT programs.
doi:10.1083/jcb.201103097
PMCID: PMC3206336
PMID: 22024162
Objective. To evaluate diagnostic utility of Dishevelled-3 (DVL-3) mRNA and δ-catenin mRNA expression in pleural effusions of patients with lung cancer. Methods. DVL-3 mRNA and δ-catenin mRNA levels were assessed by performing RT-PCR on pleural effusion specimens from patients with lung cancer (n = 75) and with lung benign disease (n = 51). Results. The expressions of DVL-3 mRNA and δ-catenin mRNA were significantly higher in malignant than in benign lung disease (P < 0.01) and were obviously higher than cytology in adenocarcinoma (P < 0.01). In single use, DVL-3 mRNA had the highest specificity (94.1%) and PPV (95.7%), whereas δ-catenin mRNA had the highest sensitivity (92.0%) and NPV (88.5%). When combinations of markers were evaluated together, DVL-3 mRNA and δ-catenin mRNA gave a high-diagnostic performance: sensitivity of 100.0%, NPV of 100.0%, and accuracy of 96.0%, respectively. Conclusion. As molecular markers of detecting pleural micrometastasis, DVL-3 mRNA and δ-catenin mRNA are helpful to diagnose the cancer cells in pleural effusions of patients with lung cancer.
doi:10.1155/2012/904946
PMCID: PMC3296179
PMID: 22461838
AIM
To study the optical property and biocompatibility of a tissue engineering cornea.
METHODS
: The cross-linker of N-(3-Dimethylaminoropyl)-N'ethylcarbodiimide hydrochloride (EDC)/N-Hydroxysuccinimide (NHS) was mixed with Type I collagen at 10% (weight/volume). The final solution was molded to the shape of a corneal contact lens. The collagen concentrations of 10%, 12.5%, 15%, 17.5% and 20% artificial corneas were tested by UV/vis-spectroscopy for their transparency compared with normal rat cornea. 10-0 sutures were knotted on the edges of substitute to measure the corneal buttons's mechanical properties. Normal rat corneal tissue primary culture on the collagen scaffold was observed in 4 weeks. Histopathologic examinations were performed after 4 weeks of in vitro culturing.
RESULTS
The collagen scaffold appearance was similar to that of soft contact lens. With the increase of collagen concentration, the transparency of artificial corneal buttons was diminished, but the toughness of the scaffold was enhanced. The scaffold transparency in the 10% concentration collagen group resembled normal rat cornea. To knot and embed the scaffold under the microscope, 20% concentration collagen group was more effective during implantation than lower concentrations of collagen group. In the first 3 weeks, corneal cell proliferation was highly active. The shapes of cells that grew on the substitute had no significant difference when compared with the cells before they were moved to the scaffold. However, on the fortieth day, most cells detached from the scaffold and died. Histopathologic examination of the primary culture scaffold revealed well grown corneal cells tightly attached to the scaffold in the former culturing.
CONCLUSION
Collagen scaffold can be molded to the shape of soft contact corneal lens with NHS/EDC. The biological stability and biocompatibility of collagen from animal species may be used as material in preparing to engineer artificial corneal scaffold.
doi:10.3980/j.issn.2222-3959.2012.01.09
PMCID: PMC3340846
PMID: 22553753
tissue engineering; collagen cross-linking scaffold; primary culture in vitro; optical property; biocompatibility
In the title compound, C14H10N4O5, the molecule exists in a trans conformation with respect to the methylidene unit. The dihedral angle between the benzene rings is 9.8 (2)°. In the crystal, molecules are linked through N—H⋯O hydrogen bonds to form chains along the c axis.
doi:10.1107/S1600536812005466
PMCID: PMC3295476
PMID: 22412587
In the title compound, C14H10FN3O3, the molecule exists in a trans conformation with respect to the methylidene unit. The dihedral angle between the benzene rings is 5.1 (2)°. In the crystal, molecules are linked through N—H⋯O hydrogen bonds, forming chains along the c axis.
doi:10.1107/S1600536812005478
PMCID: PMC3295477
PMID: 22412588
The title hydrazone molecule, C14H11ClN2O2, has a trans conformation with respect to the methylidene unit. The dihedral angle between the two benzene rings is 37.6 (3)°. In the crystal, the presence of O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds leads to the formation of a three-dimensional network. The title compound crystallized in the chiral orthorhombic space group P212121 and was refined as an inversion twin [Flack parameter = −0.20 (18)].
doi:10.1107/S1600536812005661
PMCID: PMC3295484
PMID: 22412595
In the title compound, C15H12I2N2O4·CH3OH, the hydrazone molecule exists in an E conformation with respect to the C=N bond. The dihedral angle between the rings is 11.9 (2)°. There is one intramolecular O—H⋯N hydrogen bond in the hydrazone molecule. In the crystal, the hydrazone and methanol molecules are linked through O—H⋯O and N—H⋯O hydrogen bonds and C—H⋯O interactions to form two-dimensional networks lying parallel to (001).
doi:10.1107/S1600536812004552
PMCID: PMC3295446
PMID: 22412557
The title compound, C14H10N4O5, has an E conformation with respect to the C=N bond. The dihedral angle between the benzene rings is 2.41 (14)°. In the crystal, molecules are linked through N—H⋯O hydrogen bonds to form chains along the c axis. C—H⋯O interactions are also present, linking the chains to form a three-dimensional network.
doi:10.1107/S1600536812004540
PMCID: PMC3295447
PMID: 22412558
Liu, Yi | Liu, Bing | Li, Xiao-Yan | Li, Jian-Jie | Qin, Hai-Feng | Tang, Chuan-Hao | Guo, Wan-Feng | Hu, Hai-Xu | Li, Sha | Chen, Cui-Jing | Liu, Bing | Gao, Hong-Jun | Liu, Xiao-Qing
Background
Epidermal growth factor receptor (EGFR) mutation is strongly associated with the therapeutic effect of tyrosine kinase inhibitors (TKIs) in patients with non-small-cell lung cancer (NSCLC). Nevertheless, tumor tissue that needed for mutation analysis is frequently unavailable. Body fluid was considered to be a feasible substitute for the analysis, but arising problems in clinical practice such as relatively lower mutation rate and poor clinical correlation are not yet fully resolved.
Method
In this study, 50 patients (32 pleural fluids and 18 plasmas) with TKIs therapy experience and with direct sequencing results were selected from 220 patients for further analysis. The EGFR mutation status was re-evaluated by Amplification Refractory Mutation System (ARMS), and the clinical outcomes of TKIs were analyzed retrospectively.
Results
As compared with direct sequencing, 16 positive and 23 negative patients were confirmed by ARMS, and the other 11 former negative patients (6 pleural fluids and 5 plasmas) were redefined as positive, with a fairly well clinical outcome (7 PR, 3 SD, and 1 PD). The objective response rate (ORR) of positive patients was significant, 81.3% (direct sequencing) and 72.7% (ARMS) for pleural fluids, and 80% (ARMS) for plasma. Notably, even reclassified by ARMS, the ORR for negative patients was still relatively high, 60% for pleural fluids and 46.2% for plasma.
Conclusions
When using body fluids for EGFR mutation analysis, positive result is consistently a good indicator for TKIs therapy, and the predictive effect was no less than that of tumor tissue, no matter what method was employed. However, even reclassified by ARMS, the correlation between negative results and clinical outcome of TKIs was still unsatisfied. The results indicated that false negative mutation still existed, which may be settled by using method with sensitivity to single DNA molecule or by optimizing the extraction procedure with RNA or CTC to ensure adequate amount of tumor-derived nucleic acid for the test.
doi:10.1186/1756-9966-30-111
PMCID: PMC3287118
PMID: 22142557
Body Fluids; EGFR Mutation; Direct Sequencing; ARMS; TKIs; NSCLC
AIM
To study the impact of scleral flap position, under which the posterior chamber intraocular lenses (PC-IOL) were sulcus-fixed by trans-scleral suture, on cornea astigmatism.
METHODS
Twenty-six aphakic or cataract eyes were comprised in this prospective noncomparative case series study. Eleven eyes had traumatic cataract removed without sufficient capsular support, 3 had blunt trauma with subluxated traumatic cataract, 8 had undergone vitreoretinal surgery and 4 had congenital cataract removed. The average age was 54 years (range 21-74 years), with 17 men and 7 women. The foldable PC-IOL was fixed in sulcus by trans-scleral suture. The incision for IOL implantation was made 1mm posterior to limbus along the steepest meridian of cornea, while scleral flaps to bury the knots of trans-scleral suture were made along the flattest meridian. All the surgeries were performed by a single doctor (Ma L), and the follow up was at least 13 months (range 13-28 months). The preoperative, 3 months and 1 year postoperative corneal curvature along the steepest and flattest cornea meridian and overall cornea astigmatism were compared.
RESULTS
The curvature along the steepest meridian changed from 44.25±2.22D preoperatively to 44.08±2.16D at 3 months postoperatively, and 43.65±5.23D at 1 year postoperatively (P>0.05); the curvature along the flattest meridian changed from 41.24±2.21D preoperatively to 43.15±3.94D at 3 months postoperatively, and 42.85±5.17D at 1 year postoperatively (P<0.05); and the surgery induced astigmatism (SIA) on cornea was calculated by vector analysis, which was 2.42±2.13D at 3 months postoperatively, and 2.18±3.42D at 1 year postoperatively, the difference was statistically significant (P<0.05).
CONCLUSION
The scleral flap made along the flattest meridian, under which the posterior chamber intraocular lenses (PCIOL) were sulcus-fixed by trans-scleral suture, can steepen the cornea in varying degrees, thus reducing preexisting corneal astigmatism.
doi:10.3980/j.issn.2222-3959.2011.05.09
PMCID: PMC3340717
PMID: 22553711
intraocular lens; suture fixation; astigmatism; lack of posterior capsule
There are three independent molecules in the asymmetric unit of the title compound, C19H16N2O3, in which the dihedral angles between the naphthalene ring system and the benzene ring are 7.52 (16), 18.15 (18), and 13.9 (2)°. All the molecules exist in the trans configuration with respect to the methylidene units. In each molecule there is one O—H⋯N and one N—H⋯O intramolecular hydrogen bond. In the crystal, two of the molecules are linked via a bifurcated N—H⋯(O,O) hydrogen bond. All three molecules are further linked via C—H⋯O interactions.
doi:10.1107/S1600536811038153
PMCID: PMC3201446
PMID: 22065731
There are three independent moleculesi n the asymmetric unit of the title compound, C18H16BrN3O3, in which the dihedral angles between the indole and benzene rings are 76.9 (2), 4.9 (2), and 70.9 (2)°. All three molecules exist in a trans configuration with respect to the methylidene units. In each molecule, there is one intramolecular O—H⋯N hydrogen bond. In the crystal, N—H⋯O hydrogen bonds occur.
doi:10.1107/S1600536811039195
PMCID: PMC3201537
PMID: 22065413
In the title compound, C15H12BrClN2O2, the dihedral angle between the two substituted aromatic rings is 77.8 (3)°. The molecule exists in a trans conformation with respect to the methylidene unit. In the crystal structure, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R
2
8(8) loops.
doi:10.1107/S1600536811034623
PMCID: PMC3200979
PMID: 22065403
In the title compound, C15H12Cl2N2O3, the dihedral angle between the two substituted aromatic rings is 5.4 (4)°. Intramolecular O—H⋯N and N—H⋯O hydrogen bonds affect the planarity of the molcular conformation, with a mean deviation from the plane defined by the non-H atoms of 0.062 (2) Å. The molecule exists in a trans configuration with respect to the methylidene unit. In the crystal, molecules are linked by N—H⋯O interactions.
doi:10.1107/S160053681102366X
PMCID: PMC3151996
PMID: 21837171
Background
The esophageal carcinoma related gene 4 (ECRG4) was initially identified and cloned from human normal esophageal epithelium in our laboratory (GenBank accession no.AF325503). ECRG4 has been described as a novel tumor suppressor gene associated with prognosis in esophageal squamous cell carcinoma (ESCC).
Methods
In this study, binding affinity assay in vitro and co-immunoprecipitation experiment in vivo were utilized to verify the physical interaction between ECRG4 and transmembrane protease, serine 11A (TMPRSS11A, also known as ECRG1, GenBank accession no. AF 071882). Then, p21 protein expression, cell cycle and cell proliferation regulations were examined after ECRG4 and ECRG1 co-transfection in ESCC cells.
Results
We revealed for the first time that ECRG4 interacted directly with ECRG1 to inhibit cancer cell proliferation and induce cell cycle G1 phase block in ESCC. Binding affinity and co-immunoprecipitation assays demonstrated that ECRG4 interacted directly with ECRG1 in ESCC cells. Furthermore, the ECRG4 and ECRG1 co-expression remarkably upregulatd p21 protein level by Western blot (P < 0.001), induced cell cycle G1 phase block by flow cytometric analysis (P < 0.001) and suppressed cell proliferation by MTT and BrdU assay (both P < 0.01) in ESCC cells.
Conclusions
ECRG4 interacts directly with ECRG1 to upregulate p21 protein expression, induce cell cycle G1 phase block and inhibit cancer cells proliferation in ESCC.
doi:10.1186/1471-2407-11-52
PMCID: PMC3039630
PMID: 21288367
Rowe, R. Grant | Li, Xiao-Yan | Hu, Yuexian | Saunders, Thomas L. | Virtanen, Ismo | de Herreros, Antonio Garcia | Becker, Karl-Friedrich | Ingvarsen, Signe | Engelholm, Lars H. | Bommer, Guido T. | Fearon, Eric R. | Weiss, Stephen J.
Epithelial–mesenchymal transition (EMT) is required for mesodermal differentiation during development. The zinc-finger transcription factor, Snail1, can trigger EMT and is sufficient to transcriptionally reprogram epithelial cells toward a mesenchymal phenotype during neoplasia and fibrosis. Whether Snail1 also regulates the behavior of terminally differentiated mesenchymal cells remains unexplored. Using a Snai1 conditional knockout model, we now identify Snail1 as a regulator of normal mesenchymal cell function. Snail1 expression in normal fibroblasts can be induced by agonists known to promote proliferation and invasion in vivo. When challenged within a tissue-like, three-dimensional extracellular matrix, Snail1-deficient fibroblasts exhibit global alterations in gene expression, which include defects in membrane type-1 matrix metalloproteinase (MT1-MMP)-dependent invasive activity. Snail1-deficient fibroblasts explanted atop the live chick chorioallantoic membrane lack tissue-invasive potential and fail to induce angiogenesis. These findings establish key functions for the EMT regulator Snail1 after terminal differentiation of mesenchymal cells.
doi:10.1083/jcb.200810113
PMCID: PMC2646556
PMID: 19188491
In the title compound, [Co(C13H8F2O)(C3H9P)3], the cobalt(0) atom is coordinated by three trimethylphosphine ligands and a π-coordinated carbonyl group of the 2,6-difluorobenzophenone ligand in a distorted tetrahedral geometry. The Co—O and Co—C distances are 1.896 (2) and 2.049 (4) Å, respectively.
doi:10.1107/S1600536809012367
PMCID: PMC2977559
PMID: 21583745
The title three-dimensional coordination polymer, [Cu2Cl(C6H4N5)]n, is the product of the hydrothermal reaction of CuCl2·2H2O and 5-(4-pyridyl)-1H-tetrazole (4-Hptz). The two independent CuI ions are coordinated in distorted tetrahedral and distorted trigonal coordination environments. In the unique 5-(4-pyridyl)-1H-tetrazolate ligand, the dihedral angle between the pyridine and tetrazole rings is 17.3 (2)°.
doi:10.1107/S1600536809006564
PMCID: PMC2969065
PMID: 21582320
The asymmetric unit of the title compound, {[Zn(C7H7O2)2(C10H8N2)]·4H2O}n, contains a highly distorted octahedral ZnII metal center strongly coordinated by two N atoms of two 4,4′-bipyridine (4,4′-bipy) ligands and chelated by two 4-methylbenzoate anions. The crystallographic inversion center and glide plane present at the center of the C—C single bond of 4,4′-bipy, along with the cis coordination motif of the 4,4′-bipy, lead to one-dimensional zigzag chains. There are a large number of water molecules in the crystal structure, which also form one-dimensional chains through O—H⋯O hydrogen bonds.
doi:10.1107/S1600536809005571
PMCID: PMC2968618
PMID: 21582116
In the title compound, C13H9ClN4O4, there are two crystallographically independent molecules in the asymmetric unit, which have very similar conformations. The C=N—N angles in each independent molecule are 115.0 (2) and 116.6 (2)°, which are significantly smaller than the ideal value of 120° expected for sp
2-hybridized N atoms. This is probably a consequence of repulsion between the nitrogen lone pairs and the adjacent N—N bonds. Two bifurcated intramolecular N—H⋯O hydrogen bonds help to establish the molecular conformation and consolidate the crystal packing.
doi:10.1107/S1600536808033357
PMCID: PMC2959777
PMID: 21580996
Membrane type-1 matrix metalloproteinase (MT1-MMP) drives cell invasion through three-dimensional (3-D) extracellular matrix (ECM) barriers dominated by type I collagen or fibrin. Based largely on analyses of its impact on cell function under two-dimensional culture conditions, MT1-MMP is categorized as a multifunctional molecule with 1) a structurally distinct, N-terminal catalytic domain; 2) a C-terminal hemopexin domain that regulates substrate recognition as well as conformation; and 3) a type I transmembrane domain whose cytosolic tail controls protease trafficking and signaling cascades. The MT1-MMP domains that subserve cell trafficking through 3-D ECM barriers in vitro or in vivo, however, remain largely undefined. Herein, we demonstrate that collagen-invasive activity is not confined strictly to the catalytic, hemopexin, transmembrane, or cytosolic domain sequences of MT1-MMP. Indeed, even a secreted collagenase supports invasion when tethered to the cell surface in the absence of the MT1-MMP hemopexin, transmembrane, and cytosolic tail domains. By contrast, the ability of MT1-MMP to support fibrin-invasive activity diverges from collagenolytic potential, and alternatively, it requires the specific participation of MT-MMP catalytic and hemopexin domains. Hence, the tissue-invasive properties of MT1-MMP are unexpectedly embedded within distinct, but parsimonious, sequences that serve to tether the requisite matrix-degradative activity to the surface of migrating cells.
doi:10.1091/mbc.E08-01-0016
PMCID: PMC2488283
PMID: 18495869