Generation of mice with a novel conditional null allele of the <Emphasis Type="Italic">Sox9</Emphasis> gene

Sox9 is expressed in multiple tissues during mouse development and adulthood. Mutations in the Sox9 gene or changes in expression levels can be attributed to many congenital diseases. Heterozygous loss-of-function mutations in the human SOX9 gene cause Campomelic dysplasia, a semi-lethal skeletal malformation syndrome. Disruption of Sox9 by conventional gene targeting leads to perinatal lethality in heterozygous mice, hence hampering the feasibility to obtain the homozygous Sox9 null mice for in vivo functional studies. In this study, we generated a conditional allele of Sox9 (Sox9 ^tm4.Tlu ) by flanking exon 1 with loxP sites. Homozygous mice for the Sox9 ^tm4.Tlu allele (Sox9 ^flox/flox ) are viable, fertile and indistinguishable from wildtype (WT) mice, indicating that the Sox9 ^tm4.Tlu allele is a fully functional Sox9 allele. Furthermore, we demonstrated that Cre-mediated recombination using a Col2a1-Cre line resulted in specific ablation of Sox9 activity in cartilage tissues.     

The iNOS/Src/FAK axis is critical in Toll-like receptor-mediated cell motility in macrophages

The Toll-like receptors (TLRs) play a pivotal role in innate immunity for the detection of highly conserved, pathogen-expressed molecules. Previously, we demonstrated that lipopolysaccharide (LPS, TLR4 ligand)-increased macrophage motility required the participation of Src and FAK, which was inducible nitric oxide synthase (iNOS)-dependent. To investigate whether this iNOS/Src/FAK pathway is a general mechanism for macrophages to mobilize in response to engagement of TLRs other than TLR4, peptidoglycan (PGN, TLR2 ligand), polyinosinic-polycytidylic acid (polyI:C, TLR3 ligand) and CpG-oligodeoxynucleotides (CpG, TLR9 ligand) were used to treat macrophages in this study. Like LPS stimulation, simultaneous increase of cell motility and Src (but not Fgr, Hck, and Lyn) was detected in RAW264.7, peritoneal macrophages, and bone marrow-derived macrophages exposed to PGN, polyI:C and CpG. Attenuation of Src suppressed PGN-, polyI:C-, and CpG-elicited movement and the level of FAK Pi-Tyr861, which could be reversed by the reintroduction of siRNA-resistant Src. Besides, knockdown of FAK reduced the mobility of macrophages stimulated with anyone of these TLR ligands. Remarkably, PGN-, polyI:C-, and CpG-induced Src expression, FAK Pi-Tyr861, and cell mobility were inhibited in macrophages devoid of iNOS, indicating the importance of iNOS. These findings corroborate that iNOS/Src/FAK axis occupies a central role in macrophage locomotion in response to engagement of TLRs.     

Voltage‐gated K+ channels play a role in cAMP‐stimulated neuritogenesis in mouse neuroblastoma N2A cells

Neuritogenesis is essential in establishing the neuronal circuitry. An important intracellular signal causing neuritogenesis is cAMP. In this report, we showed that an increase in intracellular cAMP stimulated neuritogenesis in neuroblastoma N2A cells via a PKA‐dependent pathway. Two voltage‐gated K⁺ (Kv) channel blockers, 4‐aminopyridine (4‐AP) and tetraethylammonium (TEA), inhibited cAMP‐stimulated neuritogenesis in N2A cells in a concentration‐dependent manner that remarkably matched their ability to inhibit Kv currents in these cells. Consistently, siRNA knock down of Kv1.1, Kv1.4, and Kv2.1 expression reduced Kv currents and inhibited cAMP‐stimulated neuritogenesis. Kv1.1, Kv1.4, and Kv2.1 channels were expressed in the cell bodies and neurites as shown by immunohistochemistry. Microfluorimetric imaging of intracellular [K⁺] demonstrated that [K⁺] in neurites was lower than that in the cell body. We also showed that cAMP‐stimulated neuritogenesis may not involve voltage‐gated Ca²⁺ or Na⁺ channels. Taken together, the results suggest a role of Kv channels and enhanced K⁺ efflux in cAMP/PKA‐stimulated neuritogenesis in N2A cells. J. Cell. Physiol. 226: 1090–1098, 2011. © 2010 Wiley‐Liss, Inc.     

Chemical constituents of the fermented broth of the ascomycete Theissenia cinerea 89091602

One new betaenone, theissenoic acid (1), together with three new acetogenins, theissenolactones A-C (2-4, resp.), were isolated from the fermented broth of Theissenia cinerea 89091602 isolated in Taiwan. The structures of 1-4 were elucidated by spectroscopic methods. Biological tests revealed that 3 and 4 exhibited moderate growth-inhibitory activities against A549 lung cancer cell line with GI(50) values of 14.9 and 47.9 μM, respectively.     

Hidden malignant cells within leukocyte aggregates: seeds for invasive and metastatic cancer?

Background: Our previous studies revealed that leukocyte infiltration into aged or injured myoepithelial cell layers is a key trigger for breast tumor invasion and metastasis. Our current study further assessed the possibility that leukocyte aggregates may harbor detached individual tumor cell or clusters of tumor cells. Materials and methods: Tissue sections from patients with pregnancy-associated breast cancer (PABC) and controls were subjected to morphological and immunohistochemical assessment with a panel of leukocyte and tumor cell related markers. Results: A total of 63 leukocyte aggregates were detected in the 20 PABC cases studied. Of these, 55 (87%) were distributed within normal or hyperplastic lobules adjacent to invasive lesions. Over 70% of these leukocyte aggregates harbored detached individual tumor cell or cell clusters with malignant properties, including strong p53 positivity, elevated proliferation, reduced cell surface adhesion molecules, and cytological resemblance to adjacent invasive cancer cells. A significant number of these tumor cells or condensed chromosomes of mitotic tumor cells were observed to conjoin with the plasma membrane of leukocytes. Similar alterations were seen in leukocyte aggregates within the inter-lobular space and in non-PABC with a lower frequency. Conclusions: These findings suggest that leukocyte infiltration may trigger dissemination of tumor cells from their primary site, and that leukocyte aggregates may serve as a reservoir for disseminated tumor cells that may be physically dragged to distant sites by leukocytes during their migration.     

B-DNA structure is intrinsically polymorphic: even at the level of base pair positions

Increasingly exact measurement of single crystal X-ray diffraction data offers detailed characterization of DNA conformation, hydration and electrostatics. However, instead of providing a more clear and unambiguous image of DNA, highly accurate diffraction data reveal polymorphism of the DNA atomic positions and conformation and hydration. Here we describe an accurate X-ray structure of B-DNA, painstakingly fit to a multistate model that contains multiple competing positions of most of the backbone and of entire base pairs. Two of ten base-pairs of CCAGGCCTGG are in multiple states distinguished primarily by differences in slide. Similarly, all the surrounding ions are seen to fractionally occupy discrete competing and overlapping sites. And finally, the vast majority of water molecules show strong evidence of multiple competing sites. Conventional resolution appears to give a false sense of homogeneity in conformation and interactions of DNA. In addition, conventional resolution yields an average structure that is not accurate, in that it is different from any of the multiple discrete structures observed at high resolution. Because base pair positional heterogeneity has not always been incorporated into model-building, even some high and ultrahigh-resolution structures of DNA do not indicate the full extent of conformational polymorphism.