Loss- and gain-of-function mutations in the broadly expressed gene Lrp5 affect bone formation causing osteoporosis and high bone mass, respectively. Although Lrp5 is viewed as a Wnt coreceptor osteoblast-specific disruption of β-Catenin does not affect bone formation. Instead, we show here that Lrp5 inhibits expression of Tph1, the rate-limiting biosynthetic enzyme for serotonin in enterochromaffin cells of the duodenum. Accordingly, decreasing serotonin blood levels normalizes bone formation and bone mass in Lrp5-deficient mice and gut- but not osteoblast-specific Lrp5 inactivation decreases bone formation in a β-Catenin–independent manner. Moreover, gut-specific activation of Lrp5, or inactivation of Tph1, increases bone mass and prevents ovariectomy-induced bone loss. Serotonin acts on osteoblasts through the Htr1b receptor and CREB to inhibit their proliferation. By identifying duodenum-derived serotonin as a hormone inhibiting bone formation in an Lrp5-dependent manner this study broadens our understanding of bone remodeling and suggests novel therapies to increase bone mass.

Although regulation of chondrogenesis and cartilage development by Wnt signaling is well established, the function of Wnt in the maintenance and destruction of cartilage remains largely unknown. Here we investigated the involvement and regulatory mechanisms of Wnt signaling in cartilage destruction. We found that interleukin-1␤, the primary pro-inflammatory cytokine involved in cartilage destruction, induces expression of Wnt-5a and -7a in primary culture articular chondrocytes. The level of ␤-catenin was also increased in chondrocytes of arthritic cartilage, suggesting the association of Wnt/␤-catenin signaling with arthritic cartilage destruction. In addition, our results show that Wnt-7a induces dedifferentiation and inhibits NO-induced apoptosis of primary culture articular chondrocytes. Wnt-7a induces dedifferentiation of articular chondrocytes by stimulating transcriptional activity of ␤-catenin, whereas NO-induced apoptosis is inhibited via the activation of cell survival signaling, such as phosphatidylinositol 3-kinase and Akt, which block apoptotic signaling cascade. Our results collectively suggest that Wnt-7a is associated with cartilage destruction by regulating the maintenance of differentiation status and the apoptosis of articular chondrocytes via different mechanisms.

Accumulation of ␤-catenin and subsequent stimulation of ␤-catenin-T cell-factor (Tcf)/lymphoid-enhancerfactor (Lef) transcriptional activity causes dedifferentiation of articular chondrocytes, which is characterized by decreased type II collagen expression and initiation of type I collagen expression. This study examined the mechanisms of ␣-catenin degradation, the role of ␣-catenin in ␤-catenin signaling, and the physiological significance of ␣-catenin regulation of ␤-catenin signaling in articular chondrocytes. We found that both ␣-and ␤-catenin accumulated during dedifferentiation of chondrocytes by escaping from proteasomal degradation. ␤-Catenin degradation was ubiquitination-dependent, whereas ␣-catenin was proteasomally degraded in a ubiquitination-independent fashion. The accumulated ␣-and ␤-catenin existed as complexes in the cytosol and nucleus. The complex formation between ␣-and ␤-catenin blocked proteasomal degradation of ␣-catenin and also inhibited ␤-catenin-Tcf/Lef transcriptional activity and the suppression of type II collagen expression associated with ectopic expression of ␤-catenin, the inhibition of proteasome, or Wnt signaling. Collectively, our results indicate that ubiquitin-independent degradation of ␣-catenin regulates ␤-catenin signaling and maintenance of the differentiated phenotype of articular chondrocytes.␤-Catenin interacts with cadherin to participate in cell-cell adhesion and regulates gene expression by acting as a transcriptional co-activator (1, 2). In the absence of extracellular stimuli, cytosolic ␤-catenin is phosphorylated by glycogen synthase kinase-3␤, leading to its ubiquitination and subsequent degradation by the 26 S proteasome. However, extracellular stimuli, such as Wnt signaling, lead to the inhibition of glycogen synthase kinase-3␤, escape of ␤-catenin from ubiquitin-dependent proteolytic degradation, and subsequent cytosolic accumulation of ␤-catenin (3). The accumulated ␤-catenin translocates into the nucleus in association with members of the T cell-factor (Tcf) 1 /lymphoid-enhancer-factor (Lef) family of transcription factors, leading to stimulation or suppression of target gene transcription (2). As a transcriptional co-activator, ␤-catenin is involved in the regulation of several biological functions. Our group previously has shown that ␤-catenin regulates maintenance of differentiated phenotypes (4, 5) and expression of cyclooxygenase-2 (6) in chondrocytes by acting as a transcriptional co-activator. We have also shown that Wnt-7a causes dedifferentiation of chondrocytes characterized by suppression of type II collagen expression and the onset of type I collagen expression. Accumulation and stimulation of ␤-catenin transcriptional activity by Wnt-7a signaling is sufficient to cause chondrocyte dedifferentiation (4, 5).␤-Catenin signaling can be regulated by a variety of proteins. Cadherins regulate the transcriptional activity of ␤-catenin in a cell adhesion-independent manner (7, 8) via sequestration of ␤-catenin in the cytoplasm (9), whereas ␥-catenin ...

No abstract

Biomechanical remodeling of stroma by cancer-associated fibroblasts (CAF) in early stages of cancer is critical for cancer progression, and mechanical cues such as extracellular matrix stiffness control cell differentiation and malignant progression. However, the mechanism by which CAF activation occurs in low stiffness stroma in early stages of cancer is unclear. Here, we investigated the molecular mechanism underlying CAF regulation by SPIN90 and microtubule acetylation under conditions of mechanically soft matrices corresponding to normal stromal rigidity. SPIN90 was downregulated in breast cancer stroma but not tumor, and this low stromal expression correlated with decreased survival in breast cancer patients. deficiency facilitated recruitment of mDia2 and APC complex to microtubules, resulting in increased microtubule acetylation. This increased acetylation promoted nuclear localization of YAP, which upregulated expression of myofibroblast marker genes on soft matrices. depletion enhanced tumor progression, and blockade of microtubule acetylation in CAF significantly inhibited tumor growth in mice. Together, our data demonstrate that loss of SPIN90-mediated microtubule acetylation is a key step in CAF activation in low stiffness stroma. Moreover, correlation among these factors in human breast cancer tissue supports the clinical relevance of SPIN90 and microtubule acetylation in tumor development. .

Rheumatoid arthritis (RA) and osteoarthritis (OA), two common types of arthritis, affect the joints mainly by targeting the synovium and cartilage. Increasing evidence indicates that a significant network connects synovitis and cartilage destruction during the progression of arthritis. We recently demonstrated that hypoxia-inducible factor (HIF)-2α causes RA and OA by regulating the expression of catabolic factors in fibroblast-like synoviocytes (FLS) or chondrocytes. To address the reciprocal influences of HIF-2α on FLS and chondrocytes, we applied an in vitro co-culture system using a transwell apparatus. When co-cultured with HIF-2α-overexpressing chondrocytes, FLS exhibited increased expression of matrix metalloproteinases and inflammatory mediators, similar to the effects induced by tumor-necrosis factor (TNF)-α treatment of FLS. Moreover, chondrocytes co-cultured with HIF-2α-overexpressing FLS exhibited upregulation of Mmp3 and Mmp13, which is similar to the effects induced by interleukin (IL)-6 treatment of chondrocytes. We confirmed these differential HIF-2α-induced effects via distinct secretory mediators using Il6-knockout cells and a TNF-α-blocking antibody. The FLS-co-culture-induced gene expression changes in chondrocytes were significantly abrogated by IL-6 deficiency, whereas TNF-α neutralization blocked the alterations in gene expression associated with co-culture of FLS with chondrocytes. Our results further suggested that the observed changes might reflect the HIF-2α-induced upregulation of specific receptors for TNF-α (in FLS) and IL-6 (in chondrocytes). This study broadens our understanding of the possible regulatory mechanisms underlying the crosstalk between the synovium and cartilage in the presence of HIF-2α, and may suggest potential new anti-arthritis therapies.

Periodontal disease is one of the most prevalent chronic disorders worldwide. It is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss. Here, we focused on the role of adipokines, which are locally expressed by periodontal tissues, in the regulation of catabolic gene expression leading to periodontal inflammation. The expression of the nicotinamide phosphoribosyltransferase (NAMPT) adipokine was dramatically increased in inflamed human and mouse gingival tissues. NAMPT expression was also increased in lipopolysaccharide- and proinflammatory cytokine-stimulated primary cultured human gingival fibroblasts (GF). Adenovirus-mediated NAMPT (Ad-Nampt) overexpression upregulated the expression and activity of COX-2, MMP1 and MMP3 in human GF. The upregulation of IL-1β- or Ad-Nampt-induced catabolic factors was significantly abrogated by the intracellular NAMPT (iNAMPT) inhibitor, FK866 or by the sirtuin (SIRT) inhibitor, nicotinamide (NIC). Recombinant NAMPT protein or extracellular NAMPT (eNAMPT) inhibition using a blocking antibody did not alter NAMPT target gene expression levels. Moreover, intragingival Ad-Nampt injection mediated periodontitis-like phenotypes including alveolar bone loss in mice. SIRT2, a part of the SIRT family, was positively associated with NAMPT actions in human GF. Furthermore, in vivo inhibition of the NAMPT-NAD+-SIRT axis by NIC injection in mice ameliorated the periodontal inflammation and alveolar bone erosion caused by intragingival injection of Ad-Nampt. Our findings indicate that NAMPT is highly upregulated in human GF, while its enzymatic activity acts as a crucial mediator of periodontal inflammation and alveolar bone destruction via regulation of COX-2, MMP1, and MMP3 levels.

Hysteroscopic sterilization is a minimally invasive, nonincisional method of permanent sterilization that is a valid alternative to laparoscopic sterilization, the conventional method of female sterilization. Under hysteroscopic guidance, an expanding microinsert is introduced into the proximal portion of each fallopian tube; local fibrosis and, ultimately, complete tubal occlusion occurs within 3 months. This retrospective study examined trends in sterilization in women at an outpatient surgery center and university teaching hospitals following the introduction of Essure hysteroscopic sterilization in 2002. A chart review was conducted on women undergoing interval sterilization procedures and postpartum sterilization procedures between 2002 and 2007. Interventions evaluated included minilaparotomy tubal ligation, laparoscopic sterilization, Essure hysteroscopic sterilization, and postpartum tubal ligation performed after vaginal delivery or at the time of cesarean section.Of the 5509 permanent sterilization procedures examined, 2484 were interval sterilization procedures and 3025 were postpartum tubal ligations. For all interval sterilizations performed during the 6-year-study period, a shift toward Essure hysteroscopic sterilizations from 0.0% to 51.3% corresponded significantly with a decrease in laparoscopic sterilizations from 97.9% to 48.5% (P Ͻ 0.001). During the study period, the number of postpartum tubal ligations performed after vaginal delivery decreased significantly from 7.9% to 3.3% of all vaginal deliveries (P Ͻ 0.001), whereas the number of tubal ligations performed at the time of cesarean section did not change significantly (P ϭ 0.51).These findings suggest the high likelihood that Essure hysteroscopic sterilization will replace the laparoscopic approach as the method of choice for permanent sterilization. ABSTRACTIt is becoming increasingly common to enable a woman to see her ambulatory hysteroscopy procedure on a monitor. However, there is only limited evidence on the potential impact of seeing or not seeing the procedure on patient mood, perception of pain, and patient-physician interaction. This randomized controlled trial compared the effects of seeing or not seeing the screen during an outpatient hysteroscopy procedure on patient's experience. At two outpatient clinics, 157 women scheduled for a hysteroscopy procedure were randomized either to see the screen (n ϭ 81) or not to see the screen (n ϭ 76). Before and after the procedure, the patients completed questionnaires to evaluate various parameters of their experience (mood, pain perception, illness cognitions, and communication with the health professional). After 232Obstetrical and Gynecological Survey Office Gynecology 233ABSTRACT Some investigators have reported that presence of the inner border may be a colposcopic sign for the presence of high-grade cervical neoplasia. The inner border can be defined as a sharp acetowhite demarcation or transformation zone within a less opaque acetowhite area. The association of the colposcopic si...