Tm4sf19 deficiency inhibits osteoclast multinucleation and prevents bone loss.

BACKGROUND: Multinucleation is a hallmark of osteoclast formation and has a unique ability to resorb bone matrix. During osteoclast differentiation, the cytoskeleton reorganization results in the generation of actin belts and eventual bone resorption. Tetraspanins are involved in adhesion, migration and fusion in various cells. However, its function in osteoclast is still unclear. In this study, we identified Tm4sf19, a member of the tetraspanin family, as a regulator of osteoclast function. MATERIALS AND METHODS: We investigate the effect of Tm4sf19 deficiency on osteoclast differentiation using bone marrow-derived macrophages obtained from wild type (WT), Tm4sf19 knockout (KO) and Tm4sf19 LELΔ mice lacking the large extracellular loop (LEL). We analyzed bone mass of young and aged WT, KO and LELΔ mice by µCT analysis. The effects of Tm4sf19 LEL-Fc fusion protein were accessed in osteoclast differentiation and osteoporosis animal model. RESULTS: We found that deficiency of Tm4sf19 inhibited osteoclast function and LEL of Tm4sf19 was responsible for its function in osteoclasts in vitro. KO and LELΔ mice exhibited higher trabecular bone mass compared to WT mice. We found that Tm4sf19 interacts with integrin αvß3 through LEL, and that this binding is important for cytoskeletal rearrangements in osteoclast by regulating signaling downstream of integrin αvß3. Treatment with LEL-Fc fusion protein inhibited osteoclast function in vitro and administration of LEL-Fc prevented bone loss in an osteoporosis mouse model in vivo. CONCLUSION: We suggest that Tm4sf19 regulates osteoclast function and that LEL-Fc may be a promising drug to target bone destructive diseases caused by osteoclast hyper-differentiation.

N-linked glycosylation is essential for anti-tumor activities of KIAA1324 in gastric cancer.

KIAA1324 is a transmembrane protein largely reported as a tumor suppressor and favorable prognosis marker in various cancers, including gastric cancer. In this study, we report the role of N-linked glycosylation in KIAA1324 as a functional post-translational modification (PTM). Loss of N-linked glycosylation eliminated the potential of KIAA1324 to suppress cancer cell proliferation and migration. Furthermore, we demonstrated that KIAA1324 undergoes fucosylation, a modification of the N-glycan mediated by fucosyltransferase, and inhibition of fucosylation also significantly suppressed KIAA1324-induced cell growth inhibition and apoptosis of gastric cancer cells. In addition, KIAA1324-mediated apoptosis and tumor regression were inhibited by the loss of N-linked glycosylation. RNA sequencing (RNAseq) analysis revealed that genes most relevant to the apoptosis and cell cycle arrest pathways were modulated by KIAA1324 with the N-linked glycosylation, and Gene Regulatory Network (GRN) analysis suggested novel targets of KIAA1324 for anti-tumor effects in the transcription level. The N-linked glycosylation blockade decreased protein stability through rapid proteasomal degradation. The non-glycosylated mutant also showed altered localization and lost apoptotic activity that inhibits the interaction between GRP78 and caspase 7. These data demonstrate that N-linked glycosylation of KIAA1324 is essential for the suppressive role of KIAA1324 protein in gastric cancer progression and indicates that KIAA1324 may have anti-tumor effects by targeting cancer-related genes with N-linked glycosylation. In conclusion, our study suggests the PTM of KIAA1324 including N-linked glycosylation and fucosylation is a necessary factor to consider for cancer prognosis and therapy improvement.

Mast4 determines the cell fate of MSCs for bone and cartilage development.

Mesenchymal stromal cells (MSCs) differentiation into different lineages is precisely controlled by signaling pathways. Given that protein kinases play a crucial role in signal transduction, here we show that Microtubule Associated Serine/Threonine Kinase Family Member 4 (Mast4) serves as an important mediator of TGF-ß and Wnt signal transduction in regulating chondro-osteogenic differentiation of MSCs. Suppression of Mast4 by TGF-ß1 led to increased Sox9 stability by blocking Mast4-induced Sox9 serine 494 phosphorylation and subsequent proteasomal degradation, ultimately enhancing chondrogenesis of MSCs. On the other hand, Mast4 protein, which stability was enhanced by Wnt-mediated inhibition of GSK-3ß and subsequent Smurf1 recruitment, promoted ß-catenin nuclear localization and Runx2 activity, increasing osteogenesis of MSCs. Consistently, Mast4-/- mice demonstrated excessive cartilage synthesis, while exhibiting osteoporotic phenotype. Interestingly, Mast4 depletion in MSCs facilitated cartilage formation and regeneration in vivo. Altogether, our findings uncover essential roles of Mast4 in determining the fate of MSC development into cartilage or bone.

Refining personality disorder subtypes and classification using finite mixture modeling.

The current Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic system for Axis II disorders continues to be characterized by considerable heterogeneity and poor discriminant validity. Such problems impede accurate personality disorder (PD) diagnosis. As a result, alternative assessment tools are often used in conjunction with the DSM. One popular framework is the object relational model developed by Kernberg and his colleagues (J. F. Clarkin, M. F. Lenzenweger, F. Yeomans, K. N. Levy, & O. F. Kernberg, 2007, An object relations model of borderline pathology, Journal of Personality Disorders, Vol. 21, pp. 474-499; O. F. Kernberg, 1984, Severe Personality Disorders, New Haven, CT: Yale University Press; O. F. Kernberg & E. Caligor, 2005, A psychoanalytic theory of personality disorders, in M. F. Lenzenweger & J. F. Clarkin, Eds., Major Theories of Personality Disorder, New York, NY: Guilford Press). Drawing on this model and empirical studies thereof, the current study attempted to clarify Kernberg's (1984) PD taxonomy and identify subtypes within a sample with varying levels of personality pathology using finite mixture modeling. Subjects (N = 141) were recruited to represent a wide range of pathology. The finite mixture modeling results indicated that 3 components were harbored within the variables analyzed. Group 1 was characterized by low levels of antisocial, paranoid, and aggressive features, and Group 2 was characterized by elevated paranoid features. Group 3 revealed the highest levels across the 3 variables. The validity of the obtained solution was then evaluated by reference to a variety of external measures that supported the validity of the identified grouping structure. Findings generally appear congruent with previous research, which argued that a PD taxonomy based on paranoid, aggressive, and antisocial features is a viable supplement to current diagnostic systems. Our study suggests that Kernberg's object relational model offers a plausible substantive aid in refining PD classification.

Perceptions of aging in two cultures: Korean and American views on old age.

The current study investigated whether beliefs about aging vary by culture, age, and gender. The Lasher and Faulkender (Int. J. Aging Hum. Dev., 37:247-259, 1993) Anxiety about Aging scale was administered to 153 American and 167 South Korean men and women divided into three age groups: young (18-39), middle-aged (40-59), and older (60-91) adults. Significant cultural differences were found for the total anxiety scale and three of the four subscales. Compared to Americans, Koreans portrayed higher overall levels of anxiety about aging, and greater fear of old people, psychological concerns, and concerns over physical appearance. For Koreans, younger adults had greater fear of old people, whereas among Americans, older adults had greater fear of old people. In both cultures, the older adults had greater psychological concerns and fear of losses than did the younger groups, and American women showed more anxiety about aging and concerns over physical appearance than their male counterparts. Results are discussed in relation to aging in different cultural contexts.