Overexpression of FAM46A, a Non-canonical Poly(A) Polymerase, Promotes Hemin-Induced Hemoglobinization in K562 Cells.

FAM46A belongs to the FAM46 subfamily of the nucleotidyltransferase-fold superfamily and is predicted to be a non-canonical poly(A) polymerase. FAM46A has been linked to several human disorders including retinitis pigmentosa, bone abnormality, cancer, and obesity. However, its molecular and functional characteristics are largely unknown. We herein report that FAM46A is expressed in cells of the hematopoietic system and plays a role in hemin-induced hemoglobinization. FAM46A is a nucleocytoplasmic shuttle protein modified by Tyr-phosphorylation only in the cytosol, where it is closely associated with ER. On the other hand, it is located proximal to the chromatin regions of active transcription in the nucleus. FAM46A is a cell cycle-dependent poly-ubiquitinated short-lived protein degraded mostly by proteasome and its overexpression inhibits cell growth and promotes hemin-induced hemoglobinization in K562 cell. Site-directed mutagenesis experiments confirm the non-canonical poly(A) polymerase activity of FAM46A is essential for enhanced hemin-induced hemoglobinization. In summary, FAM46A is a novel poly(A) polymerase that functions as a critical intracellular modulator of hemoglobinization.

Stimulation of Vibratory Urticaria-Associated Adhesion-GPCR, EMR2/ADGRE2, Triggers the NLRP3 Inflammasome Activation Signal in Human Monocytes.

EMR2/ADGRE2 is an adhesion G protein-coupled receptor differentially expressed by human myeloid cells. It modulates diverse cellular functions of innate immune cells and a missense EMR2 variant is directly responsible for vibratory urticaria. Recently, EMR2 was found to activate NLRP3 inflammasome in monocytes via interaction with FHR1, a regulatory protein of complement Factor H. However, the functional involvement of EMR2 activation and its signaling mechanisms in eliciting NLRP3 inflammasome activation remain elusive. In this study, we show that EMR2-mediated signaling plays a critical role in triggering the activation (2nd) signal for the NLRP3 inflammasome in both THP-1 monocytic cell line and primary monocytes. Stimulation of EMR2 by its agonistic 2A1 monoclonal antibody elicits a Gα16-dependent PLC-ß activation pathway, inducing the activity of downstream Akt, MAPK, NF-κB, and Ca2+ mobilization, eventually leading to K+ efflux. These results identify EMR2 and its associated signaling intermediates as potential intervention targets of NLRP3 inflammasome activation in inflammatory disorders.

CD97 inhibits cell migration in human fibrosarcoma cells by modulating TIMP-2/MT1- MMP/MMP-2 activity--role of GPS autoproteolysis and functional cooperation between the N- and C-terminal fragments.

CD97 is a tumor-associated adhesion-class G-protein-coupled receptor involved in modulating cell migration. Adhesion-class G-protein-coupled receptors are characterized by proteolytic cleavage at a G-protein-coupled receptor proteolysis site (GPS) into an N-terminal fragment (NTF) and a C-terminal fragment (CTF), which remain associated noncovalently. The molecular mechanism and the role of GPS proteolysis in CD97-modulated cell migration are not completely understood. We report here that CD97 expression in HT1080 fibrosarcoma cells enhanced tissue inhibitor of metalloproteinase-2 secretion, leading to reduced membrane type 1 matrix metalloproteinase and matrix metalloproteinase 2 activities. This, in turn, impaired cell migration and invasion in vitro and lung macrometastasis in vivo. CD97 expression also upregulated the expression of integrins, promoting cell adhesion. Importantly, these cellular functions absolutely required the presence of both the NTF and the CTF of CD97, confirming functional cooperation between the two receptor subunits. CD97 gene knockdown reversed these phenotypic changes. We conclude that GPS proteolysis and the functional interplay between the NTF and the CTF are indispensible for CD97 to inhibit HT1080 cell migration by suppressing matrix metalloproteinase activity.

Tissue engineering-based cartilage repair with mesenchymal stem cells in a porcine model.

This in vivo pilot study explored the use of mesenchymal stem cell (MSC) containing tissue engineering constructs in repair of osteochondral defects. Osteochondral defects were created in the medial condyles of both knees of 16 miniature pigs. One joint received a cell/collagen tissue engineering construct with or without pretreatment with transforming growth factor ß (TGF-ß) and the other joint from the same pig received no treatment or the gel scaffold only. Six months after surgery, in knees with no treatment, all defects showed contracted craters; in those treated with the gel scaffold alone, six showed a smooth gross surface, one a hypertrophic surface, and one a contracted crater; in those with undifferentiated MSCs, five defects had smooth, fully repaired surfaces or partially repaired surfaces, and one defect poor repair; in those with TGF-ß-induced differentiated MSCs, seven defects had smooth, fully repaired surfaces or partially repaired surfaces, and three defects showed poor repair. In Pineda score grading, the group with undifferentiated MSC, but not the group with TGF-ß-induced differentiated MSCs, had significantly lower subchondral, cell morphology, and total scores than the groups with no or gel-only treatment. The compressive stiffness was larger in cartilage without surgical treatment than the treated area within each group. In conclusion, this preliminary pilot study suggests that using undifferentiated MSCs might be a better approach than using TGF-ß-induced differentiated MSCs for in vivo tissue engineered treatment of osteochondral defects.

Home-based mobile cardio-pulmonary rehabilitation consultant system.

Cardiovascular diseases are the most popular cause of death in the world recently. For postoperatives, cardiac rehabilitation is still asked to maintain at home (phase II) to improve cardiac function. However, only one third of outpatients do the exercise regularly, reflecting the difficulty for home-based healthcare: lacking of monitoring and motivation. Hence, a cardio-pulmonary rehabilitation system was proposed in this research to improve rehabilitation efficiency for better prognosis. The proposed system was built on mobile phone and receiving electrocardiograph (ECG) signal from a wireless ECG holter via Bluetooth connection. Apart from heart rate (HR) monitor, an ECG derived respiration (EDR) technique is also included to provide respiration rate (RR). Both HR and RR are the most important vital signs during exercise but only used one physiological signal recorder in this system. In clinical test, there were 15 subjects affording Bruce Task (treadmill) to simulate rehabilitation procedure. Correlation between this system and commercial product (Custo-Med) was up to 98% in HR and 81% in RR. Considering the prevention of sudden heart attack, an arrhythmia detection expert system and healthcare server at the backend were also integrated to this system for comprehensive cardio-pulmonary monitoring whenever and wherever doing the exercise.

Psychological impact of severe acute respiratory syndrome on health workers in a tertiary hospital.

BACKGROUND: The sudden emergence of severe acute respiratory syndrome (SARS) caused international anxiety owing to its highly contagious and pandemic transmission. Health workers are vulnerable and are at high risk of infection. AIMS: To assess SARS-related stress and its immediate psychological impact and responses among health workers. METHOD: Health workers in a tertiary hospital affected by SARS were invited to complete a questionnaire designed to evaluate exposure experience, psychological impact and psychiatric morbidity. The risk and rates of psychiatric morbidity were estimated for exposure experience. RESULTS: Altogether, 1257 health workers successfully completed the survey. In the initial phase of the outbreak, when the infection was spreading rapidly, feelings of extreme vulnerability, uncertainty and threat to life were perceived, dominated by somatic and cognitive symptoms of anxiety. During the 'repair' phase, when the infection was being brought under control, depression and avoidance were evident. The estimated prevalence of psychiatric morbidity measured by the Chinese Health Questionnaire was about 75%. CONCLUSIONS: The outbreak of SARS could be regarded as an acute episode of a bio-disaster, leading to a significantly high rate of psychiatric morbidity.