TAp73 regulates the spindle assembly checkpoint by modulating BubR1 activity

The role of various p73 isoforms in tumorigenesis has been controversial. However, as we have recently shown, the generation of TAp73-deficient (TAp73^−/−) mice reveals that TAp73 isoforms exert tumor-suppressive functions, indicating an emerging role for Trp-73 in the maintenance of genomic stability. Unlike mice lacking all p73 isoforms, TAp73^−/− mice show a high incidence of spontaneous tumors. Moreover, TAp73^−/− mice are infertile and produce oocytes exhibiting spindle abnormalities. These data suggest a link between TAp73 activities and the common molecular machinery underlying meiosis and mitosis. Previous studies have indicated that the spindle assembly checkpoint (SAC) complex, whose activation leads to mitotic arrest, also regulates meiosis. In this study, we demonstrate in murine and human cells that TAp73 is able to interact directly with several partners of the SAC complex (Bub1, Bub3, and BubR1). We also show that TAp73 is involved in SAC protein localization and activities. Moreover, we show that decreased TAp73 expression correlates with increases of SAC protein expression in patients with lung cancer. Our results establish TAp73 as a regulator of SAC responses and indicate that TAp73 loss can lead to mitotic arrest defects. Our data suggest that SAC impairment in the absence of functional TAp73 could explain the genomic instability and increased aneuploidy observed in TAp73-deficient cells.     

Characterization of endoplasmic reticulum-associated degradation of a protein S mutant identified in a family of quantitative protein S deficiency

INTRODUCTION: Misfolded and unassembled glycoproteins are eliminated from the endoplasmic reticulum (ER) lumen by the ER-associated degradation (ERAD).We previously identified a Tyr595Cys (Y595C) mutation of protein S (PS) in a family of a quantitative PS deficiency. The mutation causes intracellular degradation and decreased secretion of the Y595C mutant PS. The aim of the present study was to further characterize the molecular basis of the intracellular degradation of the mutant. MATERIALS AND METHODS: We stably expressed the mutant in mammalian cells, and analyzed the intracellular localization of the protein. The intracellular degradation pathway was determined by pulse-chase analyses in the presence of various inhibitors of ERAD. RESULTS AND CONCLUSIONS: Endoglycosidase H digestion and immunofluorescence staining revealed the mutant being retained in the ER. Epoxomicin, a potent and specific proteasome inhibitor, and Ala-Ala-Phe-CH(2)Cl (AAF), an inhibitor of tripeptidyl peptidase II (TPPII), suppressed the intracellular degradation of the mutant by about 65% and 50%, respectively. When epoxomicin was combined with AAF, the inhibitory effect was substantially enhanced. Although castanospermine, an inhibitor of glucosidases I and II, did not affect the degradation, kifunensine, an inhibitor of ER mannosidase I, suppressed it. Thus, it appears that the Y595C mutant is degraded through more than one pathway of ERAD, including the proteasome-dependent pathway and an alternate proteasome-independent pathway where proteases such as TPPII may be involved. Production of the critical B isoform of Man(8)GlcNAc(2) targets the mutant for ERAD, however, the interaction with calnexin/calreticulin through monoglucosylated oligosaccharides may not be required for the degradation of the mutant.     

Taxol increases the amount and T cell activating ability of self-immune stimulatory multimolecular complexes found in ovarian cancer cells

It has been proposed that chemotherapy enhances tumor antigen (TA)-specific immunity. The molecular form of TA from ovarian tumor that activates cellular immunity is unknown. We report here identification of a novel molecular form of immunogenic TA for CD8(+) cells named self-immune stimulatory multimolecular complexes (ISMMC). ISMMC consist of a molecular complex of polyosome/ribosome-bound ubiquitinated nascent HER-2 polypeptides. This complex is chaperoned by heat shock protein Gp96, which mediates ISMMC uptake by antigen-presenting cells through the scavenger receptor CD91. RNAs in ISMMC stimulate immature dendritic cells to secrete interleukin 12 and induce IFN-gamma in peripheral blood mononuclear cells. ISMMC dissociate, retrotranslocate from the lysosome to cytoplasm, and are processed to peptides by the proteasome. At subpharmacologic doses, Taxol increased the amount of ISMMC by three to four times and modified their composition by inducing the attachment of cochaperones of HSP70, such as the mitotic-phase phosphoprotein 11J. On a total protein basis, Taxol induced ISMMC, expanded more CD8(+) cells, activated more CD56(+) NKG2D(+) cells to produce IFN-gamma, and were more potent inducers of high T-cell receptor density Perforin(+) cells than native ISMMC and peptide E75. Elucidation of the composition of ISMMC and identification of adducts formed by Taxol should be important for developing molecular cancer vaccines.     

Factors affecting rejection of bariatric patients from an academic weight loss program

BackgroundTo determine the factors affecting rejection of bariatric candidates at an accredited, American College of Surgeons Level 1A, bariatric program. Bariatric surgery “Centers of Excellence” use a multidisciplinary team to screen patients for eligibility for surgery using insurance, medical history, psychological evaluation findings, and the surgeon assessment. Few studies have reported on the frequency or reasons for patients not being accepted for surgery among high-volume academic bariatric programs.MethodsFrom March to September 2007, 299 consecutive patients were accepted for evaluation into an accredited bariatric program and tracked for the incidence of rejection for weight loss surgery. The primary reasons for rejection included a lack of insurance coverage, being medically unfit, psychological or social inappropriateness, and a body mass index (BMI) that did not meet the cutoff (BMI <35 kg/m² or <40 kg/m² without co-morbid conditions).ResultsOf 299 screened patients, 90 (30.1%) were not accepted for surgery by the multidisciplinary team. The most frequent reason was the lack of insurance coverage (47.8%). Primary care physicians were the most common source of patient referral. All but 1 of the patients excluded because of an inadequate BMI (n = 13) had been referred by friends, co-workers, or themselves from information received from the Internet or television.ConclusionApproximately one third of screened patients were not accepted for surgery by an academic bariatric program. Self- or social referral appeared to correlate with rejection because the BMI did not meet the criteria for surgery. This suggests inadequate information among social referral networks and/or in the media. Long-term follow-up will determine the health outcomes of patients not cleared for weight loss surgery.     

Effect of 14-membered-ring macrolides on production of interleukin-8 mediated by protease-activated receptor 2 in human keratinocytes

The production of interleukin-8 induced by the activation of protease-activated receptor 2 and its synergism with interleukin-1beta were modulated by 14-membered-ring macrolides, namely, roxithromycin, erythromycin, and clarithromycin, in cultured normal human epidermal keratinocytes. Those macrolides may attenuate the protease-activated receptor 2-interleukin-8 axis and thereby modulate proinflammatory responses in the skin.     

Uncontrollable midbrain hemorrhage due to brain metastasis of pulmonary pleomorphic carcinoma

A 54-year-old man who had been treated hypertension admitted our hospital due to midbrain hemorrhage. Pulmonary abnormal shadow was also found by chest radiological examinations and it was diagnosed as stage IB (T2N0M0) non-small-cell lung cancer. Right upper lobectomy with combined resection of azygos vein and parietal pleura facing to the tumor was conducted because the direct invasion of the tumor was strongly suspected. Pathological diagnosis was pleomorphic carcinoma. Although, postoperative course was uneventful, midbrain hemorrhage recurred 3rd postoperative day. Since the hemorrhage continued in spite of the conservative treatment, the craniotomy was performed on the 13th postoperative day. The pathological examination revealed the hemorrhage to be caused by the brain metastasis.