VPS72/YL1-Mediated H2A.Z Deposition Is Required for Nuclear Reassembly after Mitosis.

The eukaryotic nucleus remodels extensively during mitosis. Upon mitotic entry, the nuclear envelope breaks down and chromosomes condense into rod-shaped bodies, which are captured by the spindle apparatus and segregated during anaphase. Through telophase, chromosomes decondense and the nuclear envelope reassembles, leading to a functional interphase nucleus. While the molecular processes occurring in early mitosis are intensively investigated, our knowledge about molecular mechanisms of nuclear reassembly is rather limited. Using cell free and cellular assays, we identify the histone variant H2A.Z and its chaperone VPS72/YL1 as important factors for reassembly of a functional nucleus after mitosis. Live-cell imaging shows that siRNA-mediated downregulation of VPS72 extends the telophase in HeLa cells. In vitro, depletion of VPS72 or H2A.Z results in malformed and nonfunctional nuclei. VPS72 is part of two chromatin-remodeling complexes, SRCAP and EP400. Dissecting the mechanism of nuclear reformation using cell-free assays, we, however, show that VPS72 functions outside of the SRCAP and EP400 remodeling complexes to deposit H2A.Z, which in turn is crucial for formation of a functional nucleus.

Chromosome alignment maintenance requires the MAP RECQL4, mutated in the Rothmund-Thomson syndrome.

RecQ-like helicase 4 (RECQL4) is mutated in patients suffering from the Rothmund-Thomson syndrome, a genetic disease characterized by premature aging, skeletal malformations, and high cancer susceptibility. Known roles of RECQL4 in DNA replication and repair provide a possible explanation of chromosome instability observed in patient cells. Here, we demonstrate that RECQL4 is a microtubule-associated protein (MAP) localizing to the mitotic spindle. RECQL4 depletion in M-phase-arrested frog egg extracts does not affect spindle assembly per se, but interferes with maintaining chromosome alignment at the metaphase plate. Low doses of nocodazole depolymerize RECQL4-depleted spindles more easily, suggesting abnormal microtubule-kinetochore interaction. Surprisingly, inter-kinetochore distance of sister chromatids is larger in depleted extracts and patient fibroblasts. Consistent with a role to maintain stable chromosome alignment, RECQL4 down-regulation in HeLa cells causes chromosome misalignment and delays mitotic progression. Importantly, these chromosome alignment defects are independent from RECQL4's reported roles in DNA replication and damage repair. Our data elucidate a novel function of RECQL4 in mitosis, and defects in mitotic chromosome alignment might be a contributing factor for the Rothmund-Thomson syndrome.

A phase II randomized trial of adjuvant chemotherapy with S-1 versus S-1 plus cisplatin for completely resected pathological stage II/IIIA non-small cell lung cancer.

OBJECTIVES: Platinum-based combination chemotherapy is the standard postoperative adjuvant treatment for pathological stage II/III non-small cell lung cancer (NSCLC). Oral S-1 therapy has good efficacy and relatively low toxicity for the treatment of advanced NSCLC. We investigated whether long-term S-1 monotherapy is also useful as an adjuvant therapy after surgery in patients with NSCLC. PATIENTS AND METHODS: We conducted a phase II randomized open-label multi-institutional study in patients with pathological stage II/IIIA NSCLC (7th TNM classification) who underwent complete resection from 2009 to 2013. The primary endpoint, the 2-year disease-free survival (DFS) rate, was evaluated using the Bayesian method. Eligible patients were randomly assigned to two arms: oral S-1 monotherapy (S-1 arm) and S-1 plus cisplatin combination therapy followed by S-1 (S-1 plus cisplatin arm) both for a total of 1 year. RESULTS: A total of 70 and 71 patients were enrolled in S-1 arm and S-1 plus cisplatin arm, respectively. The 2-year DFS rates were 52% (95% confidence interval [CI], 0.40-0.63) and 61% (95% CI, 0.48-0.70) for S-1 arm and S-1 plus cisplatin arm, respectively. Both arms met the primary endpoint. Neither DFS nor OS was significantly different between the arms (log-rank test: P = 0.1695 and P = 0.8684, respectively). The main G3/4 adverse events were loss of appetite and anemia (S-1 vs. S-1 plus cisplatin: 4.3% vs. 11.6% and 0% vs. 5.8%, respectively). The treatment completion rate did not differ between the two arms (S-1 vs. S-1 plus cisplatin: 45.7%, 95% CI, 41.9-66.3% vs. 43.5% 95% CI, 44.0-68.4%). CONCLUSIONS: Long-term adjuvant chemotherapy with S-1 was a feasible and promising treatment for patients with completely resected NSCLC, regardless of cisplatin addition. S-1 monotherapy should be investigated further, based on its low toxicity and practical convenience.

A rare case of gradual enlargement of a multifocal myelolipoma of the posterior mediastinum for 12 years after surgical resection of an adrenal myelolipoma.

INTRODUCTION: A myelolipoma is a rare benign tumor that is composed of adipose tissue and hematopoietic elements. Myelolipomas most commonly occur in the unilateral adrenal gland. Posterior mediastinal myelolipomas are extremely rare. We herein present a rare case of a multifocal myelolipoma of the mediastinum that gradually enlarged over a 12-year period after surgical resection of an adrenal myelolipoma. This is the first report of multifocal myelolipomas of the posterior mediastinum and adrenal gland. PRESENTATION OF CASE: A posterior mediastinal tumor was incidentally found by chest X-ray and computed tomography (CT) examination of a 74-year-old woman. The patient had a medical history of resection of a myelolipoma of the left adrenal gland 12 years earlier. We performed tumor extirpation under video-assisted thoracic surgery (VATS). The size of the tumor was 4.5 cm, and the postoperative diagnosis was a myelolipoma. DISCUSSION: Posterior mediastinal myelolipomas are extremely rare, and only 39 cases of mediastinal myelolipoma have been reported to date. No reports have described a multifocal myelipoma of mediastinal myelolipoma. To our knowledge, this is the first report of multifocal myelipomas of the adrenal gland and posterior mediastinum. CONCLUSION: A differential diagnosis of myelolipoma of the posterior mediastinum is important in patients with a history of myelolipoma of the adrenal gland.

Acute lower limb ischemia and intestinal necrosis due to arterial tumor embolism from advanced lung cancer: a case report and literature review.

BACKGROUND: Arterial tumor embolism (ATE) is a rare but life-threating complication. PRESENTATION OF CASE: A 55-year-old man with acute lower-limb ischemia was referred to our hospital after endovascular intervention failed and underwent above-the-knee amputation for severe limb necrosis. On postoperative day 8, he developed small bowel necrosis and underwent resection. Histopathological examination of the resected bowel revealed that the submucosal arterial emboli were positive for the markers of squamous cells. He had unresectable lung squamous cell carcinoma with left atrium invasion. The subsequent embolisms were thought to be caused by the advanced lung cancer. CONCLUSION: ATE is rare but should be considered as a differential diagnosis for unidentified arterial occlusion.

Developmentally Regulated GTP binding protein 1 (DRG1) controls microtubule dynamics.

The mitotic spindle, essential for segregating the sister chromatids into the two evolving daughter cells, is composed of highly dynamic cytoskeletal filaments, the microtubules. The dynamics of microtubules are regulated by numerous microtubule associated proteins. We identify here Developmentally regulated GTP binding protein 1 (DRG1) as a microtubule binding protein with diverse microtubule-associated functions. In vitro, DRG1 can diffuse on microtubules, promote their polymerization, drive microtubule formation into bundles, and stabilize microtubules. HeLa cells with reduced DRG1 levels show delayed progression from prophase to anaphase because spindle formation is slowed down. To perform its microtubule-associated functions, DRG1, although being a GTPase, does not require GTP hydrolysis. However, all domains are required as truncated versions show none of the mentioned activities besides microtubule binding.

A rare case of an intercostal lung herniation with fractures of the fifth and sixth ribs after thoracic surgery.

INTRODUCTION: Lung herniation is a rare condition defined as a protrusion of the pleural-covered lung parenchyma through an abnormal defect or weakness in the thoracic wall. Postoperative lung herniation is reported to result from a preceding operation with inadequate closure of the chest wall. PRESENTATION OF CASE: A 77-year-old woman was admitted to our hospital for treatment of hemoptysis and nausea. One year previously, she had undergone wedge resection of the right lower lobe (S6) for treatment of primary lung adenocarcinoma. Upon admission, chest radiograph and chest computed tomography showed a right lung herniation through the fifth enlarged intercostal space with right fifth and sixth rib fractures. She underwent surgical closure of the intercostal hernia using synthetic materials with fixation of the fifth and sixth ribs. The patient had developed no recurrence 9 months after surgical repair. DISCUSSION: In the present case, adequate closure of the right pleural cavity was ensured by fixation of both fifth and sixth ribs during the preceding video-assisted thoracic surgery for the primary lung carcinoma. Our patient may have had some exacerbation factors for lung herniation, increased intrathoracic pressure, attenuation of chest wall by prolonged coughing and rib fracture, and high abdominal pressure due to her hunched-over posture. CONCLUDION: It is important to know some exacerbation factors for postoperative intercostal lung herniation. Addition of monofirament-suture fixation of the ribs to patch repair is very effective for lung herniation repair in patients with concurrent lung herniation and rib fractures.

Chromatin-Binding Proteins Moonlight as Mitotic Microtubule Regulators.

Some microtubule (MT)-associated proteins bind to MTs and chromatin simultaneously to fulfill their mitotic spindle function. By contrast, a growing number of chromatin-binding proteins leave mitotic chromatin and interact with MTs via their chromatin-binding domains. I discuss this switch from chromatin to MT binding as a key regulatory principle of spindle formation.

A Multiplexed NMR-Reporter Approach to Measure Cellular Kinase and Phosphatase Activities in Real-Time.

Cell signaling is governed by dynamic changes in kinase and phosphatase activities, which are difficult to assess with discontinuous readout methods. Here, we introduce an NMR-based reporter approach to directly identify active kinases and phosphatases in complex physiological environments such as cell lysates and to measure their individual activities in a semicontinuous fashion. Multiplexed NMR profiling of reporter phosphorylation states provides unique advantages for kinase inhibitor studies and reveals reversible modulations of cellular enzyme activities under different metabolic conditions.

Lung cancer surgery in patients aged 80 years or older: an analysis of risk factors, morbidity, and mortality.

INTRODUCTION: As the population ages, the age of patients undergoing thoracic surgery increases, and elderly patients often have more comorbidities than younger patients. METHODS: This retrospective study observed preoperative comorbidities, surgical procedures and postoperative morbidity and mortality after lung cancer surgery in patients 80 years of age or older. The medical records of lung cancer patients 80 years of age or older who underwent surgery from January 2003 to December 2012 were reviewed. RESULTS: There were 49 patients (27 males, 22 females), with a median age of 83 years. Thirty patients underwent major pulmonary resection and 18 patients underwent limited pulmonary resection. The median Charlson comorbidity index was 3. Although approximately two-thirds of the patients (20 patients; 40.8%) experienced some kind of postoperative morbidity, more than 80% of the complications were grade 1 or 2 according to the Clavien-Dindo classification. Cerebrovascular disease and chronic obstructive pulmonary disease were significantly associated with moderate-to-severe complications. Postoperative death was observed in two cases (4.1%). In addition, an increased American Society of Anesthesiologists classification score and past history of myocardial infarction, congestive heart failure and/or diabetes mellitus with end-organ damage were significantly associated with mortality. The overall survival rate was 79.6% at 3 years and 53.1% at 5 years. CONCLUSIONS: Thoracic surgery shows acceptable morbidity and mortality in patients 80 years of age or older. Patients 80 years of age or older should be offered the best treatments, including surgery, with careful patient evaluation and selection.

Purification of nuclear localization signal-containing proteins and its application to investigation of the mechanisms of the cell division cycle.

The GTP bound form of the Ran GTPase (RanGTP) in the nucleus promotes nuclear import of the proteins bearing nuclear localization signals (NLS). When nuclear envelopes break down during mitosis, RanGTP is locally produced around chromosomes and drives the assembly of the spindle early in mitosis and the nuclear envelope (NE) later. RanGTP binds to the heterodimeric nuclear transport receptor importin α/ß and releases NLS proteins from the receptor. Liberated NLS proteins around chromosomes have been shown to play distinct, essential roles in spindle and NE assembly. Here we provide a highly specific protocol to purify NLS proteins from crude cell lysates. The pure NLS fraction is an excellent resource to investigate the NLS protein function and identify new mitotic regulators, uncovering fundamental mechanisms of the cell division cycle. It takes 2-3 days to obtain the NLS fraction.

A case of primary effusion lymphoma diagnosed by open cardiocentesis.

Primary effusion lymphoma is a type of B-cell lymphoma that is primarily related to human immunodeficiency virus. Thoracic surgeons rarely encounter this disease because of its rarity. We herein report a case of primary effusion lymphoma which required surgery for successful treatment. An 83-year-old man was admitted to our hospital with signs of cardiac tamponade. A radiological examination revealed a pericardial effusion. Performing percutaneous pericardiocentesis was difficult due to the patient's anatomical features. We performed open cardiocentesis under general anesthesia. A cytologic examination revealed primary effusion lymphoma. The patient underwent chemotherapy, resulting in complete remission.

The nucleoporin MEL-28 promotes RanGTP-dependent γ-tubulin recruitment and microtubule nucleation in mitotic spindle formation.

The GTP-bound form of the Ran GTPase (RanGTP), produced around chromosomes, drives nuclear envelope and nuclear pore complex (NPC) re-assembly after mitosis. The nucleoporin MEL-28/ELYS binds chromatin in a RanGTP-regulated manner and acts to seed NPC assembly. Here we show that, upon mitotic NPC disassembly, MEL-28 dissociates from chromatin and re-localizes to spindle microtubules and kinetochores. MEL-28 directly binds microtubules in a RanGTP-regulated way via its C-terminal chromatin-binding domain. Using Xenopus egg extracts, we demonstrate that MEL-28 is essential for RanGTP-dependent microtubule nucleation and spindle assembly, independent of its function in NPC assembly. Specifically, MEL-28 interacts with the γ-tubulin ring complex and recruits it to microtubule nucleation sites. Our data identify MEL-28 as a RanGTP target that functions throughout the cell cycle. Its cell cycle-dependent binding to chromatin or microtubules discriminates MEL-28 functions in interphase and mitosis, and ensures that spindle assembly occurs only after NPC breakdown.

CHD4 is a RanGTP-dependent MAP that stabilizes microtubules and regulates bipolar spindle formation.

BACKGROUND: Production of the GTP-bound form of the Ran GTPase (RanGTP) around chromosomes induces spindle assembly by activating nuclear localization signal (NLS)-containing proteins. Several NLS proteins have been identified as spindle assembly factors, but the complexity of the process led us to search for additional proteins with distinct roles in spindle assembly. RESULTS: We identify a chromatin-remodeling ATPase, CHD4, as a RanGTP-dependent microtubule (MT)-associated protein (MAP). MT binding occurs via the region containing an NLS and chromatin-binding domains. In Xenopus egg extracts and cultured cells, CHD4 largely dissociates from mitotic chromosomes and partially localizes to the spindle. Immunodepletion of CHD4 from egg extracts significantly reduces the quantity of MTs produced around chromatin and prevents spindle assembly. CHD4 RNAi in both HeLa and Drosophila S2 cells induces defects in spindle assembly and chromosome alignment in early mitosis, leading to chromosome missegregation. Further analysis in egg extracts and in HeLa cells reveals that CHD4 is a RanGTP-dependent MT stabilizer. Moreover, the CHD4-containing NuRD complex promotes organization of MTs into bipolar spindles in egg extracts. Importantly, this function of CHD4 is independent of chromatin remodeling. CONCLUSIONS: Our results uncover a new role for CHD4 as a MAP required for MT stabilization and involved in generating spindle bipolarity.

The centriolar satellite protein SSX2IP promotes centrosome maturation.

Meiotic maturation in vertebrate oocytes is an excellent model system for microtubule reorganization during M-phase spindle assembly. Here, we surveyed changes in the pattern of microtubule-interacting proteins upon Xenopus laevis oocyte maturation by quantitative proteomics. We identified the synovial sarcoma X breakpoint protein (SSX2IP) as a novel spindle protein. Using X. laevis egg extracts, we show that SSX2IP accumulated at spindle poles in a Dynein-dependent manner and interacted with the γ-tubulin ring complex (γ-TuRC) and the centriolar satellite protein PCM-1. Immunodepletion of SSX2IP impeded γ-TuRC loading onto centrosomes. This led to reduced microtubule nucleation and spindle assembly failure. In rapidly dividing blastomeres of medaka (Oryzias latipes) and in somatic cells, SSX2IP knockdown caused fragmentation of pericentriolar material and chromosome segregation errors. We characterize SSX2IP as a novel centrosome maturation and maintenance factor that is expressed at the onset of vertebrate development. It preserves centrosome integrity and faithful mitosis during the rapid cleavage division of blastomeres and in somatic cells.

New mitotic regulators released from chromatin.

Faithful action of the mitotic spindle segregates duplicated chromosomes into daughter cells. Perturbations of this process result in chromosome mis-segregation, leading to chromosomal instability and cancer development. Chromosomes are not simply passengers segregated by spindle microtubules but rather play a major active role in spindle assembly. The GTP bound form of the Ran GTPase (RanGTP), produced around chromosomes, locally activates spindle assembly factors. Recent studies have uncovered that chromosomes organize mitosis beyond spindle formation. They distinctly regulate other mitotic events, such as spindle maintenance in anaphase, which is essential for chromosome segregation. Furthermore, the direct function of chromosomes is not only to produce RanGTP but, in addition, to release key mitotic regulators from chromatin. Chromatin-remodeling factors and nuclear pore complex proteins, which have established functions on chromatin in interphase, dissociate from mitotic chromatin and function in spindle assembly or maintenance. Thus, chromosomes actively organize their own segregation using chromatin-releasing mitotic regulators as well as RanGTP.

Surgical resection of a primary pulmonary epithelioid hemangioendothelioma in bilateral lungs.

Pulmonary epithelioid hemangioendothelioma (PEH) is a rare pulmonary neoplasm that was initially described in 1975 as an intravascular bronchioloalveolar tumor. This report presents the case of a patient with multifocal primary pulmonary PEH (11 tumors) in the bilateral lungs. All of the tumors detected in the preoperative computed tomography scan were surgically resected. The patient has been doing well for 9 years after surgery. No tumor recurred for 8 years after surgery until a single recurrent nodule appeared and was thoracoscopically resected.

ISWI is a RanGTP-dependent MAP required for chromosome segregation.

Production of RanGTP around chromosomes induces spindle assembly by activating nuclear localization signal (NLS)-containing factors. Here, we show that the NLS protein ISWI, a known chromatin-remodeling ATPase, is a RanGTP-dependent microtubule (MT)-associated protein. Recombinant ISWI induces MT nucleation, stabilization, and bundling in vitro. In Xenopus culture cells and egg extract, ISWI localizes within the nucleus in interphase and on spindles during mitosis. Depletion of ISWI in egg extracts does not affect spindle assembly, but in anaphase spindle MTs disappear and chromosomes do not segregate. We show directly that ISWI is required for the RanGTP-dependent stabilization of MTs during anaphase independently of its effect on chromosomes. ISWI depletion in Drosophila S2 cells induces defects in spindle MTs and chromosome segregation in anaphase, and the cells eventually stop growing. Our results demonstrate that distinctly from its role in spindle assembly, RanGTP maintains spindle MTs in anaphase through the local activation of ISWI and that this is essential for proper chromosome segregation.