The differences in code status conversation approaches reported by emergency medicine and palliative care clinicians: A mixed-method study.

BACKGROUND: During acute health deterioration, emergency medicine and palliative care clinicians routinely discuss code status (e.g., shared decision making about mechanical ventilation) with seriously ill patients. Little is known about their approaches. We sought to elucidate how code status conversations are conducted by emergency medicine and palliative care clinicians and why their approaches are different. METHODS: We conducted a sequential-explanatory, mixed-method study in three large academic medical centers in the Northeastern United States. Attending physicians and advanced practice providers working in emergency medicine and palliative care were eligible. Among the survey respondents, we purposefully sampled the participants for follow-up interviews. We collected clinicians' self-reported approaches in code status conversations and their rationales. A survey with a 5-point Likert scale ("very unlikely" to "very likely") was used to assess the likelihood of asking about medical procedures (procedure based) and patients' values (value based) during code status conversations, followed by semistructured interviews. RESULTS: Among 272 clinicians approached, 206 completed the survey (a 76% response rate). The reported approaches differed greatly (e.g., 91% of palliative care clinicians reported asking about a patient's acceptable quality of life compared to 59% of emergency medicine clinicians). Of the 206 respondents, 118 (57%) agreed to subsequent interviews; our final number of semistructured interviews included seven emergency medicine clinicians and nine palliative care clinicians. The palliative care clinicians stated that the value-based questions offer insight into patients' goals, which is necessary for formulating a recommendation. In contrast, emergency medicine clinicians stated that while value-based questions are useful, they are vague and necessitate extended discussions, which are inappropriate during emergencies. CONCLUSIONS: Emergency medicine and palliative care clinicians reported conducting code status conversations differently. The rationales may be shaped by their clinical practices and experiences.

Theilovirus 3C Protease Cleaves the C-Terminal Domain of the Innate Immune RNA Sensor, Melanoma Differentiation-Associated Gene 5, and Impairs Double-Stranded RNA-Mediated IFN Response.

Melanoma differentiation-associated gene 5 (MDA5), a member of the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), has pivotal roles in innate immune responses against many positive-stranded RNA viruses, including picornavirus and coronavirus. Upon engagement with dsRNA derived from viral infection, MDA5 initiates coordinated signal transduction leading to type I IFN induction to restrict viral replication. In this study, we describe a targeted cleavage events of MDA5 by the 3C protease from Theilovirus. Upon ectopic expression of theilovirus 3C protease from Saffold virus or Theiler's murine encephalomyelitis virus but not encephalomyocarditis virus, fragments of cleaved MDA5 were observed in a dose-dependent manner. When enzymatically inactive Theilovirus 3C protease was expressed, MDA5 cleavage was completely abrogated. Mass spectrometric analysis identified two cleavage sites at the C terminus of MDA5, cleaving off one of the RNA-binding domains. The same cleavage pattern was observed during Theilovirus infection. The cleavage of MDA5 by Theilovirus protease impaired ATP hydrolysis, RNA binding, and filament assembly on RNA, resulting in dysfunction of MDA5 as an innate immune RNA sensor for IFN induction. Furthermore, the cleavage-resistant MDA5 mutant against the 3C protease showed an enhanced IFN response during Saffold virus infection, indicating that Theilovirus has a strategy to circumvent the antiviral immune response by cleaving MDA5 using 3C protease. In summary, these data suggest MDA5 cleavage by 3C protease as a novel immune evasive strategy of Theilovirus.

Seasonality of mortality and in-hospital complications in hip fracture surgery: Retrospective cohort research using a nationwide inpatient database.

AIM: Among older patients undergoing hip fracture surgery, previous studies have shown a seasonal variation of in-hospital surgical complications. However, little is known about seasonal effects on mortality and systemic complications after hip fracture surgery. In the present study, we evaluated whether mortality and in-hospital systemic complications are influenced by seasonal differences. METHODS: We enrolled patients from a nationwide database who underwent hip fracture surgery between 2010 and 2018. The primary outcome was in-hospital mortality. The secondary outcomes were in-hospital systemic complications. The association between the seasonality and in-hospital outcomes was investigated using multivariable Cox, logistic regression and causal mediation analysis. RESULTS: With 425 856 patients (mean age 83.5 years; 79% women), overall in-hospital mortality was 5324 (1.2%). Fall and winter were associated with a higher mortality than spring (hazard ratio [HR] 1.16; P < 0.001; HR 1.14; P = 0.001, respectively). Across all the seasons, there were 36 834 overall systemic complications (8.6%), with respiratory infection being the most frequent (18 637 [4.4%]). Among these complications, only respiratory infection showed seasonal variation, with a higher prevalence in fall and winter. The mediated effect of respiratory infection on mortality was significantly higher in fall and winter compared with spring (fall, HR 1.06, proportion mediated 36.7%; winter, HR 1.14, proportion mediated 55.0%; all P < 0.001). CONCLUSIONS: We found a significantly higher mortality in fall and winter after hip fracture surgery. Specifically, in winter, the increased in-hospital death was largely attributed to the increased incidence of respiratory infection. Geriatr Gerontol Int 2021; 21: 398-403.

MAGI-1 expression is decreased in several types of human T-cell leukemia cell lines, including adult T-cell leukemia.

Membrane-associated guanylate kinase with inverted orientation protein 1 (MAGI-1) is a cytoplasmic scaffold protein that interacts with various signaling molecules; it negatively controls the cell growth of various types of cells and positively controls cell-cell interaction. In T cells, MAGI-1 has been shown to inhibit Akt activity through its interaction with PTEN and MEK1. In this study we found that MAGI-1 expression is decreased in multiple (9 out of 15) human T-cell leukemia cell lines, including adult T-cell leukemia (ATL), T-cell acute lymphoblastic leukemia and chronic T-cell lymphocytic leukemia. The overexpression of MAGI-1 protein in a MAGI-1-low ATL cell line reduced cellular growth. While the overexpression of MAGI-1 protein in a MAGI-1-low ATL cell line reduced the Akt and MEK activities, the knockdown of MAGI-1 in a MAGI-1-high ATL cell line augmented the Akt and MEK activities. Collectively, the findings of the present study suggest that the decreased expression of MAGI-1 in human T cells contributes to the development of several types of T-cell leukemia, partly through the stimulation of the Akt and MEK pathways.

Sox2-dependent inhibition of p21 is associated with poor prognosis of endometrial cancer.

Sex-determining region Y-box 2 (SOX2) is an essential factor involved in the self-renewal and pluripotency of embryonic stem cells and has functions in cell survival and progression in many types of cancers. Here, we found that several endometrial cancer cell lines expressed SOX2, which was required for cell growth. Additionally, SOX2 overexpression regulated the expression of cyclin-dependent kinase inhibitor 1A (CDKN1A), and SOX2 specifically bound to p21 promoter DNA in endometrial cancer cell lines expressing SOX2. Expressions of SOX2 in endometrial cancer patients were significantly correlated with histological grade and poor prognosis. Moreover, low p21 together with high SOX2 expressions in advanced endometrial cancer patients were associated with the most unfavorable outcomes of patients. These results indicated that simultaneous measurement of SOX2 and p21 expression in endometrial cancer patients may be a useful biomarker for patient prognosis.

USP10 Is an Essential Deubiquitinase for Hematopoiesis and Inhibits Apoptosis of Long-Term Hematopoietic Stem Cells.

Self-renewal, replication, and differentiation of hematopoietic stem cells (HSCs) are regulated by cytokines produced by niche cells in fetal liver and bone marrow. HSCs must overcome stresses induced by cytokine deprivation during normal development. In this study, we found that ubiquitin-specific peptidase 10 (USP10) is a crucial deubiquitinase for mouse hematopoiesis. All USP10 knockout (KO) mice died within 1 year because of bone marrow failure with pancytopenia. Bone marrow failure in these USP10-KO mice was associated with remarkable reductions of long-term HSCs (LT-HSCs) in bone marrow and fetal liver. Such USP10-KO fetal liver exhibited enhanced apoptosis of hematopoietic stem/progenitor cells (HSPCs) including LT-HSCs but not of lineage-committed progenitor cells. Transplantation of USP10-competent bone marrow cells into USP10-KO mice reconstituted multilineage hematopoiesis. These results suggest that USP10 is an essential deubiquitinase in hematopoiesis and functions by inhibiting apoptosis of HSPCs including LT-HSCs.

[Usefulness and Problems of Intraoperative Monitoring for Unruptured Aneurysm Surgery with the Motor Evoked Potential].

It has been pointed out that the motor evoked potential(MEP)with a subdural electrode is useful in the intraoperative monitoring for unruptured aneurysm surgery. However, in some cases, we experienced postoperative ischemic complications despite evaluating the motor function via MEP monitoring. Herein, we have reported the usefulness and problems of intraoperative monitoring with MEP to evaluate brain dysfunction caused by insufficiency of cerebral blood flow. Out of 279 aneurysm surgery procedures, we performed MEP monitoring in 142 cases and successfully recorded in 126 cases. We compared the ischemic complication rate of the group for which MEP was monitored with that of the group for which MEP was not monitored. The whole ischemic complication rate was decreased in the group that underwent MEP monitoring. Thus, it was suggested that MEP monitoring was useful for avoiding ischemic complications. In internal carotid artery aneurysms, the amplitude of MEP changed and recovered in 2 cases and disappeared in one case. In anterior cerebral artery aneurysms, the amplitude of MEP changed and recovered in 2 cases. In middle cerebral artery aneurysms, the amplitude of MEP changed and recovered in 5 cases. We could avoid ischemic complications by intraoperative MEP monitoring in many cases. However, in some cases, we found ischemic complications that were not detected by MEP monitoring with a subdural electrode. In these cases, transcranial stimulation in combination with subdural electrode might be effective in avoiding ischemic complications that might occur after dural closure.

Induction of Cell Death in Growing Human T-Cells and Cell Survival in Resting Cells in Response to the Human T-Cell Leukemia Virus Type 1 Tax.

Tax1 encoded by the human T-cell leukemia virus type 1 (HTLV-1) has been believed to dysregulate the expression of cellular genes involved in cell survival and mortality, leading to the development of adult T-cell leukemia (ATL). The function of Tax1 in ATL development however is still controversial, primarily because Tax1 induces cell cycle progression and apoptosis. To systemically understand cell growth phase-dependent induction of cell survival or cell death by Tax1, we established a single experimental system using an interleukin 2 (IL-2)-dependent human T-cell line Kit 225 that can be forced into resting phase by IL-2 deprivation. Introduction of Tax1 and HTLV-2 Tax (Tax2B) decreased mitochondrial activity alongside apoptosis in growing cells but not in resting cells. Cell cycle profile analysis indicated that Tax1 and Tax2B were likely to perturb the S phase in growing cells. Studies with Tax1 mutants and siRNA for NF-κB/RelA revealed that Tax1-mediated cell growth inhibition and apoptosis in growing Kit 225 cells depend on RelA. Interestingly, inactivation of the non-canonical NF-κB and p38 MAPK pathways relieved Tax1-mediated apoptosis, suggesting that the Tax1-NF-κB-p38 MAPK axis may be associated with apoptosis in growing cells. Inflammatory mediators such as CCL3 and CCL4, which are involved in oncogene-induced senescence (OIS), were induced by Tax1 and Tax2B in growing cells. In contrast, RelA silencing in resting cells reduced mitochondrial activity, indicating that NF-κB/RelA is also critical for Tax1-mediated cell survival. These findings suggest that Tax1-mediated cell survival and death depend on the cell growth phase. Both effects of Tax1 may be implicated in the long latency of HTLV-1 infection.

Human T-cell leukemia virus type 1 (HTLV-1) Tax1 oncoprotein but not HTLV-2 Tax2 induces the expression of OX40 ligand by interacting with p52/p100 and RelB.

Human T-cell leukemia virus type 1 (HTLV-1) is a causative retrovirus of adult T-cell leukemia and HTLV-1-associated myelopathy. Unlike HTLV-1, the same group of retrovirus HTLV-2 has not been found to be associated with these diseases. HTLV-1 and HTLV-2 encode transforming proteins Tax1 and Tax2, and a few distinct activities of Tax1 from those of Tax2 have been proposed to contribute to the HTLV-1-specific pathogenesis of disease. One significant difference of Tax1 from Tax2 is the activation of transcription factor NF-κB2/p100/p52. We found that Tax1 but not Tax2 induces the expression of OX40 ligand (OX40L) in a human T-cell line. To induce the OX40L expression, Tax1 but not Tax2 was observed to interact with NF-κB2/p100/p52 and RelB and the distinct interaction activity was mediated by the Tax1 amino acid region of 225-232. In addition, Tax1 but not Tax2 or Tax1/225-232 interacted with p65, p50, and c-Rel; however, the interactions were much less than those noted with NF-κB2/p100/p52 and RelB. OX40L is a T-cell costimulatory molecule of the tumor necrosis factor family, and its signal plays a critical role in establishing adaptive immunity by inducing the polarized differentiation of T-cells to cells such as T helper type 2 and T follicular helper cells. Therefore, the present findings suggest that Tax1 might alter the immune response to HTLV-1 and/or differentiation of HTLV-1-infected T-cells via OX40L induction, thereby acting as a factor mediating the distinct phenotypes and pathogenesis of HTLV-1 from that of HTLV-2.

RASAL3, a novel hematopoietic RasGAP protein, regulates the number and functions of NKT cells.

Ras GTPase-activating proteins negatively regulate the Ras/Erk signaling pathway, thereby playing crucial roles in the proliferation, function, and development of various types of cells. In this study, we identified a novel Ras GTPase-activating proteins protein, RASAL3, which is predominantly expressed in cells of hematopoietic lineages, including NKT, B, and T cells. We established systemic RASAL3-deficient mice, and the mice exhibited a severe decrease in NKT cells in the liver at 8 weeks of age. The treatment of RASAL3-deficient mice with α-GalCer, a specific agonist for NKT cells, induced liver damage, but the level was less severe than that in RASAL3-competent mice, and the attenuated liver damage was accompanied by a reduced production of interleukin-4 and interferon-γ from NKT cells. RASAL3-deficient NKT cells treated with α-GalCer in vitro presented augmented Erk phosphorylation, suggesting that there is dysregulated Ras signaling in the NKT cells of RASAL3-deficient mice. Taken together, these results suggest that RASAL3 plays an important role in the expansion and functions of NKT cells in the liver by negatively regulating Ras/Erk signaling, and might be a therapeutic target for NKT-associated diseases.

Human T-cell leukemia virus type 1 Tax oncoprotein represses the expression of the BCL11B tumor suppressor in T-cells.

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T cell leukemia (ATL), which is an aggressive form of T-cell malignancy. HTLV-1 oncoproteins, Tax and HBZ, play crucial roles in the immortalization of T-cells and/or leukemogenesis by dysregulating the cellular functions in the host. Recent studies show that HTLV-1-infected T-cells have reduced expression of the BCL11B tumor suppressor protein. In the present study, we explored whether Tax and/or HBZ play a role in downregulating BCL11B in HTLV-1-infected T-cells. Lentiviral transduction of Tax in a human T-cell line repressed the expression of BCL11B at both the protein and mRNA levels, whereas the transduction of HBZ had little effect on the expression. Tax mutants with a decreased activity for the NF-κB, CREB or PDZ protein pathways still showed a reduced expression of the BCL11B protein, thereby implicating a different function of Tax in BCL11B downregulation. In addition, the HTLV-2 Tax2 protein reduced the BCL11B protein expression in T-cells. Seven HTLV-1-infected T-cell lines, including three ATL-derived cell lines, showed reduced BCL11B mRNA and protein expression relative to an uninfected T-cell line, and the greatest reductions were in the cells expressing Tax. Collectively, these results indicate that Tax is responsible for suppressing BCL11B protein expression in HTLV-1-infected T-cells; Tax-mediated repression of BCL11B is another mechanism that Tax uses to promote oncogenesis of HTLV-1-infected T-cells.

Downregulation of proapoptotic Bim augments IL-2-independent T-cell transformation by human T-cell leukemia virus type-1 Tax.

Human T-cell leukemia virus type 1 (HTLV-1), an etiological agent of adult T-cell leukemia, immortalizes and transforms primary human T cells in vitro in both an interleukin (IL)-2-dependent and IL-2-independent manner. Expression of the HTLV-1 oncoprotein Tax transforms the growth of the mouse T-cell line CTLL-2 from being IL-2-dependent to IL-2-independent. Withdrawal of IL-2 from normal activated T cells induces apoptosis, which is mediated through the inducible expression of several proapoptotic proteins, including Bim. In this study, we found that Tax protects IL-2-depleted T cells against Bim-induced apoptosis. Withdrawal of IL-2 from CTLL-2 cells induced a prominent increase in the level of Bim protein in CTLL-2 cells, but not in Tax-transformed CTLL-2 cells. This inhibition of Bim in Tax-transformed CTLL-2 cells was mediated by two mechanisms: downregulation of Bim mRNA and posttranscriptional reduction of Bim protein. Transient expression of Tax in CTLL-2 cells also inhibited IL-2 depletion-induced expression of Bim, however, this decrease in Bim protein expression was not due to downregulation of Bim mRNA, thus indicating that Bim mRNA downregulation in Tax-transformed CTLL-2 occurs only after long-term expression of Tax. Transient expression of Tax in CTLL-2 cells also induced Erk activation, however, this was not involved in the reduction of Bim protein. Knockdown of Bim expression in CTLL-2 cells augmented Tax-induced IL-2-independent transformation. HTLV-1 infection of human T cells also reduced their levels of Bim protein, and restoring Bim expression in HTLV-1-infected cells reduced their proliferation by inducing apoptosis. Taken together, these results indicate that Tax-induced downregulation of Bim in HTLV-1-infected T cells promotes their IL-2-independent growth, thereby supporting the persistence of HTLV-1 infection in vivo.

HTLV-1 Tax oncoprotein stimulates ROS production and apoptosis in T cells by interacting with USP10.

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL), and the viral oncoprotein Tax plays key roles in the immortalization of human T cells, lifelong persistent infection, and leukemogenesis. We herein identify the ubiquitin-specific protease 10 (USP10) as a Tax-interactor in HTLV-1-infected T cells. USP10 is an antistress factor against various environmental stresses, including viral infections and oxidative stress. On exposure to arsenic, an oxidative stress inducer, USP10 is recruited into stress granules (SGs), and USP10-containing SGs reduce reactive oxygen species (ROS) production and inhibit ROS-dependent apoptosis. We found that interaction of Tax with USP10 inhibits arsenic-induced SG formation, stimulates ROS production, and augments ROS-dependent apoptosis in HTLV-1-infected T cells. These findings suggest that USP10 is a host factor that inhibits stress-induced ROS production and apoptosis in HTLV-1-infected T cells; however, its activities are attenuated by Tax. A clinical study showed that combination therapy containing arsenic is effective against some forms of ATL. Therefore, these findings may be relevant to chemotherapy against ATL.

Failure in activation of the canonical NF-κB pathway by human T-cell leukemia virus type 1 Tax in non-hematopoietic cell lines.

Human T-cell leukemia virus type 1 (HTLV-1) Tax (Tax1) plays crucial roles in leukemogenesis in part through activation of NF-κB. In this study, we demonstrated that Tax1 activated an NF-κB binding (gpκB) site of the gp34/OX40 ligand gene in a cell type-dependent manner. Our examination showed that the gpκΒ site and authentic NF-κB (IgκB) site were activated by Tax1 in hematopoietic cell lines. Non-hematopoietic cell lines including hepatoma and fibroblast cell lines were not permissive to Tax1-mediated activation of the gpκB site, while the IgκB site was activated in those cells in association with binding of RelB. However RelA binding was not observed in the gpκB and IgκB sites. Our results suggest that HTLV-1 Tax1 fails to activate the canonical pathway of NF-κB in non-hematopoietic cell lines. Cell type-dependent activation of NF-κB by Tax1 could be associated with pathogenesis by HTLV-1 infection.

Human T-cell leukemia virus type 1 Tax protein interacts with and mislocalizes the PDZ domain protein MAGI-1.

Human T-cell leukemia virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL). HTLV-1 encodes the oncoprotein Tax1, which is essential for immortalization of human T-cells and persistent HTLV-1 infection in vivo. Tax1 has a PDZ binding motif (PBM) at its C-terminus. This motif is crucial for the transforming activity of Tax1 to a T-cell line and persistent HTLV-1 infection. Tax1 through the PBM interacts with PDZ domain proteins such as Dlg1 and Scribble, but it has not been determined yet, which cellular PDZ proteins mediate the functions of Tax1 PBM. Here we demonstrate that Tax1 interacts with the PDZ domain protein MAGI-1 in a PBM-dependent manner, and the interaction mislocalizes MAGI-1 from the detergent-soluble to the detergent-insoluble cellular fraction in 293T cells and in HTLV-1-infected T-cells. In addition, Tax1-transformation of a T-cell line from interleukin (IL)-2-dependent to IL-2-independent growth selects cells with irreversibly reduced expression of MAGI-1 at mRNA level. These findings imply that Tax1, like other viral oncoproteins, targets MAGI-1 as a mechanism to suppress its anti-tumor functions in HTLV-1-infected cells to contribute to the transforming activity of T-cells and persistent HTLV-1 infection.

Human T cell leukemia virus type 2 (HTLV-2) Tax2 has a dominant activity over HTLV-1 Tax1 to immortalize human CD4+ T cells.

While human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T cell leukemia, a close relative, HTLV-2, is not associated with any leukemia. HTLV-1 and HTLV-2 encode the Tax1 and Tax2 proteins, respectively, which are essential for the immortalization of human T cells by the respective viruses, thereby causing persistent infection. In this study, we compared Tax1 and Tax2 with respect to their immortalization activity in human T cells. Lentivirus-mediated transduction of the tax2 gene into human peripheral blood mononuclear cells stimulated with phytohemagglutinin and interleukin-2 in 96-well plates induced outgrowing T cells in most wells, but the cells infected with the control viruses died within 3 weeks. Surprisingly, the number of outgrowing cells induced by Tax2 was much higher than that induced by Tax1, and the appearance of outgrowing cells by Tax2 was earlier than that induced by Tax1. Nevertheless, both Tax2 and Tax1 preferentially immortalized CD4(+) T cells, but not CD8(+) T cells. Our study showed that HTLV-2 Tax2 can immortalize human CD4(+) T cells, and the activity is much higher than that of Tax1. The distinct T cell immortalization activities of Tax2 and Tax1 might therefore play a role in the different pathogeneses observed for these two viruses.

Stress granules inhibit apoptosis by reducing reactive oxygen species production.

Cells can undergo two alternative fates following exposure to environmental stress: they either induce apoptosis or inhibit apoptosis and then repair the stress-induced alterations. These processes minimize cell loss and prevent the survival of cells with aberrant DNA and protein alterations. These two alternative fates are partly controlled by stress granules (SGs). While arsenite, hypoxia, and heat shock induce the formation of SGs that inhibit apoptosis, X-ray irradiation and genotoxic drugs do not induce SGs, and they are more prone to trigger apoptosis. However, it is unclear precisely how SGs control apoptosis. This study found that SGs suppress the elevation of reactive oxygen species (ROS), and this suppression is essential for inhibiting ROS-dependent apoptosis. This antioxidant activity of SGs is controlled by two SG components, GTPase-activating protein SH3 domain binding protein 1 (G3BP1) and ubiquitin-specific protease 10 (USP10). G3BP1 elevates the steady-state ROS level by inhibiting the antioxidant activity of USP10. However, following exposure to arsenite, G3BP1 and USP10 induce the formation of SGs, which uncovers the antioxidant activity of USP10. We also found that the antioxidant activity of USP10 requires the protein kinase activity of ataxia telangiectasia mutated (ATM). This work reveals that SGs are critical redox regulators that control cell fate under stress conditions.

Activation of mTOR by human T-cell leukemia virus type 1 Tax is important for the transformation of mouse T cells to interleukin-2-independent growth.

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia, and it immortalizes and transforms human T cells in both an interleukin (IL)-2-dependent and -independent manner. HTLV-1 encodes Tax, which plays crucial roles in HTLV-1-mediated immortalization and transformation of human T cells. A previous study showed that Tax can transform a mouse T-cell line, CTLL-2, from having IL-2-dependent growth to IL-2-independent growth. Given that the Akt/mTOR pathway is essential for IL-2-induced cell growth in T cells, we examined whether the Akt/mTOR pathway is involved in Tax-induced transformation to IL-2-independent growth. The stable and transient expression of Tax in CTLL-2 induced the phosphorylation of p70S6 kinase and ribosomal protein S6, downstream targets of the mTOR kinase, whereas that of Akt was only minimally induced. Studies with Tax mutants indicated that the activation of mTOR by Tax was correlated with the transformation of CTLL-2 cells to IL-2-independent growth. Rapamycin, an inhibitor of mTOR kinase, reduced the growth of Tax-transformed CTLL-2 cells. Moreover, the transduction of a constitutively active form of Akt in the CTLL-2 cells also induced IL-2-independent growth. Like CTLL-2/Tax, constitutive phosphorylation of p70S6 kinase was detected in the absence of IL-2 in all of the HTLV-1-infected human T-cell lines. These results suggest that Tax activates the mTOR pathway in T cells, and that this activation plays a crucial role in the growth of HTLV-1-infected T cells when a limited amount of IL-2 is available.

Effects of vitamin E on the osteoblast differentiation.

Vitamin E is thought to affect bone formation and bone remodeling. In this study, we investigated the effects of vitamin E (alpha-tocopherol and delta-tocopherol) on the osteoblasts isolated from rat calvariae. At 4 and 7 days (Day 4 and 7) after induction of osteoblastic differentiation, treatment of alpha-tocopherol (100 and 200 microM) and delta-tocopherol (2 and 20 microM) for 3 days significantly decreased alkaline phophatase activity of the cultured osteoblasts. At Day 14, however, no significant change was detected in ALP activity and expression of bone sialoprotein mRNA in the osteoblasts treated with alpha-tocopherol or delta-tocopherol for 3 days. Expression of osteocalcin mRNA was decreased by treatment of alpha-tocopherol (100 and 200 microM) and delta-tocopherol (2 and 20 microM) at Day 4 and 7. At Day 14, expression of osteocalcin mRNA was decreased only with treatment of 200 microM alpha-tocopherol. In addition, the noncalcified nodules were decreased by treatment of alpha-tocopherol (200 microM) and delta-tocopherol (20 microM) at Day 7. However, treatment of alpha-tocopherol and delta-tocopherol showed no significant change of formation of calcified nodules at Day 14. These results indicate that vitamin E inhibits differentiation of osteoblasts especially from early stage to osteoid-producing stage.

The PDZ domain binding motif (PBM) of human T-cell leukemia virus type 1 Tax can be substituted by heterologous PBMs from viral oncoproteins during T-cell transformation.

Several tumor viruses, such as human T-cell leukemia virus (HTLV), human papilloma virus (HPV), human adenovirus, have high-oncogenic and low-oncogenic subtypes, and such subtype-specific oncogenesis is associated with the PDZ-domain binding motif (PBM) in their transforming proteins. HTLV-1, the causative agent of adult T-cell leukemia, encodes Tax1 with PBM as a transforming protein. The Tax1 PBM was substituted with those from other oncoviruses, and the transforming activity was examined. Tax1 mutants with PBM from either HPV-16 E6 or adenovirus type 9 E4ORF1 are fully active in the transformation of a mouse T-cell line from interleukin-2-dependent growth into independent growth. Interestingly, one such Tax1 PBM mutant had an extra amino acid insertion derived from E6 between PBM and the rest of Tax1, thus suggesting that the amino acid sequences of the peptides between PBM and the rest of Tax1 and the numbers only slightly affect the function of PBM in the transformation. Tax1 and Tax1 PBM mutants interacted with tumor suppressors Dlg1 and Scribble with PDZ-domains. Unlike E6, Tax1 PBM mutants as well as Tax1 did not or minimally induced the degradations of Dlg1 and Scribble, but instead induced their subcellular translocation from the detergent-soluble fraction into the insoluble fraction, thus suggesting that the inactivation mechanism of these tumor suppressor proteins is distinct. The present results suggest that PBMs of high-risk oncoviruses have a common function(s) required for these three tumor viruses to transform cells, which is likely associated with the subtype-specific oncogenesis of these tumor viruses.