Dysfunctional ErbB2, an EGF receptor family member, hinders repair of airway epithelial cells from asthmatic patients.

BACKGROUND: Genetic and genomic data increasingly point to the airway epithelium as critical to asthma pathogenesis. Epithelial growth factor (EGF) family members play a fundamental role in epithelial differentiation, proliferation, and repair. Although expression of erythroblastosis oncogene B2 (ErbB2) mRNA, an EGF family receptor, was reported to be lower in asthmatic patients, little is understood about its functional role. OBJECTIVE: We sought to determine whether decreased ErbB2 activation in freshly isolated human airway epithelial cells (HAECs) from asthmatic patients associated with impaired wound closure in vitro. METHODS: An in vitro scratch-wound model of air-liquid interface cultured and freshly isolated HAECs were compared between HAECs from healthy control subjects (HCs) and asthmatic patients in relation to ErbB2. RESULTS: Freshly brushed HAECs from asthmatic patients had impaired ErbB2 activation compared with those from HCs. In an in vitro scratch-wound model, HAECs from asthmatic patients showed delayed wound closure compared with HAECs from HCs. Cell proliferation, as assessed based on [3H] thymidine incorporation after wounding, and expression or activation of ErbB2 and cyclin D1 at the leading edge of the wound were lower in HAECs from asthmatic patients and HCs. A selective ErbB2 tyrosine kinase inhibitor, mubritinib, impaired wound closure and decreased cyclin D1 expression in healthy HAECs, with less effect on cells from asthmatic patients, supporting diminished activity in asthmatic patients. CONCLUSION: These results implicate a primary defect in the ErbB2 pathway as constraining epithelial repair processes in asthmatic patients. Restoration of homeostatic ErbB2 function should be considered a novel asthma therapeutic target.

[Prevalence of adult asthma and allergic rhinitis in Kamishihoro, Hokkaido -trends from 2006 through 2011-].

PURPOSE: To investigate changes in the prevalence of adult asthma and allergic rhinitis from 2006 to 2011 in Kamishihoro, a town in Hokkaido, Japan. METHODS: The Japanese edition of the European Community Respiratory Health Survey questionnaire was completed by 1472 residents aged from 20 to 81 years old. (718 men, 749 women). The age and gender distribution of respondents matched that of respondents in 2006. RESULTS: Response rates were 98.1% in 2011 and 95.8% in 2006. Wheezing in the last 12 months was reported by 10.7% of men and 8.3% of women in 2011, compared to 12.9% and 9.8%, respectively, in 2006. The questions "Have you ever had asthma?" followed by "Was this confirmed by a doctor?" both received positive answers from 7.9% of men and 7.5% of women in 2011, compared to 5.7% and 6.3%, respectively, in 2006. The rate of current smoking was 34.8% in men and 14.7% in women in 2011, compared to 42.8% and 17.2%, respectively, in 2006. A "Yes" answer to the questionnaire item, "Do you have any nasal allergies, including hay fever?" (defining allergic rhinitis) was given by 23.2% of men and 25.4% of women in 2011, compared to 17.6% and 23.0%, respectively, in 2006. The prevalence of allergic rhinitis was increased, particularly among younger respondents. CONCLUSION: Rates of current asthma and allergic rhinitis increased, whereas the rate of wheezing in the past 12 months decreased from 2006 to 2011. Optimal treatment of asthma might be related to these trends.

Association of the CAT-262C>T polymorphism with asthma in smokers and the nonemphysematous phenotype of chronic obstructive pulmonary disease.

BACKGROUND: Catalase (CAT) is a part of the active antioxidant defense system and has been studied with regard to its association with asthma and chronic obstructive pulmonary disease (COPD), which are heterogeneous obstructive pulmonary diseases characterized by chronic airway inflammation. We hypothesized that the CAT gene might be involved in the common pathogenesis underlying asthma and COPD. OBJECTIVE: To evaluate the association of CAT polymorphisms with specific phenotypes of asthma and COPD to identify the common underlying pathophysiologic mechanisms of these 2 diseases. METHODS: The -262C>T and -21A>T polymorphisms in the CAT gene were genotyped in 493 individuals with asthma, 265 with COPD, and 1,076 healthy controls. Asthmatic patients were categorized according to smoking status (smokers and nonsmokers) and age at onset (early onset and adult onset) as part of a case-control study. In patients with COPD, visual scoring (computed tomographic score) was assessed to determine emphysema severity, which was used to evaluate associations with CAT gene polymorphisms. RESULTS: Overall, the -262C>T and -21A>T polymorphisms were not associated with asthma. However, the -262CT+TT genotype was significantly associated with adult-onset asthma in smokers (P = .005), and a significant interaction between smoking status and the effect of -262C>T genotype on asthma were observed (P = .01). In patients with COPD, this genotype was significantly associated with a low computed tomographic score (P = .03), which indicates a nonemphysematous type of COPD. CONCLUSION: The present study indicates that the CAT gene is involved in the common pathogenesis underlying adult-onset asthma in smokers and the nonemphysematous type of COPD.

Increased prevalence of cigarette smoking in Japanese patients with sarcoidosis.

BACKGROUND AND OBJECTIVE: Several studies have shown that individuals with sarcoidosis in Western populations are less likely to have smoked before diagnosis. Epidemiological characteristics of sarcoidosis are known to differ between Japanese and Westerners. Therefore, the relationship between cigarette smoking and sarcoidosis in a Japanese population was investigated. METHODS: Three hundred eighty-eight patients newly diagnosed with sarcoidosis between 2000 and 2008 were retrospectively identified. The results of two large surveys of smoking prevalence in Japan provided reference data. Specific clinical manifestations of sarcoidosis were compared between current smokers and never-smokers, after excluding former smokers. RESULTS: The prevalence of current smokers at the time of the diagnosis of sarcoidosis was 59.6% in men and 27.9% in women. With the exception of men in their 30s, the prevalence was higher in all age groups compared with the general Japanese population. The prevalence of lung parenchymal involvement tended to be higher in current smokers than in never-smokers (odds ratio = 1.33 (0.99-1.77), P = 0.054). CONCLUSIONS: This retrospective cohort study suggests that smoking prevalence is higher in Japanese sarcoidosis patients than that reported in Western sarcoidosis patients and that there could be different relationships between smoking and the development of sarcoidosis in these populations.

Phase II trial of combined regional hyperthermia and gemcitabine for locally advanced or metastatic pancreatic cancer.

PURPOSE: Despite advances in cancer therapy, treating pancreatic cancer remains one of the major challenges in the field of medical oncology. We conducted this phase II study to evaluate the efficacy and safety of regional hyperthermia combined with gemcitabine for the treatment of unresectable advanced pancreatic cancer. METHODS: Eligibility criteria included histologically proven, locally advanced or metastatic pancreatic cancer. Gemcitabine was administered intravenously at a dose of 1000 mg/m(2) on days 1, 8, and 15 every 4 weeks. Regional hyperthermia was performed once weekly, 1 day preceding or following gemcitabine administration. The primary end point was the 1-year survival rate. Secondary objectives were determination of tumour response and safety. RESULTS: We enrolled 18 patients with advanced pancreatic cancer between November 2008 and May 2010. The major grade 3-4 adverse events were neutropenia and anaemia; however, there were no episodes of infection. The objective response rate (ORR) and disease control rate (ORR + stable disease) were 11.1% and 61.1%, respectively. Median overall survival (OS) was 8 months, and the 1-year survival rate was 33.3%. Median OS of patients with locally advanced pancreatic cancer was 17.7 months. CONCLUSIONS: Regional hyperthermia combined with gemcitabine is well tolerated and active in patients with locally advanced pancreatic cancer.

Gene expression profiles of diabetic mice treated with whole body hyperthermia: A high-density DNA microarray analysis.

Previously we have demonstrated that whole body hyperthermia (WBH) improves insulin resistance in diabetic mice. The aim of the present study was to perform a gene expression analysis of the liver and adipose tissue of obesity-induced insulin resistant diabetic mice (db/db mice) after WBH and to define the molecules that play the important role in improvement of insulin resistance by WBH. Male db/db mice were treated with WBH 3 times per week for 12 weeks. Total RNA was extracted from the liver and adipose tissue of db/db mice, and differences in the gene expression profiles among db/+ mice, untreated db/db mice, and WBH-treated db/db mice were investigated using a high-density DNA microarray. WBH directly targets liver and adipose tissue, resulting in modifications in NF-kappaB and IL-6 signalling pathways, as well as lipid metabolism. Although the mechanisms have not yet been completely investigated, we can conclude that WBH may provide a new therapeutic or preventive modality against type 2 diabetes mellitus and metabolic or insulin resistance syndrome through the modification of several signalling pathways.

Levels of transferrin in bronchoalveolar lavage fluid in sarcoidosis.

There has been only one report showing high levels of transferrin (Tf) in bronchoalveolar lavage fluid (BALF) in patients with sarcoidosis. This study was designed to assess the levels of Tf in both BALF and serum and to examine the relationship between the levels of Tf and other disease markers in sarcoidosis. Subjects were 64 sarcoidosis and 10 healthy controls. Tf in BALF and serum was measured by nephelometric assay. Median Tf levels in BALF from sarcoidosis was 0.70 (range, 0.00-3.97) mg/dl, which was significantly higher compared with controls (0.36 (range, 0.00-1.02) mg/dl; p = 0.005). In contrast, median Tf levels in serum from sarcoidosis was 258 (range, 171- 383) mg/dl, which was significantly lower compared with controls (322 (range, 234-356) mg/dl; p = 0.003). Tf levels in BALF were significantly correlated with both the percentage of lymphocytes (r = 0.617, p = 0.001) and serum angiotensin-converting enzyme activity (r = 0.363, p = 0.003) and serum soluble interleukin-2 receptor (r = 0.450, p = 0.001) in sarcoidosis. Levels of Tf in BALF from patients with sarcoidosis were not influenced by smoking status. The levels of Tf in sarcoidosis are high in BALF, but low in serum. Increased levels of Tf in BALF may reflect the disease activity.

[A case of rectal GIST treated with imatinib mesylate neoadjuvant therapy to preserve the anus].

A 64-year-old man was admitted to our hospital with anal pain on evacuation. MRI revealed a large rectal submucosal tumor, more than 6 cm in diameter. Fine needle histological diagnosis indicated GIST with moderate risk. The patient was treated with imatinib mesylate in order to preserve the anus. The anal pain and tumor size decreased. Trans-anal local excision was performed. This case suggests that imatinib mesylate can make it possible to treat large rectal GIST cases by preserving anus, if neoadjuvant chemotherapy can be effective.

Genetic variants in the mannose receptor gene (MRC1) are associated with asthma in two independent populations.

Mannose receptor is a member of the C-type lectin receptor family involved in pathogen molecular pattern recognition and thought to be critical in shaping host immune responses and maintaining homeostasis. The aim of this study was to investigate potential associations of genetic variants in the MRC1 gene with asthma in two independent populations. Seven single-nucleotide polymorphisms (SNPs; rs2477637, rs2253120, rs2477631, rs2477664, rs692527, rs1926736, and rs691005) in the MRC1 gene locus were genotyped and evaluated regarding association with asthma in 870 unrelated Japanese subjects (446 asthmatics, 424 controls). The same markers were validated in 176 unrelated African-American subjects (86 asthmatics, 90 controls). Suggestive evidence of association between five SNPs (rs2477637, rs2253120, rs2477664, rs692527, and rs1926736) and asthma was observed in the analysis of the Japanese population independent of sex, age, smoking status, and atopic status. SNPs rs692527 and rs691005 showed significant association with asthma in the African-American population. Haplotypes containing two linked SNPs (rs692527 and rs1926736) were significantly associated with asthma in both Japanese and African-American populations. Our results suggest that sequence variations in the MRC1 gene are associated with the development of asthma in two independent and ethnically diverse populations.

[Usefulness of fluorodeoxyglucose-positron emission tomography in a case of pleural sarcoidosis].

BACKGROUND: Pleural sarcoidosis is not a rare disease, and some patients with sarcoidosis experience chest pain, although the cause is often unknown. Various studies have indicated that fluorodeoxyglucose-positron emission tomography (FDG-PET) is useful for diagnosing and monitoring sarcoidosis. CASE: A 62-year-old man noted left-side dominant chest and back pain, although chest computed tomography (CT) revealed no abnormalities. Two months later, chest and back pain rapidly increased in severity and blurred vision appeared. In addition to uveitis, renal dysfunction was observed and chest CT on admission revealed enlargement of bilateral hilar/mediastinal lymph nodes and diffuse small nodular opacities and subpleural nodules, mainly in the segment of the left upper lobe (S1+2). FDG-PET revealed intense FDG uptake in bilateral peripheral lung parenchyma, spread widely along the subpleura and right inguinal lymph nodes with high uptake in the hilar and mediastinal lymph nodes. Sarcoidosis was diagnosed by transbronchial lung biopsy and renal biopsy. Oral corticosteroid treatment was performed due to persistent chest and back pain and rapid progression of renal dysfunction. Chest and back pain immediately disappeared and renal function improved. Follow-up FDG-PET performed 2 months after corticosteroid treatment revealed no areas of intense FDG uptake.

Antitumor effect of pretreatment for colon cancer cells with hyperthermia plus geranylgeranylacetone in experimental metastasis models and a subcutaneous tumor model of colon cancer in mice.

PURPOSE: We examined whether hyperthermia attenuated the metastatic potential of colon cancer through the induction of heat shock protein 70 (Hsp70). MATERIALS AND METHODS: Colon26 cells were separated into four groups: (1) no pretreatment, (2) hyperthermia at 42 degrees C for 1 hour, (3) pretreatment with geranylgeranylacetone (GGA) 10(-6) M for 2 hours, and (4) hyperthermia after GGA treatment. We measured cell viabilities and the contents of Hsp70. We assessed nuclear factor-kappa-B (NF-kappa-B) status with and without tumor necrosis factor-alpha (TNF-alpha) stimulation. For in vivo study, colon26 cells were injected via the tail vein or into a subcutaneous area of mice and the numbers of lung metastatic nodules or the volumes of subcutaneous tumors were assessed. Untreated cells were incubated with PKH26. Experimental metastasis models were then generated and used to assess the fixed cancer cells. RESULTS: Tumor development in the subcutaneous tumor models and cell viabilities were similar among the four groups. However, the GGA plus hyperthermia group had fewer lung metastatic nodules in the experimental lung metastasis model and higher Hsp70 induction than the other cell groups. The GGA plus hyperthermia pretreatment group also showed a lower number of fixed cells in lungs and lower activation of NF-kappa-B by TNF-alpha than the other cell groups. CONCLUSIONS: It is suggested the metastatic potential but not the proliferation potency of cancer cells is inhibited by the transient induction of Hsp70.

Genetic impact of a butyrophilin-like 2 (BTNL2) gene variation on specific IgE responsiveness to Dermatophagoides farinae (Der f) in Japanese.

BACKGROUND: Dermatophagoides farinae (Der f) is one of the most frequently implicated allergens in several allergic diseases. Several genome-wide screens have identified a linkage between chromosome 6p21 and mite-specific IgE responsiveness. Butyrophilin-like 2 (BTNL2) is a member of the immunoglobulin superfamily and, on the basis of its homology to B7-1, has been implicated as a costimulatory molecule involved in T-cell activation. BTNL2 resides in the HLA region on chromosome 6p21, and significant associations between BTNL2 gene polymorphisms and several inflammatory diseases have been reported. OBJECTIVE: The aim of this study was to examine whether BTNL2 gene polymorphisms are associated with specific IgE responses to Der f. METHODS: Three single nucleotide polymorphisms (SNPs), including 2 coding SNPs and 1 intron SNP, were studied. One of the coding SNPs was the rs2076530 A > G, which has a functional consequence. A total of 863 unrelated Japanese subjects (447 positive and 416 negative for IgE to Der f) were recruited for a case-control study. RESULTS: Controlling for gender, age, smoking, and the presence of asthma, multiple logistic regression analyses showed that homozygosity of the rs2076530 A allele, which has been reported to be a risk allele for sarcoidosis, was associated with a risk of sensitization towards Der f (Odds ratio; 1.55, p = 0.0060). CONCLUSIONS: Although an association which may be due to the linkage disequilibrium with other genes in 6p21 needs to be ruled out, the present findings suggest that the BTNL2 gene might be one of the candidate genes that is responsible for the pathogenesis of Der f-specific IgE responsiveness.

[Prevalence of adult asthma and allergic rhinitis in Kamishihoro town, Hokkaido--association with smoking habit and obesity].

PURPOSE: To investigate the prevalence of adult asthma and allergic rhinitis, and to analyze associations between smoking habit, obesity and disease in Kamishihoro town, Hokkaido. METHODS: The Japanese edition of the European Community Respiratory Health Survey (ECRHS) Questionnaire was completed by 3096 residents (men: 1520, women: 1576) who ranged in age from 18 to 81. RESULTS: Among the respondents, 12.9% of the males and 9.8% of the females responded "Yes" to the questionnaire item, "Wheezing at any time in the last 12 months" (defined as having asthma) and 17.6% of the males and 23.0% of the females responded "Yes" to the question, "Do you have any nasal allergies including hay fever?" (defined as having allergic rhinitis). This prevalence tended to be higher among younger respondents. Smoking habit and obesity were significantly associated with wheezing over the last 12 months, but not with allergic rhinitis. CONCLUSION: Smoking habit and obesity are significantly associated with asthma in Kamishihoro town, located in a rural area of Hokkaido, Japan.

Antitumor effect of whole body hyperthermia with alpha-galactosylceramide in a subcutaneous tumor model of colon cancer.

AIM: Whole body hyperthermia (WBH) has been used clinically as an adjunct to radio- and chemotherapy in patients with various cancers. Recently, it has been reported that an activation of the immune system has recently been reported as a possible contributor to the therapeutic effects of WBH. Conversely, the glycolipid alpha-galactosylceramide (alpha-GalCer) is recognized by natural killer (NK) T cells together with the monomorphic MHC-like antigen, CD1d, in mice and humans. This study investigated the antitumor effects of WBH combined with alpha-GalCer in a mouse subcutaneous tumor model of colon cancer. METHODS: Colon26 cells were inoculated subcutaneously into male BALB/c mice to establish subcutaneous tumor. Colon26-bearing mice were treated with WBH using far infrared rays three times/week. Rectal temperature was maintained for 60 min at 41 degrees C. In some experimental groups, alpha-GalCer was intraperitoneally injected before WBH. We investigated the therapeutic effects of WBH, alpha-GalCer and combined therapy. RESULTS: (1) Compared with controls, WBH alone resulted in significant inhibition of tumor growth. (2) No inhibitory effect on tumor growth was seen with alpha-GalCer. (3) The combination of WBH and alpha-GalCer showed significant inhibition of tumor growth and prolongation of survival. (4) Serum IFN-gamma increased after 3 h and returned to basal levels by 24 h after alpha-GalCer administration. (5) CTL activity was enhanced following combination therapy with WBH and alpha-GalCer. CONCLUSION: WBH showed antitumor effects in a mouse subcutaneous tumor model of colon cancer. Addition of alpha-GalCer increased the efficacy of WBH, probably via enhancement of immune response.

Whole body hyperthermia improves obesity-induced insulin resistance in diabetic mice.

AIM: In this study, we examined the efficacy of whole body hyperthermia (WBH) on obesity-induced insulin resistance in diabetic mice. METHODS: Male db/db mice were treated with WBH 3 times per week for 12 weeks. The rectal temperature of mice reached 38.0 degrees C 5 min after heating, and was kept at 38.0 degrees C for 30 min. At the end of each week, tail snip glucose levels were determined under fasting conditions. The GLUT-4 gene expression of muscle tissue was analyzed by real-time PCR. RESULTS: (1) WBH-treated db/db mice showed a significant decrease in fasting blood glucose level as compared with untreated db/db mice (p < 0.01). (2) Plasma insulin levels in untreated db/db mice at the age of 10 weeks were significantly increased compared with those of db/+ mice (p < 0.0001). On the other hand, the reduction (31%) in insulin levels in WBH-treated mice indicated improved insulin sensitivity. (3) The ability of WBH to increase insulin sensitivity was further established in glucose tolerance tests and insulin tolerance tests. (4) Urine albumin of db/db mice significantly increased compared with those of db/+ mice at 18 weeks of age (p < 0.001). This increase in urinary albumin was significantly inhibited by WBH (p < 0.01). (5) WBH up-regulated the expression of GLUT4 mRNA in skeletal muscle. CONCLUSION: Although the mechanisms have not yet been completely investigated, WBH may provide a new therapeutic or preventive modality against obesity-related diseases such as T2DM and metabolic or insulin resistance syndrome.

Intracellular ATP correlates with mode of pexophagy in Pichia pastoris.

The methylotrophic yeast Pichia pastoris can degrade peroxisomes selectively though two distinct pexophagic pathways, viz., micropexophagy and macropexophagy. These micro- and macropexophagy pathways are induced by adaptation of methanol-grown cells to glucose-containing and ethanol-containing media respectively. However, our understanding of the molecular signal(s) that determine which pathway is activated or repressed in response to environmental changes is limited. In this study, the determinant for these pathways was sought using cells undergoing pexophagy under a variety of conditions. Micropexophagy and macropexophagy were distinguished in living cells by fluorescence microscopy. Our results indicate that glucose and ethanol were not specific inducers of micro- and macropexophagy respectively. Micropexophagy was found to be more sensitive to ATP-depletion than macropexophagy, suggesting that the micropexophagic process requires a higher level of ATP than the macropexophagic process. From these and other results, we postulate that intracellular ATP levels play an important role in determining which pexophagic pathway is activated.

Ganglioside GD3 promotes cell growth and invasion through p130Cas and paxillin in malignant melanoma cells.

Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3+) transfectant cells from a GD3-negative (GD3-) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3+ cells showed markedly increased cell growth and invasive characteristics. Two bands that underwent stronger tyrosine phosphorylation in GD3+ cell lines than in controls after treatment with FCS were found with molecular masses of 130 and 68 kDa. They were identified as p130Cas and paxillin by sequential immunoprecipitation. Their roles in cell growth and invasion were analyzed with a small interfering RNA (siRNA) approach. Cell growth, as analyzed by BrdUrd uptake, was strongly suppressed in GD3+ cells to near the levels of GD3- cells when treated with siRNA for p130Cas but not when treated with siRNA for paxillin. However, treatment with siRNAs of either p130Cas or paxillin resulted in the marked suppression of the invasive activity of GD3+ cells almost to the levels of control cells. These results suggested that these two molecules function as effectors of GD3-mediated signaling, leading to such malignant properties as rapid cell growth and invasion.

Analysis of the response and toxicity to gefitinib of non-small cell lung cancer.

BACKGROUND: Gefitinib is an oral agent that inhibits the tyrosine kinase of epidermal growth factor receptor (EGFR), which had antitumor activity in patients with previously treated non-small cell lung cancer (NSCLC). We analyzed the efficacy, toxicity and overall survival time of gefitinib treatment in patients with NSCLC. PATIENTS AND METHODS: One hundred and twenty-two patients with NSCLC, who received gefitinib between 2002 and 2004 in our institutes, were evaluated retrospectively. RESULTS: The objective response rate was 24.6%. The variables identified as significant in univariate analysis included gender and smoking habit. The median overall survival time was 14.4 months. Significant variables associated with improved survival included good performance status (PS), female, adenocarcinoma and never smoked status, while never smoked status and good PS were independent prognostic factors in multivariate analysis. Four patients (3.3%) developed interstitial pneumonitis associated with gefitinib. CONCLUSION: Gefitinib showed favorable anti-tumor activity in females, never smokers and adenocarcinoma.

GM1 expression in H-ras-transformed NIH3T3 results in the suppression of cell proliferation inducing the partial transfer of activated H-ras from non-raft to raft fraction.

c-H-ras is located in lipid/rafts and undergoes cholesterol dependent regulation. To analyze the regulatory effects of ganglioside GM1 on the proliferation of fibroblasts transformed with mutated ras gene, GM1 synthase cDNA was transfected into NIH3T3/H-ras cells containing mutation. In the transient expression system with EGFP-fused GM1 synthase, the ratio of BrdU-positive cells among EGFP-positive cells was compared between GM1(+) transfectant cells and control cells, indicating that the transient GM1 expression suppresses cell proliferation. Then, established transfectant cells C21 and C34 expressed definite levels of GM1, and analyzed for the cell growth with the control cells D2 and D4 expressing no GM1. GM1(+) cells showed reduced proliferation compared with controls. Phosphorylation levels of ERK1/2 after FCS treatment were examined, showing that those on the GM1(+) transfectant cells increased slowly, while those in the controls rapidly reached the plateau. Fractionation of Triton X-100 extracts with sucrose density gradient ultra-centrifugation revealed that activated H-ras proteins from controls as well as NIH3T3/H-ras were completely localized in non-GEM/raft fraction. On the other hand, some portions of activated H-ras were transferred to GEM/raft fraction, i.e., 32% in C21, and 8% in C34. Since the Ras effector Raf-1 was localized in non-GEM/raft, the growth suppression might be caused, at least partly, by the movement of activated H-ras to GEM/raft fraction.

A sorting nexin PpAtg24 regulates vacuolar membrane dynamics during pexophagy via binding to phosphatidylinositol-3-phosphate.

Diverse cellular processes such as autophagic protein degradation require phosphoinositide signaling in eukaryotic cells. In the methylotrophic yeast Pichia pastoris, peroxisomes can be selectively degraded via two types of pexophagic pathways, macropexophagy and micropexophagy. Both involve membrane fusion events at the vacuolar surface that are characterized by internalization of the boundary domain of the fusion complex, indicating that fusion occurs at the vertex. Here, we show that PpAtg24, a molecule with a phosphatidylinositol 3-phosphate-binding module (PX domain) that is indispensable for pexophagy, functions in membrane fusion at the vacuolar surface. CFP-tagged PpAtg24 localized to the vertex and boundary region of the pexophagosome-vacuole fusion complex during macropexophagy. Depletion of PpAtg24 resulted in the blockage of macropexophagy after pexophagosome formation and before the fusion stage. These and other results suggest that PpAtg24 is involved in the spatiotemporal regulation of membrane fusion at the vacuolar surface during pexophagy via binding to phosphatidylinositol 3-phosphate, rather than the previously suggested function in formation of the pexophagosome.