Podocytes in the renal glomerulus express unusual intermediate filament (IF) proteins for epithelial cells. To gain insight into the role of IF proteins in podocytes, we investigated the expression of nestin, vimentin, and desmin in puromycin aminonucleoside (PAN) nephrosis. A Western blot analysis for nestin, vimentin, and desmin demonstrated their exclusive expression in glomeruli and showed their increase in expression in nephrotic glomeruli. Immunolocalization studies showed nestin and vimentin to be located predominantly in the podocytes in both normal and nephrotic glomeruli and that enhancement of desmin staining only occurred in podocytes. A ribonuclease protection assay showed high levels of vimentin and nestin expression in normal glomeruli and an upregulation of all three IF transcripts in nephrotic glomeruli. One day after the PAN injection, however, the vimentin transcripts were found to already have significantly increased, whereas those of nestin or desmin showed no such increase. These findings indicate that podocytes express three IF proteins, namely, vimentin, desmin, and nestin, which are differentially regulated in response to injury. An upregulation of IF proteins may increase the mechanical stability of cells, thus enabling podocytes to undergo morphological changes on the tensile glomerular capillary wall.

Gel- based proteomics is one of the most versatile methods for fractionating protein complexes. Among these methods, two dimensional- polyacrylamide gel electrophoresis (2-DE) represents a mainstay orthogonal approach, which is popularly used to simultaneously fractionate, identify, and quantify proteins when coupled with mass spectrometric identification or other immunological tests. Although 2-DE was first introduced more than three decades ago, several challenges and limitations to its utility still exist. This review discusses the principles of 2-DE as well as both recent methodological advances and new applications.

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SummaryNeuronal growth cones are essential for nerve growth and regeneration, as well as for the formation and rearrangement of the neural network. To elucidate phosphorylation-dependent signaling pathways and establish useful molecular markers for axon growth and regeneration, we performed a phosphoproteomics study of mammalian growth cones, which identified >30,000 phosphopeptides of ∼1,200 proteins. The phosphorylation sites were highly proline directed and primarily MAPK dependent, owing to the activation of JNK, suggesting that proteins that undergo proline-directed phosphorylation mediate nerve growth in the mammalian brain. Bioinformatics analysis revealed that phosphoproteins were enriched in microtubules and the cortical cytoskeleton. The most frequently phosphorylated site was S96 of GAP-43 (growth-associated protein 43-kDa), a vertebrate-specific protein involved in axon growth. This previously uncharacterized phosphorylation site was JNK dependent. S96 phosphorylation was specifically detected in growing and regenerating axons as the most frequent target of JNK signaling; thus it represents a promising new molecular marker for mammalian axonal growth and regeneration.

Background. Although colony-stimulating factors have been shown to accelerate recovery from severe neutropenia after intensive chemotherapy or bone marrow transplantation, their use in acute leukemia has been controversial because in vitro they stimulate leukemic colonies as well as normal granulocyte colonies. Methods. We conducted a prospective, randomized, controlled study to determine the safety and efficacy of recombinant human granulocyte colony-stimulating factor (CSF) after a standard course of intensive therapy in 108 patients with relapsed or refractory acute leukemia (67 with acute myelogenous leukemia, 30 with acute lymphocytic leukemia, 9 in blast crisis from chronic myelogenous leukemia, and 2 with acute leukemia arising from myelodysplastic syndromes). Treatment with granulocyte CSF (200 micrograms per square meter of body-surface area per day in a 30-minute infusion) was begun two days after the end of the chemotherapy and continued until the neutrophil count rose above 1500 per cubic millimeter. Results. Treatment with granulocyte CSF accelerated the recovery of neutrophils significantly (P less than 0.01), shortening it by about a week, but it had no effect on platelet recovery. Although the incidence of febrile episodes was almost the same, documented infections were significantly less frequent in the group treated with granulocyte CSF (P = 0.028). There was no evidence that granulocyte CSF accelerated the regrowth of leukemic cells. Fifty percent of 48 patients in the CSF group who could be evaluated and 36 percent of 50 controls had complete remission. The rate of relapse was almost the same in the two groups. Conclusions. It appears that recombinant human granulocyte CSF is safe in acute leukemia, accelerating neutrophil recovery and thereby reducing the incidence of documented infection without affecting the regrowth of leukemic cells. It should be used with caution, however, pending further confirmation of these early results.

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Choline is an important methyl donor and a component of membrane phospholipids. In this study, we tested the hypothesis that choline availability can modulate cell proliferation and the methylation of genes that regulate cell cycling. In several other model systems, hypomethylation of cytosine bases that are followed by a guanosine (CpG) sites in the promoter region of a gene is associated with increased gene expression. We found that in choline-deficient IMR-32 neuroblastoma cells, the promoter of the cyclin-dependent kinase inhibitor 3 gene (CDKN3) was hypomethylated. This change was associated with increased expression of CDKN3 and increased levels of its gene product, kinase-associated phosphatase (KAP), which inhibits the G 1 /S transition of the cell cycle by dephosphorylating cyclin-dependent kinases. Choline deficiency also reduced global DNA methylation. The percentage of cells that accumulated bromodeoxyuridine (proportional to cell proliferation) was 1.8 times lower in the choline-deficient cells than in the control cells. Phosphorylated retinoblastoma (p110) levels were 3 times lower in the choline-deficient cells than in control cells. These findings suggest that the mechanism whereby choline deficiency inhibits cell proliferation involves hypomethylation of key genes regulating cell cycling. This may be a mechanism for our previously reported observation that stem cell proliferation in hippocampus neuroepithelium is decreased in choline-deficient rat and mouse fetuses.

Fecal occult blood testing by immunochemical hemagglutination has been shown to be superior to the Hemoccult test, both in sensitivity and in specificity. The test has been widely used as a tool for population screening in Japan, but there has been no study to evaluate the efficacy of screening using this test. A case-control study to evaluate the screening was conducted in study areas where no previous and no other concomitant colorectal cancer screening had been performed. Case series in the study were 193 cases who died of colorectal cancer. Three controls were selected randomly from the list of individuals who were alive at the time of diagnosis of the corresponding case and had been living in the same area as the case, matched by gender and by age. Odds ratios (OR) of dying of colorectal cancer for those screened within 1, 2 and 3 years of case diagnosis vs. those not screened were 0.40 [95% confidence interval (CI) 0.17-0.92], 0.41 (95% CI 0.20-0.82), and 0.48 (95% CI 0.25-0.92), respectively. OR increased towards 1.0 as the duration during which screening histories were compared was extended, and showed similar tendencies when analyzed by number of years since the most recent screening history. These results suggest that colorectal cancer screening by the immunochemical fecal occult blood test would reduce mortality from colorectal cancer.