Effect of inhibitors of NADPH oxidase complex and mitochondrial ATP-sensitive potassium channels on generation of dopaminergic neurons from neurospheres of mesencephalic precursors.

Reactive oxygen species signaling has been suggested to regulate stem cell development. In the present study, we treated neurospheres of rat mesencephalic precursors with inhibitors of the NADPH oxidase complex and mitochondrial ATP-sensitive potassium (mitoKATP) channel blockers during the proliferation and/or the differentiation periods to study the effects on generation of dopaminergic neurons. Treatment with low doses (100 or 250 µM) of the NADPH inhibitor apocynin during the proliferation period increased the generation of dopaminergic neurons. However, higher doses (1 mM) were necessary during the differentiation period to induce the same effect. Treatment with general (glibenclamide) or mitochondrial (5-hydroxydecanoate) KATP channel blockers during the proliferation and differentiation periods increased the number of dopaminergic neurons. Furthermore, neither increased proliferation rate nor apoptosis had a major role in the observed increase in generation of dopaminergic neurons, which suggests that the redox state is able to regulate differentiation of precursors into dopaminergic neurons.

Role of Hypertension in Aggravating Abeta Neuropathology of AD Type and Tau-Mediated Motor Impairment.

Epidemiological evidence suggests that hypertension may accelerate the onset and progression of Alzheimer's disease (AD). In this study, we explored the role of hypertension in the neurodegenerative changes associated with Abeta and tau aggregation. We induced hypertension in APP(swe) Tg2576 and P301L-tauTg mouse models. In Tg2576 mice, experimental hypertension was associated with a significant increase of the accumulation of Amyloid-beta (Abeta) peptides in brain tissue and a significant reduction of Abeta peptides in serum (P < .05). These results indicate that hypertension may promote AD-type Abeta neuropathology in Tg2576. In P301L-tauTg mice we found that the presence of hypertension was significantly associated with aggravated motor function assessed by hindlimb extension test (P = .01). These results suggest that hypertension may play a role in accelerating the progression of motor dysfunction associated with tau-related alterations. Our studies suggest that the management of blood pressure (BP) may alleviate AD-type Abeta neuropathology and neurological disorders associated with abnormal tau metabolism.

Prodigiosin induces cell death and morphological changes indicative of apoptosis in gastric cancer cell line HGT-1.

Gastric cancer is one of the most frequent malignancies and its treatment is far from satisfactory. The challenge to oncologists is the characterization of novel chemical entities with greater effectiveness. Prodigiosin is a red pigment produced by various bacteria including Serratia marcescens. Here we characterize the apoptotic action of prodigiosin in human gastric carcinoma cell line (HGT-1). Cells were assayed by the MTT assay, fragmentation pattern of DNA, Hoechst 33342 staining and study of actin microfilament architecture. Treatment of these cells with prodigiosin showed a constant decrease in viability by apoptosis. Morphological analysis of prodigiosin-treated cells demonstrated that prodigiosin induces cell shrinkage, chromatin condensation, reorganization of actin microfilament architecture, and detachment of cells from the cell culture substrate. Altogether these results suggest that prodigiosin induces apoptosis in HGT-1 human gastric cancer cells and raises the possibility of its use as a new chemotherapeutic drug.

Immunochemical localization of transforming growth factor-alpha-related protein in the rat kidney.

Transforming growth factor-alpha (TGF-alpha) is a 50-amino acid polypeptide synthesized as part of a larger precursor of 159 amino acids. Its expression has been reported in normal and neoplastic kidney. In this report, we characterized a renal TGF-alpha-immunoreactive protein, which we named TGF-alpha-related protein (TGF-alpha-RP). It was found to be present in the final part of the collecting tubules of the normal rat kidney. Western blotting analysis of kidney samples revealed a protein of 38 kD and pI = 5.5. In nonreducing conditions immunoreaction for this protein decreased and a TGF-alpha-immunoreactive protein of 150 kD was observed. The expression of TGF-alpha-RP seems to be highly conserved in the kidney of mammals and chickens. Therefore, TGF-alpha-RP may have an important role in the normal development and function of the kidney.

Immunochemical study of transforming growth factor-beta in the kidney of the rat and chicken.

Transforming growth factor-beta (TGF-beta) is a homodimeric polypeptide of 25 kDa, which regulates cell growth and differentiation and influences extracellular matrix metabolism. Using immunochemical techniques, we identified TGF-beta in the loops of Henle and the collecting and Bellini ducts of rat kidney and in the loops of Henle of chicken kidney. Furthermore, we detected two TGF-beta-immunoreactive proteins on kidney blots of the rat of 12.5 and 47 kDa, and three on chicken kidney blots of 12.5, 34, and 47 kDa. We suggest that the precursor forms of rat and chicken TGF-beta 2 or beta 3, chicken TGF-beta 4, and the mature form of all of them are expressed in the collecting and Bellini ducts of rat kidney and the loops of Henle of rat and chicken kidney.

Immunochemical study of a transforming growth factor-alpha-related protein in the chicken kidney.

A number of polypeptides are involved in renal growth and physiology. Both transforming growth factor-alpha (TGF-alpha) protein and mRNA are expressed in kidney cells during embryonic and adult stages, and exert mitogenic activity on kidney cells in culture. We studied the immunolocalization of a TGF-alpha-related protein at the ultra-structural level and found it in the basolateral membranes of dark cells from distal tubules of the chicken kidney. By Western blotting techniques, we identified a protein complex composed of a least two TGF-alpha immunoreactive subunits of 40 and 88 kDa, respectively. Both subunits were sensitive to elastase digestion, and released TGF-alpha immunoreactive products. In addition, TGF-alpha immunoreaction was found in primary culture of chicken kidney cells. These findings suggest that the TGF-alpha-related protein complex plays a very specific role in proliferation and/or differentiation of kidney cells.

Immunoelectron microscopic localisation of transforming growth factor alpha in rat colon.

Transforming growth factor alpha (TGF alpha) is a polypeptide, which binds to the epidermal growth factor receptor to carry out its function related to cell proliferation and differentiation. The ultrastructural localisation of TGF alpha was studied in both the proximal and the distal colon. The columnar cells, lining the surface epithelium of the proximal colon, showed a strong immunoreactivity in the polyribosomes and in the interdigitations of the lateral membrane. The columnar cells of the crypts and the goblet cells in both the proximal and the distal colon showed the immunostaining in the cis and trans cisternae of the Golgi apparatus. TGF alpha seems to be processed differently in the surface columnar cells and in the crypt columnar cells and goblet cells. Moreover, it probably has different roles in proliferation and differentiation.

Immunohistochemical localization of transforming growth factor-alpha in choroid plexus of the rat and chicken.

Transforming growth factor-alpha (TGF-alpha) is a polypeptide which binds to epidermal growth factor-receptor (EGF-R) to carry out its function. We have observed strong TGF-alpha immunoreactivity in the developing and adult choroid plexus of the rat and chicken and glial cells of adult rats, by using a well characterized monoclonal antibody and the peroxidase method. Preabsortion of the antibody with the peptide gave negative staining. Since previous studies have shown that EGF-R is localized in several brain regions, but not in the choroid plexus, during development and adulthood, it is suggested that TGF-alpha, synthesized in the choroid plexus and transferred to the cerebrospinal fluid, has a role in brain development. TGF-alpha immunoreactivity found in glial cells, but not in neurons of adult rats, suggests that TGF-alpha in adulthood is also synthetized in the glial cell compartment.

Immunohistochemical localization of transforming growth factor-alpha and epidermal growth factor-receptor in the mesonephros and metanephros of the chicken.

Transforming growth factor-alpha (TGF-alpha) is a polypeptide related to epidermal growth factor (EGF). Both bind to EGF-receptor (EGF-R) to carry out their function in a variety of tissues and cell lines. Several studies have shown their presence in mammalian kidney, however, nothing has to date been stated concerning their existence in avian kidney. Expression of TGF-alpha and EGF-R is reported here for the first time during the development of the chicken kidney. Using immunohistochemical techniques, we identified a TGF-alpha (but not EGF) in mesonephric distal tubule cells from day 8 to day 20 of embryonic development and in metanephric distal tubule cells from day 14 of embryonic development to the adult. The histochemical characteristics of these cells and their histological localization suggest that they may be the "principal cells" of the distal tubules. Similarly, EGF-R was found in mesonephric proximal tubule cells from day 7 to day 18 of embryonic development and in metanephric proximal tubule cells from day 13 of embryonic development up to adult stages. The coexistence of both TGF-alpha and EGF-R from the onset of development of mesonephros and metanephros supports their possible role in mechanisms of proliferation and differentiation of the cells of these organs.

Transforming growth factor-alpha expression in rat experimental hepatocarcinogenesis.

Growth factors in general and transforming growth factor-alpha in particular have been related to cell proliferation and cell differentiation. This study was designed to clarify the distribution pattern of TGF-alpha in chemically-induced hepatocarcinogenesis. Sprague-Dawley rats were subjected to different non-intensive or intensive carcinogenic treatments using diethylnitrosamine (DEN) as carcinogen and ethinyl estradiol (EE) as promoter. The livers were fixed in 2% paraformaldehyde, dehydrated in a series of ethanol solutions, embedded in paraffin and sectioned. In the preneoplastic lesions no TGF-alpha immunoreactive cells were identified, but in some hepatic tumours cell immunostained with TGF-alpha antibody were observed. These results suggest that the cells capable of expressing TGF-alpha constitutively may be involved in neoplastic development in vivo.