Depletion of intracellular Ca2+ store itself may be a major factor in thapsigargin-induced ER stress and apoptosis in PC12 cells

The mechanisms of intracellular calcium store depletion and store-related Ca(2+) dysregulation in relation to apoptotic cell death in PC12 cells were investigated at physiological temperatures with a leak-resistant fluorescent indicator dye Fura-PE3/AM by a cooled CCD imaging analysis system. Electron microscopic observations have shown thapsigargin (TG; 100 nM)-induced apoptosis in PC12 cells. Thorough starvation of stored Ca(2+) by BAPTA/AM (50 microM), or La(3+) (100 microM) enhanced while dantrolene (100 microM) attenuated the TG-induced apoptosis by preventing a calcium release from internal stores. An immunoblotting analysis revealed an enhanced expression of GRP78, the hallmark of endoplasmic reticulum (ER) stress when cells were treated by TG along with BAPTA/AM. These results indicate that the depletion of the intracellular Ca(2+) stores itself induces the ER stress and apoptosis in PC12 cells without any involvement of the capacitative calcium entry (CCE) or a sustained elevation of intracellular Ca(2+) concentrations ([Ca(2+)](i)).

Measurement of laminins in the cerebrospinal fluid obtained from patients with Alzheimer's disease and vascular dementia using a modified enzyme-linked immunosorbent assay

We developed a new enzyme-linked immunosorbent assay (ELISA) system using antibodies against intact human laminin, laminin alpha(5)-chain, laminin beta(1)-chain, laminin gamma(1)-chain and laminin alpha(1)-chain peptide (YFQRYLI). Using this ELISA, we measured the anti-laminin immunoreactivity levels in the cerebrospinal fluid (CSF) obtained from patients with Alzheimer's disease (AD), vascular dementia (VaD), and other disorders. The present study showed the levels of certain laminins in CSF to demonstrate significant differences in the chain levels in different dementias. The AD group showed a significantly lower level of anti-laminin gamma(1) immunoreactivity. The late-onset AD group showed significantly elevated anti-laminin alpha(1)-peptide (YFQRYLI) immunoreactivity levels in comparison with the early-onset AD group and controls. On the other hand, the VaD group showed significantly higher levels of anti-intact human laminin and anti-laminin beta(1) immunoreactivity. The assays of anti-laminin immunoreactivity levels in CSF provided an efficient sensitivity (85.0%) and specificity (93.7%) for the diagnosis of AD by using the ratio of tau to anti-intact human laminin immunoreactivity levels. These results suggest that CSF laminin or its derivatives may correlate with the pathogenesis of AD and VaD, and the prevention of the proteolytic activity may be an effective therapeutic method for either preventing or slowing down the progression of AD. Furthermore, it was shown that performing ELISA for CSF laminins may prove to be useful for detecting the biological markers of AD and VaD.

Amyloid-beta-protein (A beta) (25-35)-associated free radical generation is strongly influenced by the aggregational state of the peptides

We investigated whether or not the Amyloid-beta-protein (A beta) itself spontaneously generates free radicals using electron spin resonance (ESR) spectroscopy while also monitoring the aggregational state of A beta and A beta-induced cytotoxicity. The present results demonstrated a four-line spectrum in the presence of A beta25-35 with N-tert-butyl-alpha-phenylnitrone (PBN) but not in the presence of PBN alone in phosphate-buffered saline (PBS). The fact that the four-line spectrum obtained for the A beta25-35/PBN in PBS was completely abolished in the presence of the iron-chelating agent Desferal demonstrated the observed four-line spectrum to be iron-dependent. On the other hand, A beta25-35 with PBN in phosphate buffer (PB) did not produce any definite four-line spectrum. the present results showed the amyloid fibril formation of A beta25-35 in PBS to be much higher than that of A beta25-35 in PB. Moreover, A beta-induced cytotoxicity assays showed A beta incubated in PBS to be more cytotoxic than that incubated in PB. These results thus demonstrate that A beta(25-35)-associated free radical generation is strongly influenced by the aggregational state of the peptides.

Laminin A chain synthetic peptide which supports neurite outgrowth

Neurons from peripheral and central nervous tissue as well as from established cell lines respond to low concentrations of laminin with rapid extension of axon-like processes. Two sites on laminin have been identified which stimulate neurite outgrowth, the major site residing at the end of the long arm of laminin. Recently laminin has been cloned and sequenced allowing for synthetic peptides to be prepared and tested for biological activity. We report here that antisera against synthetic peptides corresponding to A and to B1 chain sequences at the end of the long arm can partially inhibit laminin-mediated neurite outgrowth. Further, we show that a 19 amino acid synthetic peptide (CSRARKQAASIKVAVSADR) from the long arm of the laminin A chain is capable of stimulating neuronal-like process formation to almost the same extent as laminin and competes with laminin for stimulation of neurite outgrowth.