Novel synthetic lipopeptides derived from Mycoplasma hyorhinis upregulate calpastatin in SH-SY5Y neuroblastoma cells and induce a neuroprotective effect against amyloid-β-peptide toxicity.

Previously, we showed that contamination of SH-SY5Y neuroblastoma cells by Mycoplasma hyorhinis strains NDMh and MCLD leads to increased levels of calpastatin (the endogenous, specific inhibitor of the Ca2+-dependent protease calpain), resulting in inhibition of calpain activation. We have found that the increased calpastatin level is promoted by the lipoprotein fraction (MhLpp) of the mycoplasmal membrane. Here, we present MhLpp-based novel synthetic lipopeptides that induce upregulation of calpastatin in SH-SY5Y neuroblastoma cells, leading to protection of the treated cells against Ca2+/amyloid-β-peptide toxicity.

Calpastatin is upregulated in non-immune neuronal cells via toll-like receptor 2 (TLR2) pathways by lipid-containing agonists.

Calpain (intracellular Ca(2+)-dependent protease) and calpastatin (calpain specific endogenous inhibitor) are widely distributed in biological systems, and have been implicated in many cellular physiological and pathological processes. Calpastatin level is of central importance to the control of calpain activity. We demonstrated for the first time that calpastatin is overexpressed in mycoplasma-contaminated cultured cells (SH-SY5Y cells that are infected by a strain of Mycoplasma hyorhinis (NDMh)).

Calpastatin upregulation in Mycoplasma hyorhinis-infected cells is promoted by the mycoplasma lipoproteins via the NF-κB pathway.

Mycoplasma hyorhinis frequently contaminates cultured cells, with effects on synthetic and metabolic pathways. We demonstrated for the first time that contamination of cells by a strain of M. hyorhinis (NDMh) results in increased levels of calpastatin (the endogenous inhibitor of the ubiquitous Ca(2+) -dependent protease calpain).

Neuroprotective effects of Mycoplasma hyorhinis against amyloid-β-peptide toxicity in SH-SY5Y human neuroblastoma cells are mediated by calpastatin upregulation in the mycoplasma-infected cells.

Mycoplasmas are frequent contaminants of cell cultures. Contamination leads to altered synthetic and metabolic pathways. We have found that contamination of neuroblastoma SH-SY5Y cells by a strain of Mycoplasma hyorhinis derived from SH-SY5Y cell culture (NDMh) leads to increased levels of calpastatin (the endogenous inhibitor of the Ca(2+)-dependent protease, calpain) in NDMh-infected cells.

Mycoplasma hyorhinis upregulates calpastatin and inhibits calpain-dependent proteolysis in SH-SY5Y neuroblastoma cells.

Mycoplasmas often contaminate cultured cells, leading to alterations in cellular gene expression, protein synthesis, signal transduction and metabolic pathways. Mycoplasmal contamination is often unnoticed, so that mycoplasma-induced alterations in cell functions may not be appreciated, unless specifically studied. Here, we show for the first time that contamination of SH-SY5Y cells by Mycoplasma hyorhinis leads to increased levels of calpastatin (the endogenous inhibitor of the Ca(2+)-dependent protease calpain), resulting in inhibition of Ca(2+)-induced calpain activation and inhibition of calpain-promoted proteolysis in the mycoplasmal-infected cells.

Calpain activates caspase-8 in neuron-like differentiated PC12 cells via the amyloid-beta-peptide and CD95 pathways.

The neurotoxic amyloid-beta-peptide (Abeta) is important in the pathogenesis of Alzheimer's disease (AD). Calpain (Ca(2+)-dependent protease) and caspase-8 (the initiating caspase for the extrinsic, receptor-mediated apoptosis pathway) have been implicated in AD/Abeta toxicity. We previously found that Abeta promoted degradation of calpastatin (the specific endogenous calpain inhibitor); calpastatin degradation was prevented by inhibitors of either calpain or caspase-8.

Amyloid beta peptide toxicity in differentiated PC12 cells: calpain-calpastatin, caspase, and membrane damage.

Amyloid beta peptide (Abeta) is implicated in the pathogenesis of Alzheimer's disease (AD). The peptide is toxic to neurons, possibly by causing initial synaptic dysfunction and neuronal membrane dystrophy, promoted by increased cellular Ca(2+). Calpain (Ca(2+)-dependent protease) and caspase have also been implicated in AD.

Calpastatin levels affect calpain activation and calpain proteolytic activity in APP transgenic mouse model of Alzheimer's disease.

The intracellular Ca(2+)-dependent protease calpain and the specific calpain endogenous inhibitor calpastatin are widely distributed, with the calpastatin/calpain ratio varying among tissues and species. Increased Ca(2+) and calpain activation have been implicated in Alzheimer's disease (AD), with scant data available on calpastatin/calpain ratio in AD. Information is lacking on calpain activation and calpastatin levels in transgenic mice that exhibit AD-like pathology.

Calpastatin in rat myoblasts: transient diminution and decreased phosphorylation depend on myogenin-directed myoblast differentiation.

The formation of skeletal muscle fibers involves cessation of myoblast division, followed by myoblast differentiation and fusion to multinucleated myofibers. The myogenic regulatory factor myogenin appears at the onset of differentiation; it is required for muscle fiber formation, and cannot be replaced by other factors. The myogenin-dependent pathways and targets are not fully known.

Nonprotein thiols and disulfides in rat epididymal spermatozoa and epididymal fluid: role of gamma-glutamyl-transpeptidase in sperm maturation.

Sperm thiol oxidation during sperm maturation is important for sperm component stabilization, the acquisition of sperm motility, and fertilizing ability. A correct degree of oxidation is required, since spermatozoa are very susceptible to oxidative damage. The pathways involved in physiologic sperm thiol oxidation in the epididymis are not completely understood.

Overexpression of calpastatin inhibits L8 myoblast fusion.

The formation of skeletal muscle fibers involves cessation of myoblast division, myoblast alignment, and fusion to multinucleated myofibers. Calpain is one of the factors shown to be involved in myoblast fusion. Using L8 rat myoblasts, we found that calpain levels did not change significantly during myoblast differentiation, whereas calpastatin diminished prior to myoblast fusion and reappeared after fusion.

Tyrosine phosphorylation, thiol status, and protein tyrosine phosphatase in rat epididymal spermatozoa.

Sperm thiol oxidation and the ability to undergo protein tyrosine phosphorylation are associated with the acquisition of sperm motility and fertilizing ability during passage of spermatozoa through the epididymis. Phosphotyrosine levels in various cells are controlled by tyrosine kinase versus phosphatase, with the latter known to be inhibited by oxidation. In the present paper we examine whether changes in thiol status during sperm maturation affect rat sperm protein phosphotyrosine levels and protein phosphotyrosine phosphatase (PTP) activity.

Caspase-1-induced calpastatin degradation in myoblast differentiation and fusion: cross-talk between the caspase and calpain systems.

Previously, we found that calpastatin diminished transiently prior to myoblast fusion (rat L8 myoblasts), allowing calpain-induced protein degradation, required for fusion. Here we show that the transient diminution in calpastatin is due to its degradation by caspase-1. Inhibition of caspase-1 prevents calpastatin diminution and prevents myoblast fusion.

Ca2+ promotes erythrocyte band 3 tyrosine phosphorylation via dissociation of phosphotyrosine phosphatase from band 3.

The anion-exchange band 3 protein is the main erythrocyte protein that is phosphorylated by protein tyrosine kinase (PTK). We have previously identified a band 3-associated phosphotyrosine phosphatase (PTP) that is normally highly active and prevents the accumulation of band 3 phosphotyrosine. Band 3 tyrosine phosphorylation can be induced by inhibition of PTP (vanadate, thiol oxidation), activation of PTK (hypertonic NaCl) or intracellular increased Ca(2+) (mechanism unknown).