Bioactive peptide drugs hold promise for therapeutic application due to their high potency and selectivity but display short plasma half‐life. Examination of selected naturally occurring peptide ...hormones derived from proteolytic cleavage of the proopiomelanocortin (POMC) precursor lead to the identification of significant plasma‐stabilizing properties of a 12‐amino acid serine‐rich orphan sequence NSSSSGSSGAGQ in human γ3‐melanocyte‐stimulating hormone (MSH) that is homologous to previously discovered NSnGGH (n = 4–24) sequences in owls. Notably, transfer of this sequence to des‐acetyl‐α‐MSH and the therapeutically relevant peptide hormones neurotensin and glucagon‐like peptide‐1 likewise enhance their plasma stability without affecting receptor signaling. The stabilizing effect of the sequence module is independent of plasma components, suggesting a direct effect in cis. This natural sequence module may provide a possible strategy to enhance plasma stability, complementing existing methods of chemical modification.
Abstract Parkinson's disease is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra. While sporadic in the majority of cases, PD-linked ...dominant mutations in the α-synuclein and LRRK-2 genes, and recessive mutations in the parkin, DJ-1 and PINK-1 genes have been identified in PD families in recent years. In this review we describe viral animal models for PD, i.e. models that are based on PD-associated mutations, and have been generated by viral delivery of the respective disease genes to the substantia nigra of rodents and non-human primates. To date, viral PD models comprise α-synuclein and LRRK-2-based overexpression models, as well as models that mimic parkin loss of function by overexpression of the parkin substrates Pael-R, CDCrel-1, p38/JTV or synphilin-1. These viral models provide valuable insights into Parkinson disease mechanisms, help to identify therapeutic targets and may contribute to the development of therapeutic approaches.
We investigated the influence of the bifunctional guidance molecule netrin-1 on axonal growth in the injured adult spinal cord. In the adult, netrin-1 is expressed on mature oligodendrocytes, cells ...of the central canal, and the meninges. Netrin-1 protein in white matter is selectively enriched adjacent to paranodal loops of myelin in nodes of Ranvier. The repulsion-mediating netrin-1 uncoordinated-5 (UNC5) receptors are expressed by neurons of the corticospinal and rubrospinal projections, and by intrinsic neurons of the spinal cord, both before and after spinal cord injury. Neutralization of netrin-1 in myelin prepared from adult rat spinal cord using UNC5 receptor bodies increases neurite outgrowth from UNC5-expressing spinal motor neurons in vitro. Furthermore, axon regeneration is inhibited in a netrin-1-enriched zone, devoid of other myelin-associated inhibitors, within spinal cord lesion sites in vivo. We conclude that netrin-1 is a novel oligodendrocyte-associated inhibitor that can contribute to axonal growth failure after adult spinal cord injury.
Benzodiazepine tranquilizers are used in the treatment of anxiety disorders. To identify the molecular and neuronal target mediating the anxiolytic action of benzodiazepines, we generated and ...analyzed two mouse lines in which the α2 or α3 GABAA(γ-aminobutyric acid type A) receptors, respectively, were rendered insensitive to diazepam by a knock-in point mutation. The anxiolytic action of diazepam was absent in mice with the α2(H101R) point mutation but present in mice with the α3(H126R) point mutation. These findings indicate that the anxiolytic effect of benzodiazepine drugs is mediated by α2 GABAAreceptors, which are largely expressed in the limbic system, but not by α3 GABAAreceptors, which predominate in the reticular activating system.
Several experimental manipulations of the CNS environment successfully elicit regeneration of sensory and bulbospinal motor axons but fail to elicit regeneration of corticospinal axons, suggesting ...that cell-intrinsic mechanisms limit the regeneration of this critical class of motor neurons. We hypothesized that enhancement of intrinsic neuronal growth mechanisms would enable adult corticospinal motor axon regeneration. Lentiviral vectors were used to overexpress the BDNF receptor trkB in layer V corticospinal motor neurons. After subcortical axotomy, trkB transduction induced corticospinal axon regeneration into subcortical lesion sites expressing BDNF. In the absence of trkB overexpression, no regeneration occurred. Selective deletion of canonical, trkB-mediated neurite outgrowth signaling by mutation of the Shc/FRS-2 activation domain prohibited Erk activation and eliminated regeneration. These findings support the hypothesis that the refractory regenerative state of adult corticospinal axons can be attributed at least in part to neuron-intrinsic mechanisms, and that activation of ERK signaling can elicit corticospinal tract regeneration.
Abstract The specific application and transport of drugs into malignant tissue is a critical point during diagnosis and therapy. Nanoparticles are known as excellent drug carrier systems and offer ...the possibility of surface modification with targeting ligands, leading to a specific accumulation in the targeted tissue. First, the specificity of such a carrier system has to be proven. In this study, cetuximab-modified nanoparticles based on biodegradable human serum albumin (HSA) are investigated regarding their cellular binding and intracellular accumulation. Different EGFR-expressing colon carcinoma cells were used to test possible cytotoxic potential, specific binding and intracellular accumulation. A specific accumulation targeting the EGFR could be shown. These results emphasize that cetuximab-modified HSA-nanoparticles are a promising carrier system for later drug transport. To our knowledge, this is the first study investigating the specific accumulation of HSA nanoparticles into different EGFR-expressing colon carcinoma cells. From the Clinical Editor In this study, cetuximab-modified nanoparticles based on human serum albumin (HSA) are investigated regarding their cellular binding and intracellular accumulation. The results suggest that these nanoparticles are a promising carrier system for EGFR overexpressing colon carcinoma cells.
The use of an “over 1000-nm near-infrared (NIR) in vivo fluorescence bioimaging” system based on lanthanide containing inorganic nanostructures emitting in the visible and NIR range under 980-nm ...excitation is proposed. It may overcome problems of currently used biomarkers including color fading, phototoxicity and scattering. Gd
2
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:Er
3+
,Yb
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nanoparticles and nanorods showing upconversion and NIR emission are synthesized and their cytotoxic behavior is investigated by incubation with B-cell hybridomas and macrophages. Surface modification with PEG-
b
-PAAc provides the necessary chemical durability reducing the release of toxic Gd
3+
ions. NIR fluorescence microscopy is used to investigate the suitability of the nanostructures as NIR–NIR biomarkers. The in vitro uptake of bare and modified nanostructures by macrophages is investigated by confocal laser scanning microscopy. In vivo investigations revealed nanostructures in liver, lung, kidneys and spleen a few hours after injection into mice, while most of the nanostructures have been removed from the body after 24 h.
► We compared the cytotoxicity of TP and TP-PM on Jurkat and HT29 cells. ► TP and TP-PM could induce an inhibition of cell growth and proliferation in both tumor cell lines. ► TP and TP-PM induced ...apoptosis and caused activation of caspase 3/7. ► TP-PM induced in tested cell lines stronger effects than TP.
Triptolide (TP), a diterpenoid triepoxide purified from the Chinese herb Tripterygium wilfordii Hook F is characterized by strong anti-tumor effects on various cancer cells. Except its anti-tumor effects, TP also shows multiple pharmacological side activities, such as anti-inflammatory, immune-suppressive and male anti-fertility. In order to reduce these side effects, especially the immuno-suppressive activity when used to cure cancer, a novel polymeric micelle system containing TP (TP-PM) was constructed. The immune-modulation effects of TP-PM have been evaluated by previous studies. In this study, we compared the cytotoxicity of TP and TP-PM on Jurkat and HT29 cells. Therefore, we determined the cell viability, membrane integrity, cell proliferation, apoptosis, and caspase 3/7 activity after exposure to TP and TP-PM. The results demonstrated that actually low concentrated TP and TP-PM could induce an inhibition of cell growth and proliferation as well as membrane damage in both tumor cell lines. TP and TP-PM induced apoptosis and caused activation of caspase 3/7 even at low concentrations. Both formulations destroyed the membrane of Jurkat cells, nevertheless, TP-PM showed stronger pernicious effects. In general, TP-PM induced in both tested cell lines stronger effects than TP. Therefore, polymeric micelles can be considered as promising carriers for TP in cancer therapy.
Examination of genetic polymorphisms in outbred wild-living species provides insights into the evolution of complex systems. In higher vertebrates, the proopiomelanocortin (POMC) precursor gives rise ...to α-, β-, and γ-melanocyte-stimulating hormones (MSH), which are involved in numerous physiological aspects. Genetic defects in POMC are linked to metabolic disorders in humans and animals. In the present study, we undertook an evolutionary genetic approach complemented with biochemistry to investigate the functional consequences of genetic polymorphisms in the POMC system of free-living outbred barn owl species (family Tytonidae) at the molecular level. Our phylogenetic studies revealed a striking correlation between a loss-of-function H9P mutation in the β-MSH receptor-binding motif and an extension of a poly-serine stretch in γ3-MSH to ≥7 residues that arose in the barn owl group 6-8 MYA ago. We found that extension of the poly-serine stretches in the γ-MSH locus affects POMC precursor processing, increasing γ3-MSH production at the expense of γ2-MSH and resulting in an overall reduction of γ-MSH signaling, which may be part of a negative feedback mechanism. Extension of the γ3-MSH poly-serine stretches ≥7 further markedly increases peptide hormone stability in plasma, which is conserved in humans, and is likely relevant to its endocrine function. In sum, our phylogenetic analysis of POMC in wild living owls uncovered a H9P β-MSH mutation subsequent to serine extension in γ3-MSH to 7 residues, which was then followed by further serine extension. The linked MSH mutations highlight the genetic plasticity enabled by the modular design of the POMC gene.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Diazepam is used clinically for its myorelaxant, anxiolytic, sedative, and anticonvulsant properties. Although the anxiolytic
action is mediated by α2 γ-aminobutyric acid A (GABA A ) receptors, the ...sedative action and in part the anticonvulsant action are mediated by α1 GABA A receptors. To identify the GABA A receptor subtypes mediating the action of diazepam on muscle tone, we have assessed the myorelaxant properties of diazepam
in α2(H101R) and α3(H126R) knock-in mice harboring diazepam-insensitive α2 or α3 GABA A receptors, respectively. Whereas in α2(H101R) mice the myorelaxant action of diazepam was almost completely abolished at
doses up to 10 mg/kg, the same dose induced myorelaxation in both wild-type and α3(H126R) mice. It was only at a very high
dose (30 mg/kg diazepam) that α2(H101R) mice showed partial myorelaxation and α3(H126R) mice were partially protected from
myorelaxation compared with wild-type mice. Thus, the myorelaxant activity of diazepam seems to be mediated primarily by α2
GABA A receptors and at high concentrations also by α3 GABA A receptors.
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