scholarly journals Two amino acids in glutamic acid decarboxylase act in concert for maintainance of conformational determinants recognised by Type I diabetic autoantibodies

Diabetologia ◽  
2000 ◽  
Vol 43 (7) ◽  
pp. 881-889 ◽  
Author(s):  
T.I.M. Tree ◽  
N. G. Morgenthaler ◽  
N. Duhindan ◽  
K. E. Hicks ◽  
A.-M. Madec ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Glutamic Acid Decarboxylase ◽  
Acid Decarboxylase ◽  
Type I

GABAergic Interneurons in the Mouse Lateral Amygdala: A Classification Study

2010 ◽  
Vol 104 (2) ◽  
pp. 617-626 ◽  
Author(s):  
Ludmila Sosulina ◽  
Stéphanie Graebenitz ◽  
Hans-Christian Pape
Keyword(s):  
Glutamic Acid ◽  
Glutamic Acid Decarboxylase ◽  
Action Potentials ◽  
Fluorescent Protein ◽  
Inward Rectification ◽  
Acid Decarboxylase ◽  
Type I ◽  
Gabaergic Interneurons ◽  
Lateral Amygdala ◽  
Frequency Adaptation

Whole cell patch-clamp recordings were performed in GABAergic interneurons labeled by green fluorescent protein (GFP) in the lateral amygdala (LA) in vitro from glutamic acid decarboxylase 67 (GAD67)-GFP mice. Neurons were characterized by electrotonic and electrogenic parameters. Cytoplasm was collected from individual neurons, and single-cell RT-PCR was used for detection of molecular markers typifying LA interneurons. Hierarchical cluster and multiple discriminant analysis demonstrated the existence of five types of GABAergic interneurons, which can be reliably identified through electrophysiological criteria. Action potentials were of a short duration followed by pronounced fast afterhyperpolarization (AHP) in interneurons of all types, except for type V, which generated broad action potentials and displayed typical spike bursts at the beginning of depolarizing stimuli and prominent anomalous inward rectification. Interneurons of type I and II generated series of action potentials with frequency adaptation on maintained depolarizing current stimulation with overall frequencies at high levels and presented delayed firing, stuttering or fast-spiking behavior. Further distinguishing features of type II interneurons were a medium AHP following spike trains and pronounced anomalous inward rectification. Types III and IV of neurons fired regularly, whereas type IV displayed no prominent spike frequency adaptation. Additionally, interneurons of all five types contained mRNA of glutamic acid decarboxylase 65 and cholecystokinin, whereas only type I interneurons were somatostatin-positive. Overall, these data represent a detailed and reliable classification scheme of LA GABAergic interneurons and will provide a feasible basis for subsequent functional studies.

scholarly journals Humoral Autoimmunity against the Extracellular Domain of the Neuroendocrine Autoantigen IA-2 Heightens the Risk of Type 1 Diabetes

Endocrinology ◽  
2010 ◽  
Vol 151 (6) ◽  
pp. 2528-2537 ◽  
Author(s):  
Michael P. Morran ◽  
Anna Casu ◽  
Vincent C. Arena ◽  
Susan Pietropaolo ◽  
Ying-Jian Zhang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Type 1 Diabetes ◽  
Glutamic Acid ◽  
Glutamic Acid Decarboxylase ◽  
Extracellular Domain ◽  
Full Length ◽  
Antigenic Determinants ◽  
Acid Decarboxylase ◽  
Glutamic Acid Decarboxylase 65

The objective of this study was to determine whether antigenic determinants localized within the extracellular domain of the neuroendocrine autoantigen tyrosine phosphatase-like protein IA-2 are targets of humoral responses in type 1 diabetes (T1DM). Previous studies indicated that the immunodominant region of IA-2 is localized within its intracellular domain (IA-2ic; amino acids 601–979). We analyzed 333 subjects from the Children’s Hospital of Pittsburgh study, 102 of whom progressed to insulin-requiring diabetes (prediabetics). Autoantibodies from these individuals were initially assayed for ICA512bdc (Barbara Davis Center amino acids 257–556; 630–979), IA-2ic (amino acids 601–979), and IA-2 full-length (amino acids 1–979) in addition to islet cell antibody (ICA), glutamic acid decarboxylase, 65-kDa isoform, and insulin autoantibodies. We identified an autoantibody response reactive with the extracellular domain of IA-2 that is associated with very high risk of T1DM progression. Relatives with no detectable autoantibodies against ICA512bdc (or IA-2ic) exhibited antibody responses against the IA-2 full-length peptide (log rank, P = 0.008). This effect was also observed in first-degree relatives who were positive for glutamic acid decarboxylase, 65–kDa isoform (log rank, P = 0.026) or at least two islet autoantibodies but were negative for ICA512bdc (log rank, P = 0.022). Competitive binding experiments and immunoprecipitation of the IA-2 extracellular domain (amino acid residues 26–577) further lend support for the presence of autoantibodies reactive with new antigenic determinants within the extracellular domain of IA-2. In summary, the addition of measurements of autoantibodies reactive with the IA-2 extracellular domain to assays geared to assess the progression of autoimmunity to clinical T1DM may more accurately characterize this risk. This has considerable implications not only for stratifying high diabetes risk but also facilitating the search for pathogenic epitopes to enable the design of peptide-based immunotherapies that may prevent the progression to overt T1DM at its preclinical stages.

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