title: Opening/blocking actions of pyruvate kinase antibodies on neuronal and muscular KATP channels.
abstract: ATP-sensitive-K(+) (KATP) channels couple metabolism to the electrical activity of the cells. This channel is associated with glycolytic enzymes to form complexes regulating the channel activity in various tissues. The pyruvate-kinase (PK) enzyme is an antigen in the Paediatric Autoimmune Neuropsychiatric Disorders Associated Streptococcal infection known as PANDAS which is characterized by an abnormal production of auto-antibodies against PK. Here, the effects of the anti-pyruvate kinase antibody (anti-PK-ab) on the muscle and neuronal KATP channels were investigated in native rat skeletal muscle fibres and human neuroblastoma cell-line (SH-SY5Y), respectively. Furthermore, the interaction of PK with the inwardly rectifier potassium channel (Kir6.1/Kir6.2) subunits of the KATP channels was investigated by co-immunoprecipitation experiments in mouse brain using the anti-PK-ab. Patch-clamp experiments showed that the short-term incubation (1h) of the fibres with the anti-PK-ab at the dilutions of 1:500 and 1:300 enhanced the KATP current of 19.6% and 33.5%, respectively. As opposite, the long-term incubation (24h) of the fibres with the anti-PK-ab at the dilutions of 1:500 and 1:300 reduced the KATP current of 16% and 24%, respectively, reducing the diameter with atrophy. The direct application of the anti-PK-ab to the excised patches in the absence of intracellular ATP caused channel block, while in the presence of nucleotide channel opened. In neuronal cell line, in the short-term the anti-PK-ab potentiated KATP currents without affecting survival, while in the long-term the anti-PK-ab reduced KATP currents inducing neuronal death. Opening/blocking actions of the anti-PK antibodies on the KATP channels were observed, the blocking action causes fibre atrophy and neuronal death. We demonstrated that PK and Kir subunits are physically/functionally coupled in neurons. The KATP/PK complex can be proposed a novel target in the autoimmune diseases associated with anti-PK production as in PANDAS.
authors.affiliation: Unit of Pharmacology, Department of Pharmacy, via Orabona no. 4, University of Bari, I-70126 Bari, Italy.
authors.forename: Antonietta
authors.initials: A
authors.lastname: Mele
authors.forename: Maura
authors.initials: M
authors.lastname: Buttiglione
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Cannone
authors.forename: Francesco
authors.initials: F
authors.lastname: Vitiello
authors.forename: Diana Conte
authors.initials: DC
authors.lastname: Camerino
authors.forename: Domenico
authors.initials: D
authors.lastname: Tricarico
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D001921:Brain / Q000502:physiology; D045744:Cell Line, Tumor; D006801:Humans; D054086:KATP Channels / Q000502:physiology*; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D011770:Pyruvate Kinase / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000906:Antibodies; D054086:KATP Channels; D011770:Pyruvate Kinase