Rabbit Anti-Human COLQ (a.a. 301-400) Polyclonal antibody

The beta-adrenergic agonists salbutamol and ephedrine have proven to be effective as therapies for human disorders of the neuromuscular junction, in particular many subsets of congenital myasthenic syndromes. However, the mechanisms underlying this clinical benefit are unknown and improved understanding of the effect of adrenergic signalling on the neuromuscular junction is essential to facilitate the development of more targeted therapies. Here, we investigated the effect of salbutamol treatment on the neuromuscular junction in the ColQ deficient mouse, a model of end-plate acetylcholinesterase deficiency. ColQ(-/-) mice received 7 weeks of daily salbutamol injection, and the effect on muscle strength and neuromuscular junction morphology was analysed. We show that salbutamol leads to a gradual improvement in muscle strength in ColQ(-/-) mice. In addition, the neuromuscular junctions of salbutamol treated mice showed significant improvements in several postsynaptic morphological defects, including increased synaptic area, acetylcholine receptor area and density, and extent of postjunctional folds. These changes occurred without alterations in skeletal muscle fibre size or type. These findings suggest that beta-adrenergic agonists lead to functional benefit in the ColQ(-/-) mouse and to long-term structural changes at the neuromuscular junction. These effects are primarily at the postsynaptic membrane and may lead to enhanced neuromuscular transmission.

The presence of a collagenous protein ( ColQ) characterizes the collagen-tailed forms of acetylcholinesterase and butyrylcholinesterase at vertebrate neuromuscular junctions which is tethered in the synaptic basal lamina. ColQ subunits, differing mostly by their signal sequences, are encoded by transcripts ColQ-1 and ColQ-1a, which are differentially expressed in slow and fast twitch muscles in mammals. Two distinct promoters, pColQ-1 and pColQ-1a, were isolated from the upstream sequences of human COLQ gene; they showed muscle-specific expression and were activated by myogenic transcriptional elements in cultured myotubes. After in vivo DNA transfection, pColQ-1 showed strong activity in slow twitch muscle ( e. g. soleus), whereas pColQ-1a was preferably expressed in fast twitch muscle ( e. g. tibialis). Mutation analysis of the ColQ promoters suggested that the muscle fiber type-specific expression pattern of ColQ transcripts were regulated by a slow upsteam regulatory element ( SURE) and a fast intronic regulatory element ( FIRE). These regulatory elements were responsive to a calcium ionophore and to calcineurin inhibition by cyclosporine A. The slow fiber type-specific expression of ColQ-1 was abolished by the mutation of an NFAT element in pColQ-1. Moreover, both the ColQ promoters contained N-box element that was responsible for the synapse-specific expression of ColQ transcripts. These results explain the specific expression patterns of collagen-tailed acetylcholinesterase in slow and fast muscle fibers.