2016
Metallomics. 2016 Jun 13.
Characterizing the molecular phenotype of an Atp7aT985I conditional knock in mouse model for X-linked distal hereditary motor neuropathy (dHMNX).
ANZAC Research Institute, Concord, NSW, Australia. University of Sydney, Sydney, NSW, Australia. School of Life and Environmental Sciences, Deakin University, Burwood, VIC, Australia. The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia. University of Miami Miller School of Medicine, Miami, FL, USA. Sarah Network Rehabilitation Hospitals, Brasilia, DF, Brazil. Concord Hospital, Concord, NSW, Australia.
Service type: Knock-in mice
Abstract
ATP7A is a P-type ATPase essential for cellular copper (Cu) transport and homeostasis. Loss-of-function ATP7A mutations causing systemic Cu deficiency are associated with severe Menkes disease or its milder allelic variant, occipital horn syndrome. We previously identified two rare ATP7A missense mutations (P1386S and T994I) leading to a non-fatal form of motor neuron disorder, X-linked distal hereditary motor neuropathy (dHMNX), without overt signs of systemic Cu deficiency. Recent investigations using a tissue specific Atp7a knock out model have demonstrated that Cu plays an essential role in motor neuron maintenance and function, however the underlying pathogenic mechanisms of ATP7A mutations causing axonal degeneration remain unknown. We have generated an Atp7a conditional knock in mouse model of dHMNX expressing Atp7aT985I, the orthologue of the human ATP7AT994I identified in dHMNX patients. Although a degenerative motor phenotype is not observed, the knock in Atp7aT985I/Y mice show altered Cu levels within the peripheral and central nervous systems, an increased diameter of the muscle fibres and altered myogenin and myostatin gene expression. Atp7aT985I/Y mice have reduced Atp7a protein levels and recapitulate the defective trafficking and altered post-translational regulatory mechanisms observed in the human ATP7AT994I patient fibroblasts. Our model provides a unique opportunity to characterise the molecular phenotype of dHMNX and the time course of cellular events leading to the process of axonal degeneration in this disease.
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