Pathogenic LRRK2 mutations, through increased kinase activity, produce enlarged lysosomes with reduced degradative capacity and increase ATP13A2 expression

Abstract

Lysosomal dysfunction plays a central role in the pathogenesis of several neurodegenerative disorders, including Parkinson's disease (PD). Several genes linked to genetic forms of PD, including leucine-rich repeat kinase 2 (LRRK2), functionally converge on the lysosomal system. While mutations in LRRK2 are commonly associated with autosomal-dominant PD, the physiological and pathological functions of this kinase remain poorly understood. Here, we demonstrate that LRRK2 regulates lysosome size, number and function in astrocytes, which endogenously express high levels of LRRK2. Expression of LRRK2 G2019S, the most common pathological mutation, produces enlarged lysosomes and diminishes the lysosomal capacity of these cells. Enlarged lysosomes appears to be a common phenotype associated with pathogenic LRRK2 mutations, as we also observed this effect in cells expressing other LRRK2 mutations; R1441C or Y1699C. The lysosomal defects associated with these mutations are dependent on both the catalytic activity of the kinase and autophosphorylation of LRRK2 at serine 1292. Further, we demonstrate that blocking LRRK2's kinase activity, with the potent and selective inhibitor PF-06447475, rescues the observed defects in lysosomal morphology and function. The present study also establishes that G2019S mutation leads to a reduction in lysosomal pH and increased expression of the lysosomal ATPase ATP13A2, a gene linked to a parkinsonian syndrome (Kufor-Rakeb syndrome), in brain samples from mouse and human LRRK2 G2019S carriers. Together, these results demonstrate that PD-associated LRRK2 mutations perturb lysosome function in a kinase-dependent manner, highlighting the therapeutic promise of LRRK2 kinase inhibitors in the treatment of PD.

Disorders of lysosomal acidification—The emerging role of v-ATPase in aging and neurodegenerative disease

“…The most common pathological mutation of LRRK2 (G2019S) causes a phenotype exhibiting lysosomal expansion and diminished lysosomal degradation of substrate. This phenotype is dependent on the catalytic activity of LRRK2 (Henry et al, 2015). The G2019S mutation also leads to decreased lysosomal pH and impaired cathepsin function, as well as increased expression of the lysosomal ATPase ATP13A2 in brains from mouse and human LRRK2 G2019S carriers (Henry et al, 2015), possibly as a compensatory response.…”

“…This phenotype is dependent on the catalytic activity of LRRK2 (Henry et al, 2015). The G2019S mutation also leads to decreased lysosomal pH and impaired cathepsin function, as well as increased expression of the lysosomal ATPase ATP13A2 in brains from mouse and human LRRK2 G2019S carriers (Henry et al, 2015), possibly as a compensatory response. Notably, in a c. elegans tauopathy model, LRRK2 mutations lead to HNE modification of the subunits V1A and V1B of v-ATPase (Di Domenico et al, 2012), reminiscent of the oxidative modifications of v-ATPase in AD and DS.…”

Achieving neuroprotection with LRRK2 kinase inhibitors in Parkinson disease

“…It is important to note that while the pSer935 site may reflect LRRK2 kinase inhibition, it is an indirect measure of LRRK2 kinase activity and expected phosphorylation of substrates. So far in model systems, pSer935 has mirrored the dephosphorylation of the LRRK2 substrate pSer1292 and pRab (Fraser et al, 2016a; Henry et al, 2015; Steger et al, 2016). …”

68 and FX2149 Attenuate Mutant LRRK2-R1441C-Induced Neural Transport Impairment

“…Mutant LRRK2 has been shown to cause lysosome/autophagic pathway impairment (Alegre-Abarrategui and Wade-Martins, 2009; Henry et al, 2015; Esteves and Cardoso, 2016). A recent study has identified that LRRK2 mutations lead to an increase in lysosomal size and a decrease in their ability for degradation (Bandyopadhyay et al, 2014), as well as impairs the autophagic cycle's ability to clear toxic proteins (Alegre-Abarrategui and Wade-Martins, 2009; Esteves and Cardoso, 2016).…”