PARK2 patient neuroprogenitors show increased mitochondrial sensitivity to copper

Abstract

Poorly-defined interactions between environmental and genetic risk factors underlie Parkinson’s disease (PD) etiology. Here we tested the hypothesis that human stem cell derived forebrain neuroprogenitors from patients with known familial risk for early onset PD will exhibit enhanced sensitivity to PD environmental risk factors compared to healthy control subjects without a family history of PD. Two male siblings (SM and PM) with biallelic loss-of-function mutations in PARK2 were identified. Human induced pluripotent stem cells (hiPSCs) from SM, PM, and four control subjects with no known family histories of PD or related neurodegenerative diseases were utilized. We tested the hypothesis that hiPSC-derived neuroprogenitors from patients with PARK2 mutations would show heightened cell death, mitochondrial dysfunction, and reactive oxygen species generation compared to control cells as a result of exposure to heavy metals (PD environmental risk factors). We report that PARK2 mutant neuroprogenitors showed increased cytotoxicity with copper (Cu) and cadmium (Cd) exposure but not manganese (Mn) or methyl mercury (MeHg) relative to control neuroprogenitors. PARK2 mutant neuroprogenitors also showed a substantial increase in mitochondrial fragmentation, initial ROS generation, and loss of mitochondrial membrane potential following Cu exposure. Our data substantiate Cu exposure as an environmental risk factor for PD. Furthermore, we report a shift in the lowest observable effect level (LOEL) for greater sensitivity to Cu-dependent mitochondrial dysfunction in patients SM and PM relative to controls, correlating with their increased genetic risk for PD.

Combinatorial polymer matrices enhance in vitro maturation of human induced pluripotent stem cell-derived cardiomyocytes

“…S1a and S1b). [19, 23] The absence of episomal vector genomic integration was confirmed by PCR (data not shown). Immunostaining for pluripotency markers used the following antibodies; OCT4 (mouse monoclonal, Millipore), NANOG (affinity purified anti-goat IgG), and SSEA4 (rabbit monoclonal, Millipore) (Fig.…”

“…S2a). [19–21] Direct differentiation of these iPSCs cultured on Matrigel, outlined in Fig. S2b, successfully yielded iPSC-CMs.…”

“…[19–21] Maintenance and culture of human iPSCs followed our established methods. [19–22] Pluripotency was validated by PluriTest, a bioinformatics assay,[23] using a teratoma-validated line as a positive control, and normal chromosomal karyotype was confirmed (Genetic Associates, Nashville TN) as previously described (Fig. S1a and S1b).…”

Gut microbiome in health and disease: Linking the microbiome–gut–brain axis and environmental factors in the pathogenesis of systemic and neurodegenerative diseases

“…During the last few years, a number of epidemiological and clinical studies have suggested potential environmental risk factors for PD, including environmental exposure to certain pesticides and fungicides such as paraquat, rotenone and maneb, and some surrogate factors such as living in rural areas, drinking well water and farming. In addition, exposure to heavy metals such as iron, lead, mercury, cadmium, arsenic and manganese, as well as to metal-based nanoparticles, has also been shown to increase the risk of PD through the accumulation of metals in the mid brain and increased oxidative stress-mediated apoptosis (Aboud, et al, 2014; Afeseh Ngwa, et al, 2009; Afeseh Ngwa, et al, 2011; Harischandra, Jin, Anantharam, Kanthasamy, & Kanthasamy, 2015; Kanthasamy, et al, 2012; Milatovic, Zaja-Milatovic, Gupta, Yu, & Aschner, 2009). Currently, the effect of environmental factors on the host gut microbiome is completely unknown.…”

Metals and neurodegeneration

“…The study concludes that this synergism induces cell death via the perturbation of the ubiquitin-proteasome and autophagic systems, albeit independently from protein aggregation. The study from Aboud et al (2014) explores the synergism between complete loss-of-function of parkin caused by homozygous mutations in the PARK2 gene and exposure to metals. The rationale of the approach stems from the incomplete penetrance of PARK2 loss-of-function mutations, which causes high intra-familial and inter-familial variability in ages of onset, and therefore reinforces the role of environmental exposure in eliciting pathogenesis.…”