Mutations in the genes for PINK1 and parkin cause Parkinson's disease. PINK1 and parkin cooperate in the selective autophagic degradation of damaged mitochondria (mitophagy) in cultured cells. ...However, evidence for their role in mitophagy in vivo is still scarce. Here, we generated a
model expressing the mitophagy probe mt-Keima. Using live mt-Keima imaging and correlative light and electron microscopy (CLEM), we show that mitophagy occurs in muscle cells and dopaminergic neurons in vivo, even in the absence of exogenous mitochondrial toxins. Mitophagy increases with aging, and this age-dependent rise is abrogated by PINK1 or parkin deficiency. Knockdown of the
homologues of the deubiquitinases USP15 and, to a lesser extent, USP30, rescues mitophagy in the parkin-deficient flies. These data demonstrate a crucial role for parkin and PINK1 in age-dependent mitophagy in
in vivo.
Parkinson disease (PD) is a disabling, incurable disorder with increasing prevalence in the western world. In rare cases PD is caused by mutations in the genes for PINK1 (PTEN induced kinase 1) or ...PRKN (parkin RBR E3 ubiquitin protein ligase), which impair the selective autophagic elimination of damaged mitochondria (mitophagy). Mutations in the gene encoding LRRK2 (leucine rich repeat kinase 2) are the most common monogenic cause of PD. Here, we report that the LRRK2 kinase substrate RAB10 accumulates on depolarized mitochondria in a PINK1- and PRKN-dependent manner. RAB10 binds the autophagy receptor OPTN (optineurin), promotes OPTN accumulation on depolarized mitochondria and facilitates mitophagy. In PD patients with the two most common LRRK2 mutations (G2019S and R1441C), RAB10 phosphorylation at threonine 73 is enhanced, while RAB10 interaction with OPTN, accumulation of RAB10 and OPTN on depolarized mitochondria, depolarization-induced mitophagy and mitochondrial function are all impaired. These defects in LRRK2 mutant patient cells are rescued by LRRK2 knockdown and LRRK2 kinase inhibition. A phosphomimetic RAB10 mutant showed less OPTN interaction and less translocation to depolarized mitochondria than wild-type RAB10, and failed to rescue mitophagy in LRRK2 mutant cells. These data connect LRRK2 with PINK1- and PRKN-mediated mitophagy via its substrate RAB10, and indicate that the pathogenic effects of mutations in LRRK2, PINK1 and PRKN may converge on a common pathway.
Abbreviations : ACTB: actin beta; ATP5F1B: ATP synthase F1 subunit beta; CALCOCO2: calcium binding and coiled-coil domain 2; CCCP: carbonyl cyanide m-chlorophenylhydrazone; Co-IP: co-immunoprecipitation; EBSS: Earle's balanced salt solution; GFP: green fluorescent protein; HSPD1: heat shock protein family D (Hsp60) member 1; LAMP1: lysosomal associated membrane protein 1; LRRK2: leucine rich repeat kinase 2; IF: immunofluorescence; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MFN2: mitofusin 2; OMM: outer mitochondrial membrane; OPTN: optineurin; PD: Parkinson disease; PINK1: PTEN induced kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; RHOT1: ras homolog family member T1; ROS: reactive oxygen species; TBK1: TANK binding kinase 1; WB: western blot.
For decades, when contrast agents are administrated, physicians have been concerned because of the risk of inducing acute kidney injury (AKI). Recent literature questions the existence of AKI induced ...by contrast, but animal studies clearly showed harmful effects. The occurrence of contrast-associated AKI was likely overestimated in the past because of confounders for AKI. Several strategies have been investigated to reduce contrast-associated AKI but even for the most important one, hydration, there are conflicting data. Even if the occurrence rate of contrast-associated AKI is low, AKI is related to worse outcomes. Therefore, besides limiting contrast agent usage, general AKI preventive measurements should be applied in at-risk patients.
The clinical associations of glycine receptor antibodies have not yet been described fully. We identified prospectively 52 antibody-positive patients and collated their clinical features, ...investigations and immunotherapy responses. Serum glycine receptor antibody endpoint titres ranged from 1:20 to 1:60 000. In 11 paired samples, serum levels were higher than (n = 10) or equal to (n = 1) cerebrospinal fluid levels; there was intrathecal synthesis of glycine receptor antibodies in each of the six pairs available for detailed study. Four patients also had high glutamic acid decarboxylase antibodies (>1000 U/ml), and one had high voltage-gated potassium channel-complex antibody (2442 pM). Seven patients with very low titres (<1:50) and unknown or alternative diagnoses were excluded from further study. Three of the remaining 45 patients had newly-identified thymomas and one had a lymphoma. Thirty-three patients were classified as progressive encephalomyelitis with rigidity and myoclonus, and two as stiff person syndrome; five had a limbic encephalitis or epileptic encephalopathy, two had brainstem features mainly, two had demyelinating optic neuropathies and one had an unclear diagnosis. Four patients (9%) died during the acute disease, but most showed marked improvement with immunotherapies. At most recent follow-up, (2-7 years, median 3 years, since first antibody detection), the median modified Rankin scale scores (excluding the four deaths) decreased from 5 at maximal severity to 1 (P < 0.0001), but relapses have occurred in five patients and a proportion are on reducing steroids or other maintenance immunotherapies as well as symptomatic treatments. The glycine receptor antibodies activated complement on glycine receptor-transfected human embryonic kidney cells at room temperature, and caused internalization and lysosomal degradation of the glycine receptors at 37°C. Immunoglobulin G antibodies bound to rodent spinal cord and brainstem co-localizing with monoclonal antibodies to glycine receptor-α1. Ten glycine receptor antibody positive samples were also identified in a retrospective cohort of 56 patients with stiff person syndrome and related syndromes. Glycine receptor antibodies are strongly associated with spinal and brainstem disorders, and the majority of patients have progressive encephalomyelitis with rigidity and myoclonus. The antibodies demonstrate in vitro evidence of pathogenicity and the patients respond well to immunotherapies, contrasting with earlier studies of this syndrome, which indicated a poor prognosis. The presence of glycine receptor antibodies should help to identify a disease that responds to immunotherapies, but these treatments may need to be sustained, relapses can occur and maintenance immunosuppression may be required.
Exaggerated activity in the beta band (13–35 Hz) is a hallmark of basal ganglia signals in patients with Parkinson's disease (PD). Beta activity however is not constantly elevated, but comes in ...bursts. In previous work we showed that the longer beta bursts are maintained, the more the oscillatory synchronisation within the subthalamic nucleus (STN) increases, which is posited to limit the information coding capacity of local circuits. Accordingly, a higher incidence of longer bursts correlates positively with clinical impairment, while the opposite is true for short, more physiological bursts. Here, we test the hypothesis that beta bursts not only indicate local synchronisation within the STN, but also phasic coupling across the motor network and hence entail an even greater restriction of information coding capacity in patients with PD. Local field potentials from the subthalamic nucleus and EEG over the motor cortex area were recorded in nine PD patients after temporary lead externalization after surgery for deep brain stimulation and overnight withdrawal of levodopa. Beta bursts were defined as periods exceeding the 75th percentile of signal amplitude and the coupling between bursts was considered using two distinct measurements, first the % overlapping (%OVL) as a feature of the amplitude coupling and secondly the phase synchrony index (PSI) to measure the phase coupling between regions. %OVL between STN and cortex and between the left and the right STN was higher than expected between the regions than if they had been independent. Similarly, PSI was higher during bursts as opposed to non-bursts periods. In addition, %OVL was greater for long compared to short bursts. Our results support the hypothesis that beta bursts involve long-range coupling between structures in the basal ganglia-cortical network. The impact of this is greater during long as opposed to short duration beta bursts. Accordingly, we posit that episodes of simultaneously elevated coupling across multiple structures in the basal ganglia-cortical circuit further limit information coding capacity and may have further impact upon motor impairment.
•Beta bursts are coupled across the basal-ganglia-cortical circuit•Phase coupling is greater during as opposed to outside of beta bursts•Pathological long beta bursts involve more long range synchronisation•Exaggerated circuit synchronisation may impact motor symptoms
Symmetric biphasic pulses have been shown to increase the therapeutic window compared to standard cathodic pulses in ET Vim-DBS patients. Furthermore, three hours of stimulation with biphasic pulses ...caused less stimulation-induced ataxia compared to cathodic pulses. Therefore, an investigation of the longer-term safety of biphasic pulses is warranted.
Seven ET patients were included in a randomized double-blind, cross-over design of one week home-use of symmetric biphasic stimulation (anodic phase first) versus cathodic stimulation. Amplitude was set in a double-blinded way, at the tremor arrest threshold. The primary outcome was safety assessed by documenting the adverse events. Secondary outcome parameters were stimulation amplitude, tremor (Fahn-Tolosa-Marin Tremor Rating Scale) and ataxia (International Cooperative Ataxia Rating Scale) severity, quality of life (Quality of Life in Essential Tremor Questionnaire) and cognition (Montreal Cognitive Assessment). Three patients continued in the open-label extension phase for 3 months, during which biphasic stimulation-only was further assessed by the same outcome parameters.
During the 1 week testing, no adverse effects were reported. To obtain equivalent tremor control, the amplitude of the biphasic pulse was significantly higher compared to that of the cathodic pulse (
= 0.003). The other outcome parameters were not significantly different. During the open-label study, one patient used the remote control to increase the amplitude, leading to two falls caused by stimulation-induced ataxia. No other adverse effects occurred.
In a small cohort, when tested for one week, symmetric biphasic pulses suggest to be safe, but require higher stimulation amplitudes. Further follow-up studies are needed to investigate long-term effects and safety.
The T61I mutation in coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2), a protein residing in the mitochondrial intermembrane space (IMS), causes an autosomal dominant form of ...Parkinson's disease (PD), but the underlying pathogenic mechanisms are not well understood. Here, we compared the subcellular localization and solubility of wild-type (WT) and T61I mutant CHCHD2 in human cells. We found that mitochondrial targeting of both WT and T61I CHCHD2 depended on the four cysteine residues in the C-terminal coiled-coil-helix-coiled-coil-helix (CHCH) domain but not on the N-terminal predicted mitochondrial targeting sequence. The T61I mutation did not interfere with mitochondrial targeting of the mutant protein but induced its precipitation in the IMS. Moreover, T61I CHCHD2 induced increased mitochondrial production of reactive oxygen species and apoptosis, which was prevented by treatment with anti-oxidants. Retention of T61I CHCHD2 in the cytosol through mutation of the cysteine residues in the CHCH domain prevented its precipitation as well as its apoptosis-inducing effect. Importantly, T61I CHCHD2 potently impaired the solubility of WT CHCHD2. In conclusion, our data show that the T61I mutation renders mutant CHCHD2 insoluble inside mitochondria, suggesting loss of function of the mutant protein. In addition, T61I CHCHD2 exerts a dominant-negative effect on the solubility of WT CHCHD2, explaining the dominant inheritance of this form of PD.
Abstract
Background
Acute kidney injury (AKI) has been reported as a frequent complication of critical COVID-19. We aimed to evaluate the occurrence of AKI and use of kidney replacement therapy (KRT) ...in critical COVID-19, to assess patient and kidney outcomes and risk factors for AKI and differences in outcome when the diagnosis of AKI is based on urine output (UO) or on serum creatinine (sCr).
Methods
Multicenter, retrospective cohort analysis of patients with critical COVID-19 in seven large hospitals in Belgium. AKI was defined according to KDIGO within 21 days after ICU admission. Multivariable logistic regression analysis was used to explore the risk factors for developing AKI and to assess the association between AKI and ICU mortality.
Results
Of 1286 patients, 85.1% had AKI, and KRT was used in 9.8%. Older age, obesity, a higher APACHE II score and use of mechanical ventilation at day 1 of ICU stay were associated with an increased risk for AKI. After multivariable adjustment, all AKI stages were associated with ICU mortality. AKI was based on sCr in 40.1% and UO in 81.5% of patients. All AKI stages based on sCr and AKI stage 3 based on UO were associated with ICU mortality. Persistent AKI was present in 88.6% and acute kidney disease (AKD) in 87.6%. Rapid reversal of AKI yielded a better prognosis compared to persistent AKI and AKD. Kidney recovery was observed in 47.4% of surviving AKI patients.
Conclusions
Over 80% of critically ill COVID-19 patients had AKI. This was driven by the high occurrence rate of AKI defined by UO criteria. All AKI stages were associated with mortality (NCT04997915).
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