Comparative Transcriptomic Analysis of Cerebellar Astrocytes across Developmental Stages and Brain Regions.

Astrocytes are the most abundant glial cell type in the central nervous system, and they play a crucial role in normal brain function. While gliogenesis and glial differentiation occur during perinatal cerebellar development, the processes that occur during early postnatal development remain obscure. In this study, we conducted transcriptomic profiling of postnatal cerebellar astrocytes at postnatal days 1, 7, 14, and 28 (P1, P7, P14, and P28), identifying temporal-specific gene signatures at each specific time point. Comparing these profiles with region-specific astrocyte differentially expressed genes (DEGs) published for the cortex, hippocampus, and olfactory bulb revealed cerebellar-specific gene signature across these developmental timepoints. Moreover, we conducted a comparative analysis of cerebellar astrocyte gene signatures with gene lists from pediatric brain tumors of cerebellar origin, including ependymoma and medulloblastoma. Notably, genes downregulated at P14, such as Kif11 and HMGB2, exhibited significant enrichment across all pediatric brain tumor groups, suggesting the importance of astrocytic gene repression during cerebellar development to these tumor subtypes. Collectively, our studies describe gene expression patterns during cerebellar astrocyte development, with potential implications for pediatric tumors originating in the cerebellum.

Integrative Korean Medicine Treatments for Traumatic Facial Palsy Following Mandibular Fracture: A Case Report and Literature Review.

Prior studies exploring the effectiveness of traditional Korean medicine (TKM) treatment for facial palsy have mainly focused on Bell's palsy, and there are few studies on the effectiveness of TKM treatments for traumatic facial palsy following mandibular fracture. The patient was a 24-year-old Korean man with left-sided facial paralysis following a left mandibular fracture. Surgery was performed for the fracture and the facial palsy was treated using conventional medicine (CM) treatments for approximately 3 months, but there was no improvement observed in the patient's condition. Subsequently, the patient underwent an integrative Korean medicine treatment regimen consisting of acupuncture, pharmacopuncture, cupping, moxibustion, and herbal medication for a duration of 2 months. After 2 months of treatments, the House-Brackmann facial grading scale changed from Ⅴ to II and Yanagihara's unweighted grading score increased from 9 to 34. This case presentation and previous studies of traumatic facial palsy using TKM treatment show that TKM treatment may be considered a complementary or alternative treatment method to CM treatment in patients with traumatic facial palsy. PROSPERO registration number: CRD42023445051.

Induction of astrocytic Slc22a3 regulates sensory processing through histone serotonylation.

Neuronal activity drives alterations in gene expression within neurons, yet how it directs transcriptional and epigenomic changes in neighboring astrocytes in functioning circuits is unknown. We found that neuronal activity induces widespread transcriptional up-regulation and down-regulation in astrocytes, highlighted by the identification of Slc22a3 as an activity-inducible astrocyte gene that encodes neuromodulator transporter Slc22a3 and regulates sensory processing in the mouse olfactory bulb. Loss of astrocytic Slc22a3 reduced serotonin levels in astrocytes, leading to alterations in histone serotonylation. Inhibition of histone serotonylation in astrocytes reduced the expression of γ-aminobutyric acid (GABA) biosynthetic genes and GABA release, culminating in olfactory deficits. Our study reveals that neuronal activity orchestrates transcriptional and epigenomic responses in astrocytes while illustrating new mechanisms for how astrocytes process neuromodulatory input to gate neurotransmitter release for sensory processing.

The genomic landscape of familial glioma.

Glioma is a rare brain tumor with a poor prognosis. Familial glioma is a subset of glioma with a strong genetic predisposition that accounts for approximately 5% of glioma cases. We performed whole-genome sequencing on an exploratory cohort of 203 individuals from 189 families with a history of familial glioma and an additional validation cohort of 122 individuals from 115 families. We found significant enrichment of rare deleterious variants of seven genes in both cohorts, and the most significantly enriched gene was HERC2 (P = 0.0006). Furthermore, we identified rare noncoding variants in both cohorts that were predicted to affect transcription factor binding sites or cause cryptic splicing. Last, we selected a subset of discovered genes for validation by CRISPR knockdown screening and found that DMBT1, HP1BP3, and ZCH7B3 have profound impacts on proliferation. This study performs comprehensive surveillance of the genomic landscape of familial glioma.

Activity-dependent induction of astrocytic Slc22a3 regulates sensory processing through histone serotonylation.

Neuronal activity drives global alterations in gene expression within neurons, yet how it directs transcriptional and epigenomic changes in neighboring astrocytes in functioning circuits is unknown. Here we show that neuronal activity induces widespread transcriptional upregulation and downregulation in astrocytes, highlighted by the identification of a neuromodulator transporter Slc22a3 as an activity-inducible astrocyte gene regulating sensory processing in the olfactory bulb. Loss of astrocytic Slc22a3 reduces serotonin levels in astrocytes, leading to alterations in histone serotonylation. Inhibition of histone serotonylation in astrocytes reduces expression of GABA biosynthetic genes and GABA release, culminating in olfactory deficits. Our study reveals that neuronal activity orchestrates transcriptional and epigenomic responses in astrocytes, while illustrating new mechanisms for how astrocytes process neuromodulatory input to gate neurotransmitter release for sensory processing.

The current status and outcomes of in-hospital P2Y12 receptor inhibitor switching in Korean patients with acute myocardial infarction.

BACKGROUND/AIMS: While switching strategies of P2Y12 receptor inhibitors (RIs) have sometimes been used in acute myocardial infarction (AMI) patients, the current status of in-hospital P2Y12RI switching remains unknown. METHODS: Overall, 8,476 AMI patients who underwent successful revascularization from Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH) were divided according to in-hospital P2Y12RI strategies, and net adverse cardiovascular events (NACEs), defined as a composite of cardiac death, non-fatal myocardial infarction (MI), stroke, or thrombolysis in myocardial infarction (TIMI) major bleeding during hospitalization were compared. RESULTS: Patients with in-hospital P2Y12RI switching accounted for 16.5%, of which 867 patients were switched from clopidogrel to potent P2Y12RI (C-P) and 532 patients from potent P2Y12RI to clopidogrel (P-C). There were no differences in NACEs among the unchanged clopidogrel, the unchanged potent P2Y12RIs, and the P2Y12RI switching groups. However, compared to the unchanged clopidogrel group, the C-P group had a higher incidence of non-fatal MI, and the P-C group had a higher incidence of TIMI major bleeding. In clinical events of in-hospital P2Y12RI switching, 90.9% of non-fatal MI occurred during pre-switching clopidogrel administration, 60.7% of TIMI major bleeding was related to pre-switching P2Y12RIs, and 71.4% of TIMI major bleeding was related to potent P2Y12RIs. Only 21.6% of the P2Y12RI switching group switched to P2Y12RIs after a loading dose (LD); however, there were no differences in clinical events between patients with and without LD. CONCLUSION: In-hospital P2Y12RI switching occurred occasionally, but had relatively similar clinical outcomes compared to unchanged P2Y12RIs in Korean AMI patients. Non-fatal MI and bleeding appeared to be mainly related to pre-switching P2Y12RIs.

Kir4.1 is coexpressed with stemness markers in activated astrocytes in the injured brain and a Kir4.1 inhibitor BaCl2 negatively regulates neurosphere formation in culture.

Astrocytes are activated in response to brain damage. Here, we found that expression of Kir4.1, a major potassium channel in astrocytes, is increased in activated astrocytes in the injured brain together with upregulation of the neural stem cell markers, Sox2 and Nestin. Expression of Kir4.1 was also increased together with that of Nestin and Sox2 in neurospheres formed from dissociated P7 mouse brains. Using the Kir4.1 blocker BaCl2 to determine whether Kir4.1 is involved in acquisition of stemness, we found that inhibition of Kir4.1 activity caused a concentration-dependent increase in sphere size and Sox2 levels, but had little effect on Nestin levels. Moreover, induction of differentiation of cultured neural stem cells by withdrawing epidermal growth factor and fibroblast growth factor from the culture medium caused a sharp initial increase in Kir4.1 expression followed by a decrease, whereas Sox2 and Nestin levels continuously decreased. Inhibition of Kir4.1 had no effect on expression levels of Sox2 or Nestin, or the astrocyte and neuron markers glial fibrillary acidic protein and ß-tubulin III, respectively. Taken together, these results indicate that Kir4.1 may control gain of stemness but not differentiation of stem cells.

Critical roles of astrocytic-CCL2-dependent monocyte infiltration in a DJ-1 knockout mouse model of delayed brain repair.

Monocyte-derived macrophages play a role in the repair of the injured brain. We previously reported that a deficiency of the Parkinson's disease (PD)-associated gene DJ-1 delays repair of brain injury produced by stereotaxic injection of ATP, a component of damage-associated molecular patterns. Here, we show that a DJ-1 deficiency attenuates monocyte infiltration into the damaged brain owing to a decrease in C-C motif chemokine ligand 2 (CCL2) expression in astrocytes. Like DJ-1-knockout (KO) mice, CCL2 receptor (CCR2)-KO mice showed defects in monocyte infiltration and delayed recovery of brain injury, as determined by 9.4 T magnetic resonance imaging analysis and immunostaining for tyrosine hydroxylase and glial fibrillary acid protein. Notably, transcriptome analyses showed that genes related to regeneration and synapse formation were similarly downregulated in injured brains of DJ-1-KO and CCR2-KO mice compared with the injured wild-type brain. These results indicate that defective astrogliosis in DJ-1-KO mice is associated with decreased CCL2 expression and attenuated monocyte infiltration, resulting in delayed repair of brain injury. Thus, delayed repair of brain injury could contribute to the development of PD. MAIN POINTS: A DJ-1 deficiency attenuates infiltration of monocytes owing to a decrease in CCL2 expression in astrocytes, which in turn led to delay in repair of brain injury.

Axonal degeneration in an in vitro model of ischemic white matter injury.

Ischemic white matter injuries underlie cognitive decline in the elderly and vascular dementia. Ischemia in the subcortical white matter is caused by chronic reduction of blood flow due to narrowing of small arterioles. However, it remains unclear how chronic ischemia leads to white matter pathology. We aimed to develop an in vitro model of ischemic white matter injury using organotypic slice cultures. Cultured cerebellar slices preserved fully myelinated white matter tracts that were amenable to chronic hypoxic insult. Prolonged hypoxia caused progressive morphological evidence of axonal degeneration with focal constrictions and swellings. In contrast, myelin sheaths and oligodendrocytes exhibited remarkable resilience to hypoxia. The cytoskeletal degradation of axons was accompanied by mitochondrial shortening and lysosomal activation. Multiple pharmacological manipulations revealed that the AMPA glutamate receptor, calpain proteolysis, and lysosomal proteases were independently implicated in hypoxia-induced axonal degeneration in our model. Thus, our in vitro model would be a novel experimental system to explore molecular mechanisms of ischemic white matter injury. Furthermore, we verified that the in vitro assay could be successfully utilized to screen for molecules that can ameliorate hypoxia/ischemia-induced axonal degeneration.

A Parkinson's disease gene, DJ-1, regulates anti-inflammatory roles of astrocytes through prostaglandin D2 synthase expression.

Dysfunctional regulation of inflammation may contribute to the progression of neurodegenerative diseases. The results of this study revealed that DJ-1, a Parkinson's disease (PD) gene, regulated expression of prostaglandin D2 synthase (PTGDS) and production of prostaglandin D2 (PGD2), by which DJ-1 enhanced anti-inflammatory function of astrocytes. In injured DJ-1 knockout (KO) brain, expression of tumor necrosis factor-alpha (TNF-α) was more increased, but that of anti-inflammatory heme oxygenase-1 (HO-1) was less increased compared with that in injured wild-type (WT) brain. Similarly, astrocyte-conditioned media (ACM) prepared from DJ-1-KO astrocytes less induced HO-1 expression and less inhibited expression of inflammatory mediators in microglia. With respect to the underlying mechanism, we found that PTGDS that induced expression of HO-1 was lower in DJ-1 KO astrocytes and brains compared with their WT counterparts. In addition, PTGDS levels increased in the injured brain of WT mice, but barely in that of KO mice. We also found that DJ-1 regulated PTGDS expression through Sox9. Thus, Sox9 siRNAs reduced PTGDS expression in WT astrocytes, and Sox9 overexpression rescued PTGDS expression in DJ-1 KO astrocytes. In agreement with these results, ACM from Sox9 siRNA-treated astrocytes and that from Sox9-overexpression astrocytes exerted opposite effects on HO-1 expression and anti-inflammation. These findings suggest that DJ-1 positively regulates anti-inflammatory functions of astrocytes, and that DJ-1 dysfunction contributes to the excessive inflammatory response in PD development.

Characterization of Parkinson's disease-related pathogenic TMEM230 mutants.

Parkinson's disease (PD) is the second most common neurodegenerative disease. Although most PD cases are sporadic, 5-10% of them are hereditary and several pathogenic mutations in related genes have been identified. Mutations in TMEM230 were recently identified as a cause of autosomal dominant PD. However, the basic properties of the mutant proteins are not yet known. We examined stability and neurotoxicity, important characteristics of PD pathogenesis-related proteins, of WT TMEM230 and two pathogenic mutants, R78L and PG5ext, in a dopaminergic neuronal cell line. Our study showed that amount of protein expressed in the same vector backbone was R78L > WT > PG5ext. The stabilities of the mutant proteins were similar to each other, but lower than that of the WT. In addition, overexpression of mutants and WT TMEM230 caused similar levels of neurotoxicity upon MPP+ treatment when compared to the cells transfected with an empty vector. Because the proteins encoded by two PD-causing genes, TMEM230 and LRRK2, function in vesicle trafficking, we tested whether they interact. LRRK2 neither interacts with, nor phosphorylates TMEM230. We also investigated the levels of several Rab proteins (Rab1A, 5, 7, 8A and 11) involved in vesicle trafficking after TMEM230 overexpression. However, there was no clear difference of any Rab proteins among cells transfected with an empty vector, TMEM230 WT and mutants-expressing cells, suggesting that TMEM230 does not directly regulate these Rab proteins. Thus, these TMEM230 PG5ext and R78L mutant proteins are not distinctly different from the WT proteins except for their stability. Abbreviations: LRRK2: Leucine-rich repeat kinase 2; PD: Parkinson's disease; AD: Alzheimer's disease; RT-PCR: reverse transcription-polymerase chain reaction; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; FACS: fluorescence-activated cell sorting; PBS: phosphate buffered saline; FBS: fetal bovine serum; PI: propidium iodide.

A Parkinson's disease gene, DJ-1, regulates astrogliosis through STAT3.

In the injured brain, astrocytes become activated and increase GFAP expression; a phenomenon termed as astrogliosis. Previously, we have reported that DJ-1, a Parkinson's disease gene, positively regulates astrogliosis in the injured brain. Moreover, STAT3 is known to play a key role in the regulation of astrogliosis. The purpose of this study was to evaluate whether DJ-1 regulates astrogliosis, via STAT3 activation. The results of this study reveal that DJ-1 is a positive regulator of STAT3 activation, the most important mediator of astrogliosis. In brain slice cultures obtained from wild-type (WT) mice, STAT3 was activated, as demonstrated by its phosphorylation to pSTAT3, within 3 h, and GFAP expression was increased within 2 days after slice preparation. Interestingly, levels of pSTAT3 and GFAP in DJ-1 knockout brain slice were attenuated compared with that of WT. STAT3 inhibitors, DPP (5 µM) and S3I-201 (50 µM), reduced expression of BDNF, GDNF, and GFAP. However, the STAT3 inhibitors did not affect mRNA levels of Sox9, another important regulator of astrogliosis. Additionally, Sox9 siRNAs did not affect STAT3 phosphorylation. These results indicate that STAT3 and Sox9 may be the independent targets of DJ-1.

Astrocytes, Microglia, and Parkinson's Disease.

Astrocytes and microglia support well-being and well-function of the brain through diverse functions in both intact and injured brain. For example, astrocytes maintain homeostasis of microenvironment of the brain through up-taking ions and neurotransmitters, and provide growth factors and metabolites for neurons, etc. Microglia keep surveying surroundings, and remove abnormal synapses or respond to injury by isolating injury sites and expressing inflammatory cytokines. Therefore, their loss and/or functional alteration may be directly linked to brain diseases. Since Parkinson's disease (PD)-related genes are expressed in astrocytes and microglia, mutations of these genes may alter the functions of these cells, thereby contributing to disease onset and progression. Here, we review the roles of astrocytes and microglia in intact and injured brain, and discuss how PD genes regulate their functions.

Optimal Timing of Percutaneous Coronary Intervention in Patients With Non-ST-Segment Elevation Myocardial Infarction Complicated by Acute Decompensated Heart Failure (from the Korea Acute Myocardial Infarction Registry-National Institutes of Health [KAMIR-NIH]).

The optimal timing of percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation myocardial infarction (NSTEMI), complicated by acute decompensated heart failure (ADHF), is unclear. A total of 1,027 patients with NSTEMI complicated by ADHF who underwent successful PCI were analyzed using a Korean multicenter registry. All patients were divided into 4 groups by the timing of PCI: group 1 (PCI < 2 hour after admission, n = 149), group 2 (2 to 24 hours, n = 577), group 3 (24 to 72 hours, n = 189), and group 4 (≥72 hours, n = 112). We analyzed the incidences of 12-month mortality, nonfatal myocardial infarction (MI), target-vessel revascularization, and rehospitalization because of HF. The prevalence of ADHF in patients with NSTEMI was 15.2% at initial presentation, and in-hospital mortality was higher in group 1 than in the other groups. There were no significant differences in mortality, nonfatal MI, target-vessel revascularization, or rehospitalization for HF during the 12-month follow-up between groups, regardless of initial PCI timing, except for a higher 12-month mortality in patients who received PCI within 24 hours (vs ≥24 hours) (hazard ratio 1.52, 95% confidence interval 1.09 to 2.29, p = 0.046). Early PCI did not reduce adverse clinical outcomes in patients with NSTEMI complicated by ADHF. Delayed PCI after stabilization may be reasonable in such high-risk patients.

DJ-1 deficiency impairs synaptic vesicle endocytosis and reavailability at nerve terminals.

Mutations in DJ-1 (PARK7) are a known cause of early-onset autosomal recessive Parkinson's disease (PD). Accumulating evidence indicates that abnormalities of synaptic vesicle trafficking underlie the pathophysiological mechanism of PD. In the present study, we explored whether DJ-1 is involved in CNS synaptic function. DJ-1 deficiency impaired synaptic vesicle endocytosis and reavailability without inducing structural alterations in synapses. Familial mutants of DJ-1 (M26I, E64D, and L166P) were unable to rescue defective endocytosis of synaptic vesicles, whereas WT DJ-1 expression completely restored endocytic function in DJ-1 KO neurons. The defective synaptic endocytosis shown in DJ-1 KO neurons may be attributable to alterations in membrane cholesterol level. Thus, DJ-1 appears essential for synaptic vesicle endocytosis and reavailability, and impairment of this function by familial mutants of DJ-1 may be related to the pathogenesis of PD.

Comparison of prasugrel versus clopidogrel in Korean patients with acute myocardial infarction undergoing successful revascularization.

BACKGROUND: Although there have been several reports that prasugrel can improve clinical outcomes, the efficacy and safety of prasugrel is unknown in Korean patients with acute myocardial infarction (AMI) undergoing successful revascularization. METHODS: A total of 4421 patients [637 patients were prescribed prasugrel (60/10 or 5mg, loading/maintenance dose) and 3784 patients clopidogrel (600 or 300/75mg)] with AMI undergoing successful revascularization were enrolled from the core clinical cohort of Korea Acute Myocardial Infarction Registry-National Institute of Health. RESULTS: After propensity score matching (637 pairs), there were no significant differences in baseline clinical and procedural characteristics and in-hospital medications between the two groups. The primary efficacy endpoint, defined as the composite of cardiac death, MI, stroke, or target vessel revascularization at 6 months showed no significant difference between prasugrel and clopidogrel (2.4% vs. 2.9%, p=0.593). Also, no difference was observed in the composite of cardiac death, MI, or stroke during hospitalization between two groups (0.8% vs. 0.9%, p=0.762). However, the incidence of in-hospital Thrombolysis in Myocardial Infarction (TIMI) major or minor bleeding was significantly higher in prasugrel compared with clopidogrel (5.3% vs. 2.7%, p=0.015). In multivariate linear regression analysis, trans-femoral intervention, use of glycoprotein IIb/IIIa inhibitors, use of calcium channel blocker, and use of prasugrel were independent predictors of in-hospital TIMI major or minor bleeding [odds ratio (OR)=6.918; 95% confidence interval (CI)=2.453-19.510, OR=2.577; 95% CI=1.406-4.724, OR=4.016; 95% CI=1.382-11.668, OR=2.022; 95% CI=1.101-3.714]. CONCLUSIONS: Our study shows that the recommended dose of prasugrel had significantly higher in-hospital bleeding complications without reducing ischemic events compared with clopidogrel. However, further large-scale, long-term, randomized clinical trials are required to accurately assess the efficacy and safety of prasgurel and to find out the optimal dose for Korean AMI patients.

A Parkinson's disease gene, DJ-1, repairs brain injury through Sox9 stabilization and astrogliosis.

Defects in repair of damaged brain accumulate injury and contribute to slow-developing neurodegeneration. Here, we report that a deficiency of DJ-1, a Parkinson's disease (PD) gene, delays repair of brain injury due to destabilization of Sox9, a positive regulator of astrogliosis. Stereotaxic injection of ATP into the brain striatum produces similar size of acute injury in wild-type and DJ-1-knockout (KO) mice. However, recovery of the injury is delayed in KO mice, which is confirmed by 9.4T magnetic resonance imaging and tyrosine hydroxylase immunostaining. DJ-1 regulates neurite outgrowth from damaged neurons in a non-cell autonomous manner. In DJ-1 KO brains and astrocytes, Sox9 protein levels are decreased due to enhanced ubiquitination, resulting in defects in astrogliosis and glial cell-derived neurotrophic factor/ brain-derived neurotrophic factor expression in injured brain and astrocytes. These results indicate that DJ-1 deficiency causes defects in astrocyte-mediated repair of brain damage, which may contribute to the development of PD.

Comparison of short-term clinical outcomes between ticagrelor versus clopidogrel in patients with acute myocardial infarction undergoing successful revascularization; from Korea Acute Myocardial Infarction Registry-National Institute of Health.

BACKGROUND: Although ticagrelor has been well-known to improve clinical outcomes in patients with acute myocardial infarction (AMI) without increased bleeding risk, its clinical impacts have not been well established in East Asian patients. METHODS: Between November 2011 and June 2015, a total of 8010 patients (1377 patients were prescribed ticagrelor and 6633 patients clopidogrel) undergoing successful revascularization were analyzed from Korea Acute Myocardial Infarction Registry-National Institute of Health. The patients who discontinued or occurred in-hospital switching between two antiplatelet agents were excluded. RESULTS: After propensity score matching (1377 pairs), no difference in the composite of cardiac death, MI, stroke, or target vessel revascularization at 6months was observed between two groups (4.2% vs. 4.9%, p=0.499). However, the incidences of in-hospital Thrombolysis In Myocardial Infarction (TIMI) major and minor bleeding were higher in ticagrelor than clopidogrel (2.6% vs. 1.2%, p=0.008; 3.8% vs. 2.5%, p=0.051). The in-hospital mortality was higher in patients with than those without TIMI major bleeding (11.3% vs. 0.9%, p<0.001). In a subgroup analysis, a higher risk for in-hospital TIMI major bleeding with ticagrelor was observed in patients≥75years or with body weight<60kg (odd ratio [OR]=3.209; 95% confidence interval [CI]=1.356-7.592) and in those received trans-femoral intervention (OR=1.996; 95% CI=1.061-3.754). CONCLUSIONS: Our study shows that ticagrelor did not reduce ischemic events yet, however, was associated with increased risk of bleeding complications compared with clopidogrel. Further large-scale, long-term, randomized trials should be required to assess the outcomes of ticagrelor for East Asian patients with AMI.

PINK1 expression increases during brain development and stem cell differentiation, and affects the development of GFAP-positive astrocytes.

BACKGROUND: Mutation of PTEN-induced putative kinase 1 (PINK1) causes autosomal recessive early-onset Parkinson's disease (PD). Despite of its ubiquitous expression in brain, its roles in non-neuronal cells such as neural stem cells (NSCs) and astrocytes were poorly unknown. RESULTS: We show that PINK1 expression increases from embryonic day 12 to postnatal day 1 in mice, which represents the main period of brain development. PINK1 expression also increases during neural stem cell (NSC) differentiation. Interestingly, expression of GFAP (a marker of astrocytes) was lower in PINK1 knockout (KO) mouse brain lysates compared to wild-type (WT) lysates at postnatal days 1-8, whereas there was little difference in the expression of markers for other brain cell types (e.g., neurons and oligodendrocytes). Further experiments showed that PINK1-KO NSCs were defective in their differentiation to astrocytes, producing fewer GFAP-positive cells compared to WT NSCs. However, the KO and WT NSCs did not differ in their self-renewal capabilities or ability to differentiate to neurons and oligodendrocytes. Interestingly, during differentiation of KO NSCs there were no defects in mitochondrial function, and there were not changes in signaling molecules such as SMAD1/5/8, STAT3, and HES1 involved in differentiation of NSCs into astrocytes. In brain sections, GFAP-positive astrocytes were more sparsely distributed in the corpus callosum and substantia nigra of KO animals compared with WT. CONCLUSION: Our study suggests that PINK1 deficiency causes defects in GFAP-positive astrogliogenesis during brain development and NSC differentiation, which may be a factor to increase risk for PD.