Unveiling the regulatory of miR-101-3p on ZNF746 in a Parkinson's disease cell model: Implications for therapeutic targeting

In this study, we explored the regulatory role of microRNA miR-101-3p on the zinc finger protein 746 (ZNF746), also known as PARIS, which is implicated in both sporadic and familial forms of Parkinson's disease. In a Parkinson's disease cell model, utilizing SH-SY5Y cells treated with 1-methyl-4-phenylpyridine (MPP+), we observed that miR-101-3p was downregulated, while ZNF746 was upregulated. To investigate the direct impact of miR-101-3p on ZNF746, our team conducted overexpression experiments, successfully reversing ZNF746's expression at both the mRNA and protein levels, as confirmed through quantitative PCR and western blotting. We also performed luciferase assays, providing compelling evidence that ZNF746 is a direct target of miR-101-3p. Additionally, we noted that miR-101-3p overexpression resulted in increased expression of PGC1α, a gene targeted by ZNF746. Functionally, we assessed the implications of miR-101-3p overexpression through MTS assays and flow cytometry, revealing significant promotion of cell viability, inhibition of ROS production, and reduced apoptosis in the Parkinson's disease cell model. In conclusion, this study highlights the role of miR-101-3p in regulating ZNF746 expression and suggests its potential as a therapeutic target for Parkinson's disease. These findings provide valuable molecular insights that could pave the way for innovative treatment strategies in combating this debilitating neurodegenerative disorder.

ZNF746 promotes M2 macrophage polarisation and favours tumour progression in breast cancer via the Jagged1/Notch pathway

Breast cancer (BC) is a major threat to women's health. BC is a heterogeneous disease and treatment strategies and outcomes differ between subtypes. Investigating the molecular mechanisms of BC will help to identify potential therapeutic targets and develop new therapies. Here we report that zinc finger protein 746 (ZNF746), a Krüppel-associated box and zinc finger protein, exhibits tumour-promoting properties in BC. Functional experiments (cell growth, colony formation, cell cycle analysis, and transwell analysis) were used to evaluate the proliferation, migration, and invasion capacity of BC cells. Immunohistochemistry was performed to detect the expression of ZNF746, CD163 (M2 macrophage marker), and HES1 (Notch target) in BC tissues. ZNF746 was highly expressed in BC tissues compared to adjacent paired non-tumour tissues. Patients with M1 BC had higher expression of ZNF746 compared to patients with non-metastatic (M0) BC, and higher expression of ZNF746 was associated with poorer overall survival. The immunohistochemical results showed a positive correlation between the expression of ZNF746 and the expression of CD163 or HES1. ZNF746 promoted BC cell proliferation, migration, and invasion and increased the expression of molecules essential for monocyte recruitment and differentiation (CCL2 and CSF1). Furthermore, THP-1 monocytes cultured in the conditioned medium derived from BC cells overexpressing ZNF746 exhibited enhanced M2 polarisation. In contrast, ZNF746 knockdown reduced BC cell proliferation, migration, and invasion and suppressed M2 polarisation. Mechanistically, ZNF746 promoted the activation of the Jagged1/Notch pathway, and the Jagged1 siRNA-mediated blockade of this pathway prevented the tumour-promoting functions of ZNF746. In conclusion, this study uncovers the role of ZNF746 in promoting M2 macrophage polarisation and suggests that ZNF746 may be a promising therapeutic target for limiting BC progression.

Chiisanoside Mediates the Parkin/ZNF746/PGC-1α Axis by Downregulating MiR-181a to Improve Mitochondrial Biogenesis in 6-OHDA-Caused Neurotoxicity Models In Vitro and In Vivo: Suggestions for Prevention of Parkinson's Disease

The degeneration of dopamine (DA) neurons is known to be associated with defects in mitochondrial biogenesis caused by aging, environmental factors, or mutations in genes, leading to Parkinson's disease (PD). As PD has not yet been successfully cured, the strategy of using small molecule drugs to protect and restore mitochondrial biogenesis is a promising direction. This study evaluated the efficacy of synthetic chiisanoside (CSS) identified in the leaves of Acanthopanax sessiliflorus to prevent PD symptoms. The results show that in the 6-hydroxydopamine (6-OHDA) model, CSS pretreatment can effectively alleviate the reactive oxygen species generation and apoptosis of SH-SY5Y cells, thereby lessening the defects in the C. elegans model including DA neuron degeneration, dopamine-mediated food sensitivity behavioral disorders, and shortened lifespan. Mechanistically, we found that CSS could restore the expression of proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α), a key molecule in mitochondrial biogenesis, and its downstream related genes inhibited by 6-OHDA. We further confirmed that this is due to the enhanced activity of parkin leading to the ubiquitination and degradation of PGC-1α inhibitor protein Zinc finger protein 746 (ZNF746). Parkin siRNA treatment abolished this effect of CSS. Furthermore, we found that CSS inhibited 6-OHDA-induced expression of miR-181a, which targets parkin. The CSS's ability to reverse the 6-OHDA-induced reduction in mitochondrial biogenesis and activation of apoptosis was abolished after the transfection of anti-miR-181a and miR-181a mimics. Therefore, the neuroprotective effect of CSS mainly promotes mitochondrial biogenesis by regulating the miR-181a/Parkin/ZNF746/PGC-1α axis. CSS potentially has the opportunity to be developed into PD prevention agents.

Neuronal NLRP3 is a parkin substrate that drives neurodegeneration in Parkinson's disease

Parkinson's disease (PD) is mediated, in part, by intraneuronal accumulation of α-synuclein aggregates andsubsequent death of dopamine (DA) neurons in the substantia nigra pars compacta (SNpc). Microglial hyperactivation of the NOD-like receptor protein 3 (NLRP3) inflammasome has been well-documented in various neurodegenerative diseases, including PD. We show here that loss of parkin activity in mouse and human DA neurons results in spontaneous neuronal NLRP3 inflammasome assembly, leading to DA neuron death. Parkin normally inhibits inflammasome priming by ubiquitinating and targeting NLRP3 for proteasomal degradation. Loss of parkin activity also contributes to the assembly of an active NLRP3 inflammasome complex via mitochondrial-derived reactive oxygen species (mitoROS) generation through the accumulation of another parkin ubiquitination substrate, ZNF746/PARIS. Inhibition of neuronal NLRP3 inflammasome assembly prevents degeneration of DA neurons in familial and sporadic PD models. Strategies aimed at limiting neuronal NLRP3 inflammasome activation hold promise as a disease-modifying therapy for PD.

Defects in Mitochondrial Biogenesis Drive Mitochondrial Alterations in PARKIN-Deficient Human Dopamine Neurons

Mutations and loss of activity in PARKIN, an E3 ubiquitin ligase, play a role in the pathogenesis of Parkinson's disease (PD). PARKIN regulates many aspects of mitochondrial quality control including mitochondrial autophagy (mitophagy) and mitochondrial biogenesis. Defects in mitophagy have been hypothesized to play a predominant role in the loss of dopamine (DA) neurons in PD. Here, we show that although there are defects in mitophagy in human DA neurons lacking PARKIN, the mitochondrial deficits are primarily due to defects in mitochondrial biogenesis that are driven by the upregulation of PARIS and the subsequent downregulation of PGC-1α. CRISPR/Cas9 knockdown of PARIS completely restores the mitochondrial biogenesis defects and mitochondrial function without affecting the deficits in mitophagy. These results highlight the importance mitochondrial biogenesis versus mitophagy in the pathogenesis of PD due to inactivation or loss of PARKIN in human DA neurons.

PARIS induced defects in mitochondrial biogenesis drive dopamine neuron loss under conditions of parkin or PINK1 deficiency

BACKGROUND

Mutations in PINK1 and parkin cause autosomal recessive Parkinson's disease (PD). Evidence placing PINK1 and parkin in common pathways regulating multiple aspects of mitochondrial quality control is burgeoning. However, compelling evidence to causatively link specific PINK1/parkin dependent mitochondrial pathways to dopamine neuron degeneration in PD is lacking. Although PINK1 and parkin are known to regulate mitophagy, emerging data suggest that defects in mitophagy are unlikely to be of pathological relevance. Mitochondrial functions of PINK1 and parkin are also tied to their proteasomal regulation of specific substrates. In this study, we examined how PINK1/parkin mediated regulation of the pathogenic substrate PARIS impacts dopaminergic mitochondrial network homeostasis and neuronal survival in Drosophila.

METHODS

The UAS-Gal4 system was employed for cell-type specific expression of the various transgenes. Effects on dopamine neuronal survival and function were assessed by anti-TH immunostaining and negative geotaxis assays. Mitochondrial effects were probed by quantitative analysis of mito-GFP labeled dopaminergic mitochondria, assessment of mitochondrial abundance in dopamine neurons isolated by Fluorescence Activated Cell Sorting (FACS) and qRT-PCR analysis of dopaminergic factors that promote mitochondrial biogenesis. Statistical analyses employed two-tailed Student's T-test, one-way or two-way ANOVA as required and data considered significant when P < 0.05.

RESULTS

We show that defects in mitochondrial biogenesis drive adult onset progressive loss of dopamine neurons and motor deficits in Drosophila models of PINK1 or parkin insufficiency. Such defects result from PARIS dependent repression of dopaminergic PGC-1α and its downstream transcription factors NRF1 and TFAM that cooperatively promote mitochondrial biogenesis. Dopaminergic accumulation of human or Drosophila PARIS recapitulates these neurodegenerative phenotypes that are effectively reversed by PINK1, parkin or PGC-1α overexpression in vivo. To our knowledge, PARIS is the only co-substrate of PINK1 and parkin to specifically accumulate in the DA neurons and cause neurodegeneration and locomotor defects stemming from disrupted dopamine signaling.

CONCLUSIONS

Our findings identify a highly conserved role for PINK1 and parkin in regulating mitochondrial biogenesis and promoting mitochondrial health via the PARIS/ PGC-1α axis. The Drosophila models described here effectively recapitulate the cardinal PD phenotypes and thus will facilitate identification of novel regulators of mitochondrial biogenesis for physiologically relevant therapeutic interventions.

DUF3669, a "domain of unknown function" within ZNF746 and ZNF777, oligomerizes and contributes to transcriptional repression

Background

ZNF746 and ZNF777 belong to a subset of the large Krüppel-associated box (KRAB) zinc finger (ZNF) transcription factor family. They contain, like four other members in human, an additional conserved domain, the “domain of unknown function 3669” (DUF3669). Previous work on members of this subfamily suggested involvement in transcriptional regulation and aberrant ZNF746 overexpression leads to neuronal cell death in Parkinson’s disease.

Results

Here we demonstrate that N-terminal protein segments of the ZNF746a major isoform and ZNF777 act in concert to exert moderate transcriptional repression activities. Full potency depended on the intact configuration consisting of DUF3669, a variant KRAB domain and adjacent sequences. While DUF3669 contributes an intrinsic weak inhibitory activity, the isolated KRAB-AB domains did not repress. Importantly, DUF3669 provides a novel protein-protein interaction interface and mediates direct physical interaction between the members of the subfamily in oligomers. The ZNF746 protein segment encoded by exons 5 and 6 boosted repressor potency, potentially due to the presence of an acceptor lysine for sumoylation at K189. Repressor activity of the potent canonical ZNF10 KRAB domain was not augmented by heterologous transfer of DUF3669, pointing to the importance of context for DUF3669’s impact on transcription. Neither ZNF746a nor ZNF777 protein segments stably associated with TRIM28 within cells. Isoform ZNF746b that contains, unlike the major isoform, a full-length KRAB-A subdomain, displayed substantially increased repressor potency. This increase is due to canonical mechanisms known for KRAB domains since it did not take place in HAP1 knockout models of TRIM28 and SETDB1. A glycine to glutamic acid replacement that complies with a bona fide conserved “MLE” sequence within KRAB-A led to a further strong gain in repressor potency to levels comparable to those of the canonical ZNF10 KRAB domain. Each gain of repressive activity was accompanied by an enhanced interaction with TRIM28 protein.

Conclusion

DUF3669 adds a protein-protein interaction surface to a subgroup of KRAB-ZNF proteins within an N-terminal configuration with variant KRAB and adjacent sequences likely regulated by sumoylation. DUF3669 contributes to transcriptional repression strength and its homo- and hetero-oligomerization characteristics probably extended the regulatory repertoire of KRAB-ZNF transcription factors during amniote evolution.

Melatonin-mediated downregulation of ZNF746 suppresses bladder tumorigenesis mainly through inhibiting the AKT-MMP-9 signaling pathway

There still lacking effective treatment for bladder cancer. This study investigated whether melatonin (Mel) can suppress the growth and invasion of bladder cancer cells. Male C57B/L6 mice were categorized into control group (ie, subcutaneous injection of HT1197 bladder cancer cell line at the back] and treatment group [subcutaneous HT1197 cells + intraperitoneal Mel (100 mg/kg/d) from day 8 to day 21 after tumor cell injection]. In vitro Mel suppressed cell growth of four bladder cancer cell lines (ie, T24, RT4, HT1197, HT1376), cell migration in HT1197/HT1376, mitochondrial membrane potential (MMP) in T24 and colony formation in RT4 cells as well as arrested the cell cycle at G0 phase and inhibited the mitotic phase of T24 cells (all P < 0.0001). Protein expression of ZNF746 in RT4/T24 cells and protein expression phosphorylated (p)-AKT/MMP-2/MMP-9 in HT1197/HT1376 cells were reduced following Mel treatment (all P < 0.001). Transfection of T24 cells with plasmid-based shRNA (ie, ZNF746-silencing) downregulated the protein expression of MMP-9, cell growth, and invasion and attachment to endothelial cells but upregulated the colony formation (all P < 0.001). Mel suppressed oxidative stress and MMP but upregulated mitochondria mass in ZNF746-silenced T24 cells, whereas these parameters exhibited a similar patter to Mel treatment in ZNF746-silenced T24 cells (all P < 0.0001). In vivo study demonstrated that Mel treatment significantly suppressed cellular expressions of MMP-9/MMP-2, protein expressions of ZNF746/p-AKT, and tumor size (all P < 0.001). Mel treatment suppressed the growth, migration, and invasion of bladder carcinoma cells through downregulating ZNF746-regulated MMP-9/MMP-2 signaling.

PINK1 Primes Parkin-Mediated Ubiquitination of PARIS in Dopaminergic Neuronal Survival

Mutations in PTEN-induced putative kinase 1 (PINK1) and parkin cause autosomal-recessive Parkinson's disease through a common pathway involving mitochondrial quality control. Parkin inactivation leads to accumulation of the parkin interacting substrate (PARIS, ZNF746) that plays an important role in dopamine cell loss through repression of proliferator-activated receptor gamma coactivator-1-alpha (PGC-1α) promoter activity. Here, we show that PARIS links PINK1 and parkin in a common pathway that regulates dopaminergic neuron survival. PINK1 interacts with and phosphorylates serines 322 and 613 of PARIS to control its ubiquitination and clearance by parkin. PINK1 phosphorylation of PARIS alleviates PARIS toxicity, as well as repression of PGC-1α promoter activity. Conditional knockdown of PINK1 in adult mouse brains leads to a progressive loss of dopaminergic neurons in the substantia nigra that is dependent on PARIS. Altogether, these results uncover a function of PINK1 to direct parkin-PARIS-regulated PGC-1α expression and dopaminergic neuronal survival.

Parkin loss leads to PARIS-dependent declines in mitochondrial mass and respiration

Mutations in parkin lead to early-onset autosomal recessive Parkinson's disease (PD) and inactivation of parkin is thought to contribute to sporadic PD. Adult knockout of parkin in the ventral midbrain of mice leads to an age-dependent loss of dopamine neurons that is dependent on the accumulation of parkin interacting substrate (PARIS), zinc finger protein 746 (ZNF746), and its transcriptional repression of PGC-1α. Here we show that adult knockout of parkin in mouse ventral midbrain leads to decreases in mitochondrial size, number, and protein markers consistent with a defect in mitochondrial biogenesis. This decrease in mitochondrial mass is prevented by short hairpin RNA knockdown of PARIS. PARIS overexpression in mouse ventral midbrain leads to decreases in mitochondrial number and protein markers and PGC-1α-dependent deficits in mitochondrial respiration. Taken together, these results suggest that parkin loss impairs mitochondrial biogenesis, leading to declining function of the mitochondrial pool and cell death.