The Relationship between Iron and LRRK2 in a 6-OHDA-Induced Parkinson's Disease Model.

The pathogenesis of Parkinson's disease (PD) is very complex and still needs further exploration. Leucine-rich repeat kinase 2 (LRRK2) is associated with familial PD in mutant forms and sporadic PD in the wild-type form. Abnormal iron accumulation is found in the substantia nigra of PD patients, but its exact effects are not very clear. Here, we show that iron dextran exacerbates the neurological deficit and loss of dopaminergic neurons in 6-OHDA lesioned rats. 6-OHDA and ferric ammonium citrate (FAC) significantly increase the activity of LRRK2 as reflected by the phosphorylation of LRRK2, at S935 and S1292 sites. 6-OHDA-induced LRRK2 phosphorylation is attenuated by the iron chelator deferoxamine, especially at the S1292 site. 6-OHDA and FAC markedly induce the expression of pro-apoptotic molecules and the production of ROS by activating LRRK2. Furthermore, G2019S-LRRK2 with high kinase activity showed the strongest absorptive capacity for ferrous iron and the highest intracellular iron content among WT-LRRK2, G2019S-LRRK2, and kinase-inactive D2017A-LRRK2 groups. Taken together, our results demonstrate that iron promotes the activation of LRRK2, and active LRRK2 accelerates ferrous iron uptake, suggesting that there exists an interplay between iron and LRRK2 in dopaminergic neurons, providing a new perspective to uncover the underlying mechanisms of PD occurrence.

Enhanced recovery after surgery in transurethral surgery for benign prostatic hyperplasia.

Enhanced recovery after surgery (ERAS) measures have not been systematically applied in transurethral surgery for benign prostatic hyperplasia (BPH). This study was performed on patients with BPH who required surgical intervention. From July 2019 to June 2020, the ERAS program was applied to 248 patients, and the conventional program was applied to 238 patients. After 1 year of follow-up, the differences between the ERAS group and the conventional group were evaluated. The ERAS group had a shorter time of urinary catheterization compared with the conventional group (mean ± standard deviation [s.d.]: 1.0 ± 0.4 days vs 2.7 ± 0.8 days, P < 0.01), and the pain (mean ± s.d.) was significantly reduced through postoperative hospitalization days (PODs) 0-2 (POD 0: 1.7 ± 0.8 vs 2.4 ± 1.0, P < 0.01; POD 1: 1.6 ± 0.9 vs 3.5 ± 1.3, P < 0.01; POD 2: 1.2 ± 0.7 vs 3.0 ± 1.3, P < 0.01). No statistically significant difference was found in the rate of postoperative complications, such as postoperative bleeding (P = 0.79), urinary retention (P = 0.40), fever (P = 0.55), and readmission (P = 0.71). The hospitalization cost of the ERAS group was similar to that of the conventional group (mean ± s.d.: 16 927.8 ± 5808.1 Chinese Yuan [CNY] vs 17 044.1 ± 5830.7 CNY, P =0.85). The International Prostate Symptom Scores (IPSS) and quality of life (QoL) scores in the two groups were also similar when compared at 1 month, 3 months, 6 months, and 12 months after discharge. The ERAS program we conducted was safe, repeatable, and efficient. In conclusion, patients undergoing the ERAS program experienced less postoperative stress than those undergoing the conventional program.

PIAS1 regulates breast tumorigenesis through selective epigenetic gene silencing.

Epigenetic gene silencing by histone modifications and DNA methylation is essential for cancer development. The molecular mechanism that promotes selective epigenetic changes during tumorigenesis is not understood. We report here that the PIAS1 SUMO ligase is involved in the progression of breast tumorigenesis. Elevated PIAS1 expression was observed in breast tumor samples. PIAS1 knockdown in breast cancer cells reduced the subpopulation of tumor-initiating cells, and inhibited breast tumor growth in vivo. PIAS1 acts by delineating histone modifications and DNA methylation to silence the expression of a subset of clinically relevant genes, including breast cancer DNA methylation signature genes such as cyclin D2 and estrogen receptor, and breast tumor suppressor WNT5A. Our studies identify a novel epigenetic mechanism that regulates breast tumorigenesis through selective gene silencing.

PIAS1 SUMO ligase regulates the self-renewal and differentiation of hematopoietic stem cells.

The selective and temporal DNA methylation plays an important role in the self-renewal and differentiation of hematopoietic stem cells (HSCs), but the molecular mechanism that controls the dynamics of DNA methylation is not understood. Here, we report that the PIAS1 epigenetic pathway plays an important role in regulating HSC self-renewal and differentiation. PIAS1 is required for maintaining the quiescence of dormant HSCs and the long-term repopulating capacity of HSC. Pias1 disruption caused the abnormal expression of lineage-associated genes. Bisulfite sequencing analysis revealed the premature promoter demethylation of Gata1, a key myeloerythroid transcription factor and a PIAS1-target gene, in Pias1(-/-) HSCs. As a result, Pias1 disruption caused the inappropriate induction of Gata1 in HSCs and common lymphoid progenitors (CLPs). The expression of other myeloerythroid genes was also enhanced in CLPs and lineage-negative progenitors, with a concurrent repression of B cell-specific genes. Consistently, Pias1 disruption caused enhanced myeloerythroid, but reduced B lymphoid lineage differentiation. These results identify a novel role of PIAS1 in maintaining the quiescence of dormant HSCs and in the epigenetic repression of the myeloerythroid program.

Targeting the PIAS1 SUMO ligase pathway to control inflammation.

Protein sumoylation is a post-translational-modification event, in which small ubiquitin-like modifier (SUMO) is covalently attached to protein substrates by a three-step process. Sumoylation has been suggested to regulate multiple cellular processes, including inflammation. Inflammation is initiated in response to pathogenic infections, but uncontrolled inflammatory responses can lead to the development of inflammatory disorders such as rheumatoid arthritis. Recent studies indicate that proinflammatory stimuli, such as tumor necrosis factor alpha and lipopolysaccharide, can activate PIAS1 [protein inhibitor of activated STAT1 (signal transducer and activator of transcription 1)] SUMO E3 ligase through a SUMO-dependent, inhibitor of kappaB kinase alpha (IKKalpha)-mediated phosphorylation event. Activated PIAS1 is then recruited to inflammatory gene promoters to repress transcription. These findings support a hypothesis that therapies targeting the PIAS1 SUMO ligase pathway might be developed for the treatment of inflammatory disorders such as rheumatoid arthritis and atherosclerosis.

Regulation of the sumoylation system in gene expression.

Protein sumoylation has emerged as an important regulatory mechanism for the transcriptional machinery. Sumoylation is a highly dynamic process that is regulated in response to cellular stimuli or pathogenic challenges. Altered activity of the small ubiquitin-like modifier (SUMO) conjugation system is associated with human cancers and inflammation. Thus, understanding the regulation of protein sumoylation is important for the design of SUMO-based therapeutic strategies for the treatment of human diseases. Recent studies indicate that the sumoylation system can be regulated through multiple mechanisms, including the regulation of the expression of various components of the sumoylation pathway, and the modulation of the activity of SUMO enzymes. In addition, extracellular stimuli can signal the nucleus to trigger the rapid promoter recruitment of SUMO E3 ligases, resulting in the immediate repression of transcription. Finally, the sumoylation system can also be regulated through crosstalk with other post-translational modifications, including phosphorylation, ubiquitination, and acetylation.

Resolution of sister centromeres requires RanBP2-mediated SUMOylation of topoisomerase IIalpha.

RanBP2 is a nucleoporin with SUMO E3 ligase activity that functions in both nucleocytoplasmic transport and mitosis. However, the biological relevance of RanBP2 and the in vivo targets of its E3 ligase activity are unknown. Here we show that animals with low amounts of RanBP2 develop severe aneuploidy in the absence of overt transport defects. The main chromosome segregation defect in cells from these mice is anaphase-bridge formation. Topoisomerase IIalpha (Topo IIalpha), which decatenates sister centromeres prior to anaphase onset to prevent bridges, fails to accumulate at inner centromeres when RanBP2 levels are low. We find that RanBP2 sumoylates Topo IIalpha in mitosis and that this modification is required for its proper localization to inner centromeres. Furthermore, mice with low amounts of RanBP2 are highly sensitive to tumor formation. Together, these data identify RanBP2 as a chromosomal instability gene that regulates Topo IIalpha by sumoylation and suppresses tumorigenesis.

Proinflammatory stimuli induce IKKalpha-mediated phosphorylation of PIAS1 to restrict inflammation and immunity.

How inflammatory stimuli signal to the nucleus to restrict inflammation is poorly understood. Protein inhibitor of activated STAT1 (PIAS1), a transcriptional regulator that possesses small ubiquitin-related modifier (SUMO) E3 ligase activity, inhibits immune responses by selectively blocking the binding of NF-kappaB and STAT1 to gene promoters. We report here that PIAS1 becomes rapidly phosphorylated on Ser90 residue in response to various inflammatory stimuli. Mutational studies indicate that Ser90 phosphorylation is required for PIAS1 to repress transcription. Upon TNF treatment, wild-type PIAS1, but not the Ser90A mutant, becomes rapidly associated with the promoters of NF-kappaB target genes. Furthermore, IKKalpha, but not IKKbeta, interacts with PIAS1 in vivo and mediates PIAS1 Ser90 phosphorylation, a process that requires the SUMO ligase activity of PIAS1. Our results identify a signaling pathway in which proinflammatory stimuli activate the IKKalpha-mediated sumoylation-dependent phosphorylation of PIAS1 for the immediate repression of inflammatory gene activation.

[Expression of minichromosome maintenance protein 6 in craniopharyngioma and its correlation with prognosis].

OBJECTIVE: To investigate the expression of minichromosome maintenance protein 6 (MCM6) in tissue sections of craniopharyngioma and observe its relation with the outcome of patients with craniopharyngiomas. METHODS: Prospective cohorts were composed of 32 adamantine epithelioma (AE) patients and 31 squamous papillary tumor (SP) patients. The average of follow-up phase was 84. 26 months, of 60 patients with craniopharyngioma, 20 suffered from recurrence and underwent operation again for removal of tumor, and the specimens of the tumors patients were collected. MCM6 as proliferative marker expression in the specimen sections was measured by immunohistochemical method (avidin-biotin-peroxidase); quantitatively, scoring for MCM6 protein variation was performed by TE2000-U inverted biological microscope and Image-Pro Plus professional image analysis software. Oncocyte proliferation potential was evaluated for inter-group comparison in three pair of groups, including AE/SP, recurrence/recurrence-free, and primary/relapse groups. RESULTS: 14 of 32 AE patients and 6 of 31 SP patients had recurrence during follow-up. MCM6 protein expression showed significant difference between AE/SP groups and between recurrence/recurrence-free groups (P < 0.05, two-tailed), but there was no statistically significant difference between primary and recurrent craniopharyngiomas. CONCLUSION: The subtype and MCM6 protein expression in craniopharyngiomas are related to the prognosis of tumor and thus may be useful in predicting the risk of tumor relapse.

Regulation of protein tyrosine phosphatase 1B by sumoylation.

Protein-tyrosine phosphatase 1B (PTP1B) is an ubiquitously expressed enzyme that negatively regulates growth-factor signalling and cell proliferation by binding to and dephosphorylating key receptor tyrosine kinases, such as the insulin receptor. It is unclear how the activity of PTP1B is regulated. Using a yeast two-hybrid assay, a protein inhibitor of activated STAT1 (PIAS1) was isolated as a PTP1B-interacting protein. Here, we show that PIAS1, which functions as a small ubiquitin-like modifier (SUMO) E3 ligase, associates with PTP1B in mammalian fibroblasts and catalyses sumoylation of PTP1B. Sumoylation of PTP1B reduces its catalytic activity and inhibits the negative effect of PTP1B on insulin receptor signalling and on transformation by the oncogene v-crk. Insulin-stimulated sumoylation of endogenous PTP1B results in a transient downregulation of the enzyme; this event does not occur when the endogenous enzyme is replaced with a sumoylation-resistant mutant of PTP1B. These results suggest that sumoylation, which has been implicated primarily in processes in the nucleus and nuclear pore, also modulates a key enzyme-substrate signalling complex that regulates metabolism and cell proliferation.

Regulation of gene-activation pathways by PIAS proteins in the immune system.

The protein inhibitor of activated STAT (PIAS) family of proteins has been proposed to regulate the activity of many transcription factors, including signal transducer and activator of transcription proteins (STATs), nuclear factor-kappaB, SMA- and MAD-related proteins (SMADs), and the tumour-suppressor protein p53. PIAS proteins regulate transcription through several mechanisms, including blocking the DNA-binding activity of transcription factors, recruiting transcriptional corepressors or co-activators, and promoting protein sumoylation. Recent genetic studies support an in vivo function for PIAS proteins in the regulation of innate immune responses. In this article, we review the current understanding of the molecular basis, specificity and physiological roles of PIAS proteins in the regulation of gene-activation pathways in the immune system.

[Therapeutic effect of far lateral approach on the lesions located ventral to cranial-cervical junction].

OBJECTIVE: To investigate the administration of far-lateral approach in lesions located anterior or anterolateral to brain stem and upper cervical spinal cord. METHODS: Twenty-three patients underwent far lateral approach, including 12 retrocondylar approach, 5 partial transcondylar approach, 3 transfacetal and partial transcondylar approach, 2 transtubercular approach and 1 complete transcondylar approach. RESULTS: Total tumor removal was achieved in 15 patients, subtotal removal in 5 patients, 3 vertibral artery aneurysms were clipped successfully, 3 patients were given occipitalcervical fusion. There was no operative mortality. The most frequent complications were lower cranial nerve deficit, CSF leakage, injury to vertibral artery, and ischemia of brain stem, cerebellum or spinal cord. No patient presented clinical instability of the occipitocervical junction after surgery. CONCLUSIONS: The far-lateral approach is an ideal approach to structures located ventral to cranial-cervicle junction. But some of the surgical steps are technically difficult and carry some degree of risk. The choice of approach depends on the pathological feature and degree of exposure required for effective surgical treatment. Bone removal should be quantified for individual lesion. The approach may be limited to less aggressive steps, while still achieving significant exposure and surgical space.

Negative regulation of NF-kappaB signaling by PIAS1.

The NF-kappaB family of transcription factors is activated by a wide variety of signals to regulate a spectrum of cellular processes. The proper regulation of NF-kappaB activity is critical, since abnormal NF-kappaB signaling is associated with a number of human illnesses, such as chronic inflammatory diseases and cancer. We report here that PIAS1 (protein inhibitor of activated STAT1) is an important negative regulator of NF-kappaB. Upon cytokine stimulation, the p65 subunit of NF-kappaB translocates into the nucleus, where it interacts with PIAS1. The binding of PIAS1 to p65 inhibits cytokine-induced NF-kappaB-dependent gene activation. PIAS1 blocks the DNA binding activity of p65 both in vitro and in vivo. Consistently, chromatin immunoprecipitation assays indicate that the binding of p65 to the promoters of NF-kappaB-regulated genes is significantly enhanced in Pias1-/- cells. Microarray analysis indicates that the removal of PIAS1 results in an increased expression of a subset of NF-kappaB-mediated genes in response to tumor necrosis factor alpha and lipopolysaccharide. Consistently, Pias1 null mice showed elevated proinflammatory cytokines. Our results identify PIAS1 as a novel negative regulator of NF-kappaB.

PIAS1 selectively inhibits interferon-inducible genes and is important in innate immunity.

Interferon (IFN) activates the signal transducer and activator of transcription (STAT) pathway to regulate immune responses. The protein inhibitor of activated STAT (PIAS) family has been suggested to negatively regulate STAT signaling. To understand the physiological function of PIAS1, we generated Pias1(-/-) mice. Using PIAS1-deficient cells, we show that PIAS1 selectively regulates a subset of IFN-gamma- or IFN-beta-inducible genes by interfering with the recruitment of STAT1 to the gene promoter. The antiviral activity of IFN-gamma or IFN-beta was consistently enhanced by Pias1 disruption. Pias1(-/-) mice showed increased protection against pathogenic infection. Our data indicate that PIAS1 is a physiologically important negative regulator of STAT1 and suggest that PIAS1 is critical for the IFN-gamma- or IFN-beta-mediated innate immune responses.

PIASy-mediated repression of the androgen receptor is independent of sumoylation.

PIASy, a member of the protein inhibitor of activated STAT (PIAS) family, represses the transcriptional activity of the androgen receptor (AR). In this report, we investigate the mechanism of PIASy-mediated repression of AR. We show that AR binds to the RING-finger like domain of PIASy. PIASy contains two transcriptional repression domains, RD1 and RD2. RD1, but not RD2, is required for PIASy-mediated repression of AR. We show that the RD1 domain binds HDAC1 and HDAC2 and that HDAC activity is required for PIASy-mediated AR repression. PIAS proteins possess small ubiquitin-related modifier (SUMO) E3 ligase activity. Conjugation of SUMO-1 to AR has been implicated in the regulation of AR activity. We examine if the SUMO ligase activity of PIASy is required for PIASy to repress AR. We show that a mutant PIASy, defective in promoting sumoylation, retains the ability to repress AR transcription. In addition, mutation of all the known sumoylation acceptor sites of AR does not affect the transrepression activity of PIASy on AR. Our results suggest that PIASy may repress AR by recruiting histone deacetylases, independent of its SUMO ligase activity.

Protein ISGylation modulates the JAK-STAT signaling pathway.

ISG15 is one of the most strongly induced genes upon viral infection, type I interferon (IFN) stimulation, and lipopolysaccharide (LPS) stimulation. Here we report that mice lacking UBP43, a protease that removes ISG15 from ISGylated proteins, are hypersensitive to type I IFN. Most importantly, in UBP43-deficient cells, IFN-beta induces a prolonged Stat1 tyrosine phosphorylation, DNA binding, and IFN-mediated gene activation. Furthermore, restoration of ISG15 conjugation in protein ISGylation-defective K562 cells increases IFN-stimulated promoter activity. These findings identify UBP43 as a novel negative regulator of IFN signaling and suggest the involvement of protein ISGylation in the regulation of the JAK-STAT pathway.