Pt on Atomic-Layered WO3 Islands: Electronic Tuning of Platinum-Tungsten Heterostructures for Highly Efficient Low-Temperature VOC Combustion.

Adjusting the electronic state of noble metal catalysts on a nanoscale is crucial for optimizing the performance of nanocatalysts in many important environmental catalytic reactions, particularly in volatile organic compound (VOC) combustion. This study reports a novel strategy for optimizing Pt catalysts by modifying their electronic structure to enhance the electron density of Pt. The research illustrates the optimal 0.2Pt-0.3W/Fe2O3 heterostructure with atomic-thick WO3 layers as a bulking block to electronically modify supported Pt nanoparticles. Methods such as electron microscopy, X-ray photoelectron spectroscopy, and in situ Fourier transform infrared spectroscopy confirm Pt's electron-enriched state resulting from electron transfer from atomic-thick WO3. Testing for benzene oxidation revealed enhanced low-temperature activity with moderate tungsten incorporation. Kinetic and mechanistic analyses provide insights into how the enriched electron density benefits the activation of oxygen and the adsorption of benzene on Pt sites, thereby facilitating the oxidation reaction. This pioneering work on modifying the electronic structure of supported Pt nanocatalysts establishes an innovative catalyst design approach. The electronic structure-performance-dependent relationships presented in this study assist in the rational design of efficient VOC abatement catalysts, contributing to clean energy and environmental solutions.

Enhancing reductive C-N coupling of nitrocompounds through interfacial engineering of MoO2 in thin carbon layers.

In this study, we developed an approach by coating silica nanospheres with polydopamine and metal precursor, followed by carbonization to create interfacial engineered MoO2. The presence of numerous crystal interfaces and metal-carbon interactions resulted in a remarkable enhancement of C-N coupling activity and stability of catalyst compared to one obtained by air calcination.

VDAC1 negatively regulates melanogenesis through the Ca2+-calcineurin-CRTC1-MITF pathway.

Melanocytes produce melanin for protecting DNA from ultraviolet exposure to maintain genomic stability. However, the precise regulation of melanogenesis is not fully understood. VDAC1, which is mainly localized in the outer mitochondrial membrane, functions as a gatekeeper for the entry or exit of Ca2+ between mitochondria and the cytosol and participates in multiple physiological processes. Here, we showed a novel role of VDAC1 in melanogenesis. Depletion of VDAC1 increased pigment content and up-regulated melanogenic genes, TYR, TYRP1, and TYRP2 Knockdown of VDAC1 increased free cytosolic Ca2+ in cultured melanocytes at the resting state, which activated calcineurin through the Ca2+-calmodulin-CaN pathway. The activated CaN dephosphorylated CRTC1 to facilitate its nuclear translocation and ultimately up-regulated the transcription of the master regulator of melanogenesis MITF. Consistently, depletion of Vdac1 in mice led to up-regulation of the transcription of MITF and thereafter its targeted melanogenic genes. These findings suggest that VDAC1 is an important negative regulator of melanogenesis, which expands our knowledge about pigment production and implies its potential role in melanoma.

Identification of a Novel MLPH Missense Mutation in a Chinese Griscelli Syndrome 3 Patient.

Melanophilin (MLPH) functions as a linker between RAB27A and myosin Va (MYO5A) in regulating skin pigmentation during the melanosome transport process. The MYO5A-MLPH-RAB27A ternary protein complex is required for anchoring mature melanosomes in the peripheral actin filaments of melanocytes for subsequent transfer to adjacent keratinocytes. Griscelli syndrome type 3 (GS3) is caused by mutations in the MLPH gene. So far, only five variants of MLPH associated with GS3 have been reported. Here, we reported the first patient with GS3 in a Chinese population. The proband carried a novel homozygous missense mutation (c.73G>C; p.D25H), residing in the conserved Slp homology domain of MLPH, and presented with hypopigmentation of the hair, eyebrows, and eyelashes. Light microscopy revealed the presence of abnormal pigment clumping in his hair shaft. In silico tools predicted this MLPH variant to be likely pathogenic. Using immunoblotting and immunofluorescence analysis, we demonstrated that the MLPH (D25H) variant had an inhibitory effect on melanosome transport by exhibiting perinuclear melanosome aggregation in melanocytes, and greatly reduced its binding to RAB27A, although the protein level of MLPH in the patient was not changed. Our findings suggest that MLPH (D25H) is a pathogenic variant that expands the genetic spectrum of the MLPH gene.

New insights into the pathogenesis of Hermansky-Pudlak syndrome.

Hermansky-Pudlak syndrome (HPS) is characterized by defects of multiple tissue-specific lysosome-related organelles (LROs), typically manifesting with oculocutaneous albinism or ocular albinism, bleeding tendency, and in some cases with pulmonary fibrosis, inflammatory bowel disease or immunodeficiency, neuropsychological disorders. Eleven HPS subtypes in humans and at least 15 subtypes in mice have been molecularly identified. Current understanding of the underlying mechanisms of HPS is focusing on the defective biogenesis of LROs. Compelling evidences have shown that HPS protein-associated complexes (HPACs) function in cargo transport, cargo recycling, and cargo removal to maintain LRO homeostasis. Further investigation on the molecular and cellular mechanism of LRO biogenesis and secretion will be helpful for better understanding of its pathogenesis and for the precise intervention of HPS.

Mycobacterium tuberculosis infection up-regulates MFN2 expression to promote NLRP3 inflammasome formation.

Tuberculosis (TB), caused by the infection of Mycobacterium tuberculosis (MTB), is one of the leading causes of death worldwide, especially in children. However, the mechanisms by which MTB infects its cellular host, activates an immune response, and triggers inflammation remain unknown. Mitochondria play important roles in the initiation and activation of the nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) inflammasome, where mitochondria-associated endoplasmic reticulum membranes (MAMs) may serve as the platform for inflammasome assembly and activation. Additionally, mitofusin 2 (MFN2) is implicated in the formation of MAMs, but, the roles of mitochondria and MFN2 in MTB infection have not been elucidated. Using mircroarry profiling of TB patients and in vitro MTB stimulation of macrophages, we observed an up-regulation of MFN2 in the peripheral blood mononuclear cells of active TB patients. Furthermore, we found that MTB stimulation by MTB-specific antigen ESAT-6 or lysate of MTB promoted MFN2 interaction with NLRP3 inflammasomes, resulting in the assembly and activation of the inflammasome and, subsequently, IL-1ß secretion. These findings suggest that MFN2 and mitochondria play important role in the pathogen-host interaction during MTB infection.

Mitochondrial NCKX5 regulates melanosomal biogenesis and pigment production.

Oculocutaneous albinism (OCA) is a heterogeneous and autosomal recessive hypopigmentation disorder, which is caused by mutations of genes involved in pigment biosynthesis or melanosome biogenesis. We have previously identified NCKX5 (also known as SLC24A5) as a causative gene for OCA type 6 (OCA6). However, the pathogenesis of OCA6 is unknown. We found that NCKX5 is localized to mitochondria, not to melanosomes. Pharmacological inhibition of mitochondrial function or NCKX exchanger activity reduced pigment production. Loss of NCKX5 attenuated Ca2+ enrichment in melanosomes, which compromised PMEL fibril formation, melanosome maturation and pigment production. Thus, we have defined a new class of hypopigmentation attributable to dysfunctional mitochondria and an impairment of mitochondrial Ca2+ transfer into melanosomes. Thus, it is possible that mitochondrial function could have a role in the graying of hair in older people and formation of hypopigmented lesions in vitiligo patients.

Miro2 supplies a platform for Parkin translocation to damaged mitochondria.

PINK1/Parkin-mediated mitophagy is an important process in selective removal of damaged mitochondria, in which translocation of Parkin to damaged mitochondria is recognized as an initiation step. At present, how the damaged mitochondria are selectively recognized and targeted by Parkin is not fully understood. Here we show that Miro2, an outer mitochondrial membrane protein, undergoes demultimerization from a tetramer to a monomer and alteration in mitochondrial localization upon CCCP treatment, suggesting a CCCP-induced realignment of Miro2. The realignment of Miro2 is tightly regulated by PINK1-mediated phosphorylation at Ser325/Ser430 and by Ca2+ binding to EF2 domain, which are both essential for the subsequent Parkin translocation. Interestingly, ablation of Miro2 in mouse causes delayed reticulocyte maturation, lactic acidosis and cardiac disorders. Furthermore, several Miro2 mutations found in the congenital lactic acidosis patients also disable its realignment and Parkin translocation. These findings reveal an important role of Miro2 to mediate Parkin translocation by sensing both depolarization and Ca2+ release from damaged mitochondria to ensure the accuracy of mitophagy.

Targeting the Dvl-1/ß-arrestin2/JNK3 interaction disrupts Wnt5a-JNK3 signaling and protects hippocampal CA1 neurons during cerebral ischemia reperfusion.

It is well known that Wnt5a activation plays a pivotal role in brain injury and ß-arrestin2 induces c-Jun N-terminal kinase (JNK3) activation is involved in neuronal cell death. Nonetheless, the relationship between Wnt5a and JNK3 remains unexplored during cerebral ischemia/reperfusion (I/R). In the present study, we tested the hypothesis that Wnt5a-mediated JNK3 activation via the Wnt5a-Dvl-1-ß-arrestin2-JNK3 signaling pathway was correlated with I/R brain injury. We found that cerebral I/R could enhance the assembly of the Dvl-1-ß-arrestin2-JNK3 signaling module, Dvl-1 phosphorylation and JNK3 activation. Activated JNK3 could phosphorylate the transcription factor c-Jun, prompt caspase-3 activation and ultimately lead to neuronal cell death. To further explore specifically Wnt5a mediated JNK3 pathway activation in neuronal injury, we used Foxy-5 (a peptide that mimics the effects of Wnt5a) and Box5 (a Wnt5a antagonist) both in vitro and in vivo. AS-ß-arrestin2 (an antisense oligonucleotide against ß-arrestin2) and RRSLHL (a small peptide that competes with ß-arrestin2 for binding to JNK3) were applied to confirm the positive signal transduction effect of the Dvl-1-ß-arrestin2-JNK3 signaling module during cerebral I/R. Furthermore, Box5 and the RRSLHL peptide were found to play protective roles in neuronal death both in vivo global and focal cerebral I/R rat models and in vitro oxygen glucose deprivation (OGD) neural cells. In summary, our results indicate that Wnt5a-mediated JNK3 activation participates in I/R brain injury by targeting the Dvl-1-ß-arrestin2/JNK3 interaction. Our results also point to the possibility that disrupting Wnt5a-JNK3 signaling pathway may provide a new approach for stroke therapy.

RNA-splicing factor SART3 regulates translesion DNA synthesis.

Translesion DNA synthesis (TLS) is one mode of DNA damage tolerance that uses specialized DNA polymerases to replicate damaged DNA. DNA polymerase η (Polη) is well known to facilitate TLS across ultraviolet (UV) irradiation and mutations in POLH are implicated in skin carcinogenesis. However, the basis for recruitment of Polη to stalled replication forks is not completely understood. In this study, we used an affinity purification approach to isolate a Polη-containing complex and have identified SART3, a pre-mRNA splicing factor, as a critical regulator to modulate the recruitment of Polη and its partner RAD18 after UV exposure. We show that SART3 interacts with Polη and RAD18 via its C-terminus. Moreover, SART3 can form homodimers to promote the Polη/RAD18 interaction and PCNA monoubiquitination, a key event in TLS. Depletion of SART3 also impairs UV-induced single-stranded DNA (ssDNA) generation and RPA focus formation, resulting in an impaired Polη recruitment and a higher mutation frequency and hypersensitivity after UV treatment. Notably, we found that several SART3 missense mutations in cancer samples lessen its stimulatory effect on PCNA monoubiquitination. Collectively, our findings establish SART3 as a novel Polη/RAD18 association regulator that protects cells from UV-induced DNA damage, which functions in a RNA binding-independent fashion.

RBM45 competes with HDAC1 for binding to FUS in response to DNA damage.

DNA damage response (DDR) is essential for genome stability and human health. Recently, several RNA binding proteins (RBPs), including fused-in-sarcoma (FUS), have been found unexpectedly to modulate this process. The role of FUS in DDR is closely linked to the pathogenesis of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Given that RBM45 is also an ALS-associated RBP, we wondered whether RBM45 plays any function during this process. Here, we report that RBM45 can be recruited to laser microirradiation-induced DNA damage sites in a PAR- and FUS-dependent manner, but in a RNA-independent fashion. Depletion of RBM45 leads to abnormal DDR signaling and decreased efficiency in DNA double-stranded break repair. Interestingly, RBM45 is found to compete with histone deacetylase 1 (HDAC1) for binding to FUS, thereby regulating the recruitment of HDAC1 to DNA damage sites. A common familial ALS-associated FUS mutation (FUS-R521C) is revealed to prefer to cooperate with RBM45 than HDAC1. Our findings suggest that RBM45 is a key regulator in FUS-related DDR signaling whose dysfunction may contribute to the pathogenesis of ALS.

Parkin regulates translesion DNA synthesis in response to UV radiation.

Deficiency of Parkin is a major cause of early-onset Parkinson's disease (PD). Notably, PD patients also exhibit a significantly higher risk in melanoma and other skin tumors, while the mechanism remains largely unknown. In this study, we show that depletion of Parkin causes compromised cell viability and genome stability after ultraviolet (UV) radiation. We demonstrate that Parkin promotes efficient Rad18-dependent proliferating cell nuclear antigen (PCNA) monoubiquitination by facilitating the formation of Replication protein A (RPA)-coated ssDNA upon UV radiation. Furthermore, Parkin is found to physically interact with NBS1 (Nijmegen breakage syndrome 1), and to be required for optimal recruitment of NBS1 and DNA polymerase eta (Polη) to UV-induced damage sites. Consequently, depletion of Parkin leads to increased UV-induced mutagenesis. These findings unveil an important role of Parkin in protecting genome stability through positively regulating translesion DNA synthesis (TLS) upon UV damage, providing a novel mechanistic link between Parkin deficiency and predisposition to skin cancers in PD patients.

Ataxin-3 promotes genome integrity by stabilizing Chk1.

The Chk1 protein is essential for genome integrity maintenance and cell survival in eukaryotic cells. After prolonged replication stress, Chk1 can be targeted for proteasomal degradation to terminate checkpoint signaling after DNA repair finishes. To ensure proper activation of DNA damage checkpoint and DNA repair signaling, a steady-state level of Chk1 needs to be retained under physiological conditions. Here, we report a dynamic signaling pathway that tightly regulates Chk1 stability. Under unperturbed conditions and upon DNA damage, ataxin-3 (ATX3) interacts with Chk1 and protects it from DDB1/CUL4A- and FBXO6/CUL1-mediated polyubiquitination and subsequent degradation, thereby promoting DNA repair and checkpoint signaling. Under prolonged replication stress, ATX3 dissociates from Chk1, concomitant with a stronger binding between Chk1 and its E3 ligase, which causes Chk1 proteasomal degradation. ATX3 deficiency results in pronounced reduction of Chk1 abundance, compromised DNA damage response, G2/M checkpoint defect and decreased cell survival after replication stress, which can all be rescued by ectopic expression of ATX3. Taken together, these findings reveal ATX3 to be a novel deubiquitinase of Chk1, providing a new mechanism of Chk1 stabilization in genome integrity maintenance.

CSB-PGBD3 Mutations Cause Premature Ovarian Failure.

Premature ovarian failure (POF) is a rare, heterogeneous disorder characterized by cessation of menstruation occurring before the age of 40 years. Genetic etiology is responsible for perhaps 25% of cases, but most cases are sporadic and unexplained. In this study, through whole exome sequencing in a non-consanguineous family having four affected members with POF and Sanger sequencing in 432 sporadic cases, we identified three novel mutations in the fusion gene CSB-PGBD3. Subsequently functional studies suggest that mutated CSB-PGBD3 fusion protein was impaired in response to DNA damage, as indicated by delayed or absent recruitment to damaged sites. Our data provide the first evidence that mutations in the CSB-PGBD3 fusion protein can cause human disease, even in the presence of functional CSB, thus potentially explaining conservation of the fusion protein for 43 My since marmoset. The localization of the CSB-PGBD3 fusion protein to UVA-induced nuclear DNA repair foci further suggests that the CSB-PGBD3 fusion protein, like many other proteins that can cause POF, modulates or participates in DNA repair.

Momordica charantia polysaccharides could protect against cerebral ischemia/reperfusion injury through inhibiting oxidative stress mediated c-Jun N-terminal kinase 3 signaling pathway.

Momordica charantia (MC) is a medicinal plant for stroke treatment in Traditional Chinese Medicine, but its active compounds and molecular targets are unknown yet. M. charantia polysaccharide (MCP) is one of the important bioactive components in MC. In the present study, we tested the hypothesis that MCP has neuroprotective effects against cerebral ischemia/reperfusion injury through scavenging superoxide (O2(-)), nitric oxide (NO) and peroxynitrite (ONOO(-)) and inhibiting c-Jun N-terminal protein kinase (JNK3) signaling cascades. We conducted experiments with in vivo global and focal cerebral ischemia/reperfusion rat models and in vitro oxygen glucose deprivation (OGD) neural cells. The effects of MCP on apoptotic cell death and infarction volume, the bioactivities of scavenging O2(-), NO and ONOO(-), inhibiting lipid peroxidation and modulating JNK3 signaling pathway were investigated. Major results are summarized as below: (1) MCP dose-dependently attenuated apoptotic cell death in neural cells under OGD condition in vitro and reduced infarction volume in ischemic brains in vivo; (2) MCP had directing scavenging effects on NO, O2(-) and ONOO(-) and inhibited lipid peroxidation; (3) MCP inhibited the activations of JNK3/c-Jun/Fas-L and JNK3/cytochrome C/caspases-3 signaling cascades in ischemic brains in vivo. Taken together, we conclude that MCP could be a promising neuroprotective ingredient of M. charantia and its mechanisms could be at least in part attributed to its antioxidant activities and inhibiting JNK3 signaling cascades during cerebral ischemia/reperfusion injury.

Neuroprotection of paclitaxel against cerebral ischemia/reperfusion-induced brain injury through JNK3 signaling pathway.

In this study, we investigated the neuroprotective effects of paclitaxel in transient cerebral ischemia and possible regulatory mechanism of these neuroprotection. Our data showed that paclitaxel can down-regulate the increased MLK3, JNK3, c-Jun, Bcl-2, and caspase-3 phosphorylation induced by ischemia injury. Cresyl violet staining and immunohistochemistry results demonstrated that paclitaxel had neuroprotective effect against ischemia/reperfusion-induced neuronal cell death. These results indicated that paclitaxel has neuroprotection in ischemic injury through JNK3 signaling pathway and provided a novel possible drug in therapeutics of brain ischemia.