A TAG1-APP signalling pathway through Fe65 negatively modulates neurogenesis

The release of amyloid precursor protein (APP) intracellular domain (AICD) may be triggered by extracellular cues through gamma-secretase-dependent cleavage. AICD binds to Fe65, which may have a role in AICD-dependent signalling; however, the functional ligand has not been characterized. In this study, we have identified TAG1 as a functional ligand of APP. We found that, through an extracellular interaction with APP, TAG1 increased AICD release and triggered Fe65-dependent activity in a gamma-secretase-dependent manner. TAG1, APP and Fe65 colocalized in the neural stem cell niche of the fetal ventricular zone. Neural precursor cells from TAG1-/-, APP-/- and TAG1-/-;APP-/- mice had aberrantly enhanced neurogenesis, which was significantly reversed in TAG1-/- mice by TAG1 or AICD but not by AICD mutated at the Fe65 binding site. Notably, TAG1 reduced normal neurogenesis in Fe65+/+ mice. Abnormally enhanced neurogenesis also occurred in Fe65-/- mice but could not be reversed by TAG1. These results describe a TAG1-APP signalling pathway that negatively modulates neurogenesis through Fe65.

BSCL2/seipin regulates adipogenesis through actin cytoskeleton remodelling

Seipin regulates lipid homeostasis by preventing lipid droplet (LD) formation in non-adipocytes but promoting it in developing adipocytes. Here, we report that seipin interacts with 14-3-3β through its N- and C-termini. Expression of 14-3-3β is upregulated during adipogenesis, and its deletion results in defective adipogenesis without affecting key adipogenic transcription factors. We further identified the actin-severing protein cofilin-1 as an interacting partner to 14-3-3β. Cofilin-1 was spatiotemporally recruited by 14-3-3β in the cytoplasm during adipocyte differentiation. Extensive actin cytoskeleton remodelling, from stress fibres to cortical structures, was apparent during adipogenesis, but not under lipogenic conditions, indicating that actin cytoskeleton remodelling is only required for adipocyte development. Similar to seipin and 14-3-3β, cofilin-1 knockdown led to impaired adipocyte development. At the cellular level, differentiated cells with knockdown of cofilin-1, 14-3-3β or seipin continued to maintain relatively intact stress fibres, in contrast to cortical actin structure in control cells. Finally, 3T3-L1 cells expressing a severing-resistant actin mutant exhibited impaired adipogenesis. We propose that seipin regulates adipogenesis by recruiting cofilin-1 to remodel actin cytoskeleton through the 14-3-3β protein.

Morphological and functional characterization of predifferentiation of myelinating glia-like cells from human bone marrow stromal cells through activation of F3/Notch signaling in mouse retina

Recently, we have demonstrated that F3/contactin and NB-3 are trans-acting extracellular ligands of Notch that promote differentiation of neural stem cells and oligodendrocyte precursor cells into mature oligodendrocytes (OLs). Here, we demonstrate that human bone marrow stromal cells (hBMSCs) can be induced to differentiate into cells with myelinating glial cell characteristics in mouse retina after predifferentiation in vitro. Isolated CD90(+) hBMSCs treated with beta-mercaptoethanol for 1 day and retinoic acid for 3 days in culture changed into myelinating glia-like cells (MGLCs). More cells expressed NG2, an early OL marker, after treatment, but expression of O4, a mature OL marker, was negligible. Subsequently, the population of O4(+) cells was significantly increased after the MGLCs were predifferentiated in culture in the presence of either F3/contactin or multiple factors, including forskolin, basic fibroblast growth factor, platelet-derived growth factor, and heregulin, in vitro for another 3 days. Notably, 2 months after transplantation into mouse retina, the predifferentiated cells changed morphologically into cells resembling mature MGLCs and expressing O4 and myelin basic protein, two mature myelinating glial cell markers. The cells sent out processes to contact and wrap axons, an event that normally occurs during early stages of myelination, in the retina. The results suggest that CD90(+) hBMSCs are capable of morphological and functional differentiation into MGLCs in vivo through predifferentiation by triggering F3/Notch signaling in vitro.

Targeted Inhibition of LPL/FABP4/CPT1 fatty acid metabolic axis can effectively prevent the progression of nonalcoholic steatohepatitis to liver cancer

Rationale: Nonalcoholic steatohepatitis (NASH), as one of the key stages in the development of nonalcoholic fatty liver disease (NAFLD), can directly progress to HCC, but the underlying mechanism is not fully understood.

Methods: Differentially expressed genes (DEGs) in each stage of disease development were studied through a GEO dataset deriving from a Stelic Animal Model (STAM), which can simulate the evolution of NAFLD/NASH to HCC in humans. GSVA analysis was performed to analyze the differentially expressed oncogenic signatures in each stage. A human NAFLD-related dataset from GEO database was utilized for gene expression verification and further validated in the protein level in STAM mice. Small molecule inhibitors were applied to STAM mice for investigating whether inhibition of the LPL/FABP4/CPT1 axis could prevent the occurrence of NASH-related HCC in vivo. Microsphere formation and clonal formation assays in vitro were applied to study if inhibition of the LPL/FABP4/CPT1 axis can reduce the viability of liver cancer stem cells (LCSCs).

Results: We found that upregulation of the LPL/FABP4/CPT1 molecular axis, as a fatty acid metabolic reprogramming process, occurred specifically during the NASH phase. GSVA analysis showed widespread activation of a large number of oncogenic signals, which may contribute to malignant transformation during NASH. Furthermore, inhibition of the LPL/FABP4/CPT1 axis could effectively delay the tumor growth in STAM mice. Cell assays revealed inhibitors targeting this axis can significantly reduce the sphere-forming, proliferation, and clonality of LCSCs.

Conclusion: These results suggest that activation of the LPL/FABP4/CPT1 axis is essential for LCSCs maintenance, which acts synergistically with a variety of up-regulated oncogenic signals that drive the hepatocyte-LCSCs transdifferentiation during NASH to HCC progression. Thus, targeting the LPL/FABP4/CPT1 axis may provide a potential direction for NASH-related HCC prevention.

Regulation of adipogenesis by cytoskeleton remodelling is facilitated by acetyltransferase MEC-17-dependent acetylation of α-tubulin

Cytoskeleton remodelling is a prerequisite step for the morphological transition from preadipocytes to mature adipocytes. Although microtubules play a pivotal role in organizing cellular structure, regulation of microtubule dynamics during adipogenesis remains unclear. In the present paper we show that acetylation of α-tubulin is up-regulated during adipogenesis, and adipocyte development is dependent on α-tubulin acetylation, as expression of an acetylation-resistant α-tubulin mutant significantly inhibits adipogenesis. Moreover, acetylation of α-tubulin is under the control of the acetyltransferase MEC-17 and deacetylases SIRT2 (Sirtuin 2) and HDAC6 (histone deacetylase 6). Adipocyte development is inhibited in MEC-17-knockdown cells, but enhanced in MEC-17-overexpressing cells. Finally, we show that katanin, a microtubule-severing protein with enhanced activity on acetylated α-tubulin, is actively involved in adipogenesis. We propose that co-ordinated up-regulation of α-tubulin acetylation initiates cytoskeleton remodelling by promoting α-tubulin severing by katanin which, in turn, allows expansion of lipid droplets and accelerates the morphological transition toward mature adipocytes.

Seipin differentially regulates lipogenesis and adipogenesis through a conserved core sequence and an evolutionarily acquired C-terminus

Homozygous mutations in BSCL2 (Berardinelli–Seip congenital lipodystrophy)/seipin cause CGL2 (congenital generalized lipodystrophy type 2). Recent data suggest that seipin regulates LD (lipid droplet) dynamics and adipocyte differentiation, but whether these roles are mechanistically linked remains unclear. To understand how seipin regulates these processes, we investigated the evolutionary changes of seipin orthologues, and studied individual domains in regulating lipid accumulation in non-adipocytes and adipocytes. Mammalian seipins comprise at least two distinct functional domains, a conserved core sequence and an evolutionarily acquired C-terminus. Despite its requirement for adipocyte formation, seipin overexpression inhibited oleate-induced LD formation and accumulation in nonadipocytes, which was mediated by the core sequence. In contrast, seipin overexpression did not inhibit LD accumulation during adipocyte differentiation or the adipogenic process in 3T3-L1 cells. However, adipogenesis and LD accumulation were impaired in 3T3-L1 cells expressing a seipin mutant lacking the C-terminus. Furthermore, expression of the same mutant without the C-terminus failed to rescue the adipogenic defects in seipin-knockdown cells, demonstrating the importance of the C-terminus for seipin's function in adipocyte development. We propose that seipin is involved in lipid homoeostasis by restricting lipogenesis and LD accumulation in non-adipocytes, while promoting adipogenesis to accommodate excess energy storage.

Seipin Knockout Mice Develop Heart Failure With Preserved Ejection Fraction

The lean diabetic patients with heart failure with preserved ejection fraction (HFpEF) in Asia suffer from adverse clinical outcomes and poor life quality. The suitable animal models are urgently needed for mechanistic study and therapeutic innovations. Our study reports that lipodystrophic mice with seipin depletion are lean, diabetic, and recapitulate major manifestations of clinical HFpEF, thereby clarifying that lean diabetes per se may produce HFpEF characteristics. We further demonstrate that increased cardiac titin phosphorylation and reactive interstitial fibrosis associated with neutrophil extracellular traps lead to left ventricular stiffness and suggest that both pathways may be potential therapeutic targets in Asian HFpEF patients.

Adipose specific disruption of seipin causes early-onset generalised lipodystrophy and altered fuel utilisation without severe metabolic disease

Objective

Mutations to the BSCL2 gene disrupt the protein seipin and cause the most severe form of congenital generalised lipodystrophy (CGL). Affected individuals exhibit a near complete loss of white adipose tissue (WAT) and suffer from metabolic disease. Seipin is critical for adipocyte development in culture and mice with germline disruption to Bscl2 recapitulate the effects of BSCL2 disruption in humans. Here we examined whether loss of Bscl2 specifically in developing adipocytes in vivo is sufficient to prevent adipose tissue development and cause all features observed with congenital BSCL2 disruption.

Methods

We generated and characterised a novel mouse model of Bscl2 deficiency in developing adipocytes (Ad-B2^(−/−)) using the adipose-specific Adiponectin-Cre line.

Results

We demonstrate that Ad-B2^(−/−) mice display early onset lipodystrophy, in common with congenital Bscl2 null mice and CGL2 patients. However, glucose intolerance, insulin resistance, and severe hepatic steatosis are not apparent. Food intake and energy expenditure are unchanged, but Ad-B2^(−/−) mice exhibit significantly altered substrate utilisation. We also find differential effects of seipin loss between specific adipose depots revealing new insights regarding their varied characteristics. When fed a high-fat diet, Ad-B2^(−/−) mice entirely fail to expand adipose mass but remain glucose tolerant.

Conclusions

Our findings demonstrate that disruption of Bscl2 specifically in developing adipocytes is sufficient to cause the early-onset generalised lipodystrophy observed in patients with mutations in BSCL2. However, this significant reduction in adipose mass does not cause the overt metabolic dysfunction seen in Bscl2 knockout mice, even following a high-fat diet challenge.

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Seipin loss only in developing adipocytes drives severe early-onset lipodystrophy.

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This leads to significantly altered use of metabolic substrates.

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We uncover developmental differences between poorly characterised adipose depots.

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Despite severely reduced adipose mass mice do not show overt metabolic disease.

Matrix Metalloproteinase 11 Is a Potential Therapeutic Target in Lung Adenocarcinoma

Lung cancer is one of the leading causes of cancer-associated death, with the etiology largely unknown. The aim of this study was to identify key driver genes with therapeutic potentials in lung adenocarcinoma (LUAD). Transcriptome microarray data from four GEO datasets (GEO: GSE7670, GSE10072, GSE68465, and GSE43458) were jointly analyzed for differentially expressed genes (DEGs). Ontologic analysis showed that most of the upregulated DEGs enriched in collagen catabolic and fibril organization processes were regulated by matrix metalloproteinases (MMPs). Matrix metalloproteinase 11 (MMP11), the highest upregulated MMP family member in LUAD-transformed cells, acted in an autocrine manner and was significantly increased in sera of LUAD patients. MMP11 depletion severely impaired LUAD cell proliferation, migration, and invasion in vitro, in line with retarded tumor growth in xenograft models. Treatment of different human LUAD cell lines with anti-MMP11 antibody significantly retarded cell growth and migration. Administration of anti-MMP11 antibody at a dose of 1 μg/g body weight significantly suppressed tumor growth in xenograft models. These findings indicate that MMP11 is a key cancer driver gene in LUAD and is an appealing target for antibody therapy.

Oligodendrocytes regulate formation of nodes of Ranvier via the recognition molecule OMgp

The molecular mechanisms underlying the involvement of oligodendrocytes in formation of the nodes of Ranvier (NORs) remain poorly understood. Here we show that oligodendrocyte-myelin glycoprotein (OMgp) aggregates specifically at NORs. Nodal location of OMgp does not occur along demyelinated axons of either Shiverer or proteolipid protein (PLP) transgenic mice. Over-expression of OMgp in OLN-93 cells facilitates process outgrowth. In transgenic mice in which expression of OMgp is down-regulated, myelin thickness declines, and lateral oligodendrocyte loops at the node-paranode junction are less compacted and even join together with the opposite loops, which leads to shortened nodal gaps. Notably, each of these structural abnormalities plus modest down-regulation of expression of Na(+) channel alpha subunit result in reduced conduction velocity in the spinal cords of the mutant mice. Thus, OMgp that is derived from glia has distinct roles in regulating nodal formation and function during CNS myelination.

Systematic expression analysis of WEE family kinases reveals the importance of PKMYT1 in breast carcinogenesis

OBJECTIVES

Many cancer cells depend on G2 checkpoint mechanism regulated by WEE family kinases to maintain genomic integrity. The PKMYT1 gene, as a member of WEE family kinases, participates in G2 checkpoint surveillance and probably links with tumorigenesis, but its role in breast cancer remains largely unclear.

MATERIALS AND METHODS

In this study, we used a set of bioinformatic tools to jointly analyse the expression of WEE family kinases and investigate the prognostic value of PKMYT1 in breast cancer.

RESULTS

The results indicated that PKMYT1 is the only frequently overexpressed member of WEE family kinases in breast cancer. KM plotter data suggests that abnormally high expression of PKMYT1 predicts poor prognosis, especially for some subtypes, such as luminal A/B and triple-negative (TNBC) types. Moreover, the up-regulation of PKMYT1 was associated with HER2-positive (HER2+), basal-like (Basal-like), TNBC statuses and increased classifications of Scarff, Bloom and Richardson (SBR). Co-expression analysis showed PKMYT1 has a strong positive correlation with Polo-like kinase 1 (PLK1), implying they may cooperate in regulating cancer cell proliferation by synchronizing rapid cell cycle with high quality of genome maintenance.

CONCLUSIONS

Collectively, this study demonstrates that overexpression of PKMYT1 is always found in breast cancer and predicts unfavourable prognosis, implicating it as an appealing therapeutic target for breast carcinoma.

Towards a mechanistic understanding of lipodystrophy and seipin functions

CGL (Congenital generalized lipodystrophy) is a genetic disorder characterized by near complete loss of adipose tissue along with increased ectopic fat storage in other organs including liver and muscle. Of the four CGL types, BSCL2 (Berardinelli-Seip Congenital lipodystrophy type 2), resulting from mutations in the BSCL2/seipin gene, exhibits the most severe lipodystrophic phenotype with loss of both metabolic and mechanical adipose depots. The majority of Seipin mutations cause C-terminal truncations, along with a handful of point mutations. Seipin localizes to the ER and is composed of a conserved region including a luminal loop and two transmembrane domains, plus cytosolic N- and C-termini. Animal models deficient in seipin recapitulate the human lipodystrophic phenotype. Cells isolated from seipin knockout mouse models also exhibit impaired adipogenesis. Mechanistically, seipin appears to function as a scaffolding protein to bring together interacting partners essential for lipid metabolism and LD (lipid droplet) formation during adipocyte development. Moreover, cell line and genetic studies indicate that seipin functions in a cell-autonomous manner. Here we will provide a brief overview of the genetic association of the CGLs, and focus on the current understanding of differential contributions of distinct seipin domains to lipid storage and adipogenesis. We will also discuss the roles of seipin-interacting partners, including lipin 1 and 14-3-3β, in mediating seipin-dependent regulation of cellular pathways such as actin cytoskeletal remodelling.

Seipin regulates excitatory synaptic transmission in cortical neurons

Heterozygosity for missense mutations in Seipin, namely N88S and S90L, leads to a broad spectrum of motor neuropathy, while a number of loss-of-function mutations in Seipin are associated with the Berardinelli-Seip congenital generalized lipodystrophy type 2 (CGL2, BSCL2), a condition that is characterized by severe lipoatrophy, insulin resistance, and intellectual impairment. The mechanisms by which Seipin mutations lead to motor neuropathy, lipodystrophy, and insulin resistance, and the role Seipin plays in central nervous system (CNS) remain unknown. The goal of this study is to understand the functions of Seipin in the CNS using a loss-of-function approach, i.e. by knockdown (KD) of Seipin gene expression. Excitatory post-synaptic currents (EPSCs) were impaired in Seipin-KD neurons, while the inhibitory post-synaptic currents (IPSCs) remained unaffected. Expression of a shRNA-resistant human Seipin rescued the impairment of EPSC produced by Seipin KD. Furthermore, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced whole-cell currents were significantly reduced in Seipin KD neurons, which could be rescued by expression of a shRNA-resistant human Seipin. Fluorescent imaging and biochemical studies revealed reduced level of surface AMPA receptors, while no obvious ultrastructural changes in the pre-synapse were found. These data suggest that Seipin regulates excitatory synaptic function through a post-synaptic mechanism.

Ameliorating replicative senescence of human bone marrow stromal cells by PSMB5 overexpression

Multipotent human bone marrow stromal cells (hBMSCs) potentially serve as a source for cell-based therapy in regenerative medicine. However, in vitro expansion was inescapably accompanied with cell senescence, characterized by inhibited proliferation and compromised pluripotency. We have previously demonstrated that this aging process is closely associated with reduced 20S proteasomal activity, with down-regulation of rate-limiting catalytic β-subunits particularly evident. In the present study, we confirmed that proteasomal activity directly contributes to senescence of hBMSCs, which could be reversed by overexpression of the β5-subunit (PSMB5). Knocking down PSMB5 led to decreased proteasomal activity concurrent with reduced cell proliferation in early-stage hBMSCs, which is similar to the senescent phenotype observed in late-stage cells. In contrast, overexpressing PSMB5 in late-stage cells efficiently restored the normal activity of 20S proteasomes and promoted cell growth, possibly via upregulating the Cyclin D1/CDK4 complex. Additionally, PSMB5 could enhance cell resistance to oxidative stress, as evidenced by the increased cell survival upon exposing senescent hBMSCs to hydrogen peroxide. Furthermore, PSMB5 overexpression retained the pluripotency of late-stage hBMSCs by facilitating their neural differentiation both in vitro and in vivo. Collectively, our work reveals a critical role of PSMB5 in 20S proteasome-mediated protection against replicative senescence, pointing to a possible strategy for maintaining the integrity of culture-expanded hBMSCs by manipulating the expression of PSMB5.

Essential role of proteasomes in maintaining self-renewal in neural progenitor cells

Protein turnover and homeostasis are regulated by the proteasomal system, which is critical for cell function and viability. Pluripotency of stem cells also relies on normal proteasomal activity that mitigates senescent phenotypes induced by intensive cell replications, as previously demonstrated in human bone marrow stromal cells. In this study, we investigated the role of proteasomes in self-renewal of neural progenitor cells (NPCs). Through both in vivo and in vitro analyses, we found that the expression of proteasomes was progressively decreased during aging. Likewise, proliferation and self-renewal of NPCs were also impaired in aged mice, suggesting that the down-regulation of proteasomes might be responsible for this senescent phenotype. Lowering proteasomal activity by loss-of-function manipulations mimicked the senescence of NPCs both in vitro and in vivo; conversely, enhancing proteasomal activity restored and improved self-renewal in aged NPCs. These results collectively indicate that proteasomes work as a key regulator in promoting self-renewal of NPCs. This potentially provides a promising therapeutic target for age-dependent neurodegenerative diseases.

Arp2/3 complex regulates adipogenesis by controlling cortical actin remodelling

Extensive actin cytoskeleton remodelling occurs during adipocyte development. We have previously shown that disruption of stress fibres by the actin-severing protein cofilin is a requisite step in adipogenesis. However, it remains unclear whether actin nucleation and assembly into the cortical structure are essential for adipocyte development. In the present study we investigated the role of cortical actin assembly and of actin nucleation by the actin-related protein 2/3 (Arp2/3) complex in adipogenesis. Cortical actin structure formation started with accumulation of filamentous actin (F-actin) patches near the plasma membrane during adipogenesis. Depletion of Arp2/3 by knockdown of its subunits Arp3 or ARPC3 strongly impaired adipocyte differentiation, although adipogenesis-initiating factors were unaffected. Moreover, the assembly of F-actin-rich structures at the plasma membrane was suppressed and the cortical actin structure poorly developed after adipogenic induction in Arp2/3-deficient cells. Finally, we provide evidence that the cortical actin cytoskeleton is essential for efficient glucose transporter 4 (GLUT4) vesicle exocytosis and insulin signal transduction. These results show that the Arp2/3 complex is an essential regulator of adipocyte development through control of the formation of cortical actin structures, which may facilitate nutrient uptake and signalling events.

Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway

Amyloid precursor protein (APP), commonly associated with Alzheimer's disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668.

Solution structure of the first HMG box domain in human upstream binding factor

Human upstream binding factor is a nucleolar transcription factor involved in transcription by RNA polymerase I. It contains six HMG box domains; the HMG box is a minor groove DNA-binding domain that has been found in hundreds of proteins with different functions. Among the six HMG box domains in hUBF, the first one can bind to the ribosomal promoter specifically by itself and is essential for the whole protein's DNA binding specificity. Here we report the three-dimensional structure of this first HMG box free in solution determined by multidimensional NMR using (13)C,(15)N-labeled protein. Like the previously determined HMG box structures, hUBF HMG box 1 adopts a twisted L-shape consisting of three alpha-helices: helix 1 (17-30) and helix 2 (38-51) pack onto each other to form the short arm, while helix 3 (57-76) is associated with an extended strand N-terminal to helix 1 and forms the long arm. A cluster of conserved residues, in particular the aromatic residues F21, Y49, and Y60, is important to maintain the fold. The short arm is rigid due to extensive hydrophobic interaction between helix 1 and helix 2, while the long arm is less rigid.

Current progress of immune checkpoint inhibitors in the treatment of advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver cancer worldwide. The onset of the disease is occult and develops rapidly. As a result, the disease is often detected when it is already in advanced stages, resulting in patients losing the best opportunity for liver transplantation and surgical treatment. Therefore, effective treatment of HCC is particularly important in clinical practice. During the past decades, there have been considerable advances in the treatment of HCC, and immunotherapy is increasingly recognized as a promising approach in clinical trials. In this review, an overview of immune checkpoint (ICP) inhibitors (ICIs) and their role in the treatment of liver cancers, particularly advanced HCC, is presented and the recent therapeutic progress with treatment with different ICIs alone or in combination with other methods/therapeutic agents is summarized. In addition, the identification of biomarkers to predict treatment response and the limitations of current ICIs are analyzed, and future directions for ICI treatment are discussed.

Recombinant DNA vaccine against neurite outgrowth inhibitors attenuates behavioral deficits and decreases Abeta in an Alzheimer's disease mouse model

Alzheimer's disease (AD) is a chronic neurodegenerative disease that causes a progressive loss in learning and memory capabilities and eventually results in dementia. The non-renewable nature of neurons in the central nervous system leads to the basic pathological changes that are related to the various behavioral and psychological symptoms of AD. Oligodendrocyte- and myelin-related neurite outgrowth inhibitors (NOIs) tend to hinder the regeneration of neurons. We designed a recombinant DNA vaccine composed of multiple specific inhibitory domains of NOIs. Vaccination induced effective antibodies against the specific domains in the sera of mice treated with a DNA primed-vaccinia virus boost regimen. The vaccine attenuated neuronal degeneration in the mouse brain and protected the model mice from behavioral deficits. Vaccination also decreased the formation of soluble Aβ oligomer and amyloid plaques in the co-transgenic mice brain. What's more, astrocytosis in brains of APP/PS1 co-transgenic mice was also relieved. The results suggested that immunotherapy with multiple specific domains of myelin- and oligodendrocyte-related NOIs may be a promising approach for Alzheimer's disease and other degenerative central nervous system diseases.

Solution structure and DNA binding property of the fifth HMG box domain in comparison with the first HMG box domain in human upstream binding factor

Human upstream binding factor (hUBF) is a nucleolar transcription factor involved in transcription by RNA polymerase I. It contains six HMG box domains. The contribution of each HMG box motif to its function is different. hUBF HMG box 1 shows a very strong binding affinity for both the four-way DNA junction and a 15 bp GC-rich rRNA gene core promoter fragment, but hUBF HMG box 5 shows a much weaker binding affinity for the four-way DNA junction and the GC-rich rRNA gene core promoter fragment. To illustrate the molecular basis of their DNA binding difference, the solution structure of box 5 was studied by NMR. The tertiary structure of box 5 shows a common flattened L-shaped fold, similar to box 1 and other HMG boxes with known structures. It is formed by intersection of three helical arms: helix 1 (residues 9-25) and helix 2 (residues 30-42) pack into each other to form the major wing, while helix 3 (residues 48-70) is aligned with the extended N-terminal segment to form the minor wing. A hydrophobic core is formed by three tryptophans (W14, W41, and W52) to maintain the fold. Although there is similarity between the two structures, negative charged electrostatic surface potential in the concave face of the molecule of box 5 exhibits great difference compared to that of box 1 and other HMG boxes with known structures. That surface is involved in DNA binding. Besides, in positions which are involved in intercalating into a DNA base pair, there are hydrophobic residues in box 1 and other HMG boxes but polar residues in box 5. These differences may contribute to the loss of the DNA binding ability of box 5.

Proteasome activation by insulin-like growth factor-1/nuclear factor erythroid 2-related factor 2 signaling promotes exercise-induced neurogenesis

Physical exercise-induced enhancement of learning and memory and alleviation of age-related cognitive decline in humans have been widely acknowledged. However, the mechanistic relationship between exercise and cognitive improvement remains largely unknown. In this study, we found that exercise-elicited cognitive benefits were accompanied by adaptive hippocampal proteasome activation. Voluntary wheel running increased hippocampal proteasome activity in adult and middle-aged mice, contributing to an acceleration of neurogenesis that could be reversed by intrahippocampal injection of the proteasome inhibitor MG132. We further found that increased levels of insulin-like growth factor-1 (IGF-1) in both serum and hippocampus may be essential for exercise-induced proteasome activation. Our in vitro study demonstrated that IGF-1 stimulated proteasome activity in cultured adult neural progenitor cells (NPCs) by promoting nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), followed by elevated expressions of proteasome subunits such as PSMB5. In contrast, pretreating adult mice with the selective IGF-1R inhibitor picropodophyllin diminished exercise-induced neurogenesis, concurrent with reduced Nrf2 nuclear translocation and proteasome activity. Likewise, lowering Nrf2 expression by RNA interference with bilateral intrahippocampal injections of recombinant adeno-associated viral particles significantly suppressed exercise-induced proteasome activation and attenuated cognitive function. Collectively, our work demonstrates that proteasome activation in hippocampus through IGF-1/Nrf2 signaling is a key adaptive mechanism underlying exercise-related neurogenesis, which may serve as a potential targetable pathway in neurodegeneration.

Identification of FPR3 as a Unique Biomarker for Targeted Therapy in the Immune Microenvironment of Breast Cancer

Although research into immunotherapy is growing, its use in the treatment of breast cancer remains limited. Thus, identification and evaluation of prognostic biomarkers of tissue microenvironments will reveal new immune-based therapeutic strategies for breast cancer. Using an in silico bioinformatic approach, we investigated the tumor microenvironmental and genetic factors related to breast cancer. We calculated the Immune score, Stromal score, Estimate score, Tumor purity, TMB (Tumor mutation burden), and MATH (Mutant-allele tumor heterogeneity) of Breast cancer patients from the Cancer Genome Atlas (TCGA) using the ESTIMATE algorithm and Maftools. Significant correlations between Immune/Stromal scores with breast cancer subtypes and tumor stages were established. Importantly, we found that the Immune score, but not the Stromal score, was significantly related to the patient's prognosis. Weighted correlation network analysis (WGCNA) identified a pattern of gene function associated with Immune score, and that almost all of these genes (388 genes) are significantly upregulated in the higher Immune score group. Protein-protein interaction (PPI) network analysis revealed the enrichment of immune checkpoint genes, predicting a good prognosis for breast cancer. Among all the upregulated genes, FPR3, a G protein-coupled receptor essential for neutrophil activation, is the sole factor that predicts poor prognosis. Gene set enrichment analysis analysis showed FRP3 upregulation synergizes with the activation of many pathways involved in carcinogenesis. In summary, this study identified FPR3 as a key immune-related biomarker predicting a poor prognosis for breast cancer, revealing it as a promising intervention target for immunotherapy.

Physiological Roles of Neurite Outgrowth Inhibitors in Myelinated Axons of the Central Nervous System - Implications for the Therapeutic Neutralization of Neurite Outgrowth Inhibitors

It has long been recognized that the central nervous system (CNS) exhibits only limited capacity for axonal regeneration following injury. It has been proposed that myelin-associated inhibitory molecules are responsible for the nonpermissive nature of the CNS environment to axonal regeneration. Experimental strategies to enhance regeneration by neutralizing these inhibitory molecules are rapidly advancing toward clinical application. It is therefore important that the physiological distribution and functions of these supposed inhibitory molecules should be understood. In this review, we examine the distribution of these inhibitors of neurite outgrowth in relation to the longitudinal polarization of the myelinated axon into the node of Ranvier and associated domains and explore their potential domain specific physiological functions. Potential implications for the therapeutic strategy of neutralizing these inhibitory molecules to promote neural repair are discussed.