An ankyrin G-binding motif mediates TRAAK periodic localization at axon initial segments of hippocampal pyramidal neurons.

The axon initial segment (AIS) is a critical compartment in neurons. It converts postsynaptic input into action potentials that subsequently trigger information transfer to target neurons. This process relies on the presence of several voltage-gated sodium (NaV) and potassium (KV) channels that accumulate in high densities at the AIS. TRAAK is a mechanosensitive leak potassium channel that was recently localized to the nodes of Ranvier. Here, we uncover that TRAAK is also present in AISs of hippocampal and cortical neurons in the adult rat brain as well as in AISs of cultured rat hippocampal neurons. We show that the AIS localization is driven by a C-terminal ankyrin G-binding sequence that organizes TRAAK in a 190 nm spaced periodic pattern that codistributes with periodically organized ankyrin G. We furthermore uncover that while the identified ankyrin G-binding motif is analogous to known ankyrin G-binding motifs in NaV1 and KV7.2/KV7.3 channels, it was acquired by convergent evolution. Our findings identify TRAAK as an AIS ion channel that convergently acquired an ankyrin G-binding motif and expand the role of ankyrin G to include the nanoscale organization of ion channels at the AIS.

Efficacy and safety of candidate biosimilar CT-P41 versus reference denosumab: a double-blind, randomized, active-controlled, Phase 3 trial in postmenopausal women with osteoporosis.

This 78-week (18-month) study conducted in 479 postmenopausal women with osteoporosis evaluated the efficacy, pharmacodynamics, pharmacokinetics, safety, and immunogenicity of candidate biosimilar CT-P41 relative to US reference denosumab. CT-P41 had equivalent efficacy and pharmacodynamics to US-denosumab, with similar pharmacokinetics and comparable safety and immunogenicity profiles. PURPOSE: To demonstrate equivalence of candidate biosimilar CT-P41 and US reference denosumab (US-denosumab) in postmenopausal women with osteoporosis. METHODS: This 78-week (18-month), double-blind, randomized, active-controlled Phase 3 study (NCT04757376) comprised two treatment periods (TPs). In TPI, patients (N = 479) were randomized 1:1 to 60 mg subcutaneous CT-P41 or US-denosumab. At Week 52, those who had received CT-P41 in TPI continued to do so. Those who had received US-denosumab were randomized (1:1) to continue treatment or switch to CT-P41 in TPII. The primary efficacy endpoint was percent change from baseline in lumbar spine bone mineral density at Week 52. Efficacy equivalence was concluded if associated 95% confidence intervals (CI) for least squares (LS) mean group differences fell within ± 1.503%. The primary pharmacodynamic (PD) endpoint was area under the effect curve for serum carboxy-terminal cross-linking telopeptide of type I collagen through the first 26 weeks, with an equivalence margin of 80-125% (for 95% CIs associated with geometric LS mean ratios). RESULTS: Equivalence was demonstrated for CT-P41 and US-denosumab with respect to primary efficacy (LS mean difference [95% CI]: - 0.139 [- 0.826, 0.548] in the full analysis set and - 0.280 [- 0.973, 0.414] in the per-protocol set) and PD (geometric LS mean ratio [95% CI]: 94.94 [90.75, 99.32]) endpoints. Secondary efficacy, PD, pharmacokinetics, and safety results were comparable among all groups up to Week 78, including after transitioning to CT-P41 from US-denosumab. CONCLUSIONS: CT-P41 was equivalent to US-denosumab in women with postmenopausal osteoporosis, with respect to primary efficacy and PD endpoints.

A randomized, double-blind, single-dose, phase 1 study comparing the pharmacokinetics, pharmacodynamics, safety, and immunogenicity of denosumab biosimilar CT­P41 and reference denosumab in healthy males.

BACKGROUND: This study's objective was to demonstrate pharmacokinetic (PK) similarity and safety of denosumab biosimilar, CT­P41, and United States-licensed reference denosumab (US-denosumab) in healthy male Asian adults, considering also pharmacodynamic (PD) outcomes. RESEARCH DESIGN AND METHODS: This double-blind, two-arm, parallel-group, Phase 1 study randomized (1:1) healthy males to a single (60-mg) subcutaneous dose of CT­P41 or US-denosumab. Primary endpoints were area under the concentration - time curve (AUC) from time zero to infinity (AUC0-inf), AUC from time zero to the last quantifiable concentration (AUC0-last), and maximum serum concentration (Cmax). PK equivalence was determined if 90% confidence intervals (CIs) for ratios of geometric least-squares means (gLSMs) were within the predefined 80-125% equivalence margin. Secondary PK, PD, safety, and immunogenicity outcomes were also evaluated. RESULTS: Of 154 participants randomized (76 CT­P41; 78 US-denosumab), 151 received study drug (74 CT­P41; 77 US-denosumab). Primary and secondary PK results, PD results, safety, and immunogenicity were comparable between groups. Ninety percent CIs for ratios of gLSMs were within the predefined equivalence margin for AUC0-inf (100.4-114.7), AUC0-last (99.9-114.3), and Cmax (95.2-107.3). CONCLUSIONS: Following a single dose in healthy males, CT­P41 demonstrated PK equivalence with US-denosumab. TRIAL REGISTRATION: ClinicalTrials.gov: NCT06037395.

Classical Borrelia Serology Does Not Aid in the Diagnosis of Persistent Symptoms Attributed to Lyme Borreliosis: A Retrospective Cohort Study.

OBJECTIVE: The diagnosis of Lyme borreliosis is based on two-tier testing using an ELISA and Western blot. About 5-10% of patients report persistent symptoms of unknown etiology after treatment, resulting in substantial difficulties in further diagnostic workup. This paper presents a study aimed at determining whether serology can differentiate between patients with persistent symptoms attributed to Lyme and other patients with Lyme borreliosis. METHODS: A retrospective cohort study included 162 samples from four subgroups: patients with persistent symptoms of Lyme (PSL), early Lyme borreliosis with erythema migrans (EM), patients tested in a general practitioner setting (GP), and healthy controls (HC). ELISA, Western blots, and multiplex assays from different manufacturers were used to determine inter-test variations in PSL and to compare reactivity against Borrelia-specific antigens among the groups. RESULTS: In comparing the IgG and IgM reactivity by Western blot, IgG was more often positive in the PSL group than in the GP group. The individual antigen reactivity was similar between the PSL and EM or GP groups. Inter-test agreement among the manufacturers was variable, and agreement was higher for IgG testing compared to IgM. CONCLUSIONS: Serological testing is unable to define the subgroup of patients with persistent symptoms attributed to Lyme borreliosis. Additionally, the current two-tier testing protocol shows a large variance among different manufacturers in these patients.

Long non-coding RNA KRT8P41/miR-193a-3p/FUBP1 axis modulates the proliferation and invasion of chordoma cells.

Chordomas are low-grade malignancies accounting for 1-4% of primary bone malignancies. Moreover, local recurrences increase the rate of metastasis. Our previous study identified the far upstream element (FUSE)-binding protein 1 (FUBP1) as a biomarker and potential therapeutic target for chordoma. In this study, lncRNA KRT8P41 was identified as a lncRNA positively correlated with FUBP1. In chordoma patients, higher lncRNA KRT8P41 expression was correlated with a poorer prognosis. LncRNA KRT8P41 silencing significantly inhibited chordoma cell proliferation and invasion. miR-193a was negatively correlated with lncRNA KRT8P41 and FUBP1; lncRNA KRT8P41 inhibited miR-193a expression, and miR-193a inhibited FUBP1 expression. Furthermore, miR-193a directly bound to lncRNA KRT8P41 and FUBP1 and lncRNA KRT8P41 competed with FUBP1 for miR-193a binding and relieved miR-193a-mediated FUBP1 inhibition. LncRNA KRT8P41 silencing inhibited, whereas miR-193a inhibition promoted chordoma cell proliferation and invasion; the inhibition of miR-193a attenuated the roles of lncRNA KRT8P41. Within chordoma tissues, the expression of miR-193a was decreased, and the expression of FUBP1 increased compared to normal control tissues. LncRNA KRT8P41 exhibited a positive correlation with FUBP1 and a negative correlation with miR-193a in vivo. Therefore, it was concluded that lncRNA KRT8P41, miR-193a-3p, and FUBP1 form a lncRNA-miRNA-mRNA axis, modulating the proliferation and invasion of chordoma cells.

Expression, Purification and Characterization of Hiv-1 Capsid Precursor Protein p41.

Human immunodeficiency virus type 1 (HIV-1) has been a global epidemic since 1983; yet, the virology and immunology related to HIV-1 remain elusive. Furthermore, as there is still no effective chemoprophylaxis or vaccine to treat patients with HIV-1, most research focuses on strategies to prevent HIV-1 infection, such as with antiviral drugs, novel therapeutics, or improved diagnostic kits. The HIV-1 Gag precursor protein (p55)-comprising the matrix (MA/p17), capsid (CA/p24), and nucleocapsid (NC/p7) protein domains-is the main structural HIV-1 protein, and is uniquely responsible for virion assembly within the virus life cycle. Recently, the immature and mature capsid structures were solved; however, the precursor protein structure is still unknown. Here, we expressed two subtypes of HIV-1 MA-CA stretch of the Gag protein, referred to as p41, in a bacterial expression system. We characterized the purified p41 protein, and showed its superior antigenicity over that of p24, highlighting the potential influence of the p17 domain on p24 structure. We further showed that p41 has good immunogenicity to induce an antibody response in mice. These results will aid future investigations into the HIV-1 capsid precursor structure, and potentially contribute to improving the design of diagnostic kits.

Xenopus laevis oocyte as a model for the study of the cytoskeleton.

At the beginning of diplotene, the oocyte of Xenopus laevis is a cell of about 10-20 microns destined to increase 10,000-fold its size when the oocyte becomes filled with yolk platelets and has accumulated a great number of pigment granules in a half of its periphery. Its internal architecture is gradually accomplished during growth because of several factors, especially because of cytoskeletal changes. In the fully-grown oocyte, the cytoskeleton appears to sustain the eccentrically located germinal vesicle through arms radiating from the cortex to the germinal vesicle, a unique organization not to be found in other Amphibians. In this report, we summarized and analysed steps of cytoskeletal proteins and related mRNAs organization and function throughout diplotene stage, highlighting our studies in this animal model. The cytoskeletal proteins appear to exploit their activity with respect to ribosomal 60S subunit maturation and during translation. Most importantly, the polarity of the oocyte is achieved through a sophisticated and highly organized localization of mRNAs and cytoskeletal proteins in one side of the cell. This asymmetry will start the construction of the oocyte polarity that is instrumental for determining the characteristic of this cell, which will become an embryo. Moreover, in the same time membrane composition, conditioned by the underlying cytoskeletal organization, will acquire the prerequisites for sperm binding and fusion.

Casp8p41: The Protean Mediator of Death in CD4 T-cells that Replicate HIV.

HIV cure is now the focus of intense research after Timothy Ray Brown (the Berlin patient) set the precedent of being the first and only person cured. A major barrier to achieving this goal on a meaningful scale is an elimination of the latent reservoir, which is thought to comprise CD4-positive cells that harbor integrated, replication-competent HIV provirus. These cells do not express viral proteins, are indistinguishable from uninfected CD4 cells, and are thought to be responsible for HIV viral rebound-that occurs within weeks of combination anti retroviral therapy (cART) interruption. Modalities to engineer transcriptional stimulation (reactivation) of this dormant integrated HIV provirus, leading to expression of cytotoxic viral proteins, are thought to be a specific way to eradicate the latently infected CD4 pool and are becoming increasingly relevant in the era of HIV cure. HIV protease is one such protein produced after HIV reactivation that cleaves procaspase-8 to generate a novel protein Casp8p41. Casp8p41 then binds to the BH3 domain of BAK, leading to BAK oligomerization, mitochondrial depolarization, and apoptosis. In central memory T cells (TCMs) from HIV-infected patients, an elevated Bcl-2/procaspase-8 ratio was observed, and Casp8p41 binding to Bcl-2 was associated with a lack of reactivation-induced cell death. This was reversed by priming cells with a specific Bcl-2 antagonist prior to reactivation, resulting in increased cell death and decreased HIV DNA in a Casp8p41-dependent pathway. This review describes the biology, clinical relevance, and implications of Casp8p41 for a potential cure.

Determination of Mother Centriole Maturation in CPAP-Depleted Cells Using the Ninein Antibody.

BACKGROUND: Mutations in centrosomal protein genes have been identified in a number of genetic diseases in brain development, including microcephaly. Centrosomal P4.1-associated protein (CPAP) is one of the causal genes implicated in primary microcephaly. We previously proposed that CPAP is essential for mother centriole maturation during mitosis. METHODS: We immunostained CPAP-depleted cells using the ninein antibody, which selectively detects subdistal appendages in mature mother centrioles. RESULTS: Ninein signals were significantly impaired in CPAP-depleted cells. CONCLUSION: The results suggest that CPAP is required for mother centriole maturation in mammalian cells. The selective absence of centriolar appendages in young mother centrioles may be responsible for asymmetric spindle pole formation in CPAP-depleted cells.

HLA-A(∗)02, gender and tobacco smoking, but not multiple sclerosis, affects the IgG antibody response against human herpesvirus 6.

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system. Both genetic and environmental factors contribute to disease susceptibility and two viruses associated with MS are human herpesvirus (HHV)-6A and HHV-6B, together referred to as HHV-6. This study characterized the plasma IgG antibody response against HHV-6 in MS patients (n=446) and healthy controls (n=487), and the relationship between MS susceptibility factors and the anti-HHV-6 response was investigated. In addition, 134 samples were further investigated for IgG against the early HHV-6 antigen p41. Antibody levels were measured with ELISA. The overall seroprevalence against HHV-6 was 90%, with no significant difference in positivity or levels between MS patients and controls. Interestingly, carriership of HLA-A(∗)02 and tobacco smoking was associated with lower anti-HHV-6 IgG levels (p=0.0017 and p=0.026 respectively), whereas females sex was associated with higher levels (p=0.0090). No difference in IgG titers against p41 was observed between MS patients and controls. In conclusion, the IgG response against HHV-6 was associated with several factors that have previously been associated with MS susceptibility, possibly reflecting a relation between autoimmunity and how the immune system handles viral infections.

Making sense of how HIV kills infected CD4 T cells: implications for HIV cure.

Defining how HIV does, and does not, kill the host CD4 T cell that it infects is of paramount importance in an era when research is approaching a cure for infection. Three mutually exclusive pathways can lead to the death of HIV-infected cells during the HIV life cycle, before, coincident and after HIV integration and consequently may affect viral replication. We discuss the molecular mechanism underlying these pathways, the evidence supporting their roles in vivo, and contemplate how understanding these pathways might inform novel approaches to promote viral cure of HIV.

Determination of Mother Centriole Maturation in CPAP-Depleted Cells Using the Ninein Antibody

BACKGROUND: Mutations in centrosomal protein genes have been identified in a number of genetic diseases in brain development, including microcephaly. Centrosomal P4.1-associated protein (CPAP) is one of the causal genes implicated in primary microcephaly. We previously proposed that CPAP is essential for mother centriole maturation during mitosis. METHODS: We immunostained CPAP-depleted cells using the ninein antibody, which selectively detects subdistal appendages in mature mother centrioles. RESULTS: Ninein signals were significantly impaired in CPAP-depleted cells. CONCLUSION: The results suggest that CPAP is required for mother centriole maturation in mammalian cells. The selective absence of centriolar appendages in young mother centrioles may be responsible for asymmetric spindle pole formation in CPAP-depleted cells.

p41-Arc, a regulatory subunit of Arp2/3 complex, can induce premature senescence in the absence of p53 and Rb

Cellular senescence is a tumor-suppressive process instigated by proliferation in the absence of telomere replication, by cellular stresses such as oncogene activation, or by activation of the tumor suppressor proteins, such as Rb or p53. This process is characterized by an irreversible cell cycle exit, a unique morphology, and expression of senescence-associated-beta-galactosidase (SA-beta-gal). Despite the potential biological importance of cellular senescence, little is known of the mechanisms leading to the senescent phenotype. p41-Arc has been known to be a putative regulatory component of the mammalian Arp2/3 complex, which is required for the formation of branched networks of actin filaments at the cell cortex. In this study, we demonstrate that p41-Arc can induce senescent phenotypes when it is overexpressed in human tumor cell line, SaOs-2, which is deficient in p53 and Rb tumor suppressor genes, implying that p41 can induce senescence in a p53-independent way. p41-Arc overexpression causes a change in actin filaments, accumulating actin filaments in nuclei. Therefore, these results imply that a change in actin filament can trigger an intrinsic senescence program in the absence of p53 and Rb tumor suppressor genes.