Development of antisense oligonucleotide combinatorial therapies for spinal muscular atrophy (SMA)

Spinal muscular atrophy (SMA) is a devastating genetically inherited neuromuscular disorder characterized by the progressive loss of α-motor neurons (MNs) in the anterior horn of the spinal cord, leading to muscle atrophy and weakness. Without treatment, SMA is the leading genetic cause of infant death. Although SMA is caused by homozygous mutations in survival motor neuron 1 (SMN1) gene, the disease severity is mainly determined by SMN2 copy number, an almost identical gene that produces ~10% correctly spliced full length SMN transcripts. Recently, three FDA- and EMA-approved therapies that either increase correctly spliced SMN2 transcripts (nusinersen - antisense oligonucleotide, ASO - and risdiplam - small molecule - ) or replace SMN1 gene (onasemnogen abeparvovec-xioi) have revolutionized the clinical outcome of SMA patients. However, clinical and scientific evidence emphasize the importance of a presymptomatic treatment in order achieve a significant therapeutic outcome. Moreover, there is a significant number of patients that do not respond to the SMN-enhancing treatments. Indeed, for severely affected SMA individuals carrying only two SMN2 copies even a presymptomatic therapy might be insufficient to fully counteract disease development. Therefore, SMN-independent compounds supporting SMN-dependent therapies represent a promising therapeutic approach. In this regard, genetic modifiers such as PLS3, NCALD or CHP1 have proved to act protective against SMA across species. Therefore, the aims of this work are the following: 1) To test a combinatorial therapy using SMN-ASO and Chp1-ASOs in SMA mice, 2) To develop an efficient MN differentiation protocol from healthy and SMA hiPSCs to use as a platform for compound screening (ASOs), 3) To test the long-term effect of the combinatorial therapy based on SMN-ASO and Ncald-ASO. In the first part of this work, we focused on the combinatorial treatment enhancing SMN protein levels and reducing CHP1 protein amount. CHP1, calcineurin-like EF-hand protein 1, is an interacting partner of PLS3, a strong modifier of SMA, and acts as a negative regulator of neurite outgrowth and endocytosis. Importantly, a significant amelioration of SMA disease hallmarks was observed in a severely affected SMA mouse model carrying a mutant Chp1 allele when combined with a suboptimal dose of SMN-ASO treatment. In this work, we aimed to pharmacologically reduce CHP1 levels in an ASO-based combinatorial therapy targeting SMN and Chp1 in SMA mice. Notably, Chp1 modulation represents a major challenge since its reduction to ~50% showed an amelioration of SMA pathology, while the downregulation below those levels is detrimental and prompts cerebellar ataxia characterized by Purkinje neuron loss. Hereby, efficacy and tolerability studies in neonatal wild type mice determined that a single injection of 30 µg Chp1-ASO4 in the CNS is a safe dosage that significantly reduced CHP1 levels to about 50% at postnatal day (PND)14 in the brain and the spinal cord. Unfortunately, neither electrophysiological predictors such as compound muscle action potential XVI | S U M M A R Y (CMAP) or motor unit number estimation (MUNE) nor morphological properties of the neuromuscular junctions (NMJ), the spinal cord or the tibialis anterior muscle were ameliorated in SMA mice treated with Chp1-ASO4 compared to CTRL-ASO at PND21. Unexpectedly, CHP1 levels were not reduced at 4- weeks post injection, indicating a rather short-term effect and stability of the ASO. Next, we re�administrated Chp1-ASO4 by i.c.v. bolus injection at PND28. However, no significant improvement of SMA hallmarks was observed at 2 month-of-age. Taken together, in contrast to the protective effect of the genetically-induced Chp1 reduction on SMA, combinatorial therapy based on Chp1- and SMN�ASOs failed to significantly ameliorate the SMA pathology in mice. The short-term stability of Chp1- ASOs compared to SMN-ASO suggests that further optimization of the ASO may be required to fully explore the combination of treatments. The second part of this work focused on the long-term combinatorial treatment targeting SMN upregulation and Ncald reduction. NCALD, neurocalcin delta, was identified as an SMA protective modifier in a SMA discordant family, where asymptomatic individuals exhibited a 4-5 fold NCALD reduction. NCALD is a calcium sensor protein that negatively regulates clathrin-mediated endocytosis and axonal outgrowth. NCALD reduction improves impaired endocytosis and ameliorates SMA pathology across species. Moreover, previous work carried out in our research group demonstrated that NCALD pharmacological reduction using Ncald-ASO in a low-dose SMN-ASO treated severe SMA mouse model, significantly improved electrophysiological and morphological pathology hallmarks at PND21. However, at 3 months of age SMA mice exhibited amelioration of motoric abilities solely. In the present work, we aimed to study the long-term effect of Ncald-ASO by re-injecting it via i.c.v. bolus administration at PND28. In parallel, we aimed to test the therapeutic effect of human NCALD-ASOs in MNs differentiated from patient-derived hiPSCs. First, 500µg Ncald-ASO administered via i.c.v. bolus injection at PND28 in wild type mice showed a good tolerability of the procedure and a significant reduction of NCALD in the brain and the spinal cord after two weeks. Importantly, Ncald-ASO re�injection prolonged the amelioration of electrophysiological parameters and rescued denervation defects. Moreover, human NCALD-ASO69 significantly downregulated NCALD levels in hiPSC derived MNs from healthy and SMA type I individuals. In addition, growth cone morphology and spontaneous neuronal activity were improved upon NCALD-ASO69 treatment. These data strongly supports the therapeutic role of NCALD in SMA and the importance of maintaining its reduction in order to achieve better clinical outcome

Geometries of third-row transition-metal complexes from density-functional theory

A set of 41 metal-ligand bond distances in 25 third-row transition-metal complexes, for which precise structural data are known in the gas phase, is used to assess optimized and zero-point averaged geometries obtained from DFT computations with various exchange-correlation functionals and basis sets. For a given functional (except LSDA) Stuttgart-type quasi-relativistic effective core potentials and an all-electron scalar relativistic approach (ZORA) tend to produce very similar geometries. In contrast to the lighter congeners, LSDA affords reasonably accurate geometries of 5d-metal complexes, as it is among the functionals with the lowest mean and standard deviations from experiment. For this set the ranking of some other popular density functionals, ordered according to decreasing standard deviation, is BLYP > VSXC > BP86 approximate to BPW91 approximate to TPSS approximate to B3LYP approximate to PBE > TPSSh > B3PW91 approximate to B3P86 approximate to PBE hybrid. In this case hybrid functionals are superior to their nonhybrid variants. In addition, we have reinvestigated the previous test sets for 3d- (Buhl M.; Kabrede, H. J. Chem. Theory Comput. 2006, 2, 1282-1290) and 4d- (Waller, M. P.; Buhl, M. J. Comput. Chem. 2007,28,1531-1537) transition-metal complexes using all-electron scalar relativistic DFT calculations in addition to the published nonrelativistic and ECP results. For this combined test set comprising first-, second-, and third-row metal complexes, B3P86 and PBE hybrid are indicated to perform best. A remarkably consistent standard deviation of around 2 pm in metal-ligand bond distances is achieved over the entire set of d-block elements.PostprintPeer reviewe

Design of CO2 hydrogenation catalysts based on phosphane/borane frustrated Lewis pairs and xanthene-derived scaffolds

UK Catalysis Hub is kindly thanked for resources and support provided via our membership of the UK Catalysis Hub Consortium and funded by EPSRC grant: EP/R026939/1, EP/R026815/1, EP/R026645/1, EP/R027129/1, and EP/M013219/1. J.W.M.C. acknowledges financial support from FAPERJ (grants E-26/203.001/2017, E-26/010.101118/2018, and E-26010.001424/2019) and CNPq (grants 309080/2015-0 and 434955/2018-3). M.B. thanks the School of Chemistry in St Andrews and EaStCHEM for support.New naphtho[2,1,8,7-klmn]xanthene and benzo[kl]xanthene-based intramolecular phosphane–borane frustrated Lewis pairs (FLPs) were investigated in catalyzed H2 activation and CO2 hydrogenation processes. According to DFT predictions at the B3LYP-D3 level, the presence of rigid scaffolds and increased P···B distances in the investigated FLPs lead to a remarkable drop in the energy barrier for CO2 hydrogenation (by up to 19.2 kcal mol−1, compared to the parent dimethylxanthene-based FLP). Furthermore, the energy differences between the transition states for H2 activation and CO2 hydrogenation are significantly reduced, making both processes feasible under relatively mild experimental conditions.Publisher PDFPeer reviewe

Sterically restricted tin phosphines, stabilized by weak intramolecular donor-acceptor interactions

Funding: Engineering and Physical Sciences Research Council (EPSRC)Four related sterically restricted pen-substituted acenaphthenes have been prepared containing mixed tin phosphorus moieties in the proximal 5,6-positions (Acenap[SnR3][(PPr2)-Pr-i]; Acenap = acenaphthene-5,6-diyl; R-3 = Ph-3 (1), Ph2Cl (2), Me2Cl (3), Bu2Cl (4)). The degree of intramolecular P-Sn bonding within the series was investigated by X-ray crystallography, solution and solid-state NMR spectroscopy, and density functional theory (DFT/B3LYP/SBKJC/PCM) calculations. All members of the series adopt a conformation such that the phosphorus lone pair is located directly opposite the tin center, promoting an intramolecular donor acceptor P -> Sn type interaction. The extent of covalent bonding between Sn and P is found to be much greater in triorganotin chlorides 2-4 in comparison with the triphenyl derivative 1. Coordination of a highly electronegative chlorine atom naturally increases the Lewis acidity of the tin center, enhancing the Ip(P)-sigma*(Sn-Y) donor acceptor 3c-4e type interaction, as indicated by conspicuously short Sn-P peri distances and significant (1)J(P-31,Sn-119) spin spin coupling constants (SSCCs) in the range 740-754 Hz. Evidence supporting the presence of this interaction was also found in solid-state NMR spectra of some of the compounds which exhibit an indirect spin spin coupling on the same order of magnitude as observed in solution. DFT calculations confirm the increased covalent bonding between P and Sn in 2-4, with notable WBIs of ca. 0.35 obtained, in comparison to 0.1 in 1.PostprintPeer reviewe

Pandemic Pedagogy: Elements of Online Supportive Course Design

The purpose of this study was to identify which course design elements students perceive as supporting an easier transition to emergency remote teaching due to COVID-19, as well as to use those items to develop the Online Supportive Course Design (OSCD) measure. By asking students to rate their course with the easiest transition and hardest transition to emergency remote teaching, this study identified which structural elements were most important for supporting students during the transition. Using exploratory and confirmatory factor analyses, a seven-item measure was developed to operationalize OSCD, and initial validity was established by examining the relationships between OSCD, autonomy support, and teacher competence. Finally, practical implications for university faculty and areas for future research are discussed

Unveiling the mechanism of N‐methylation of indole with dimethylcarbonate using either DABCO or DBU as catalyst

B.R.V.F., P.H.V. and M.N.E. acknowledge the São Paulo State Science Foundation (FAPESP) and the Brazilian National Science Council (CNPq) for financial support. L.A.Z. thanks CNPQ for his PhD scholarship (142476/2018-8), R.A.C. thanks SDumont and CESUP. M.B. thanks the School of Chemistry and EaStCHEM for support and for access to a computer cluster maintained by Dr. H. Früchtl.Depending on the catalyst used, N‐methylation of indole with dimethylcarbonate (DMC) ‐ an environmentally friendly alkylation agent – yields different products. With 1,4‐diazabicyclo[2.2.2]octane (DABCO), the reaction forms only N‐methylated indole but with or 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), both N‐methylated and N‐methoxycarbonylated indole are formed. Using direct ESI(+)‐MS monitoring to collect actual snapshots of the changing ionic composition of the reaction solution, we report on the interception and characterization of key intermediates for such reactions. Although a mechanism has been proposed with methoxycarbonylated base as the key intermediate for both DBU and DABCO, the ESI(+)‐MS data as well as B3LYP‐D3/6‐311+G** calculations suggest that the reaction of DMC with indole under either DABCO or DBU catalysis follow contrasting mechanisms.PostprintPeer reviewe

Constrained phosphine chalcogenide selenoethers supported by peri-substitution

A series of phosphorus and selenium peri-substituted acenaphthene species with the phosphino group oxidized by O, S, and Se has been isolated and fully characterized, including by single-crystal X-ray diffraction. The P(V) and Se(II) systems showed fluxional behavior in solution due to the presence of two major rotamers, as evidenced with solution NMR spectroscopy. Using Variable-Temperature NMR (VT NMR) and supported by DFT (Density Functional Theory) calculations and solid-state NMR, the major rotamers in the solid and in solution were identified. All compounds showed a loss of the through-space JPSe coupling observed in the unoxidized P(III) and Se(II) systems due to the sequestration of the lone pair of the phosphine, which has been previously identified as the major contributor to the coupling pathway.Publisher PDFPeer reviewe

Isothiourea-catalyzed enantioselective Michael addition of malonates to α,β-unsaturated aryl esters

MB thanks EaStCHEM and the School of Chemistry for support.An enantioselective Michael addition of malonates to α,β-unsaturated para-nitrophenyl esters was achieved using the Lewis basic isothiourea HyperBTM, giving excellent levels of product enantioselectivity (up to >99:1 enantiomeric ratio) in good yields and with complete regioselectivity (>20:1 regioselectivity ratio) in the presence of alternative (phenyl ketone and ethyl ester) Michael acceptors. Density functional theory calculations indicate that N-acylation is rate-limiting. This constitutes a rare example of a highly enantioselective addition of simple, readily available malonates to α,β-unsaturated esters.Publisher PDFPeer reviewe

Structure-directing effects in (110)-layered hybrid perovskites containing two distinct organic moieties

We acknowledge support from the University of St Andrews, the China Scholarship Council (studentship to YYG) and the Leverhulme trust (RPG-2018-065).The hybrid perovskites (ImH)(GuH)PbBr4 and (TzH)(GuH)PbBr4 (ImH+ = imidazolium, GuH+ = guanidinium, TzH+ = 1,2,4-triazolium) both adopt (110)-oriented layer structures. However, the GuH+ cation adopts differing crystallographic sites in the two structures (intra-layer versus inter-layer); this is discussed in terms of the sizes of the organic cations and their hydrogen-bonding preferences.PostprintPeer reviewe

Formation of metallacarboxylic acids through Hieber base reaction. A density functional theory study

We thank EaStCHEM and the School of Chemistry for support.Using density functional theory (B97-D/ECP2/PCM//RI-BP86/ECP1 level), we have studied the effects of ligand variation on OH− uptake by transition-metal carbonyls (Hieber base reaction), i.e., LnM(CO) + OH− → [LnM(CO2H)]−, M = Fe, Ru, Os, L = CO, PMe3, PF3, py, bipy, Cl, H. The viability of this step depends notably on the nature of the co-ligands, and a large span of driving forces is predicted, ranging from ΔG = −144 kJ/mol to +122 kJ/mol. Based on evaluation of atomic charges from natural population analysis, it is the ability of the co-ligands to delocalize the additional negative charge (through their π-acidity) that is the key factor affecting the driving force for OH− uptake. Implications for the design of new catalysts for water gas shift reaction are discussed.Publisher PDFPeer reviewe