RESUMEN
Pathogenic variations in the fused in sarcoma (FUS) gene are associated with rare and aggressive forms of amyotrophic lateral sclerosis (ALS). As FUS-ALS is a dominant disease, a targeted, allele-selective approach to FUS knockdown is most suitable. Antisense oligonucleotides (AOs) are a promising therapeutic platform for treating such diseases. In this study, we have explored the potential for allele-selective knockdown of FUS. Gapmer-type AOs targeted to two common neutral polymorphisms in FUS were designed and evaluated in human fibroblasts. AOs had either methoxyethyl (MOE) or thiomorpholino (TMO) modifications. We found that the TMO modification improved allele selectivity and efficacy for the lead sequences when compared to the MOE counterparts. After TMO-modified gapmer knockdown of the target allele, up to 93% of FUS transcripts detected were from the non-target allele. Compared to MOE-modified AOs, the TMO-modified AOs also demonstrated reduced formation of structured nuclear inclusions and SFPQ aggregation that can be triggered by phosphorothioate-containing AOs. How overall length and gap length of the TMO-modified AOs affected allele selectivity, efficiency and off-target gene knockdown was also evaluated. We have shown that allele-selective knockdown of FUS may be a viable therapeutic strategy for treating FUS-ALS and demonstrated the benefits of the TMO modification for allele-selective applications.
Asunto(s)
Alelos , Esclerosis Amiotrófica Lateral , Oligonucleótidos Antisentido , Proteína FUS de Unión a ARN , Humanos , Oligonucleótidos Antisentido/uso terapéutico , Oligonucleótidos Antisentido/genética , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Esclerosis Amiotrófica Lateral/terapia , Proteína FUS de Unión a ARN/genética , Fibroblastos/metabolismo , Fibroblastos/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Morfolinos/uso terapéutico , Morfolinos/genéticaRESUMEN
Aberrant alternative splicing is emerging as a cancer hallmark and a potential therapeutic target. It is the result of dysregulated or mutated splicing factors, or genetic alterations in splicing-regulatory cis-elements. Targeting individual altered splicing events associated with cancer-cell dependencies is a potential therapeutic strategy, but several technical limitations need to be addressed. Patient-derived organoids are a promising platform to recapitulate key aspects of disease states, and to facilitate drug development for precision medicine. Here, we report an efficient antisense-oligonucleotide (ASO) lipofection method to systematically evaluate and screen individual splicing events as therapeutic targets in pancreatic ductal adenocarcinoma organoids. This optimized delivery method allows fast and efficient screening of ASOs, e.g., those that reverse oncogenic alternative splicing. In combination with advances in chemical modifications of oligonucleotides and ASO-delivery strategies, this method has the potential to accelerate the discovery of antitumor ASO drugs that target pathological alternative splicing.
Asunto(s)
Empalme Alternativo , Oligonucleótidos Antisentido , Organoides , Neoplasias Pancreáticas , Humanos , Organoides/efectos de los fármacos , Organoides/metabolismo , Oligonucleótidos Antisentido/genética , Oligonucleótidos Antisentido/farmacología , Empalme Alternativo/genética , Empalme Alternativo/efectos de los fármacos , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Carcinoma Ductal Pancreático/tratamiento farmacológico , Carcinoma Ductal Pancreático/terapiaRESUMEN
Cell membrane association of proteins can be achieved by the addition of lipid moieties to the polypeptide chain, and such lipid-modified proteins have important biological functions. A class of cell surface proteins contains a complex glycosylphosphatidylinositol (GPI) glycolipid at the C-terminus, and they are accumulated in cholesterol-rich membrane microdomains, that is, lipid rafts. Semisynthetic lipoproteins prepared from recombinant proteins and designed lipids are valuable probes and model systems of the membrane-associated proteins. Because GPI-anchored proteins can be reinserted into the cell membrane with the retention of the biological function, they are appropriate candidates for preparing models via reduction of the structural complexity. A synthetic headgroup was added to the 3ß-hydroxyl group of cholesterol, an essential lipid component of rafts, and the resulting cholesterol derivative was used as a simplified GPI mimetic. In order to quantitate the membrane integrated GPI mimetic after the exogenous addition to live cells, a tritium labelled cholesterol anchor was prepared. The radioactive label was introduced into the headgroup, and the radiolabelled GPI mimetic anchor was obtained with a specific activity of 1.37 TBq/mmol. The headgroup labelled cholesterol derivative was applied to demonstrate the sensitive detection of the cell membrane association of the anchor under in vivo conditions.
Asunto(s)
Colesterol/análogos & derivados , Glicosilfosfatidilinositoles/síntesis química , Tensoactivos/síntesis química , Tritio/química , Colesterol/químicaRESUMEN
The exogenous introduction of fluorescent lipoproteins into cell membranes is a method for visualizing the cellular traffic of membrane associated proteins, and also for altering the cell surface in a controlled manner. In order to achieve the cell membrane anchoring of proteins and their subsequent fluorescence based detection, a cholesterol derivative was designed. The headgroup of the novel cholesterol anchor contains a fluorescent reporter and a thiol reactive maleimide for protein conjugation. Protein conjugation was demonstrated by the addition of a green fluorescent maleimido anchor to the C-terminus of a Cys extended red fluorescent protein, mCherry. The resulting dual fluorescent cholesteryl lipoprotein was successfully separated from the micellar associates of the surplus fluorescent lipid anchor without denaturing the protein, and the lipoprotein containing only the covalently linked, stoichiometric fluorescent lipid was efficiently delivered to the plasma membrane of live cells. It was demonstrated that the membrane fluorescence could be directly assigned to the protein-anchor conjugate, because no excess of fluorescent lipid species were present during the imaging experiment and the protein and anchor fluorescence colocalized in the cell membrane. Molecular dynamics simulations and subsequent trajectory analysis suggest also the spontaneous and stable membrane association of the cholesterol anchor. Thus, the method could be beneficially applied for studying membrane associated proteins and for preparing mimetics of glycosylphosphatidylinositol (GPI)-anchored proteins to target cholesterol-rich membrane microdomains.