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Lateral Meningocele Syndrome (LMS), a disorder associated with NOTCH3 pathogenic variants, presents with neurological, craniofacial and skeletal abnormalities. Mouse models of the disease exhibit osteopenia that is ameliorated by the administration of Notch3 antisense oligonucleotides (ASO) targeting either Notch3 or the Notch3 mutation. To determine the consequences of LMS pathogenic variants in human cells and whether they can be targeted by ASOs, induced pluripotent NCRM1 and NCRM5 stem (iPS) cells harboring a NOTCH3 6692-93insC insertion were created. Parental iPSCs, NOTCH3 6692-93insC and isogenic controls, free of chromosomal aberrations as determined by human CytoSNP850 array, were cultured under conditions of neural crest, mesenchymal and osteogenic cell differentiation. The expected cell phenotype was confirmed by surface markers and a decline in OCT3/4 and NANOG mRNA. NOTCH3 6692-93insC cells displayed enhanced expression of Notch target genes HES1 , HEY1 , 2 and L demonstrating a NOTCH3 gain-of-function. There was enhanced osteogenesis in NOTCH3 6692-93insC cells as evidenced by increased mineralized nodule formation and ALPL , BGLAP and BSP expression. ASOs targeting NOTCH3 decreased both NOTCH3 wild type and NOTCH3 6692-93insC mutant mRNA by 40% in mesenchymal and 90% in osteogenic cells. ASOs targeting the NOTCH3 insertion decreased NOTCH3 6692-93insC by 70–80% in mesenchymal cells and by 45–55% in osteogenic cells and NOTCH3 mRNA by 15–30% and 20–40%, respectively. In conclusion, a NOTCH3 pathogenic variant causes a modest increase in osteoblastogenesis in human iPS cells in vitro and NOTCH3 and NOTCH3 mutant specific ASOs downregulate NOTCH3 transcripts associated with LMS.

Obesity and metabolic syndrome are associated with mitochondrial dysfunction and deranged regulation of metabolic genes. Peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) is a transcriptional coactivator that regulates metabolism and mitochondrial biogenesis through stimulation of nuclear hormone receptors and other transcription factors. We report that the PGC-1β gene encodes two microRNAs (miRNAs), miR-378 and miR-378*, which counterbalance the metabolic actions of PGC-1β. Mice genetically lacking miR-378 and miR-378* are resistant to high-fat diet-induced obesity and exhibit enhanced mitochondrial fatty acid metabolism and elevated oxidative capacity of insulin-target tissues. Among the many targets of these miRNAs, carnitine O -acetyltransferase, a mitochondrial enzyme involved in fatty acid metabolism, and MED13, a component of the Mediator complex that controls nuclear hormone receptor activity, are repressed by miR-378 and miR-378*, respectively, and are elevated in the livers of miR-378/378* KO mice. Consistent with these targets as contributors to the metabolic actions of miR-378 and miR-378*, previous studies have implicated carnitine O -acetyltransferase and MED13 in metabolic syndrome and obesity. Our findings identify miR-378 and miR-378* as integral components of a regulatory circuit that functions under conditions of metabolic stress to control systemic energy homeostasis and the overall oxidative capacity of insulin target tissues. Thus, these miRNAs provide potential targets for pharmacologic intervention in obesity and metabolic syndrome.

Notch receptors are determinants of cell fate and function, and play an important role in the regulation of bone development and skeletal remodeling. Lateral Meningocele Syndrome (LMS) is a monogenic disorder associated with NOTCH3 pathogenic variants that result in the stabilization of NOTCH3 and a gain-of-function. LMS presents with neurological developmental abnormalities and bone loss. We created a mouse model ( Notch3 em1Ecan ) harboring a 6691TAATGA mutation in the Notch3 locus, and heterozygous Notch3 em1Ecan mice exhibit cancellous and cortical bone osteopenia. In the present work, we explored whether Notch3 antisense oligonucleotides (ASO) downregulate Notch3 and have the potential to ameliorate the osteopenia of Notch3 em1Ecan mice. Notch3 ASOs decreased the expression of Notch3 wild type and Notch3 6691-TAATGA mutant mRNA expressed by Notch3 em1Ecan mice in osteoblast cultures without evidence of cellular toxicity. The effect was specific since ASOs did not downregulate Notch1 , Notch2 or Notch4 . The expression of Notch3 wild type and Notch3 6691-TAATGA mutant transcripts also was decreased in bone marrow stromal cells and osteocytes following exposure to Notch3 ASOs. In vivo , the subcutaneous administration of Notch3 ASOs at 25 to 50 mg/Kg decreased Notch3 mRNA in the liver, heart and bone. Microcomputed tomography demonstrated that the administration of Notch3 ASOs ameliorates the cortical osteopenia of Notch3 em1Ecan mice, and ASOs decreased femoral cortical porosity and increased cortical thickness and bone volume. However, the administration of Notch3 ASOs did not ameliorate the cancellous bone osteopenia of Notch em1Ecan mice. In conclusion, Notch3 ASOs downregulate Notch3 expression in skeletal cells and their systemic administration ameliorates cortical osteopenia in Notch3 em1Ecan mice; as such ASOs may become useful strategies in the management of skeletal diseases affected by Notch gain-of-function.

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading cause of chronic liver disease. Available therapies show inconsistent results on fibrosis, probably due to heterogeneity in disease trajectory or incomplete understanding of molecular determinants. Here we identified increased KCTD17 levels in patients with MASH, and in dietary rodent models of MASH—such as those fed a diet high in palmitate, sucrose and cholesterol coupled with fructose-containing drinking water or a choline-deficient, l -amino acid-defined, high-fat diet—which showed an inverse correlation with the expression of serine protease inhibitor a3k ( SERPINA3 in humans, Serpina3k in mice). KCTD17 depletion increased SERPINA3 levels and reduced liver fibrosis in mice fed a MASH-inducing diet by inhibiting Par2/TGFβ-mediated activation of hepatic stellate cells. Mechanistically, Kctd17 regulates Serpina3k expression by facilitating the ubiquitin-mediated degradation of Zbtb7b, which in turn diminishes Serpina3k secretion. Consequently, pharmacological inhibition of Kctd17 effectively reverses MASH-induced liver fibrosis. In summary, these findings underscore the therapeutic potential of targeting KCTD17 for the treatment of MASH-induced liver fibrosis. Targeting KCTD17 offers new hope for liver fibrosis Metabolic dysfunction-associated steatotic liver disease (MASLD) affects about 25% of people worldwide. Around 20% of these cases progress to a more severe form, leading to liver damage and potentially requiring a liver transplant. Researchers studied a protein called KCTD17, which is involved in liver fibrosis. They found that reducing KCTD17 in mice with MASLD decreased liver damage. The study used mice fed a special diet to mimic human liver disease. The researchers used genetic techniques to lower KCTD17 levels and observed less liver scarring. They also discovered that KCTD17 affects another protein, Serpina3k, which helps protect the liver. Increasing Serpina3k levels reduced liver damage in mice. These findings suggest that targeting KCTD17 could be a new way to treat liver fibrosis. In the future, it could lead to new treatments for people with severe liver disease. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.

Maintenance of skeletal muscle structure and function requires efficient and precise metabolic control. Autophagy plays a key role in metabolic homeostasis of diverse tissues by recycling cellular constituents, particularly under conditions of caloric restriction, thereby normalizing cellular metabolism. Here we show that histone deacetylases (HDACs) 1 and 2 control skeletal muscle homeostasis and autophagy flux in mice. Skeletal muscle-specific deletion of both HDAC1 and HDAC2 results in perinatal lethality of a subset of mice, accompanied by mitochondrial abnormalities and sarcomere degeneration. Mutant mice that survive the first day of life develop a progressive myopathy characterized by muscle degeneration and regeneration, and abnormal metabolism resulting from a blockade to autophagy. HDAC1 and HDAC2 regulate skeletal muscle autophagy by mediating the induction of autophagic gene expression and the formation of autophagosomes, such that myofibers of mice lacking these HDACs accumulate toxic autophagic intermediates. Strikingly, feeding HDAC1/2 mutant mice a high-fat diet from the weaning age releases the block in autophagy and prevents myopathy in adult mice. These findings reveal an unprecedented and essential role for HDAC1 and HDAC2 in maintenance of skeletal muscle structure and function and show that at least in some pathological conditions, myopathy may be mitigated by dietary modifications.

Background Valosin‐containing protein (VCP) related disease, also known as multisystem proteinopathy 1 (MSP1), is an autosomal dominant disease caused by gain‐of‐function pathogenic variants of the VCP gene. The disease presents with variable combinations of inclusion body myopathy, early‐onset Paget's disease of bone, frontotemporal dementia and may also overlap with familial amyotrophic lateral sclerosis. There is currently no treatment for this progressive disease associated with early demise resulting from proximal limb girdle and respiratory muscle weakness. We hypothesise that regulating VCP hyperactivity to normal levels can reduce the disease pathology. Main topics covered In this study, we assessed the effect of antisense oligonucleotides (ASOs) specifically targeting the human VCP gene in the patient (R155H) iPSC‐derived skeletal muscle progenitor cells (SMPCs). ASOs were well tolerated up to a concentration of 5 µM and significantly reduced VCP protein expression in the SMPCs by 48% (95% CI [39–56]). We also treated the transgenic mouse model of VCP disease with the overexpressed humanised VCP severe A232E pathogenic gene variant (VCP A232E mice) with weekly subcutaneous ASO injections starting from 6 months of age for 3 months. In the skeletal muscle of transgenic mice, ASOs resulted in 30% (95% CI [27–32]) knockdown of VCP protein compared with control ASO. The ASO‐mediated reduction of VCP expression in muscle tissue was associated with improvement in autophagy flux and reduction in TAR DNA binding protein 43 (TDP‐43) expression, hallmarks of VCP related MSP1. In addition, ASO‐treated VCP A232E mice showed improvements in functional tests of muscle strength, such as rotarod and inverted screen test compared with mice treated with control ASO. Conclusions These results suggest that targeting VCP could be beneficial in preventing the progression of the VCP myopathy and hold promise for the treatment of patients with VCP related MSP1. Key points VCP multisystem proteinopathy 1 is caused by gain‐of‐function pathogenic variants of the VCP gene. VCP targeting ASOs were well tolerated and significantly reduced VCP, TAR DNA binding protein 43 (TDP 43), and autophagy protein expression in the (R155H) iPSC‐derived skeletal muscle progenitor cells (SMPCs). The ASOs reduced VCP, TDP‐43, and autophagy flux expression, and improved functional tests of muscle strength in the humanized VCP A232E mice. Multisystem proteinopathy 1 (MSP1), caused by gain‐of‐function VCP variants, leads to multisystem degeneration. Using VCP patient‐derived hiPSCs, skeletal muscle progenitor cells were generated to evaluate antisense oligonucleotide (ASO) therapy. ASOs reduced VCP expression, restored autophagy and decreased TDP‐43 pathology in patient cells and humanized transgenic mice, supporting ASO‐mediated RNA modulation as a promising MSP1 treatment.

Background/Aims: Potassium channel tetramerization domain containing 17 (KCTD17) protein, an adaptor for the cullin3 (Cul3) ubiquitin ligase complex, has been implicated in various human diseases; however, its role in hepatocellular carcinoma (HCC) remains elusive. Here, we aimed to elucidate the clinical features of KCTD17, and investigate the mechanisms by which KCTD17 affects HCC progression. Methods: We analyzed transcriptomic data from patients with HCC. Hepatocyte-specific KCTD17 deficient mice were treated with diethylnitrosamine (DEN) to assess its effect on HCC progression. Additionally, we tested KCTD17- directed antisense oligonucleotides for their therapeutic potential in vivo. Results: Our investigation revealed the upregulation of KCTD17 expression in both tumors from patients with HCC and mouse models of HCC, in comparison to non-tumor controls. We identified the leucine zipper-like transcriptional regulator 1 (Lztr1) protein, a previously identified Ras destabilizer, as a substrate for KCTD17-Cul3 complex. KCTD17- mediated Lztr1 degradation led to Ras stabilization, resulting in increased proliferation, migration, and wound healing in liver cancer cells. Hepatocyte-specific KCTD17 deficient mice or liver cancer xenograft models were less susceptible to carcinogenesis or tumor growth. Similarly, treatment with KCTD17-directed antisense oligonucleotides (ASO) in a mouse model of HCC markedly lowered tumor volume as well as Ras protein levels, compared to those in control ASO-treated mice. Conclusions: KCTD17 induces the stabilization of Ras and downstream signaling pathways and HCC progression and may represent a novel therapeutic target for HCC. (Clin Mol Hepatol 2024;30:895-913)

Pompe disease (PD) is a progressive myopathy caused by the aberrant accumulation of glycogen in skeletal and cardiac muscle resulting from the deficiency of the enzyme acid alpha‐glucosidase (GAA). Administration of recombinant human GAA as enzyme replacement therapy (ERT) works well in alleviating the cardiac manifestations of PD but loses sustained benefit in ameliorating the skeletal muscle pathology. The limited efficacy of ERT in skeletal muscle is partially attributable to its inability to curb the accumulation of new glycogen produced by the muscle enzyme glycogen synthase 1 (GYS1). Substrate reduction therapies aimed at knocking down GYS1 expression represent a promising avenue to improve Pompe myopathy. However, finding specific inhibitors for GYS1 is challenging given the presence of the highly homologous GYS2 in the liver. Antisense oligonucleotides (ASOs) are chemically modified oligomers that hybridise to their complementary target RNA to induce their degradation with exquisite specificity. In the present study, we show that ASO‐mediated Gys1 knockdown in the Gaa−/− mouse model of PD led to a robust reduction in glycogen accumulation in skeletal muscle. In addition, combining Gys1 ASO with ERT slightly further reduced glycogen content in muscle, eliminated autophagic buildup and lysosomal dysfunction, and improved motor function in Gaa−/− mice. Our results provide a strong foundation for validation of the use of Gys1 ASO, alone or in combination with ERT, as a therapy for PD. We propose that early administration of Gys1 ASO in combination with ERT may be the key to preventative treatment options in PD. Key points Antisense oligonucleotide (ASO) treatment in a mouse model of Pompe disease achieves robust knockdown of glycogen synthase (GYS1). ASO treatment reduces glycogen content in skeletal muscle. Combination of ASO and enzyme replacement therapy (ERT) further improves motor performance compared to ASO alone in a mouse model of Pompe disease. Antisense oligonucleotide (ASO) treatment in a mouse model of Pompe disease achieves robust knockdown of glycogen synthase (GYS1). ASO treatment reduces glycogen content in skeletal muscle. Combination of ASO and enzyme replacement therapy (ERT) further improves motor performance compared to ASO alone in a mouse model of Pompe disease.

Pseudoachondroplasia (PSACH), a severe dwarfing condition characterized by impaired skeletal growth and early joint degeneration, results from mutations in cartilage oligomeric matrix protein (COMP). These mutations disrupt normal protein folding, leading to the accumulation of misfolded COMP in chondrocytes. The MT-COMP mouse is a murine model of PSACH that expresses D469del human COMP in response to doxycycline and replicates the PSACH chondrocyte and clinical pathology. The basis for the mutant-COMP pathology involves endoplasmic reticulum (ER) stress signaling through the PERK/eIF2α/CHOP pathway. C/EBP homologous protein (CHOP), in conjunction with a TNFα inflammatory process, upregulates mTORC1, hindering autophagy clearance of mutant COMP protein. Life-long joint pain/degeneration diminishes quality of life, and treatments other than joint replacements are urgently needed. To assess whether molecules that reduce CHOP activity should be considered as a potential treatment for PSACH, we evaluated MT-COMP mice with 50% CHOP (MT-COMP/CHOP+/−), antisense oligonucleotide (ASO)-mediated CHOP knockdown, and complete CHOP ablation (MT-COMP/CHOP−/−). While earlier studies demonstrated that loss of CHOP in MT-COMP mice reduced intracellular retention, inflammation, and growth plate chondrocyte death, we now show that it did not normalize limb growth. ASO treatment reduced CHOP mRNA by approximately 60%, as measured by RT-qPCR, but did not improve limb length similar to MT-COMP/CHOP+/−. Interestingly, both 50% genetic reduction and complete loss of CHOP alleviated pain, while total ablation of CHOP in MT-COMP mice was necessary to preserve joint health. These results indicate that (1) CHOP reduction therapy is not an effective strategy for improving limb length and (2) pain and chondrocyte pathology are more responsive to intervention than the prevention of joint damage.