Abstract The pathogenesis and therapeutic avenues for GDP-mannose pyrophosphorylase B (GMPPB)-associated dystroglycanopathy (DPG) have not been comprehensively characterized. Recent studies have highlighted a significant association between mutations in GMPPB with DGP, a rare disease characterized by neuromuscular phenotypes. To interrogate the molecular mechanisms driving the onset and progression and to identify potential therapeutic approaches for GMPPB-associated DGP, we here constructed genetically engineered mice models of Gmppb. We show that Gmppb knockout and P32L mutant mice are lethal in the homozygous form, whereas homologous R287Q mutants are viable. Heterozygous Gmppb-P32L mutant mice exhibit reduced muscle strength, decreased locomotor ability, elevated creatine kinase levels and increased centrally nucleated myofibers. Furthermore, loss of GMPPB results in defective differentiation of muscle stem cells, leading to failure to develop into mature myotubes and diminished muscle regeneration capability. Biochemical and transcriptomic analyses indicate that loss of GMPPB is associated with significant alterations in protein glycosylation, intracellular Ca2+ storage and release, and the Wnt/β-catenin signaling pathway. Pharmacological activation of the Wnt pathway alleviated disruption of muscle differentiation and regeneration post muscle injury in Gmppb-deficient models. Additionally, adeno-associated virus (AAV)-mediated gene replacement therapy successfully ameliorated the muscular phenotypes. Collectively, our findings provide direct evidence that impaired muscle stem cell differentiation contributes to GMPPB-associated dystroglycanopathy. Wnt pathway agonists and AAV gene therapy represent potential effective intervention strategies for treating DGP disease.

Efficient skeletal muscle regeneration necessitates fine-tuned coordination among multiple cell types through an intricate network of intercellular communication. We present a protocol for generation of a time-resolved cellular interactome during tissue remodeling. We describe steps for isolating distinct cell populations from skeletal muscle of adult mice after acute damage and extracting RNA from purified cells prior to the generation of RNA sequencing data. We then detail procedures for generating and deciphering a time- and lineage-resolved model of intercellular crosstalk. For complete details on the use and execution of this protocol, please refer to Groppa et al. (2023).1.
Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

The resistance of cancer cells to therapy is responsible for the death of most patients with cancer1. Epithelial-to-mesenchymal transition (EMT) has been associated with resistance to therapy in different cancer cells2,3. However, the mechanisms by which EMT mediates resistance to therapy remain poorly understood. Here, using a mouse model of skin squamous cell carcinoma undergoing spontaneous EMT during tumorigenesis, we found that EMT tumour cells are highly resistant to a wide range of anti-cancer therapies both in vivo and in vitro. Using gain and loss of function studies in vitro and in vivo, we found that RHOJ-a small GTPase that is preferentially expressed in EMT cancer cells-controls resistance to therapy. Using genome-wide transcriptomic and proteomic profiling, we found that RHOJ regulates EMT-associated resistance to chemotherapy by enhancing the response to replicative stress and activating the DNA-damage response, enabling tumour cells to rapidly repair DNA lesions induced by chemotherapy. RHOJ interacts with proteins that regulate nuclear actin, and inhibition of actin polymerization sensitizes EMT tumour cells to chemotherapy-induced cell death in a RHOJ-dependent manner. Together, our study uncovers the role and the mechanisms through which RHOJ acts as a key regulator of EMT-associated resistance to chemotherapy.
© 2023. The Author(s).

The authors determined the effect of the GLP-1 receptor agonist liraglutide on endothelial surface expression of vascular cell adhesion molecule (VCAM)-1 in murine apolipoprotein E knockout atherosclerosis. Contrast-enhanced ultrasound molecular imaging using microbubbles targeted to VCAM-1 and control microbubbles showed a 3-fold increase in endothelial surface VCAM-1 signal in vehicle-treated animals, whereas in the liraglutide-treated animals the signal ratio remained around 1 throughout the study. Liraglutide had no influence on low-density lipoprotein cholesterol or glycated hemoglobin, but reduced TNF-α, IL-1β, MCP-1, and OPN. Aortic plaque lesion area and luminal VCAM-1 expression on immunohistology were reduced under liraglutide treatment.
© 2023 The Authors.

The size of the satellite cell pool is reduced in estradiol (E2)-deficient female mice and humans. Here, we use a combination of in vivo and in vitro approaches to identify mechanisms, whereby E2 deficiency impairs satellite cell maintenance. By measuring satellite cell numbers in mice at several early time points postovariectomy (Ovx), we determine that satellite cell numbers decline by 33% between 10 and 14 days post-Ovx in tibialis anterior and gastrocnemius muscles. At 14 days post-Ovx, we demonstrate that satellite cells have a reduced propensity to transition from G0/G1 to S and G2/M phases, compared with cells from ovary-intact mice, associated with changes in two key satellite cell cycle regulators, ccna2 and p16INK4a. Further, freshly isolated satellite cells treated with E2 in vitro have 62% greater cell proliferation and require less time to complete the first division. Using clonal and differentiation assays, we measured 69% larger satellite cell colonies and enhanced satellite cell-derived myoblast differentiation with E2 treatment compared with vehicle-treated cells. Together, these results identify a novel mechanism for preservation of the satellite cell pool by E2 via promotion of satellite cell cycling.