Biology subjects

Barajas, J. R.

Publications and source records attributed to Barajas, J. R..

3 recordsLinked to original sources

bioRxiv2026

Ctcf deficiency in myofibers induces pathological genome reprogramming toward the spontaneous development of myopathy

How perennial, postmitotic multinucleated tissues, such as skeletal myofibers, maintain their identity and transcriptional adaptation to homeostatic perturbations through adult life is an outstanding question. To address this issue, we investigated the consequences of loss of 3D-genome architecture in skeletal muscles by generating myofiber-specific Ctcf-deficient (CtcfmKO) mice. CtcfmKO mice did not exhibit muscular phenotype at birth but spontaneously developed a severe myopathy. Integrated analysis of snRNAseq, ATACseq and promoter-capture Hi-C revealed both common and fiber-type specific patterns of dysregulated gene expression associated with alterations in chromatin accessibility and promoter-based interactions in Ctcf-deficient myonuclei at distinct stages of myopathy development. Decreased chromatin accessibility at promoters and changes in their connectivity with distal elements were observed across all myonuclei as a direct consequence of Ctcf deficiency at early stages and associated with downregulation of genes implicated in myofiber contraction and anabolism, metabolism, adhesion and neuromuscular transmission. Conversely, at later stages, upregulation of genes leading to persistent activation of ER stress/UPR and catabolism resulted from global reconfiguration of chromatin structure and connectivity, partly as indirect consequence of Ctcf deficiency. Notably, type-IIB myonuclei exhibited specific alterations in gene expression that culminated in loss of fiber-type identity and ectopic expression of inflammatory genes. These results reveal a requirement of Ctcf for maintenance of fiber-type identity and transcriptional adaptation in vivo, through multilayered control of 3D genome integrity. They also indicate an unprecedented association between Ctcf deficiency in myofibers and susceptibility to develop myopathies, whereby Ctcf dispensability for developmental myogenesis confers vulnerability to develop myopathic syndromes.

molecular biology↗

bioRxiv2026

Tumor-derived SAA1-TLR4 signaling drives tumor-to-muscle communication in pancreatic cancer cachexia

Cancer cachexia limits treatment tolerance and survival in pancreatic ductal adenocarcinoma (PDAC), yet the tumor-derived signals driving tissue dysfunction remain poorly understood. Here, we identify serum amyloid A1 (SAA1) as a mediator of tumor-to-host communication acting through Toll-like receptor 4 (TLR4). Tumor-derived SAA1 was elevated in human PDAC and in a mouse PDAC model and disrupted both myofiber and muscle stem cell (MuSC) homeostasis. Genetic reduction of tumor-derived SAA1 uncoupled tumor progression from host wasting, preserving muscle mass and function and prolonging survival without affecting primary tumor growth. Mechanistically, SAA1-TLR4 signaling drove multicellular remodeling of the skeletal muscle microenvironment. Therapeutic TLR4 inhibition after cachexia onset restored muscle mass, function and MuSC abundance and prolonged survival independently of tumor growth. Conservation of SAA1-TLR4 signaling in human skeletal muscle identifies a therapeutically actionable tumor-host pathway and demonstrates that host deterioration can be targeted independently of tumor progression.

cancer biology↗

bioRxiv2026

Novel role of the lncRNA EPR as oncosuppressor in intestinal cancer.

We previously reported that the murine lncRNA Epr is essential for maintaining colon mucosal integrity and permeability. Mice lacking Epr in the colon are more susceptible to colitis and tumor development. Additionally, we demonstrated that human EPR expression is reduced in ulcerative colitis and in a small cohort of colon adenocarcinoma patients. Here, we present evidence that human and mouse EPR share several key physiological features: preferential binding to the KH1 domain of their interacting protein, KSRP; specific expression in canonical and immature goblet cells of the large intestine; and a functional role in intestinal goblet cell development. The correlation between EPR levels and survival in large cohorts of metastatic colon adenocarcinoma patients, together with the capacity of human EPR to inhibit cell proliferation and induce apoptosis in two distinct human colon adenocarcinoma cell lines, suggests that EPR may serve as both a valuable prognostic marker for goblet cell-derived adenocarcinomas and a potential therapeutic target.

cancer biology↗