👤 A Ragab

DNA methylation plays a pivotal role in the pathogenesis of Acute Lymphocytic Leukemia (ALL), a hematological malignancy marked by abnormal cellular behavior and immune dysregulation. This study aimed to investigate how alterations in DNA methylation affect lysosmal function in pediatric ALL. A total of 50 blood samples were collected from children diagnosed with ALL and analyzed for biochemical markers associated with the disease. Expression levels of key DNA methylation regulators, including DNA methyltransferase 1 (DNMT1) and DNMT3, were evaluated and compared with those from healthy controls. In addition, pro-inflammatory cytokines, interleukin-6 (IL-6), interleukin-27 (IL-27), and tumor necrosis factor-alpha (TNF-α), were monitored over a six-day period prior to treatment initiation. The study also assessed the expression of lysosome-associated membrane proteins, LAMP1 and LAMP2, which are essential for lysosomal function and the degradation of autophagosomes. To determine the DNA methylation status of the promoter regions of these genes, genomic DNA underwent sodium bisulfite treatment and digestion with methylation-sensitive and methylation-dependent restriction enzymes, followed by amplification with gene-specific primers. Our results revealed a significant upregulation of DNMT1 and DNMT3 in ALL samples, along with a marked downregulation of TET1 gene expression, which is responsible for DNA demethylation. This suggests that disrupted DNA methylation dynamics may contribute to the pathogenesis of the disease. Furthermore, methylation levels within the CpG islands of the LAMP1 and LAMP2 promoter regions were substantially elevated, showing more than a seven-fold increase in ALL samples compared to healthy control blood samples. In ALL samples, the expression levels of LAMP1 and LAMP2 were significantly reduced, may due to promoter region hypermethylation, which contributes to lysosomal dysfunction. In parallel, the expression of autophagy-related genes such as ATG5 and LC3B, markers of autophagy initiation and maturation, respectively, was markedly increased, suggesting an accumulation of autophagosomes that depend on functional lysosomes for complete degradation. Additionally, elevated levels of pro-inflammatory cytokines IL-6, IL-27, and TNF-α were consistently observed in ALL patients, indicating heightened immune activation that may drive disease progression. Collectively, these findings underscore the pivotal role of DNA methylation in disrupting lysosomal function, leading to autophagosome accumulation and impaired recycling of cytoplasmic components. Show less

Sclerosing skeletal dysplasias result from an imbalance between bone formation and resorption. We identified three homozygous, C-terminally truncating AXIN1 variants in seven individuals from four families affected by macrocephaly, cranial hyperostosis, and vertebral endplate sclerosis. Other frequent findings included hip dysplasia, heart malformations, variable developmental delay, and hematological anomalies. In line with AXIN1 being a central component of the β-catenin destruction complex, analyses of primary and genome-edited cells harboring the truncating variants revealed enhanced basal canonical Wnt pathway activity. All three AXIN1-truncating variants resulted in reduced protein levels and impaired AXIN1 polymerization mediated by its C-terminal DIX domain but partially retained Wnt-inhibitory function upon overexpression. Addition of a tankyrase inhibitor attenuated Wnt overactivity in the AXIN1-mutant model systems. Our data suggest that AXIN1 coordinates the action of osteoblasts and osteoclasts and that tankyrase inhibitors can attenuate the effects of AXIN1 hypomorphic variants. Show less

One hundred fifty-four unrelated French Caucasian subjects were typed for 11 RFLPs at or near the APOA1-C3-A4 gene cluster on the long arm of chromosome 11. All subjects belonged to families having lived in the Toulouse area (in the southwest of France) for over three generations. Allele frequencies for each RFLP were in agreement with previous studies in Caucasian populations for the APOA1/SstI marker. Pairwise linkage disequilibrium was determined. Among the 55 pairs studied, 30 are newly reported. Only three significant nonrandom associations were found: APOA1/MspI-3'APOC3/SstI, APOA1/MspI-3'APOA4/XbaI, and APOA4/DraI-APOA4/XbaI. Extended 11-marker haplotypes were constructed. Haplotype frequencies were estimated by the maximum-likelihood procedure and compared to expected frequencies calculated under the assumption of equilibrium. Among the 37 estimated haplotypes, seven containing at least four nonrandomly associated alleles showed markedly increased frequencies. These results, obtained in a geographically homogeneous population, confirm the existence of disequilibrium in the apolipoprotein cluster, but to a lower extent than previously reported in Caucasian populations, which were geographically more heterogeneous. Show less