Dp71 Point Mutations Induce Protein Aggregation, Loss of Nuclear Lamina Integrity and Impaired Braf35 and Ibraf Function in Neuronal Cells.

Dystrophin Dp71 is the most abundant product of the Duchenne muscular dystrophy gene in the nervous system, and mutations impairing its function have been associated with the neurodevelopmental symptoms present in a third of DMD patients. Dp71 is required for the clustering of neurotransmitter receptors and the neuronal differentiation of cultured cells; nonetheless, its precise role in neuronal cells remains to be poorly understood. In this study, we analyzed the effect of two pathogenic DMD gene point mutations on the Dp71 function in neurons. We engineered C272Y and E299del mutations to express GFP-tagged Dp71 protein variants in N1E-115 and SH-SY5Y neuronal cells. Unexpectedly, the ectopic expression of Dp71 mutants resulted in protein aggregation, which may be mechanistically caused by the effect of the mutations on Dp71 structure, as predicted by protein modeling and molecular dynamics simulations. Interestingly, Dp71 mutant variants acquired a dominant negative function that, in turn, dramatically impaired the distribution of different Dp71 protein partners, including ß-dystroglycan, nuclear lamins A/C and B1, the high-mobility group (HMG)-containing protein (BRAF35) and the BRAF35-family-member inhibitor of BRAF35 (iBRAF). Further analysis of Dp71 mutants provided evidence showing a role for Dp71 in modulating both heterochromatin marker H3K9me2 organization and the neuronal genes' expression, via its interaction with iBRAF and BRAF5.

The molecular pathogenesis of craniopharyngiomas.

Research from the last 20 years has provided important insights into the molecular pathogenesis of craniopharyngiomas (CPs). Besides the well-known clinical and histological differences between the subtypes of CPs, adamantinomatous (ACP) and papillary (PCP) craniopharyngiomas, other molecular differences have been identified, further elucidating pathways related to the origin and development of such tumors. The present minireview assesses current knowledge on embryogenesis and the genetic, epigenetic, transcriptomic, and signaling pathways involved in the ACP and PCP subtypes, revealing the similarities and differences in their profiles. ACP and PCP subtypes can be identified by the presence of mutations in CTNNB1 and BRAF genes, with prevalence around 60% and 90%, respectively. Therefore, ß-catenin accumulates in the nucleus-cytoplasm of cell clusters in ACPs and, in PCPs, cell immunostaining with specific antibody against the V600E-mutated protein can be seen. Distinct patterns of DNA methylation further differentiate ACPs and PCPs. In addition, research on genetic and epigenetic changes and tumor microenvironment specificities have further clarified the development and progression of the disease. No relevant transcriptional differences in ACPs have emerged between children and adults. In conclusion, ACPs and PCPs present diverse genetic signatures and each subtype is associated with specific signaling pathways. A better understanding of the pathways related to the growth of such tumors is paramount for the development of novel targeted therapeutic agents.

The Diagnostic Value of BRAF V600E Gene Detection Combined with DNA Ploidy Analysis in Thyroid Cancer.

BACKGROUND: The thyroid cancer incidence has been experimenting an accelerated growth all over the world. The serine/threonine-protein kinase (BRAF) V600E gene detection or the DNA ploidy analysis has been employed in the identification of thyroid cancer type. This study aimed to evaluate the diagnostic value of the BRAF V600E gene integrated with DNA ploidy analysis in thyroid cancer. METHODS: From August 2022 to May 2023, 400 individuals from the thyroid surgery outpatient department of our hospital were enrolled in this study. The participants were divided into low-risk groups (Ⅰ+Ⅱ+Ⅲ group; n = 200) and high-risk groups (Ⅳ+Ⅴ group; n = 200) based on the Thyroid Imaging Reporting and Data System (TI-RADS). A total of the patients were subjected to the DNA ploidy analysis, the BRAF V600E gene detection, or the combination of both techniques. We evaluated the diagnostic value of the above techniques and considered the postoperative pathology results as gold standard for cancer diagnosis. The negative predictive value (NPV), accuracy, specificity, sensitivity, and positive predictive value (PPV) of TI-RADS, BRAF V600E gene detection, DNA ploidy analysis, and BRAF V600E gene detection joined with DNA ploidy analysis were calculated. RESULTS: Among 400 subjects, 238 presented thyroid cancer and 162 had benign lesions, according to the postoperative pathology results. The obtained sensitivity, specificity, accuracy, PPV, and NPV values of TI-RADS were 55.88%, 58.64%, 57.00%, 66.50%, 47.50%, respectively; of BRAF V600E gene detection were 81.93%, 69.75%, 77.00%, 79.92%, 72.44%, respectively; of DNA ploidy analysis were 83.19%, 72.84%, 79.00%, 81.82%, 74.68%, respectively; of BRAF V600E gene combined with DNA ploidy analysis were 90.34%, 76.54%, 84.75%, 84.98%, 84.35%, respectively. Compared with TI-RADS, the sensitivity, specificity, accuracy, PPV, and NPV values of DNA ploidy analysis, BRAF V600E gene detection, and the conjunction of these last two methods were increased (p < 0.05). The combination of DNA ploidy analysis and BRAF V600E gene detection had the highest values among them all. CONCLUSIONS: BRAF V600E gene detection in conjunction with DNA ploidy analysis showed a better diagnostic value than both methods separately or TI-RADS.

Relevance of MIA and S100 serum tumor markers to monitor BRAF inhibitor therapy in metastatic melanoma patients.

BRAF V600 mutation has been reported in more than 50% of melanoma cases and its presence predicts clinical activity of BRAF inhibitors (iBRAF). We evaluated the role of MIA, S100 and LDH to monitor iBRAF efficiency in advanced melanoma patients presenting BRAF V600 mutations. This was a prospective study of melanoma patients harboring the BRAF V600 mutation and treated with iBRAF within a clinical trial (dabrafenib) or as part of an expanded access program (vemurafenib). MIA, S100 and LDH were analyzed in serum at baseline, and every 4-6 weeks during treatment. Eighteen patients with melanoma stages IIIc-IV were enrolled with 88.8% of response rate to iBRAF. Baseline concentrations of all the tumor markers correlated with tumor burden. MIA and S100 concentrations decreased significantly one month after the beginning of treatment and, upon progression, their concentrations increased significantly above the minimum levels previously achieved. MIA levels lower than 9 µg/L one month after the beginning of treatment and S100 concentrations lower than 0.1 µg/L at the moment of best response were associated with improved progression-free survival. In conclusion, MIA and S100 are useful to monitor response in melanoma patients treated with iBRAF.