Centromere defects, chromosome instability, and cGAS-STING activation in systemic sclerosis.

Centromere defects in Systemic Sclerosis (SSc) have remained unexplored despite the fact that many centromere proteins were discovered in patients with SSc. Here we report that lesion skin fibroblasts from SSc patients show marked alterations in centromeric DNA. SSc fibroblasts also show DNA damage, abnormal chromosome segregation, aneuploidy (only in diffuse cutaneous (dcSSc)) and micronuclei (in all types of SSc), some of which lose centromere identity while retaining centromere DNA sequences. Strikingly, we find cytoplasmic "leaking" of centromere proteins in limited cutaneous SSc (lcSSc) fibroblasts. Cytoplasmic centromere proteins co-localize with antigen presenting MHC Class II molecules, which correlate precisely with the presence of anti-centromere antibodies. CENPA expression and micronuclei formation correlate highly with activation of the cGAS-STING/IFN-ß pathway as well as markers of reactive oxygen species (ROS) and fibrosis, ultimately suggesting a link between centromere alterations, chromosome instability, SSc autoimmunity, and fibrosis.

Role of vitamin B12 in treating recurrent aphthous stomatitis: A review.

Vitamin B12, a water-soluble vitamin, plays a vital role in the formation of hematopoietic stem cells and has been associated with oral mucosal diseases, mainly recurrent aphthous stomatitis (RAS). The latter is a debilitating condition, and B12 was proposed as a potential treatment given its role in regenerating oral mucosal tissue. There is conflicting evidence that B12 deficiency causes RAS. Five of the seven randomized controlled trials reviewed used the inactive form of B12 (cyanocobalamin) as intervention, while the other two used the active form (methylcobalamin). Of the latter two, buccal discs (500 µg B12) showed significant improvement and reduced perceived pain in 77% of the subjects, and submucosal injections showed a significant difference in pain, starting from the second day. Moreover, three studies administered vitamin B12 sublingually with different dosages, which revealed that the higher dose (1000 µg) achieved a significant reduction in outbreaks, number, and duration of ulcers, especially after six months. Multivitamins showed no difference in new RAS episodes and duration. Injectable B12 was compared with the oral form, and nearly 50% of the injection group reported a desired response by the eighth week. An ointment form (500 µg) showed a significant reduction in pain levels after two days of treatment. Based on the available literature, we suggest that a daily dose of 1000 µg of vitamin B12 sublingually for six months can be used to treat RAS. Nevertheless, this conclusion should be considered tentative due to the lack of high quality, large scale studies.

The Genomic Landscape of Centromeres in Cancers.

Centromere genomics remain poorly characterized in cancer, due to technologic limitations in sequencing and bioinformatics methodologies that make high-resolution delineation of centromeric loci difficult to achieve. We here leverage a highly specific and targeted rapid PCR methodology to quantitatively assess the genomic landscape of centromeres in cancer cell lines and primary tissue. PCR-based profiling of centromeres revealed widespread heterogeneity of centromeric and pericentromeric sequences in cancer cells and tissues as compared to healthy counterparts. Quantitative reductions in centromeric core and pericentromeric markers (α-satellite units and HERV-K copies) were observed in neoplastic samples as compared to healthy counterparts. Subsequent phylogenetic analysis of a pericentromeric endogenous retrovirus amplified by PCR revealed possible gene conversion events occurring at numerous pericentromeric loci in the setting of malignancy. Our findings collectively represent a more comprehensive evaluation of centromere genetics in the setting of malignancy, providing valuable insight into the evolution and reshuffling of centromeric sequences in cancer development and progression.

Rapid molecular assays to study human centromere genomics.

The centromere is the structural unit responsible for the faithful segregation of chromosomes. Although regulation of centromeric function by epigenetic factors has been well-studied, the contributions of the underlying DNA sequences have been much less well defined, and existing methodologies for studying centromere genomics in biology are laborious. We have identified specific markers in the centromere of 23 of the 24 human chromosomes that allow for rapid PCR assays capable of capturing the genomic landscape of human centromeres at a given time. Use of this genetic strategy can also delineate which specific centromere arrays in each chromosome drive the recruitment of epigenetic modulators. We further show that, surprisingly, loss and rearrangement of DNA in centromere 21 is associated with trisomy 21. This new approach can thus be used to rapidly take a snapshot of the genetics and epigenetics of each specific human centromere in nondisjunction disorders and other biological settings.