Current Research
Centromere Function and Chromosome Segregation
We are studying which centromere arrays in each human chromosome are packed into nucleosomes by the histone 3-like centromere mark CENPA and recruit other centromere proteins (CENPB, CENPC, and so on) that participate in kinetochore assembly. Further, we are also characterizing which centromere sequences are essential to maintain the cohesiveness of sister chromatids during cell division through epigenetic factors HP1 and H3K9me3; factors that ensure the correct partition of chromosomes. We have developed ChIP-PCR and ChIP-Seq methods to assess this task. It is very important to understand how the deposition and assembly of centromeres as well as cohesion function is influenced when centromere sequence mutations arise. We are employing CRISPR Cas9 to mutate centromeres. These technologies will generate unprecedented findings in the study of human centromeres in disease.
Centromeres in Scleroderma
We have a special attention on the function of centromeres in Scleroderma. The contribution of centromere defects to Scleroderma remain unknown despite many of the centromere proteins were discovered due to these patient-derived antibodies. Using novel genetic and cytogenetic analysis we find that affected fibroblasts from SSc patients show marked alterations in centromeric DNA regardless of receiving treatment. Strikingly, we observed “leaking” of centromere proteins from the nucleus into the cytoplasm in all limited cutaneous Scleroderma patients who have anti-centromere antibodies. Scleroderma fibroblasts showed abnormal chromosome segregation, with micronuclei that activates the cGAS-STING pathway of autoimmunity. Our studies reveal that centromeric genomic instability and epigenetic defects may lead to the pathogenesis of Scleroderma. As both centromere genetics and epigenetics defects, together with an immune response to centromeres is seen in Scleroderma patients, we are clarifying whether Scleroderma is a centromere disease with very promising findings. The projects are currently supported by the National Scleroderma Foundation.
Centromeres in cancer
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. Currently, we are recreating these mutations occurring in cancer cells in chromosomally normal human cells using CRISPR Cas9 to determine the effect of centromere instability on centromere assembly and function and chromosome segregation. These studies will help us to understand the role of centromere deletion in genome instability and aneuploidy seen in cancer. In addition, we study the function of centromeric proteins in Cancer.
Centromeres in Trisomy 21 and Alzheimer
We have found extraordinary evidence of centromere instability specifically in the centromere core and pericentromere of Chr 21 in individuals with trisomy 21 (Down syndrome) but not other chromosomes, suggesting that centromere 21 instability is associated with this Chr 21 non-disjunction disorder. We are creating specific deletions in the centromere of Chr 21 in karyotypically normal cells and human embryonic stem cells (hESc) using CRISPR Cas9 technology in order to characterize the effect of these genetic imbalances in centromere function and Chr 21 segregation. We are also using cytogenetic analysis, including IF-FISH and other assays for chromosome segregation to study the effect of centromere 21 mutations in trisomy 21 development and also in the development of disease-associated phenotypes seen in different cells types of patients with trisomy 21. We are creating centromere 21 mutations in iPSc that differentiate into brain cells to study the effect of centromere instability in trisomy 21 brain development and Alzheimer.
