Albert is a Genetics PhD candidate in Dr. Anne Villeneuve's laboratory at Stanford University. His thesis work investigates the mechanisms underlying double-strand break initiation in meiotic recombination using genomic sequencing, fluorescence microscopy, molecular biology, nematode culturing, and classical genetics. Outside of lab, he devotes time to education, mentoring, diversity-advocacy, policy, and science outreach.
Society for the Advancement of Chicanos & Native Americans in Science Chapter at Stanford, Cofounder, Secretary (2017), President (2018)
Aurora A Kinase Contributes to a Pole-Based Error Correction Pathway
2015; 25 (14): 1842-1851
Chromosome biorientation, where sister kinetochores attach to microtubules (MTs) from opposing spindle poles, is the configuration that best ensures equal partitioning of the genome during cell division. Erroneous kinetochore-MT attachments are commonplace but are often corrected prior to anaphase. Error correction, thought to be mediated primarily by the centromere-enriched Aurora B kinase (ABK), typically occurs near spindle poles; however, the relevance of this locale is unclear. Furthermore, polar ejection forces (PEFs), highest near poles, can stabilize improper attachments by pushing mal-oriented chromosome arms away from spindle poles. Hence, there is a conundrum: erroneous kinetochore-MT attachments are weakened where PEFs are most likely to strengthen them. Here, we report that Aurora A kinase (AAK) opposes the stabilizing effect of PEFs. AAK activity contributes to phosphorylation of kinetochore substrates near poles and its inhibition results in chromosome misalignment and an increased incidence of erroneous kinetochore-MT attachments. Furthermore, AAK directly phosphorylates a site in the N-terminal tail of Ndc80/Hec1 that has been implicated in reducing the affinity of the Ndc80 complex for MTs when phosphorylated. We propose that an AAK activity gradient contributes to correcting mal-oriented kinetochore-MT attachments in the vicinity of spindle poles.
View details for DOI 10.1016/j.cub.2015.06.021
View details for Web of Science ID 000358465600021
View details for PubMedID 26166783
View details for PubMedCentralID PMC4509859
LIN54 homolog Mip120 controls two aspects of oogenesis.
The conserved multi-protein MuvB core associates with the Myb oncoproteins and with the RB-E2F-DP tumor suppressor proteins in complexes that regulate cell proliferation, differentiation, and apoptosis. Drosophila Mip120, a homolog of LIN54, is a sequence-specific DNA-binding protein within the MuvB core. A mutant of Drosophila mip120 was previously shown to cause female and male sterility. We now show that Mip120 regulates two different aspects of oogenesis. First, in the absence of the Mip120 protein, egg chambers arrest during the transition from stage 7 to 8 with a failure of the normal program of chromosomal dynamics in the ovarian nurse cells. Specifically, the decondensation, disassembly and dispersion of the endoreplicated polytene chromosomes fail to occur without Mip120. The conserved carboxy-terminal DNA-binding and protein-protein interaction domains of Mip120 are necessary but are not sufficient for this process. Second, we show that a lack of Mip120 causes a dramatic increase in the expression of benign gonial cell neoplasm (bgcn), a gene that is normally expressed in only a small number of cells within the ovary including the germline stem cells.
View details for DOI 10.1242/bio.025825
View details for PubMedID 28522430