Entry slip BUB1B: names ____________________________
Frio, T.R., Lavoie, J., Hamel, N., Geyer, F.C., Kushner, Y.B., Novak, D.J., Wark, L., Capelli, C., Reis-Filho, J.S., Mai,
S., Pastinen, T., Tischkowitz, M.D., Marcus, V.A. & Foulkes, W.D. (2010). Homozygous BUB1B mutation and
susceptibility to gastrointestinal neoplasia. N Engl J Med 363: 2628-2637.
(See also Bolanos-Garcia & Blundell (2011) BUB1 and BUBR1: miultifaceted kinases of the cell cycle. Review
article. Trends in Biochemical Sciences 36: 141-150),
You may wish to review general cell cycle control, especially Spindle Assembly Checkpoint, and Mitotic checkpoint.
1. Authors: These authors located at 4 different institutions: in two countries:
Who is the corresponding author?
2. Summary:
How many patients were in this study?
What clinical symptoms were found?
What cell cycle defects seen in cells?
What germline homozygous mutations? In what gene, and what happens?
What is the relationship between the protein encoded by BUB1B? and the APC protein?
Why is this study significant?
3. Background/Introduction:
What is Aneuploidy?
What is the Mosaic Variegated Aneuploidy (MVA) Syndrome?
And the phenotypes of these children who receive this rare autosomal recessive disease?
Of 37 cases of MVA:
Some have homozygous mutations of BUB1B gene. What is the normal role of BUB1B protein?
What if they also have premature chromatid separation?
4. Case Report:
What is a Proband?
What is a carcinoma of the Ampulla of Vater? (what anatomic structure?),
and what was a Whipple procedure he underwent?
What other cancers did the proband have between 56 and 67 years of age?
Pedigree: the proband’s parents were related. No mutations were found in a number of suspect genes.
Cytogenetic picture suggested MVA syndrome.
Fig. 1: premature chromatid separation was found in ___ % proband’s lymphocytes, compared to ____ % for his
children and siblings, and _____ % for his wife and normal controls.
These data suggested what pattern of inheritance (autosomal recessive, autosomal dominant, sex-linked, etc)?
Microarray data found 2 regions of extended homozygosity, one of which was 17.3 Mb (how many bp _______);
Fig. 2A Because gene BUB1B was in that region, they did long-range PCR and DNA sequencing:
What mutation did he have? What predicted size of protein product preferentially produced?
What about mutations of his mother and sisters?
Fig. 2B. What about levels of BUB1B mRNA and the BUBR1 protein in the +/+. +/- and -/- people?
Fig. 2C What did immunofluorescence with anti-BUBR1 protein show?
Fig. 2D. What about treatment of normal and mutant cells with microtubule depolarizing drug?
Fig. 3A, B What abnormalities were seen in the cells and colon tissue of the proband compared to others?
Fig. 3C, D. Transgenic addition of BUB1B cDNA to proband’s cells.
They added the good gene with a retroviral vector. What did they find about production of BUBR1?
When they immunoprecipitated the cell extract with anti-APC antibody, they found some BUBR1 protein was also
precipitated (Fig. 3C), from which they conclude what?
Looking at metaphase spreads of cells for PCS (premature chromatid separation), what did they find?
Discussion/ Conclusions: BUBR1 is a spindle assembly checkpoint protein (a kinase) with several roles:
What is its relationship with APC? What does APC do?
Significance: mice with the BUB1B homozygous deletions do not survive embryogenesis, so why did this many live
until age 34 before any cancers found?
What other general conclusions can be drawn from this study?
Questions: what data did you find most compelling?
Why are there so many authors on this paper?
What concerns do you have about this study?