Alterations of centromere positions in nuclei of immortalized and malignant mouse lymphocytes.
BACKGROUND
The three-dimensional (3D) positions of centromeres have been studied in several cell systems. However, data on centromere positions during cellular transformation remain elusive. This study has focused on mouse lymphocytes and investigated the centromere positions in primary, immortalized, and tumor cells.


METHODS
Eighty-to-ninety z-slices of each mouse lymphocyte nucleus were acquired using a sampling distance of 107 nm in the xy plane and 200 nm along z for each z-stack, using an Axioplan 2 microscope, an AxioCam HR CCD, a 63x/1.4 oil objective, and the Axiovision 3.1 software (Carl Zeiss, Canada). A constrained iterative algorithm (Schaefer et al., J Microsc 2001;204:99-107) was used for deconvolution. Centromere positions in 3D images were analyzed using CentroView, a program we developed to measure nuclear centromere positions.


RESULTS
Using CentroView we determined the positions of centromeres in primary lymphocytes, immortalized and malignant mouse B cells. We show that centromeres exhibit altered nuclear positions in immortalized and malignant B cells. These changes are independent of previously described cell cycle-dependent centromere dynamics.


CONCLUSIONS
The 3D positions of centromeres are altered during cellular transformation. In lymphocytes, centromeres are found in more central nuclear positions following immortalization and transformation. These nuclear changes reflect structural remodeling of mammalian nuclei during oncogenesis and may impact on the structural organization of chromosomes. How centromeric changes are linked to nuclear remodeling can now be quantitatively examined using the tools of this study.
Sarkar
Rahul
R
Manitoba Institute of Cell Biology, The University of Manitoba, CancerCare Manitoba, Winnipeg, Manitoba, Canada.
Guffei
Amanda
A
Vermolen
Bart J
BJ
Garini
Yuval
Y
Mai
Sabine
S
D000465:Algorithms; D000818:Animals; D002453:Cell Cycle / Q000235:genetics*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002503:Centromere / Q000378:metabolism*; D005434:Flow Cytometry; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase / Q000235:genetics; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D012984:Software