Developmental and growth defects in mice with combined deficiency of CK2 catalytic genes

Abstract

The CK2 α and α' catalytic gene products have overlapping biochemical activity, but in vivo, their functions are very different. Deletion of both alleles of CK2α leads to mid-gestational embryonic lethality, while deletion of both alleles of CK2α' does not interfere with viability or development of embryos; however, adult CK2α'-/-males are infertile. To further elucidate developmental roles of CK2, and analyze functional overlap between the two catalytic genes, mice with combined knockouts were bred. Mice bearing any two CK2 catalytic alleles were phenotypically normal. However, inheritance of a single CK2α allele, without either CK2α' allele, resulted in partial embryonic lethality. Such mice that survived through embryogenesis were smaller at birth than littermate controls, and weighed less throughout life. However, their cardiac function and lifespan were normal. Fibroblasts derived from CK2α+/-CK2α'-/- embryos grew poorly in culture. These experiments demonstrate that combined loss of one CK2α allele and both CK2α' alleles leads to unique abnormalities of growth and development.

Fig. 1

Body weights in the cohort of mice under study. Mice are grouped by genotype. Mice were weighed twice weekly until approximately 6 months of age. Wt/het: CK2α+/+CK2α′ +/−; wt/ko: CK2α+/+CK2α′ −/−; het/het: CK2α+/−CK2α′ +/−; het/ko: CK2α+/−CK2α′ −/−

Fig. 2

Tibia length of adult mice. Tibias were measured at necropsy in mice over 1 year old. “Het ko” refers to mice of the CK2α+/−CK2α′ −/− genotype, while “others” refers to mice of CK2α+/+CK2α′ +/−, CK2α+/+CK2α′ −/−, or CK2α+/−CK2α′ +/−genotypes

Fig. 3

Hydronephrosis and bladder dilatation in a CK2α+/+CK2α′ +/− male mouse at 17 months of age. This is representative of the obstructive phenotype occurring in CK2 catalytic subunit-deficient mice, with an onset as early as 6 months of age

Fig. 4

Doubling of MEFs. First passage “Wt/het” (CK2α+/+CK2α′ +/−) MEFs expanded in number for the first few days in culture and then declined, while “het/ko” (CK2α+/−CK2α′ −/−) MEFs failed to expand. N = 5 independent MEF lines of each genotype

Fig. 5

Expression of CK2 subunits in MEFs of different genotypes. Protein extracts were prepared from first passage MEFs. 40 μg of protein lysate was subjected to immunoblotting with antibodies specific for the CK2 catalytic and regulatory subunits, and for actin as a loading control.