Expression and Function of the Gene Encoding the Voltage-Dependent Calcium Channel β3-Subunit in the Mouse Placenta

Voltage-dependent Ca2+ channels (VDCC) exist in most excitable cells and their properly regulated activity is essential for critical biological processes as many of these are sensitive to cellular Ca2+ ion concentration. The ancillary cytoplasmic Ca2+ channel β subunits (CACNB) modulate Ca2+ channel function and are required to enhance the number of functional channels in the plasma membrane. There are four genes encoding CACNB subunits and the gene encoding CACNB3 is over expressed in hyperplastic placentas of mouse interspecies hybrids. To determine the role of CACNB3 in the mouse placenta, we performed an expression and function analysis. Our results show that Cacnb3 exhibits specific spatial and temporal expression in the mouse placenta. Deletion of Cacnb3 does not produce a strong placental phenotype, which may be due to expression of other CACNB subunit encoding genes; however, sporadic occurrence of a labyrinthine architecture phenotype, characterized by reduced density of fetal blood vessels and decrease in pericyte number, could be observed. Down-regulation of Cacnb3 expression did not rescue placental hyperplasia in a model of interspecies hybrid placentas, which indicates that up-regulation in the hyperplastic placentas is a downstream event.