Developmental localization of potassium chloride co-transporter 2 (KCC2) in the Purkinje cells of embryonic mouse cerebellum

Abstract

Developmental shift in GABA actions from depolarization to hyperpolarization occurs as a result of decreasing the intracellular Cl− concentration regulated by K+-Cl− co-transporter 2 (KCC2). To clarify the time-course of the developmental shift on the Purkinje cells, we examined KCC2-localization in the embryonic mouse cerebellum. The KCC2 was first detected within the Purkinje cells in the Purkinje cell layer of the hemisphere at embryonic day 15 (E15) and the vermis at E17, but the ventricular and intermediate zones were negative. These results suggest that GABA might become inhibitory on the Purkinje cells after their settling in the Purkinje cell layer

Direct Protein Kinase C-dependent Phosphorylation Regulates the Cell Surface Stability and Activity of the Potassium Chloride Cotransporter KCC2

“…A major band of ϳ130 kDa was seen with anti-KCC2 antibodies that was first detected at 2 weeks and reached maximal expression levels between 4 -5 weeks in culture (Fig. 6A) consistent with other studies on the developmental expression of KCC2 in culture (4,(23)(24)(25). To examine phosphorylation, 4 -5-week cultures were labeled with [ 32 P]orthophosphoric acid and subjected to immunoprecipitation with KCC2 antibody.…”

Profound morphological and functional changes of rodent Purkinje cells between the first and the second postnatal weeks: a metamorphosis?

“…For the majority of the neurons, the expression of KCC2 increases indeed at the end of the first postnatal week in rodents (for review see Ben-Ari et al, 2007). Surprisingly, Purkinje cells express KCC2 very early during development (Mikawa et al, 2002; Takayama and Inoue, 2007), but the intracellular chloride concentration can be regulated by other factors, such as the expression of WNK family kinases (Rinehart et al, 2011). How the intracellular chloride concentration is regulated within immature Purkinje cells is still an open question, and it is, therefore, not understood how the transition between GABA depolarization to hyperpolarization would be triggered in this neuron.…”

Multiple Roles of KCC2 in the Developing Brain

“…The time course of KCC2 upregulation is prolonged and varies significantly in different cell types and in different cerebellar subregions. KCC2 expression was detected already at E15 in the PCL of the anterior-dorsal part of the cerebellar hemisphere, but not in the vermis (Takayama and Inoue, 2007). PCs are generated in the ventricular zone near the fourth ventricle of the brain stem.…”

“…Purkinje cells (PCs) -the principal output cells of the cerebellum -are the first cells to differentiate in the cerebellar cortex. Importantly, the ventricular zone, intermediate zone, and external granular layer (EGL) were devoid of KCC2-ir throughout the course of embryonic development (Takayama and Inoue, 2007). Newly generated postmitotic PCs migrate radially to accumulate in one layer called the cerebellar plate.…”