| dc.description.abstract | The choroid plexus epithelium forms the blood-cerebrospinal fluid barrier, but also accumulates and transports nutritive minerals, such as zinc, into and out of the cerebrospinal fluid. The goal of this thesis was to analyze interdependent regulation of zinc transporters with metallothionein as the choroid plexus epithelium adapts to increases or decreases in extracellular zinc. My first objective was to characterize time-dependent changes in zinc transporter and MT-1 expression as extracellular zinc was pharmacologically depleted or supplemented. My second objective was to characterize changes in zinc transporter and MT-1 expression in response to exposure to prolactin.
My experimental approach was to analyze gene expression of ZnT1, Zip1, Zip6, MT-1 and carbonic anhydrase (CA-2) in primary cell cultures of neonatal rat choroid plexus and isolated tissues in which extracellular zinc was depleted with 10 μM diethylene triamine pentaacetic acid or supplemented with 25 μM ZnCl_(2) for 48 h. Gene expression was analyzed by fluorescence quantitative real-time polymerase chain reaction.
Zinc accumulation studies indicate choroid plexus cells maintain capacity to accumulate zinc, even when zinc is chelated. In cells, zinc depletion decreased expression of MT-1 and ZnT1 at 3 h and increased Zip1 expression; Zip6 expression fluctuated. In isolated tissues, zinc depletion down-regulated MT-1 and ZnT1 expression, while up-regulating Zip1 and Zip6 expression. In cells, zinc supplementation induced MT-1, ZnT1 and Zip6 expression at 3 h. Zip1 expression
decreased at 3 h. In isolated tissues zinc supplementation up-regulated MT-1 and ZnT1 expression, but did not alter Zip1 and Zip6 expression. These data indicate there is coordinated regulation of MT-1 and zinc transporters as extracellular zinc altered. Prolactin up-regulated gene expression of CA-2, MT-1, ZnT-1 and Zip6 in choroid plexus cells. The JAK/STAT inhibitor AG-490 increased CA-2 and MT-1 expression, but decreased ZnT1 and Zip6 expression. AG-490 further increased expression of CA-2 and MT-1 in prolactin treated cells. This suggests the JAK/STAT signaling pathway might tonically suppress basal expression of MT-1 and CA-2. AG-490 partially reversed
up-regulation of ZnT-1 and Zip6 expression by prolactin. These data indicate there is a coordinated regulation of MT-1 and zinc transporters during extracellular zinc depletion or supplementation. | en |
