Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activityt Especially, hippocampal PKC has ...Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activityt Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was obsereved in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.展开更多
The ubiquitously expressed transmembrane enzyme Na,K-ATPase(NKA)is vital in maintaining functionality of cells.The association of α-and β-subunits is believed to be essential for forming a functional enzyme.In the l...The ubiquitously expressed transmembrane enzyme Na,K-ATPase(NKA)is vital in maintaining functionality of cells.The association of α-and β-subunits is believed to be essential for forming a functional enzyme.In the large milkweed bug Oncopeltus fasciatus fourα1-paralogs and four β-subunits exist that can associate into NKA complexes.This diversity raises the question of possible tissue-specific distribution and function.While the α1-subunits are known to modulate cardenolide-resistance and ion-transport efficiency,the functional importance of the β-subunits needed further investigation.We here characterize all four different β-subunits at the cellular,tissue,and whole organismal scales.A knockdown of different β-subunits heavily interferes with molting success resulting in strongly hampered phenotypes.The failure of ecdysis might be related to disrupted septate junction(SJ)formation,also reflected in β2-suppression-induced alteration in tracheal morphology.Our data further suggest the existence of isolated β-subunits forming homomeric or β-heteromeric complexes.This possible standalone and structure-specific distribution of the β-subunits predicts further,yet unknown pump-independent functions.The different effects caused byβknockdowns highlight the importance of the various β-subunits to fulfill tissue-specific requirements.展开更多
文摘Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activityt Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was obsereved in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.
文摘The ubiquitously expressed transmembrane enzyme Na,K-ATPase(NKA)is vital in maintaining functionality of cells.The association of α-and β-subunits is believed to be essential for forming a functional enzyme.In the large milkweed bug Oncopeltus fasciatus fourα1-paralogs and four β-subunits exist that can associate into NKA complexes.This diversity raises the question of possible tissue-specific distribution and function.While the α1-subunits are known to modulate cardenolide-resistance and ion-transport efficiency,the functional importance of the β-subunits needed further investigation.We here characterize all four different β-subunits at the cellular,tissue,and whole organismal scales.A knockdown of different β-subunits heavily interferes with molting success resulting in strongly hampered phenotypes.The failure of ecdysis might be related to disrupted septate junction(SJ)formation,also reflected in β2-suppression-induced alteration in tracheal morphology.Our data further suggest the existence of isolated β-subunits forming homomeric or β-heteromeric complexes.This possible standalone and structure-specific distribution of the β-subunits predicts further,yet unknown pump-independent functions.The different effects caused byβknockdowns highlight the importance of the various β-subunits to fulfill tissue-specific requirements.
