Lead stimulates Golgi sialyltransferase at times coincident with the embryonic to adult conversion of the neural cell adhesion molecule (N-CAM).
The neural cell adhesion molecule N-CAM is believed to be intimately involved in the structuring of the central nervous system. During post-natal development the molecule exists in 2 forms--a sialic acid-rich form which is preferentially expressed during cell acquisition and fibre outgrowth and a sialic acid-poor form which appears at times coincident with synaptogenesis. The developmental changes between these 2 forms have been demonstrated to be impaired by chronic low-level lead exposure and this is consistent with the reduced synaptic elaboration associated with this action. Here is described the effect of lead on the Golgi-associated sialyltransferase which regulates N-CAM sialylation state. Lead chloride was found to markedly stimulate sialyltransferase with an ED50 of 5 X 10(-7) M in adult Golgi fractions. This was not observed in fractions derived from 12-day old animals. At the concentration of 5 X 10(-5) M lead was found to have a differential effect on the developmental expression of this enzyme. During the early phases of development (days 4-16) sialyltransferase activity was inhibited. However, in coincidence with periods of N-CAM desialylation (days 16-30), it was significantly stimulated. These findings are related to the perturbations of N-CAM function during chronic low-level lead exposure.
Breen
K C
KC
Dept. of Pharmacology, University College, Dublin, Ireland.
Regan
C M
CM
D000375:Aging / Q000378:metabolism; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D004789:Enzyme Activation / Q000187:drug effects; D006056:Golgi Apparatus / Q000187:drug effects* / Q000201:enzymology; D007854:Lead / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D012799:Sialyltransferases / Q000378:metabolism*
D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D007854:Lead; C029891:lead chloride; D012799:Sialyltransferases