Luteinizing hormone and follicle-stimulating hormone exhibit different secretion patterns from cultured Madin-Darby canine kidney cells.
LH, FSH, and chorionic gonadotropin (CG) are comprised of a common alpha subunit and a hormone-specific beta subunit. Using Madin-Darby canine kidney (MDCK) epithelial cells to examine the polarized secretion of human CG/LH, we previously reported that CG and LH were detected in the apical and basolateral compartments, respectively, and the carboxyl terminal end of the CGbeta subunit contains a strong apical signal. Here we show that the carboxyl seven amino acids in the LHbeta subunit contribute to the basolateral secretion of LH, and an LH chimera bearing the CGbeta apical signal is redirected from the basolateral to the apical compartments. Because LH and FSH are synthesized in the same cell, we also compared the secretion polarity of LH with FSH. MDCK cells expressing the FSH dimer displayed an almost equal distribution of protein into the apical and basolateral compartments. Given that the LHbeta and CGbeta carboxy terminal sequences, which differ from that in the FSHbeta subunit, occupy a pivotal role in their polarized behavior, the results support the hypothesis that pituitary exit of LH and FSH occur via different secretion pathways, and are released spatially from the pituitary via different circulatory routes.
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Albina
A
Jablonka-Shariff
Irving
I
Boime
D000818:Animals; D002460:Cell Line / Q000166:cytology / Q000378:metabolism; D016764:Cell Polarity / Q000502:physiology*; D006063:Chorionic Gonadotropin / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004285:Dogs; D005640:Follicle Stimulating Hormone / Q000737:chemistry / Q000378:metabolism; D037201:Follicle Stimulating Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015292:Glycoprotein Hormones, alpha Subunit / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology; D037101:Luteinizing Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014162:Transfection
D006063:Chorionic Gonadotropin; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D037101:Luteinizing Hormone, beta Subunit; D005640:Follicle Stimulating Hormone