The human growth hormone gene is regulated by a multicomponent locus control region.
The five-member human growth hormone (hGH)/chorionic somatomammotropin (hCS) gene cluster encodes the pituitary-specific hGH-N gene and four highly related genes (hGH-V, hCS-A, hCS-B, and hCS-L) that are expressed only in the placenta. When the hGH-N or hCS-A gene, together with all previously identified cis-acting regulatory sequences, was integrated into the mouse genome, it was expressed only sporadically and at low levels in the transgenic target organs. DNase I mapping of chromatin from expressing and nonexpressing cell types was used to identify a pituitary-specific set of DNase I-hypersensitive sites (HS) and a set of HS common to both the pituitary and placenta, centered approximately 15 and 30 kb 5' of hGH-N, respectively. When contained on a cosmid insert in their native genomic configuration, these HS consistently directed high-level, pituitary-specific expression of hGH-N in transgenic mice and appeared to define a locus control region required for hGH-N expression. Individually, each set of HS was able to mediate position-independent hGH-N expression in the pituitary but demonstrated loss of physiologic control and loss of tissue specificity. The gene-proximal set of HS contained a potent enhancer activity in the pituitary, while the more distal set appeared to function primarily to establish site-of-integration independence. These data indicate that synergistic interactions among multiple elements are required to restrict hGH-N transcription to the pituitary and generate appropriate levels of expression. In addition, these results suggest a role for both shared and unique regulatory sequences in locus control region-mediated expression of the hGH/hCS gene cluster in the pituitary and possibly the placenta.
Jones
B K
BK
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Monks
B R
BR
Liebhaber
S A
SA
Cooke
N E
NE
D000236:Adenoma / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D003001:Cloning, Molecular; D003360:Cosmids; D017931:DNA Primers; D003850:Deoxyribonuclease I; D004742:Enhancer Elements, Genetic; D005260:Female; D005786:Gene Expression Regulation; D015698:Genomic Library; D013006:Growth Hormone / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010902:Pituitary Gland / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping
D002843:Chromatin; D017931:DNA Primers; D012333:RNA, Messenger; D013006:Growth Hormone; D003850:Deoxyribonuclease I