Clock Gene Expression in the Human Pituitary Gland

• Published in: Endocrinology (Philadelphia) 2013-06, Vol.154 (6), p.2046-2057
• Main Authors: Wunderer, Florian, Kühne, Sina, Jilg, Antje, Ackermann, Katrin, Sebesteny, Tamas, Maronde, Erik, Stehle, Jörg H
• Format: Article
• Language: English
• Subjects: Adaptation; Adolescent; Adrenocorticotropic hormone; Adrenocorticotropic Hormone - metabolism; Adult; Aged; Aged, 80 and over; ARNTL Transcription Factors - genetics; ARNTL Transcription Factors - metabolism; Autopsy; Biological and medical sciences; Blotting, Western; BMAL1 protein; Child; Chronobiology; Circadian Rhythm; Clock gene; CLOCK Proteins - genetics; CLOCK Proteins - metabolism; Cryptochromes; Cryptochromes - genetics; Cryptochromes - metabolism; Daytime; Female; Functional plasticity; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression - radiation effects; Gene regulation; Genes; Homeostatic plasticity; Humans; Immunofluorescence; Immunohistochemistry; Male; Middle Aged; Period 1 protein; Period Circadian Proteins - genetics; Period Circadian Proteins - metabolism; Pituitary; Pituitary gland; Pituitary Gland - metabolism; Pituitary Gland - radiation effects; Plastic foam; Postmortem Changes; Protein biosynthesis; Protein transport; Proteins; Real time; Reverse Transcriptase Polymerase Chain Reaction; Synthesis; Time dependence; Time management; Time of use; Translocation; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Young Adult
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2012-2274

Pituitary function relies on strictly timed, yet plastic mechanisms, particularly with respect to the daytime-dependent coordination of hormone synthesis and release. In other systems, clock genes and their protein products are well-described candidates to anticipate the daily demands in neuroendocrine coupling and to manage cellular adaptation on changing internal or external circumstances. To elucidate possible mechanisms of time management, a total of 52 human autoptic pituitary glands were allocated to the 4 time-of-day groups, night, dawn, day, and dusk, according to reported time of death. The observed daytime-dependent dynamics in ACTH content supports a postmortem conservation of the premortem condition, and thus, principally validates the investigation of autoptic pituitary glands. Pituitary extracts were investigated for expression of clock genes Per1, Cry1, Clock, and Bmal1 and corresponding protein products. Only the clock gene Per1 showed daytime-dependent differences in quantitative real-time PCR analyses, with decreased levels observed during dusk. Although the overall amount in clock gene protein products PER1, CRY1, and CLOCK did not fluctuate with time of day in human pituitary, an indication for a temporally parallel intracellular translocation of PER1 and CRY1 was detected by immunofluorescence. Presented data suggest that the observed clock gene expression in human pituitary cells does not provide evidence for a functional intrinsic clockwork. It is suggested that clock genes and their protein products may be directly involved in the daytime-dependent regulation and adaptation of hormone synthesis and release and within homeostatic adaptive plasticity.