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Manoogian ENC, Bahiru MS, Wang EJ, Holder M, Bittman EL. Neuroendocrine effects of the duper mutation in Syrian hamsters: a role for Cryptochrome 1. Front Physiol 2024; 15:1351682. [PMID: 38444761 PMCID: PMC10912188 DOI: 10.3389/fphys.2024.1351682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/31/2024] [Indexed: 03/07/2024] Open
Abstract
Molecular and physiological determinants of the timing of reproductive events, including the pre-ovulatory LH surge and seasonal fluctuations in fertility, are incompletely understood. We used the Cryptochrome 1-deficient duper mutant to examine the role of this core circadian clock gene in Syrian hamsters. We find that the phase of the LH surge and its stability upon shifts of the light: dark cycle are altered in duper mutants. The intensity of immunoreactive PER1 in GnRH cells of the preoptic area peaks earlier in the day in duper than wild type hamsters. We note that GnRH fibers coursing through the suprachiasmatic nucleus (SCN) contact vasopressin- and VIP-immunoreactive cells, suggesting a possible locus of circadian control of the LH surge. Unlike wild types, duper hamsters do not regress their gonads within 8 weeks of constant darkness, despite evidence of melatonin secretion during the subjective night. In light of the finding that the duper allele is a stop codon in Cryptochrome 1, our results suggest important neuroendocrine functions of this core circadian clock gene.
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Affiliation(s)
| | | | | | | | - Eric L. Bittman
- Department of Biology and Program in Neuroscience, University of Massachusetts, Amherst, MA, United States
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The duper mutation reveals previously unsuspected functions of Cryptochrome 1 in circadian entrainment and heart disease. Proc Natl Acad Sci U S A 2022; 119:e2121883119. [PMID: 35930669 PMCID: PMC9371649 DOI: 10.1073/pnas.2121883119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Cryptochrome 1 (Cry1)-deficient duper mutant hamster has a short free-running period in constant darkness (τDD) and shows large phase shifts in response to brief light pulses. We tested whether this measure of the lability of the circadian phase is a general characteristic of Cry1-null animals and whether it indicates resistance to jet lag. Upon advance of the light:dark (LD) cycle, both duper hamsters and Cry1-/- mice re-entrained locomotor rhythms three times as fast as wild types. However, accelerated re-entrainment was dissociated from the amplified phase-response curve (PRC): unlike duper hamsters, Cry1-/- mice show no amplification of the phase response to 15' light pulses. Neither the amplified acute shifts nor the increased rate of re-entrainment in duper mutants is due to acceleration of the circadian clock: when mutants drank heavy water to lengthen the period, these aspects of the phenotype persisted. In light of the health consequences of circadian misalignment, we examined effects of duper and phase shifts on a hamster model of heart disease previously shown to be aggravated by repeated phase shifts. The mutation shortened the lifespan of cardiomyopathic hamsters relative to wild types, but this effect was eliminated when mutants experienced 8-h phase shifts every second week, to which they rapidly re-entrained. Our results reveal previously unsuspected roles of Cry1 in phase shifting and longevity in the face of heart disease. The duper mutant offers new opportunities to understand the basis of circadian disruption and jet lag.
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Lee YY, Cal-Kayitmazbatir S, Francey LJ, Bahiru MS, Hayer KE, Wu G, Zeller MJ, Roberts R, Speers J, Koshalek J, Berres ME, Bittman EL, Hogenesch JB. duper is a null mutation of Cryptochrome 1 in Syrian hamsters. Proc Natl Acad Sci U S A 2022; 119:e2123560119. [PMID: 35471909 PMCID: PMC9170138 DOI: 10.1073/pnas.2123560119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/08/2022] [Indexed: 12/20/2022] Open
Abstract
The duper mutation is a recessive mutation that shortens the period length of the circadian rhythm in Syrian hamsters. These animals show a large phase shift when responding to light pulses. Limited genetic resources for the Syrian hamster (Mesocricetus auratus) presented a major obstacle to cloning duper. This caused the duper mutation to remain unknown for over a decade. In this study, we did a de novo genome assembly of Syrian hamsters with long-read sequencing data from two different platforms, Pacific Biosciences and Oxford Nanopore Technologies. Using two distinct ecotypes and a fast homozygosity mapping strategy, we identified duper as an early nonsense allele of Cryptochrome 1 (Cry1) leading to a short, unstable protein. CRY1 is known as a highly conserved component of the repressive limb of the core circadian clock. The genome assembly and other genomic datasets generated in this study will facilitate the use of the Syrian hamster in biomedical research.
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Affiliation(s)
- Yin Yeng Lee
- Divisions of Human Genetics and Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45229
| | - Sibel Cal-Kayitmazbatir
- Divisions of Human Genetics and Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Lauren J. Francey
- Divisions of Human Genetics and Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Michael Seifu Bahiru
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
- Program in Neuroscience & Behavior, University of Massachusetts Amherst, Amherst, MA 01003
| | - Katharina E. Hayer
- Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA 19104
| | - Gang Wu
- Divisions of Human Genetics and Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Molly J. Zeller
- University of Wisconsin Biotechnology Center, University of Wisconsin–Madison, Madison, WI 53706
| | - Robyn Roberts
- University of Wisconsin Biotechnology Center, University of Wisconsin–Madison, Madison, WI 53706
| | - James Speers
- University of Wisconsin Biotechnology Center, University of Wisconsin–Madison, Madison, WI 53706
| | - Justin Koshalek
- University of Wisconsin Biotechnology Center, University of Wisconsin–Madison, Madison, WI 53706
| | - Mark E. Berres
- University of Wisconsin Biotechnology Center, University of Wisconsin–Madison, Madison, WI 53706
| | - Eric L. Bittman
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
- Program in Neuroscience & Behavior, University of Massachusetts Amherst, Amherst, MA 01003
| | - John B. Hogenesch
- Divisions of Human Genetics and Immunobiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
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Bittman EL. Anatomical Methods to Study the Suprachiasmatic Nucleus. Methods Mol Biol 2022; 2482:191-210. [PMID: 35610428 PMCID: PMC10752494 DOI: 10.1007/978-1-0716-2249-0_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The mammalian suprachiasmatic nucleus (SCN) functions as a master circadian pacemaker. In order to examine mechanisms by which it keeps time, entrains to periodic environmental signals (zeitgebers), and regulates subordinate oscillators elsewhere in the brain and in the periphery, a variety of molecular methods have been applied. Multiple label immunocytochemistry and in situ hybridization provide anatomical insights that complement physiological approaches (such as ex vivo electrophysiology and luminometry) widely used to study the SCN.The anatomical methods require interpretation of data gathered from groups of individual animals sacrificed at different time points. This imposes constraints on the design of the experiments that aim to observe changes that occur with circadian phase in free-running conditions. It is essential in such experiments to account for differences in the periods of the subjects. Nevertheless, it is possible to resolve intracellular colocalization and regional expression of functionally important transcripts and/or their peptide products that serve as neuromodulators or neurotransmitters. Armed with these tools and others, understanding of the mechanisms by which the hypothalamic pacemaker regulates circadian function is progressing apace.
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Affiliation(s)
- Eric L Bittman
- Department of Biology and Program in Neuroscience & Behavior, University of Massachusetts, Amherst, MA, USA.
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