51
|
Lovegrove BG, Lobban KD, Levesque DL. Mammal survival at the Cretaceous-Palaeogene boundary: metabolic homeostasis in prolonged tropical hibernation in tenrecs. Proc Biol Sci 2015; 281:20141304. [PMID: 25339721 DOI: 10.1098/rspb.2014.1304] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Free-ranging common tenrecs, Tenrec ecaudatus, from sub-tropical Madagascar, displayed long-term (nine months) hibernation which lacked any evidence of periodic interbout arousals (IBAs). IBAs are the dominant feature of the mammalian hibernation phenotype and are thought to periodically restore long-term ischaemia damage and/or metabolic imbalances (depletions and accumulations). However, the lack of IBAs in tenrecs suggests no such pathology at hibernation Tbs > 22°C. The long period of tropical hibernation that we report might explain how the ancestral placental mammal survived the global devastation that drove the dinosaurs and many other vertebrates to extinction at the Cretaceous-Palaeogene boundary following a meteorite impact. The genetics and biochemistry of IBAs are of immense interest to biomedical researchers and space exploration scientists, in the latter case, those envisioning a hibernating state in astronauts for deep space travel. Unravelling the physiological thresholds and temperature dependence of IBAs will provide new impetus to these research quests.
Collapse
Affiliation(s)
- Barry G Lovegrove
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
| | - Kerileigh D Lobban
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
| | - Danielle L Levesque
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, South Africa
| |
Collapse
|
52
|
van Breukelen F, Martin SL. The Hibernation Continuum: Physiological and Molecular Aspects of Metabolic Plasticity in Mammals. Physiology (Bethesda) 2015; 30:273-81. [DOI: 10.1152/physiol.00010.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammals are often considered to be masters of homeostasis, with the ability to maintain a constant internal milieu, despite marked changes in the environment; however, many species exhibit striking physiological and biochemical plasticity in the face of environmental fluctuations. Here, we review metabolic depression and body temperature fluctuation in mammals, with a focus on the extreme example of hibernation in small-bodied eutherian species. Careful exploitation of the phenotypic plasticity of mammals with metabolic flexibility may provide the key to unlocking the molecular secrets of orchestrating and surviving reversible metabolic depression in less plastic species, including humans.
Collapse
Affiliation(s)
| | - Sandra L. Martin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| |
Collapse
|
53
|
Jiang S, Gao Y, Zhang Y, Liu K, Wang H, Goswami N. The research on the formation mechanism of extraordinary oxidative capacity of skeletal muscle in hibernating ground squirrels ( Spermophilus dauricus). Zool Stud 2015; 54:e46. [PMID: 31966133 DOI: 10.1186/s40555-015-0124-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 06/08/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND Previous studies indicate that hibernating animals, under conditions of torpor for long periods, show an increased oxidative muscle fibers (type I) ratio and a decreased glycolytic muscle fibers (type II) ratio in skeletal muscle and accompanied by extraordinary oxidative ability. This observation is completely contrasted with non-hibernators, which show a shift of oxidative muscle fibers (type I) to glycolytic muscle fibers (type II). Presently, the mechanisms by which these changes occur remain unclear. To investigate the mechanism of high oxidative capacity of the skeletal muscles in hibernating ground squirrels, capillary density (CD), and capillary/fiber (C/F) were measured by immunohistochemistry. mRNA expression levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were determined using real-time quantitative PCR assay. Spectrophotometry was applied to determine the activities of hexokinase (PK), pyruvate kinase (HK), and cytochrome c oxidase (CcO). RESULTS Inthe soleus muscle (SOL), mRNA expression levels of HIF-1αandVEGF in torpor became slightly lower but were not statistically significant; they were, however, significantly higher in the arousal group. In hibernating animals, no significant change occurred in CD but C/F increased by 15 %. CcO showed the highest activity in torpor. There were no significant differences in the activities of HK and PK between the torpid animals and summer active animals in SOL. However, PK activity increased by 34 % after hibernation. CONCLUSIONS Oxidative capacitymay be ensured by an increase of capillary supply of skeletal muscle in hibernating animals.
Collapse
Affiliation(s)
- Shanfeng Jiang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 71069, China
| | - Yunfang Gao
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 71069, China
| | - Yangmei Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 71069, China
| | - Kun Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 71069, China
| | - Huiping Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 71069, China
| | - Nandu Goswami
- Institute of Physiology, Center of Physiological Medicine, Medical University Graz, Graz, Austria
| |
Collapse
|
54
|
Lanaspa MA, Epperson LE, Li N, Cicerchi C, Garcia GE, Roncal-Jimenez CA, Trostel J, Jain S, Mant CT, Rivard CJ, Ishimoto T, Shimada M, Sanchez-Lozada LG, Nakagawa T, Jani A, Stenvinkel P, Martin SL, Johnson RJ. Opposing activity changes in AMP deaminase and AMP-activated protein kinase in the hibernating ground squirrel. PLoS One 2015; 10:e0123509. [PMID: 25856396 PMCID: PMC4391924 DOI: 10.1371/journal.pone.0123509] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 03/04/2015] [Indexed: 12/14/2022] Open
Abstract
Hibernating animals develop fatty liver when active in summertime and undergo a switch to a fat oxidation state in the winter. We hypothesized that this switch might be determined by AMP and the dominance of opposing effects: metabolism through AMP deaminase (AMPD2) (summer) and activation of AMP-activated protein kinase (AMPK) (winter). Liver samples were obtained from 13-lined ground squirrels at different times during the year, including summer and multiples stages of winter hibernation, and fat synthesis and β-fatty acid oxidation were evaluated. Changes in fat metabolism were correlated with changes in AMPD2 activity and intrahepatic uric acid (downstream product of AMPD2), as well as changes in AMPK and intrahepatic β-hydroxybutyrate (a marker of fat oxidation). Hepatic fat accumulation occurred during the summer with relatively increased enzymes associated with fat synthesis (FAS, ACL and ACC) and decreased enoyl CoA hydratase (ECH1) and carnitine palmitoyltransferase 1A (CPT1A), rate limiting enzymes of fat oxidation. In summer, AMPD2 activity and intrahepatic uric acid levels were high and hepatic AMPK activity was low. In contrast, the active phosphorylated form of AMPK and β-hydroxybutyrate both increased during winter hibernation. Therefore, changes in AMPD2 and AMPK activity were paralleled with changes in fat synthesis and fat oxidation rates during the summer-winter cycle. These data illuminate the opposing forces of metabolism of AMP by AMPD2 and its availability to activate AMPK as a switch that governs fat metabolism in the liver of hibernating ground squirrel.
Collapse
Affiliation(s)
- Miguel A. Lanaspa
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
- * E-mail:
| | - L. Elaine Epperson
- Department of Cell and Developmental Biology, Aurora, CO, 80045, United States of America
| | - Nanxing Li
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Christina Cicerchi
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Gabriela E. Garcia
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Carlos A. Roncal-Jimenez
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Jessica Trostel
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Swati Jain
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Colin T. Mant
- Department of Biochemistry and Molecular Genetics, Aurora, CO, 80045, United States of America
| | - Christopher J. Rivard
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Takuji Ishimoto
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Michiko Shimada
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Laura Gabriela Sanchez-Lozada
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
- Laboratory of Renal Physiopathology and Nephrology Dept, INC Ignacio Chavez, Mexico City, Mexico
| | - Takahiko Nakagawa
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Alkesh Jani
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
| | - Peter Stenvinkel
- Division of Renal Medicine, Department of Clinical Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Sandra L. Martin
- Department of Cell and Developmental Biology, Aurora, CO, 80045, United States of America
| | - Richard J. Johnson
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, 80045, United States of America
- Division of Nephrology, Eastern Colorado Health System, Department of Veteran Affairs, Denver, CO, United States of America
| |
Collapse
|
55
|
Hao Q, Yadav R, Basse AL, Petersen S, Sonne SB, Rasmussen S, Zhu Q, Lu Z, Wang J, Audouze K, Gupta R, Madsen L, Kristiansen K, Hansen JB. Transcriptome profiling of brown adipose tissue during cold exposure reveals extensive regulation of glucose metabolism. Am J Physiol Endocrinol Metab 2015; 308:E380-92. [PMID: 25516548 DOI: 10.1152/ajpendo.00277.2014] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We applied digital gene expression profiling to determine the transcriptome of brown and white adipose tissues (BAT and WAT, respectively) during cold exposure. Male C57BL/6J mice were exposed to cold for 2 or 4 days. A notable induction of genes related to glucose uptake, glycolysis, glycogen metabolism, and the pentose phosphate pathway was observed in BAT from cold-exposed animals. In addition, glycerol-3-phosphate dehydrogenase 1 expression was induced in BAT from cold-challenged mice, suggesting increased synthesis of glycerol from glucose. Similarly, expression of lactate dehydrogenases was induced by cold in BAT. Pyruvate dehydrogenase kinase 2 (Pdk2) and Pdk4 were expressed at significantly higher levels in BAT than in WAT, and Pdk2 was induced in BAT by cold. Of notice, only a subset of the changes detected in BAT was observed in WAT. Based on changes in gene expression during cold exposure, we propose a model for the intermediary glucose metabolism in activated BAT: 1) fluxes through glycolysis and the pentose phosphate pathway are induced, the latter providing reducing equivalents for de novo fatty acid synthesis; 2) glycerol synthesis from glucose is increased, facilitating triacylglycerol synthesis/fatty acid re-esterification; 3) glycogen turnover and lactate production are increased; and 4) entry of glucose carbon into the tricarboxylic acid cycle is restricted by PDK2 and PDK4. In summary, our results demonstrate extensive and diverse gene expression changes related to glucose handling in activated BAT.
Collapse
Affiliation(s)
- Qin Hao
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rachita Yadav
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark
| | - Astrid L Basse
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sidsel Petersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Si B Sonne
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Simon Rasmussen
- Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark
| | - Qianhua Zhu
- BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China
| | - Zhike Lu
- BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China
| | - Jun Wang
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China; Princess Al Jawhara Center of Excellence in the Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia; Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau, China; Department of Medicine, University of Hong Kong, Hong Kong
| | - Karine Audouze
- Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark; Université Paris Diderot, Inserm UMR-S973, Paris, France; and
| | - Ramneek Gupta
- Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark
| | - Lise Madsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; National Institute of Nutrition and Seafood Research, Nordnes, Bergen, Norway
| | - Karsten Kristiansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark; BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, China
| | - Jacob B Hansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark;
| |
Collapse
|
56
|
Vermillion KL, Anderson KJ, Hampton M, Andrews MT. Gene expression changes controlling distinct adaptations in the heart and skeletal muscle of a hibernating mammal. Physiol Genomics 2015; 47:58-74. [PMID: 25572546 PMCID: PMC4346737 DOI: 10.1152/physiolgenomics.00108.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/05/2015] [Indexed: 01/12/2023] Open
Abstract
Throughout the hibernation season, the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) experiences extreme fluctuations in heart rate, metabolism, oxygen consumption, and body temperature, along with prolonged fasting and immobility. These conditions necessitate different functional requirements for the heart, which maintains contractile function throughout hibernation, and the skeletal muscle, which remains largely inactive. The adaptations used to maintain these contractile organs under such variable conditions serves as a natural model to study a variety of medically relevant conditions including heart failure and disuse atrophy. To better understand how two different muscle tissues maintain function throughout the extreme fluctuations of hibernation we performed Illumina HiSeq 2000 sequencing of cDNAs to compare the transcriptome of heart and skeletal muscle across the circannual cycle. This analysis resulted in the identification of 1,076 and 1,466 differentially expressed genes in heart and skeletal muscle, respectively. In both heart and skeletal muscle we identified a distinct cold-tolerant mechanism utilizing peroxisomal metabolism to make use of elevated levels of unsaturated depot fats. The skeletal muscle transcriptome also shows an early increase in oxidative capacity necessary for the altered fuel utilization and increased oxygen demand of shivering. Expression of the fetal gene expression profile is used to maintain cardiac tissue, either through increasing myocyte size or proliferation of resident cardiomyocytes, while skeletal muscle function and mass are protected through transcriptional regulation of pathways involved in protein turnover. This study provides insight into how two functionally distinct muscles maintain function under the extreme conditions of mammalian hibernation.
Collapse
Affiliation(s)
- Katie L Vermillion
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Kyle J Anderson
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Marshall Hampton
- Department of Mathematics and Statistics, University of Minnesota Duluth, Duluth, Minnesota
| | - Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| |
Collapse
|
57
|
Xing X, Yang M, Wang DH. The expression of leptin, hypothalamic neuropeptides and UCP1 before, during and after fattening in the Daurian ground squirrel (Spermophilus dauricus). Comp Biochem Physiol A Mol Integr Physiol 2015; 184:105-12. [PMID: 25711781 DOI: 10.1016/j.cbpa.2015.02.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 02/14/2015] [Accepted: 02/16/2015] [Indexed: 11/26/2022]
Abstract
The Daurian ground squirrel (Spermophilus dauricus) accumulates large amounts of body fat during pre-hibernation fattening. Leptin, an adipose-derived hormone, plays important roles in energy balance and thermogenesis. We predicted that body fat accumulation would lead to the elevation of leptin concentration while its effect on satiety would be suppressed in hypothalamus during fattening. In addition, the uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) would increase and correlated positively with leptin concentration before hibernation. Here, we measured serum leptin concentration and leptin mRNA in white adipose tissue (WAT), hypothalamic neuropeptides involved in energy regulation and UCP1 in BAT before, during and after fattening in squirrels. The fat mass gradually increased during fattening but serum leptin increased mainly in the late phase of fattening, which was consistent with leptin mRNA expression in WAT. During fattening, the mRNA of hypothalamic leptin receptor was up-regulated and correlated positively with serum leptin. Orexigenic neuropeptide Y mRNA increased by 67%; however agouti-related peptide remained unchanged before hibernation. There was no significant change in anorexigenic neuropeptide mRNA. No change in suppressor of cytokine signaling-3 and protein tyrosine phosphatase-1B was detected. UCP1 mRNA expression and protein content in BAT increased significantly after fattening. These changes were independent of environmental conditions and serum leptin concentration. Our results suggest that the dissociation of leptin production and adiposity during fattening may facilitate fat accumulation. No evidence of suppressed leptin signal was found in fattening squirrels. The UCP1 recruitment in post-fattening squirrels could occur without winter-like acclimation and increased leptin.
Collapse
Affiliation(s)
- Xin Xing
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ming Yang
- College of Chemistry and Life Science, Shenyang Normal University, Shenyang 110034, China
| | - De-Hua Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
| |
Collapse
|
58
|
Grabek KR, Diniz Behn C, Barsh GS, Hesselberth JR, Martin SL. Enhanced stability and polyadenylation of select mRNAs support rapid thermogenesis in the brown fat of a hibernator. eLife 2015; 4. [PMID: 25626169 PMCID: PMC4383249 DOI: 10.7554/elife.04517] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022] Open
Abstract
During hibernation, animals cycle between torpor and arousal. These cycles involve
dramatic but poorly understood mechanisms of dynamic physiological regulation at the
level of gene expression. Each cycle, Brown Adipose Tissue (BAT) drives periodic
arousal from torpor by generating essential heat. We applied digital transcriptome
analysis to precisely timed samples to identify molecular pathways that underlie the
intense activity cycles of hibernator BAT. A cohort of transcripts increased during
torpor, paradoxical because transcription effectively ceases at these low
temperatures. We show that this increase occurs not by elevated transcription but
rather by enhanced stabilization associated with maintenance and/or extension of long
poly(A) tails. Mathematical modeling further supports a temperature-sensitive
mechanism to protect a subset of transcripts from ongoing bulk degradation instead of
increased transcription. This subset was enriched in a C-rich motif and genes
required for BAT activation, suggesting a model and mechanism to prioritize
translation of key proteins for thermogenesis. DOI:http://dx.doi.org/10.7554/eLife.04517.001 Many mammals hibernate to avoid food scarcity and harsh conditions during winter.
Hibernation involves entering a state called torpor, which drastically reduces the
amount of energy used by the body. During torpor, body temperature also decreases.
This is particularly exemplified in ground squirrels, whose body temperature can
hover at just above or even below the point of freezing. However, hibernating mammals
cannot remain in this state continuously over the months of hibernation but instead
cycle between bouts of torpor lasting for 1–3 weeks and brief periods of
‘arousal’ lasting between 12–24 hr, during which their body
rapidly warms up. The heat required to start warming up the hibernator is generated from a specialized
form of fat called brown adipose tissue. Normally, the bursts of metabolic activity
that are required to create this heat depend on certain proteins being produced.
Making a protein involves ‘translating’ its sequence from template
molecules called messenger RNA (mRNA), which are ‘transcribed’ from the
gene that encodes the protein. During the low body temperatures experienced during
torpor, both of these processes stop. So how is the hibernator able to quickly and
efficiently heat itself up during the arousal periods of hibernation? Grabek et al. investigated this by analyzing the relative levels of mRNA in the brown
adipose tissue of hibernating 13-lined ground squirrels. Using a special technique to
sample and sequence small fragments of mRNA taken from brown adipose tissue, Grabek
et al. compiled a profile of the mRNA molecules present at different points in the
torpor–arousal cycle and compared this with a similar profile taken from
squirrels that were not hibernating. From this analysis, Grabek et al. detected that a particular group of mRNA molecules
that are required for producing heat increase in abundance during torpor, even though
body temperature is low enough to stop gene transcription. This increased abundance
does not occur because more of the mRNA molecules are made; instead, the mRNA
molecules are modified to become more stable and long lasting. Once the animal warms
up during arousal, gene transcription is reactivated and more new mRNA molecules are
made. Grabek et al. suggest that the key mRNAs required for brown adipose tissue function
are selectively stabilized during torpor through a temperature-dependent protective
mechanism. These mRNAs are then preferentially translated into proteins during
arousal to rapidly and efficiently heat the hibernator. Most other mRNA molecules
degrade throughout torpor, and so their numbers decline as replacements are not
transcribed until body temperature briefly recovers during arousal. Whether this
protective mechanism is also used in other tissues during torpor remains a question
for future work. DOI:http://dx.doi.org/10.7554/eLife.04517.002
Collapse
Affiliation(s)
- Katharine R Grabek
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Cecilia Diniz Behn
- Department of Applied Math and Statistics, Colorado School of Mines, Golden, United States
| | - Gregory S Barsh
- Department of Research, HudsonAlpha Institute for Biotechnology, Huntsville, United States
| | - Jay R Hesselberth
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Sandra L Martin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| |
Collapse
|
59
|
Christian M. Transcriptional fingerprinting of "browning" white fat identifies NRG4 as a novel adipokine. Adipocyte 2015; 4:50-4. [PMID: 26167402 PMCID: PMC4496975 DOI: 10.4161/adip.29853] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 12/22/2022] Open
Abstract
Brown adipocytes help to maintain body temperature by the expression of a unique set of genes that facilitate cellular metabolic events including uncoupling protein 1-dependent thermogenesis. The dissipation of energy in brown adipose tissue (BAT) is in stark contrast to white adipose tissue (WAT) which is the body's primary site of energy storage. However, adipose tissue is highly dynamic and upon cold exposure profound changes occur in WAT resulting in a BAT-like phenotype due to the presence of brown-in-white (BRITE) adipocytes. In our recent report, transcription profiling was used to identify the gene expression changes that underlie the browning process as well as the intrinsic differences between BAT and WAT. Neuregulin 4 was categorized as a cold-induced BAT gene encoding an adipokine that signals between adipocytes and nerve cells and likely to have a role in increasing adipose tissue innervation in response to cold.
Collapse
|
60
|
Wu CW, Biggar KK, Storey KB. Expression profiling and structural characterization of microRNAs in adipose tissues of hibernating ground squirrels. GENOMICS PROTEOMICS & BIOINFORMATICS 2014; 12:284-91. [PMID: 25526980 PMCID: PMC4411486 DOI: 10.1016/j.gpb.2014.08.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/24/2014] [Accepted: 08/17/2014] [Indexed: 12/05/2022]
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 miRNAs in brown (BAT) and white adipose tissue (WAT) during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six miRNAs including let-7a, let-7b, miR-107, miR-150, miR-222 and miR-31 was significantly downregulated in WAT (P < 0.05), which was 16%–54% of euthermic non-torpid control squirrels, whereas expression of three miRNAs including miR-143, miR-200a and miR-519d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more miRNAs was downregulated in BAT during torpor. We detected reduced expression of 6 miRNAs including miR-103a, miR-107, miR-125b, miR-21, miR-221 and miR-31 (48%–70% of control), while only expression of miR-138 was significantly upregulated (2.91 ± 0.8-fold of the control, P < 0.05). Interestingly, miRNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas miRNAs with altered expression in BAT during torpor were linked to mitochondrial β-oxidation. miRPath target prediction analysis showed that miRNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase (MAPK) signaling, while the miRNAs upregulated in WAT were linked to transforming growth factor β (TGFβ) signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-miRNAs for the miRNAs used in this study, suggesting no structure-influenced changes in pre-miRNA processing efficiency in the squirrel. As well, the expression of miRNA processing enzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of miRNA expression in adipose tissues may be linked to distinct biological roles in WAT and BAT during hibernation and may involve the regulation of signaling cascades.
Collapse
Affiliation(s)
- Cheng-Wei Wu
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Kyle K Biggar
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, ON K1S 5B6, Canada.
| |
Collapse
|
61
|
Biggar KK, Storey KB. New Approaches to Comparative and Animal Stress Biology Research in the Post-genomic Era: A Contextual Overview. Comput Struct Biotechnol J 2014; 11:138-46. [PMID: 25408848 PMCID: PMC4232569 DOI: 10.1016/j.csbj.2014.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/07/2014] [Accepted: 09/11/2014] [Indexed: 02/06/2023] Open
Abstract
Although much is known about the physiological responses of many environmental stresses in tolerant animals, studies evaluating the regulation of stress-induced mechanisms that regulate the transitions to and from this state are beginning to explore new and fascinating areas of molecular research. Current findings have developed a general, but refined, view of the important molecular pathways contributing to stress-survival. However, studies utilizing newly developed technologies that broadly focus on genomic and proteomic screening are beginning to identify many new targets for future study. This minireview will provide a contextual overview on the use of DNA/RNA sequencing, microRNA annotation and prediction software, protein structure and function prediction tools, as well as methods of high-throughput protein expression analysis. We will also use select examples to highlight the existing use of these technologies in stress biology research. Such tools can be used in comparative stress biology in the characterization of animal responses to environmental challenges. Although there are many areas of study left to be explored, research in comparative stress biology will always be continuing as new technologies allow the further analysis of cell function, and new paradigms in gene regulation and regulatory molecules (such as microRNAs) are continuing to be discovered. Building upon the findings of past research, while utilizing new technologies in the appropriate manner, future studies can be carried out in new and exciting areas still unexplored. Proper use of rapidly developing technologies will help to create a complete understanding of the animal stress response and survival mechanisms utilized by many diverse organisms.
Collapse
Affiliation(s)
| | - Kenneth B. Storey
- Institute of Biochemistry, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| |
Collapse
|
62
|
Prado-Lòpez S, Duffy MM, Baustian C, Alagesan S, Hanley SA, Stocca A, Griffin MD, Ceredig R. The influence of hypoxia on the differentiation capacities and immunosuppressive properties of clonal mouse mesenchymal stromal cell lines. Immunol Cell Biol 2014; 92:612-23. [PMID: 24777310 DOI: 10.1038/icb.2014.30] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 03/26/2014] [Accepted: 03/27/2014] [Indexed: 12/27/2022]
Abstract
Multipotent mesenchymal stromal cells are multipotent cells capable of differentiating into different mesodermal cell types. Enigmatically, mesenchymal stromal cells present in the bone marrow support early lymphopoiesis yet can inhibit mature lymphocyte growth. Critical features of the bone marrow microenvironment, such as the level of oxygen, play an important role in mesenchymal stromal cell biology. Herein, we show that a panel of continuously growing mouse mesenchymal stromal cell lines, namely OP9, MS5, PA6, ST2 and B16-14, exhibit mesenchymal stromal cell characteristic phenotypes and respond physiologically to oxygen deprivation. Culturing freshly isolated bone marrow-derived mesenchymal stromal cells or cell lines at 5% O2 resulted in a dramatic increase in expression of hypoxia-inducible factor family members and of key genes involved in their differentiation. Phenotypically, their osteogenic and adipogenic differentiation capacity was generally improved in hypoxia, whereas their inhibitory effects on in vitro T-cell proliferation were preserved. Taken together, we conclude that these continuously growing mouse cell lines behave as canonical mesenchymal stromal cells and respond physiologically to hypoxia, thereby providing a potent tool for the study of different aspects of mesenchymal stromal cell biology.
Collapse
Affiliation(s)
- Sonia Prado-Lòpez
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Michelle M Duffy
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Claas Baustian
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Senthilkumar Alagesan
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Shirley A Hanley
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Alessia Stocca
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Matthew D Griffin
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| | - Rhodri Ceredig
- Regenerative Medicine Institute, National Centre for Biomedical Engineering Science and School of Medicine, Nursing and Health Sciences, National University of Ireland, Galway, Ireland
| |
Collapse
|