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The effect of moderate hypothermia on gene expression by THP-1 cells

ABSTRACT: Background: Moderate hypothermia (32oC for 12 – 72 hours) has therapeutic applications, but the mechanisms by which it affects cellular function are unclear. We tested the hypothesis that moderate hypothermia produces broad changes in gene expression by human cells at the level of mRNA. Methods: Acute monocytic leukemia THP-1 cells were incubated under control conditions (37oC) or moderate hypothermia (32oC) for 24 hours. Cellular mRNA was extracted and a cold stress response was confirmed by examining the expression of the cold-inducible gene CIRBP by reverse transcription PCR (RT-PCR). Gene expression analysis was performed on seven sets of samples with Affymetrix U133A chips, using established statistical methods. Sequences were considered to be affected by cold if they showed statistically significant changes in expression and also met published post-hoc filter criteria (changes in geometric mean expression of 2-fold or greater and detection calls of “present” or “marginal” in at least half of the experiments). The changes in expression of a select number of these sequences were further confirmed by PCR. Results: 167 sequences met our prospectively defined criteria for a change in expression; 67 showed increases in expression and 100 showed decreases in expression. Consistent with prior literature, the cold-inducible genes CIRBP and RBM3 showed increases in expression. Functional categories affected by cold stress included genes involved in immune responses, cell growth, proliferation, and differentiation, and metabolism and biosynthesis. Several heat shock proteins (HSPs) showed decreases in expression. Conclusions: Moderate hypothermia produces substantial changes in cellular gene expression, in categories potentially of importance to systemic function. Interestingly, cold exposure without re-warming decreased the expression of several HSPs. Our in vitro findings suggest that moderate hypothermia in vivo might produce physiologically important changes in gene expression by circulating leukocytes. Keywords: Stress response / hypothermia

ORGANISM(S): Homo sapiens

PROVIDER: GSE4425 | GEO | 2006/04/05

SECONDARY ACCESSION(S): PRJNA94619

REPOSITORIES: GEO

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Project description:Background: Moderate hypothermia (32oC for 12 â 72 hours) has therapeutic applications, but the mechanisms by which it affects cellular function are unclear. We tested the hypothesis that moderate hypothermia produces broad changes in gene expression by human cells at the level of mRNA. Methods: Acute monocytic leukemia THP-1 cells were incubated under control conditions (37oC) or moderate hypothermia (32oC) for 24 hours. Cellular mRNA was extracted and a cold stress response was confirmed by examining the expression of the cold-inducible gene CIRBP by reverse transcription PCR (RT-PCR). Gene expression analysis was performed on seven sets of samples with Affymetrix U133A chips, using established statistical methods. Sequences were considered to be affected by cold if they showed statistically significant changes in expression and also met published post-hoc filter criteria (changes in geometric mean expression of 2-fold or greater and detection calls of âpresentâ or âmarginalâ in at least half of the experiments). The changes in expression of a select number of these sequences were further confirmed by PCR. Results: 167 sequences met our prospectively defined criteria for a change in expression; 67 showed increases in expression and 100 showed decreases in expression. Consistent with prior literature, the cold-inducible genes CIRBP and RBM3 showed increases in expression. Functional categories affected by cold stress included genes involved in immune responses, cell growth, proliferation, and differentiation, and metabolism and biosynthesis. Several heat shock proteins (HSPs) showed decreases in expression. Conclusions: Moderate hypothermia produces substantial changes in cellular gene expression, in categories potentially of importance to systemic function. Interestingly, cold exposure without re-warming decreased the expression of several HSPs. Our in vitro findings suggest that moderate hypothermia in vivo might produce physiologically important changes in gene expression by circulating leukocytes. Experiment Overall Design: Seven sets of paired THP-1 samples, grown under either control (37oC) or hypothermic (32oC) conditions for 24 hours

Project description:Non-shivering thermogenesis in adipocytes is mediated by brown adipose tissue, purportedly through the sole action of uncoupling protein 1 (UCP1). The physiological relevance of UCP1-dependent thermogenesis has primarily been inferred from the attenuation of thermogenic output of mice genetically lacking Ucp1 from birth (germline Ucp1-/-). However, germline Ucp1-/- mice harbor secondary changes within brown adipose tissue beyond UCP1, such as reduced electron transport chain abundance. We show here that these secondary changes also encompass reduced expression of genes regulating fuel liberation, changes that would attenuate the capacity of any thermogenic pathway. Therefore, the quantitative contribution of UCP1-dependent and -independent thermogenesis is not fully understood. To mitigate the potentially confounding ancillary changes to brown adipose tissue of germline Ucp1-/- mice, we constructed mice with inducible adipocyte-selective disruption of Ucp1. We find that, while germline Ucp1-/- mice succumb to cold-induced hypothermia with complete penetrance, most mice with inducible deletion of Ucp1 maintain homeothermy in the cold. However, inducible adipocyte-selective co-deletion of Ucp1 and creatine kinase B (Ckb, an effector of UCP1-independent thermogenesis) exacerbates cold-intolerance, indicative of a negative genetic interaction and thus a parallel thermogenic function. We find no evidence for impairments in insulation or non-shivering thermogenesis in skeletal muscle that would drive this phenotype. Furthermore, following UCP1 deletion or UCP1/CKB co-deletion from mature adipocytes, moderate cold exposure triggers the regeneration of mature adipocytes that coordinately restore UCP1 and CKB to brown adipose tissue, providing further evidence of their parallel thermogenic relationship. Our findings suggest that thermogenic adipocytes utilize non-paralogous protein redundancy – through UCP1 and CKB – to promote cold-induced energy dissipation.

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The effect of moderate hypothermia on gene expression by THP-1 cells

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