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Open Access Publications from the University of California

Scholarly Works (12 results)

  • Article
  • Peer Reviewed
UC San Francisco Previously Published Works (2019)
Since its initial discovery in 2002, the neuropeptide Kisspeptin (Kiss1) has been anointed as the master regulator controlling the onset of puberty in males and females. Over the last several years, multiple groups found that Kiss1 signaling is mediated by the 7TM surface receptor GPCR54. Kiss1 mRNA is highly enriched in the basal medial and lateral subregions of the arcuate nucleus (ARC) in the medial basal hypothalamus. Thus, Kiss1ARC neurons reside in a unique anatomical location ideal for sensing and responding to circulating steroid hormones as well as nutrients. Kiss1 expression is highly responsive to fluctuations of the gonadal hormone, estrogen, with nearly 90% of Kiss1ARC neurons expressing the nuclear hormone estrogen receptor alpha (ERa). Here we review recent research that extends the function of Kiss1ARC neurons beyond the regulation of puberty and highlight their emerging, novel roles in controlling energy allocation, behavioral outputs, and sex-dependent bone remodeling in females. Indeed, some of these previously unknown functions for Kiss1 neurons are quite striking as exemplified by the remarkable increase in bone mass after manipulating estrogen signaling in Kiss1ARC neurons. Taken together, we suggest that Kiss1ARC neurons are highly sensitive to nutritional and hormonal cues that dictate energy utilization and reproduction.
    Cover page: Should We Make More Bone or Not, As Told by Kisspeptin Neurons in the Arcuate Nucleus.
    • Article
    • Peer Reviewed
    UC San Francisco Previously Published Works (2019)
    Since its initial discovery in 2002, the neuropeptide Kisspeptin (Kiss1) has been anointed as the master regulator controlling the onset of puberty in males and females. Over the last several years, multiple groups found that Kiss1 signaling is mediated by the 7TM surface receptor GPCR54. Kiss1 mRNA is highly enriched in the basal medial and lateral subregions of the arcuate nucleus (ARC) in the medial basal hypothalamus. Thus, Kiss1ARC neurons reside in a unique anatomical location ideal for sensing and responding to circulating steroid hormones as well as nutrients. Kiss1 expression is highly responsive to fluctuations of the gonadal hormone, estrogen, with nearly 90% of Kiss1ARC neurons expressing the nuclear hormone estrogen receptor alpha (ERa). Here we review recent research that extends the function of Kiss1ARC neurons beyond the regulation of puberty and highlight their emerging, novel roles in controlling energy allocation, behavioral outputs, and sex-dependent bone remodeling in females. Indeed, some of these previously unknown functions for Kiss1 neurons are quite striking as exemplified by the remarkable increase in bone mass after manipulating estrogen signaling in Kiss1ARC neurons. Taken together, we suggest that Kiss1ARC neurons are highly sensitive to nutritional and hormonal cues that dictate energy utilization and reproduction.
      Cover page: Should We Make More Bone or Not, As Told by Kisspeptin Neurons in the Arcuate Nucleus
      • Thesis
      • Peer Reviewed
      UC Berkeley Electronic Theses and Dissertations (2014)

      Estrogens in hormone replacement therapy (HRT) decrease menopausal symptoms, but increase the risks of reproductive cancers. The beneficial effects of estrogen on peripheral tissues and the adverse proliferative effects on the uterus and mammary gland are mediated by ERalpha. Currently HRT is approved only for short-term use. Short-term HRT works for decreasing symptoms associated with menopause, however, long-term usage is needed to prevent subclinical diseases. Because estradiol-bound ERalpha is an agonist in all tissues there is a need for development of more tissue-selective estrogens that can be used for both short and long-term HRT. Chalcones display antiproliferative activity through ERbeta and may have benefits on menopause-induced hot flashes, however activity through ERalpha and their effects on both estradiol gene regulation and physiology are less known. The present study aimed at identifying a chalcone compound which could change the activity of ERalpha in the presence of estradiol as a coagonist, thereby modulating the response of ERalpha on gene regulation and increasing its tissue specificity. After screening a panel of five chalcone compounds for estrogenic activity in cells cotransfected with ERalpha and an ERE upstream of tk-luciferase, 2', 3', 4'-trihydroxychalcone was identified as a unique ERalpha coagonist. 2', 3', 4'-THC displayed no estrogenic activity on its own, but synergized the activation of the ERE in the presence of estradiol. Competitive binding assays with [3H]-estradiol demonstrated that 2', 3', 4'-THC binds to both ERalpha and ERbeta. Estradiol and SERM-induced genes, KRT-19 and NKG2E, were not regulated by 2', 3', 4'-THC alone. Both KRT-19 and NKG2E were synergized with the combination of 2', 3', 4'-THC and estradiol. Tamoxifen and raloxifene induced expression of NKG2E, but did not synergize the expression in the presence of estradiol. The data demonstrates that 2', 3', 4'-THC behaves as a novel coagonist and not a SERM on gene regulation. A unique gene expression profile was induced in U2OSalpha cells treated with a combination of estradiol and 2', 3', 4'-THC for 24 hours with doses that would allow binding of both ligands to ERalpha at the same time. Functional analysis utilizing the binding affinities of estradiol, 2', 3', 4'-THC and another ERalpha binding chalcone, 2, 2', 4'-THC, demonstrated that a heteroligand complex consisting of estradiol and 2', 3', 4'-THC in ERalpha is possible. Despite the synergistic activation of estradiol regulated genes in U2OSalpha cells, the combination of 2', 3', 4'-THC and estradiol did not induce proliferation of MCF-7 cells. In the same cells 2', 3', 4'-THC blocked estradiol-induced G1 to S phase cell cycle transition without blocking proliferative genes regulated by estradiol. In female ovariectomized mice on a soy-free chow diet treated for four weeks (n=5, per group), 2', 3', 4'-THC did not cause uterine proliferation and blocked estradiol-induced proliferation and gene expression. Although 2', 3', 4'-THC blocked estradiol gene expression in uterine tissue, it regulated and modulated estradiol-induced genes in adipose tissue. Because 2', 3', 4'-THC displays unique coagonist activity through ERalpha without causing proliferation, it may be useful for future HRT and expanding our knowledge of ERalpha regulation and ligand interaction.

        Cover page: 2', 3', 4'-trihydroxychalcone is an Estrogen Receptor Alpha Coagonist
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2022)
        The role of central estrogen in cognitive, metabolic, and reproductive health has long fascinated the lay public and scientists alike. In the last two decades, insight into estrogen signaling in the brain and its impact on female physiology is beginning to catch up with the vast information already established for its actions on peripheral tissues. Using newer methods to manipulate estrogen signaling in hormone-sensitive brain regions, neuroscientists are now identifying the molecular pathways and neuronal subtypes required for controlling sex-dependent energy allocation. However, the immense cellular complexity of these hormone-sensitive brain regions makes it clear that more research is needed to fully appreciate how estrogen modulates neural circuits to regulate physiological and behavioral end points. Such insight is essential for understanding how natural or drug-induced hormone fluctuations across lifespan affect women's health.
          Cover page: Running the Female Power Grid Across Lifespan Through Brain Estrogen Signaling
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (2022)
          BACKGROUND: Menopausal hormone therapy (MHT) is recommended for only five years to treat vasomotor symptoms and vulvovaginal atrophy because of safety concerns with long-term treatment. We investigated the ability of 2,3,4-trihydroxychalcone (2,3,4-THC) to modulate estrogen receptor (ER)-mediated responses in order to find drug candidates that could potentially prevent the adverse effects of long-term MHT treatment. METHODS: Transfection assays, real time-polymerase chain reaction, and microarrays were used to evaluate the effects of 2,3,4-THC on gene regulation. Radioligand binding studies were used to determine if 2,3,4-THC binds to ERα. Cell proliferation was examined in MCF-7 breast cancer cells by using growth curves and flow cytometry. Western blots were used to determine if 2,3,4-THC alters the E2 activation of the MAPK pathway and degradation of ERα. Chromatin immunoprecipitation was used to measure ERα binding to genes. RESULTS: The 2,3,4-THC/E2 combination produced a synergistic activation with ERα on reporter and endogenous genes in human U2OS osteosarcoma cells. Microarrays identified 824 genes that we termed reprogrammed genes because they were not regulated in U2OS-ERα cells unless they were treated with 2,3,4-THC and E2 at the same time. 2,3,4-THC blocked the proliferation of MCF-7 cells by preventing the E2-induced activation of MAPK and c-MYC transcription. The antiproliferative mechanism of 2,3,4-THC differs from selective estrogen receptor modulators (SERMs) because 2,3,4-THC did not bind to the E2 binding site in ERα like SERMs. CONCLUSION: Our study suggests that 2,3,4-THC may represent a new class of ERα modulators that do not act as a direct agonists or antagonists. We consider 2,3,4-THC to be a reprogramming compound, since it alters the activity of ERα on gene regulation and cell proliferation without competing with E2 for binding to ERα. The addition of a reprogramming drug to estrogens in MHT may offer a new strategy to overcome the adverse proliferative effects of estrogen in MHT by reprogramming ERα as opposed to an antagonist mechanism that involves blocking the binding of estrogen to ERα.
            Cover page: 2,3,4-Trihydroxychalcone changes estrogen receptor α regulation of genes and breast cancer cell proliferation by a reprogramming mechanism.
            • Article
            • Peer Reviewed
            UCSF Open Access Publishing Fund (2019)
              • Article
              • Peer Reviewed
              UC San Francisco Previously Published Works (2021)
              Oestrogen depletion in rodents and humans leads to inactivity, fat accumulation and diabetes1,2, underscoring the conserved metabolic benefits of oestrogen that inevitably decrease with age. In rodents, the preovulatory surge in 17β-oestradiol (E2) temporarily increases energy expenditure to coordinate increased physical activity with peak sexual receptivity. Here we report that a subset of oestrogen-sensitive neurons in the ventrolateral ventromedial hypothalamic nucleus (VMHvl)3-7 projects to arousal centres in the hippocampus and hindbrain, and enables oestrogen to rebalance energy allocation in female mice. Surges in E2 increase melanocortin-4 receptor (MC4R) signalling in these VMHvl neurons by directly recruiting oestrogen receptor-α (ERα) to the Mc4r gene. Sedentary behaviour and obesity in oestrogen-depleted female mice were reversed after chemogenetic stimulation of VMHvl neurons expressing both MC4R and ERα. Similarly, a long-term increase in physical activity is observed after CRISPR-mediated activation of this node. These data extend the effect of MC4R signalling - the most common cause of monogenic human obesity8 - beyond the regulation of food intake and rationalize reported sex differences in melanocortin signalling, including greater disease severity of MC4R insufficiency in women9. This hormone-dependent node illuminates the power of oestrogen during the reproductive cycle in motivating behaviour and maintaining an active lifestyle in women.
                Cover page: Oestrogen engages brain MC4R signalling to drive physical activity in female mice
                • Article
                • Peer Reviewed
                UC Berkeley Previously Published Works (2019)
                RDH1 is one of the several enzymes that catalyze the first of the two reactions to convert retinol into all-trans-retinoic acid (atRA). Here, we show that Rdh1-null mice fed a low-fat diet gain more weight as adiposity (17% males, 13% females) than wild-type mice by 20 weeks old, despite neither consuming more calories nor decreasing activity. Glucose intolerance and insulin resistance develop following increased adiposity. Despite the increase in white fat pads, epididymal white adipose does not express Rdh1, nor does muscle. Brown adipose tissue (BAT) and liver express Rdh1 at relatively high levels compared to other tissues. Rdh1 ablation lowered body temperatures during ambient conditions. Given the decreased body temperature, we focused on BAT. A lack of differences in BAT adipogenic gene expression between Rdh1-null mice and wild-type mice, including Pparg, Prdm16, Zfp516 and Zfp521, indicated that the phenotype was not driven by brown adipose hyperplasia. Rather, Rdh1 ablation eliminated the increase in BAT atRA that occurs after re-feeding. This disruption of atRA homeostasis increased fatty acid uptake, but attenuated lipolysis in primary brown adipocytes, resulting in increased lipid content and larger lipid droplets. Rdh1 ablation also decreased mitochondrial proteins, including CYCS and UCP1, the mitochondria oxygen consumption rate, and disrupted the mitochondria membrane potential, further reflecting impaired BAT function, resulting in both BAT and white adipose hypertrophy. RNAseq revealed dysregulation of 424 BAT genes in null mice, which segregated predominantly into differences after fasting vs after re-feeding. Exceptions were Rbp4 and Gbp2b, which increased during both dietary conditions. Rbp4 encodes the serum retinol-binding protein-an insulin desensitizer. Gbp2b encodes a GTPase. Because Gbp2b increased several hundred-fold, we overexpressed it in brown adipocytes. This caused a shift to larger lipid droplets, suggesting that GBP2b affects signaling downstream of the β-adrenergic receptor during basal thermogenesis. Thus, Rdh1-generated atRA in BAT regulates multiple genes that promote BAT adaptation to whole-body energy status, such as fasting and re-feeding. These gene expression changes promote optimum mitochondria function and thermogenesis, limiting adiposity. Attenuation of adiposity and insulin resistance suggests that RDH1 mitigates metabolic syndrome.
                  Cover page: RDH1 suppresses adiposity by promoting brown adipose adaptation to fasting and re-feeding.
                  • Article
                  • Peer Reviewed
                  UC Berkeley Previously Published Works (2015)
                  Brown adipose tissue (BAT) possesses the inherent ability to dissipate metabolic energy as heat through uncoupled mitochondrial respiration. An essential component of the mitochondrial electron transport chain is coenzyme Q (CoQ). While cells synthesize CoQ mostly endogenously, exogenous supplementation with CoQ has been successful as a therapy for patients with CoQ deficiency. However, which tissues depend on exogenous CoQ uptake as well as the mechanism by which CoQ is taken up by cells and the role of this process in BAT function are not well understood. Here, we report that the scavenger receptor CD36 drives the uptake of CoQ by BAT and is required for normal BAT function. BAT from mice lacking CD36 displays CoQ deficiency, impaired CoQ uptake, hypertrophy, altered lipid metabolism, mitochondrial dysfunction, and defective nonshivering thermogenesis. Together, these data reveal an important new role for the systemic transport of CoQ to BAT and its function in thermogenesis.
                    Cover page: Dependence of Brown Adipose Tissue Function on CD36-Mediated Coenzyme Q Uptake
                    • Article
                    • Peer Reviewed
                    UC Berkeley Previously Published Works (2019)
                    RDH1 is one of the several enzymes that catalyze the first of the two reactions to convert retinol into all-trans-retinoic acid (atRA). Here, we show that Rdh1-null mice fed a low-fat diet gain more weight as adiposity (17% males, 13% females) than wild-type mice by 20 weeks old, despite neither consuming more calories nor decreasing activity. Glucose intolerance and insulin resistance develop following increased adiposity. Despite the increase in white fat pads, epididymal white adipose does not express Rdh1, nor does muscle. Brown adipose tissue (BAT) and liver express Rdh1 at relatively high levels compared to other tissues. Rdh1 ablation lowered body temperatures during ambient conditions. Given the decreased body temperature, we focused on BAT. A lack of differences in BAT adipogenic gene expression between Rdh1-null mice and wild-type mice, including Pparg, Prdm16, Zfp516 and Zfp521, indicated that the phenotype was not driven by brown adipose hyperplasia. Rather, Rdh1 ablation eliminated the increase in BAT atRA that occurs after re-feeding. This disruption of atRA homeostasis increased fatty acid uptake, but attenuated lipolysis in primary brown adipocytes, resulting in increased lipid content and larger lipid droplets. Rdh1 ablation also decreased mitochondrial proteins, including CYCS and UCP1, the mitochondria oxygen consumption rate, and disrupted the mitochondria membrane potential, further reflecting impaired BAT function, resulting in both BAT and white adipose hypertrophy. RNAseq revealed dysregulation of 424 BAT genes in null mice, which segregated predominantly into differences after fasting vs after re-feeding. Exceptions were Rbp4 and Gbp2b, which increased during both dietary conditions. Rbp4 encodes the serum retinol-binding protein-an insulin desensitizer. Gbp2b encodes a GTPase. Because Gbp2b increased several hundred-fold, we overexpressed it in brown adipocytes. This caused a shift to larger lipid droplets, suggesting that GBP2b affects signaling downstream of the β-adrenergic receptor during basal thermogenesis. Thus, Rdh1-generated atRA in BAT regulates multiple genes that promote BAT adaptation to whole-body energy status, such as fasting and re-feeding. These gene expression changes promote optimum mitochondria function and thermogenesis, limiting adiposity. Attenuation of adiposity and insulin resistance suggests that RDH1 mitigates metabolic syndrome.
                      Cover page: RDH1 suppresses adiposity by promoting brown adipose adaptation to fasting and re-feeding
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