POS1157 SAFETY AND EFFICACY OF ALLN-346 ORAL ENZYME THERAPY IN PATIENTS WITH HYPERURICEMIA AND CHRONIC KIDNEY DISEASE (CKD): RESULTS OF THE PHASE 2A STUDY 201

Background

Currently available urate lowering therapies (ULTs) are limited in their use for gout patients with advanced CKD based on dosing restrictions, tolerability, safety concerns, and reduced effectiveness, compared to options for the broader gout population. In gout patients with advanced CKD, the intestinal tract becomes the major route of urate elimination, as opposed to in healthy people with normal kidney function where kidneys are the primary route of uric acid excretion.1 Considering some of the limitations of present urate-lowering therapies (ULTs) in gout & CKD and the extra-renal pathway of urate secretion, a new oral therapy, ALLN-346 (engineered urate oxidase), is under development as a non-absorbed, urate specific enzyme, designed to enhance degradation and secretion of urate in the intestinal tract.2

Objectives

To assess the safety, tolerability, and initial bioactivity data of ALLN-346 in adults with hyperuricemia and CKD.

Methods

This one-week inpatient Phase 2a study (NCT04987242) was conducted at a clinical pharmacology unit. Eleven otherwise healthy adult patients with hyperuricemia (sUA ≥ 6.8 mg/dL) and normal to Stage 2 CKD (eGFR ≥60), not on concurrent ULTs, were randomized (2:1) to receive either 5 capsules of ALLN-346 or matching placebo, three times daily for 7 days. Serum urate was measured daily, and urine uric acid was assessed on days -2, -1, 1, 4, and 7. Safety was monitored throughout the study. To assess possible ALLN-346 systemic absorption, a specific ELISA was used on serum samples collected pre- and post-dose over 7 days.

Results

Of the 11 patients 7 received ALLN-346 and 4 received placebo. Most patients had Stage 2 CKD, including 5 of the 7 subjects treated with ALLN-346. A statistically significant reduction in mean sUA was recorded with ALLN-346 compared to placebo [Figure 1]. The largest mean % reduction in sUA was observed among patients with stage 2 CKD; sUA reduction was correlated with eGFR in the ALLN-346 group (r=0.95; P=0.003), but not the placebo group (r=-0.2; P=0.91). No serious adverse events were reported, and clinical and laboratory parameters revealed no significant safety signals. Lack of systemic absorption of ALLN-346 was confirmed by ELISA assays.

Figure 1.

Absolute and Percent Change from Baseline in Serum Urate over 7 -days of Treatment

Conclusion

In this study, oral therapy with ALLN-346 for 7 days was well tolerated and resulted in a significant reduction in sUA. Consistent with the known pathophysiologic adaptation of increased intestinal elimination of uric acid in patients with impaired kidney function and the intestinal-based mechanism of action of ALLN-346, there was a strong correlation between the effect of ALLN-346 on sUA reduction and the level of kidney function. The generated data support proof of pharmacology for the intestinal mechanism of action of ALLN-346 to degrade urate either formed or secreted in the gut. Future studies in the larger gout population with CKD are underway.

References

[1]Sorensen BL. Role of the intestinal tract in the elimination of uric acid. Arthritis and Rheumatism, vol 8, part5 1965

[2]Pierzynowska K, Deshpande A, Mosiichuk N, et al. Oral Treatment with an Engineered Uricase, ALLN-346, Reduces Hyperuricemia, and Uricosuria in Urate Oxidase-Deficient Mice. Front Med (Lausanne). 2020 Nov 24;7:569215.

Disclosure of Interests

Robert Terkeltaub Consultant of: Allena, SOBI, Astra-Zeneca, Fortress, Grant/research support from: Astra-Zeneca, David Clark Shareholder of: Allena, Employee of: Allena, Christine Tosone Shareholder of: Allena, Employee of: Allena, Boris Kandinov Shareholder of: Allena, Employee of: Allena, Ping Zhang Shareholder of: Corbus, Employee of: Previous Corbus, Current Allena, Naomi Dahl Shareholder of: AbbVie shares, Allena options, Employee of: Allena, Danica Grujic Shareholder of: Allena, Employee of: Allena, David Goldfarb Consultant of: Allena, Alnylam, AstraZeneca, Cymabay, Dicerna, Sumitovant, Synlogic, Grant/research support from: Dicerna, Travere

POS1156 PHASE 1 TRIALS OF NOVEL ORAL ENZYME THERAPY (ALLN-346) FOR HYPERURICEMIA & GOUT: SAFETY, PHARMACODYNAMICS, AND LACK OF SYSTEMIC ABSORPTION OF SINGLE AND MULTIPLE ASCENDING DOSES IN HEALTHY VOLUNTEERS

Background

Currently available therapies for gout in patients with advanced chronic kidney disease (CKD) are either dose-limited or contraindicated due to safety and tolerability concerns. In gout patients with advanced CKD, the intestinal tract becomes the major route of urate elimination, in contrast to healthy people with normal kidney function whose kidneys are the primary route of uric acid excretion.1. Considering some of the limitations of present urate lowering therapies (ULTs) in gout & CKD and the extra-renal pathway of urate secretion, a new oral therapy with ALLN-346 (engineered urate oxidase) is under development as a non-absorbed, urate specific enzyme, designed to enhance degradation and secretion of urate in the intestinal tract. 2

Objectives

To assess safety and tolerability and evidence for the lack of systemic absorption at various dose levels of ALLN-346 in normal healthy volunteers (NHV) up to 7 days.

Methods

Two randomized, double-blind Phase 1 studies of ALLN-346 or placebo were conducted in adult NHV in a domicile setting; a single-ascending dose (SAD) study of 3 doses on a single day of dosing, and a multiple ascending dose (MAD) study of 2 doses during 7 days (NCT04236219 and NCT04829435, respectively). In the SAD study, subjects received 3 ascending doses of ALLN-346 (3 capsules,6 capsules, and 6 capsules administered twice, or placebo) and were randomized 3:1 (ALLN-346:placebo, n=24). In the MAD study, subjects received 3 (Cohort A) or 5 (Cohort B) of ALLN-346 capsules or placebo (2:1 randomization, n=18) administered orally 3 times daily for 7 days. To assess possible ALLN-346 absorption, a specific ELISA and uricase potency assay were used on PK serum samples collected from all subjects in both studies pre-dose and at intervals post dose.

Results

In both studies, all randomized subjects completed treatment with 100% compliance. ALLN-346 was well-tolerated, with no serious adverse events (AE) and with no clinically significant safety signals across all cumulative doses. Clinical and laboratory parameters revealed no clinically significant safety signals among all cumulative dosing cohorts across hematology, serum biochemistry, vital signs, or ECGs. The majority of reported AEs were mild with no pattern of differences between ALLN-346 and placebo. No evidence of systemic absorption of ALLN-346 was seen, as confirmed by both ELISA and by uricase potency assay of all PK serum samples from all subjects from SAD (n=240) and MAD (n=324).

Conclusion

ALLN-346, a new oral enzyme therapy in development for the treatment of hyperuricemia and gout in advanced CKD was well tolerated. Consistent with its mechanism of action, no evidence of systemic absorption was demonstrated. Furtherstudies in hyperuricemia patients with gout and CKD are underway.

References

[1]Sorensen BL. Role of the intestinal tract in the elimination of uric acid. Arthritis and Rheumatism, vol 8, part5 1965

[2]Pierzynowska K, Deshpande A, Mosiichuk N, et al. Oral Treatment with an Engineered Uricase, ALLN-346, Reduces Hyperuricemia, and Uricosuria in Urate Oxidase-Deficient Mice. Front Med (Lausanne). 2020 Nov 24;7:569215.

Disclosure of Interests

David Clark Shareholder of: Allena, Employee of: Allena, Danica Grujic Shareholder of: Allena, Employee of: Allena, Christine Tosone Shareholder of: Allena, Employee of: Allena, Naomi Dahl Shareholder of: AbbVie (shares), Allena (options), Employee of: Allena, Robert Terkeltaub Consultant of: Allena, SOBI, Astra-Zeneca, Fortress, Grant/research support from: Astra-Zeneca

XUV-driven plasma switch for THz: new spatio-temporal overlap tool for XUV-THz pump-probe experiments at FELs

A simple and robust tool for spatio-temporal overlap of THz and XUV pulses in in-vacuum pump-probe experiments is presented. The technique exploits ultrafast changes of the optical properties in semiconductors (i.e. silicon) driven by ultrashort XUV pulses that are probed by THz pulses. This work demonstrates that this tool can be used for a large range of XUV fluences that are significantly lower than when probing by visible and near-infrared pulses. This tool is mainly targeted at emerging X-ray free-electron laser facilities, but can be utilized also at table-top high-harmonics sources.

The pig as a model for premature infants - the importance of immunoglobulin supplementation for growth and development

Preterm human neonates, contrary to preterm piglets, obtain immunoglobulins from their mothers via the placenta during intrauterine development. However, one should note that the majority of trans-placental transfer of immunoglobulins in humans takes place during the last trimester of pregnancy. It is also known that the feeding of limited amounts of colostrum or systemic infusion of small amounts of serum improves the survival of preterm and full-term piglets. Full-term piglets deprived of their mother’s immunoglobulins exhibit strong apathy and develop watery diarrhoea, often resulting in death. The aim of the current study was to determine if provision of immunoglobulins using different approaches would be beneficial for survival outcomes. To reach the immunological sufficient level we infused immunoglobulins intravenously in amount mimicking the blood level in piglets fed with sow colostrum. Intravenous infusion of immunoglobulins in both preterm and full-term newborn piglets fully ensured their survival, growth and blood immunoglobulin G and protein levels similar to those observed in piglets fed colostrum. Piglets completely deprived of immunoglobulins exhibited significantly lower blood levels of immunoglobulins and protein compared to colostrum-fed animals. Piglets infused with only serum exhibited significantly lower blood immunoglobulin G level compared to those infused with immunoglobulins. In conclusion, based on the data obtained, we suggest that passive immune support provided by colostrum intake or early systemic infusion of Ig’s in sufficient amounts is key to ensuring the general well-being of preterm and full-term new born piglets, used as an animal model for the human infant.

Breast reconstruction with autologous tissue--our clinical experience

INTRODUCTION

Breast reconstruction after mastectomy gained new grounds since the introduction of autologous tissue and oncoplastic surgery techniques. Nowadays large postoperative breast defects can be treated with high quality tissues obtained by autogenous flap surgery, to achieve the best functional and physical results.

OBJECTIVES

The purpose of this study is to analyze our results in breast reconstruction using autologous tissue and to emphasize the importance of a multidisciplinary team.

MATERIAL AND METHODS

During a five year period (2005-2009) we performed 28 breast reconstructions after cancer surgery, 15 in delayed and 13 in primary reconstruction, using three types of flaps: latissiumus dorsi flap, transverse rectus abdominis myocutaneous flap and deep inferior epigastric artery perforator flap.

RESULTS

Functional and cosmetic results were very good, only minor complications such as seroma and hematoma of the donor site and partial/marginal flap necrosis occurred after the surgical procedure. There were no major complications like total flap loss.

CONCLUSIONS

Breast reconstruction with autologous tissue is a safe, well proved, although not easy procedure that confers best functional and cosmetic results and is at the same time oncologically safe.

Provenance of the Greater Himalayan Sequence and associated rocks: predictions of channel flow models

Numerical models for channel flow in the Himalayan—Tibetan system are compatible with many tectonic and metamorphic features of the orogen. Here we compare the provenance of crustal material in two channel flow models (HT1 and HT111) with observations from the Himalaya and southern Tibet. Thirty million years after the onset of channel flow, the entire model crust south of the India—Asia suture still consists only of ‘Indian’ material. The model Greater Himalayan Sequence (‘GHS’) is derived from Indian middle crust originating ≤1000 km south of the initial position of the suture, whereas the Lesser Himalayan Sequence (‘LHS’) is derived mainly from crust originating ≥1400 km south of the suture. Material tracking indicates little or no mixing of diverse crustal elements in the exhumed region of the model ‘GHS’, which is derived from originally contiguous materials that are transported together in the top of the channel flow zone. These results are compatible with provenance data indicating a clear distinction between GHS and LHS protoliths, with the GHS originating from a more distal position (relative to cratonic India) than the LHS. In model HT111, domes formed between the suture and the orogenic front are cored by ‘Indian’ middle crust similar to the ‘GHS’, consistent with data from the north Himalayan gneiss domes. Material tracking shows that plutons generated south of the suture should have ‘Indian’ crustal signatures, also compatible with observations. Model ‘GHS’ pressure—temperature—time (P-T-t) paths pass through the dehydration melting field between 30 and 15 Ma, consistent with observed leucogranite ages. Finally, exposure of midcrustal ‘GHS’ and ‘LHS’ material at the model erosion front is consistent with the observed appearance of sedimentary detritus in the Lesser Himalaya. We conclude that channel flow model results are compatible with provenance data from the Himalaya and southern Tibet.

Channel flow, ductile extrusion and exhumation in continental collision zones: an introduction

The channel flow model aims to explain features common to metamorphic hinterlands of some collisional orogens, notably along the Himalaya-Tibet system. Channel flow describes a protracted flow of a weak, viscous crustal layer between relatively rigid yet deformable bounding crustal slabs. Once a critical low viscosity is attained (due to partial melting), the weak layer flows laterally due to a horizontal gradient in lithostatic pressure. In the Himalaya-Tibet system, this lithostatic pressure gradient is created by the high crustal thicknesses beneath the Tibetan Plateau and ‘normal’ crustal thickness in the foreland. Focused denudation can result in exhumation of the channel material within a narrow, nearly symmetric zone. If channel flow is operating at the same time as focused denudation, this can result in extrusion of the mid-crust between an upper normal-sense boundary and a lower thrust-sense boundary. The bounding shear zones of the extruding channel may have opposite shear sense; the sole shear zone is always a thrust, while the roof shear zone may display normal or thrust sense, depending on the relative velocity between the upper crust and the underlying extruding material. This introductory chapter addresses the historical, theoretical, geological and modelling aspects of channel flow, emphasizing its applicability to the Himalaya-Tibet orogen. Critical tests for channel flow in the Himalaya, and possible applications to other orogenic belts, are also presented.

Human alpha 2A-adrenergic receptor gene expressed in transgenic mouse adipose tissue under the control of its regulatory elements

Catecholamines regulate white adipose tissue function and development by acting through beta- and alpha2-adrenergic receptors (ARs). Human adipocytes express mainly alpha 2A- but few or no beta 3-ARs while the reverse is true for rodent adipocytes. Our aim was to generate a mouse model with a human-like alpha2/beta-adrenergic balance in adipose tissue by creating transgenic mice harbouring the human alpha 2A-AR gene under the control of its own regulatory elements in a combined mouse beta 3-AR-/- and human beta 3-AR+/+ background. Transgenic mice exhibit functional human alpha 2A-ARs only in white fat cells. Interestingly, as in humans, subcutaneous adipocytes expressed higher levels of alpha2-AR than perigonadal fat cells, which are associated with a better antilipolytic response to epinephrine. High-fat-diet-induced obesity was observed in transgenic mice in the absence of fat cell size modifications. In addition, analysis of gene expression related to lipid metabolism in isolated adipocytes suggested reduced lipid mobilization and no changes in lipid storage capacity of transgenic mice fed a high-fat diet. Finally, the development of adipose tissue in these mice was not associated with significant modifications of glucose and insulin blood levels. Thus, these transgenic mice constitute an original model of diet-induced obesity for in vivo physiological and pharmacological studies with respect to the alpha2/beta-AR balance in adipose tissue.

Dual action of octopamine on glucose transport into adipocytes: inhibition via beta3-adrenoceptor activation and stimulation via oxidation by amine oxidases

Octopamine, which is closely related to norepinephrine, acts as a neurotransmitter in invertebrates and is a trace amine with undefined properties in vertebrates. The octopaminergic receptors identified in insects are targets of various pesticides but are absent in vertebrates. We have established that octopamine stimulates fat cell lipolysis in mammals via activation of beta3-adrenoceptors (ARs), whereas this amine has been described elsewhere as an alpha2-AR agonist and as a substrate for monoamine oxidase (MAO) or semicarbazide-sensitive amine oxidase (SSAO). Because we have recently reported that amine oxidase substrates promote glucose transport in rat and human adipocytes, the in vitro octopamine effects on lipolysis and glucose uptake were reassessed by using adipocytes from beta3-AR-deficient mice. The lipolytic effect and the counter-regulation of insulin action on glucose transport provoked by 0.1 to 1 mM octopamine or by 1 microM beta3-AR agonists found in control animals disappeared in adipocytes from beta3-AR-deficient mice. This revealed an insulin-like effect of octopamine on glucose uptake, which was dependent on its oxidation by MAO or SSAO, as was the case for tyramine and benzylamine, devoid of beta3-adrenergic agonism. Similarly, octopamine promoted glucose transport in human adipocytes and exhibited a weaker lipolytic stimulation than in rodent adipocytes. These findings indicate that, besides its lipolytic activity, octopamine exerts, at millimolar dose, dual effect on glucose transport in adipocytes: counteracting insulin action via beta3-AR activation and stimulating basal transport via its oxidation by MAO or SSAO.

Uncoupling protein-2 negatively regulates insulin secretion and is a major link between obesity, beta cell dysfunction, and type 2 diabetes

beta cells sense glucose through its metabolism and the resulting increase in ATP, which subsequently stimulates insulin secretion. Uncoupling protein-2 (UCP2) mediates mitochondrial proton leak, decreasing ATP production. In the present study, we assessed UCP2's role in regulating insulin secretion. UCP2-deficient mice had higher islet ATP levels and increased glucose-stimulated insulin secretion, establishing that UCP2 negatively regulates insulin secretion. Of pathophysiologic significance, UCP2 was markedly upregulated in islets of ob/ob mice, a model of obesity-induced diabetes. Importantly, ob/ob mice lacking UCP2 had restored first-phase insulin secretion, increased serum insulin levels, and greatly decreased levels of glycemia. These results establish UCP2 as a key component of beta cell glucose sensing, and as a critical link between obesity, beta cell dysfunction, and type 2 diabetes.

Expression of human alpha 2-adrenergic receptors in adipose tissue of beta 3-adrenergic receptor-deficient mice promotes diet-induced obesity

Catecholamines play an important role in controlling white adipose tissue function and development. beta- and alpha 2-adrenergic receptors (ARs) couple positively and negatively, respectively, to adenylyl cyclase and are co-expressed in human adipocytes. Previous studies have demonstrated increased adipocyte alpha 2/beta-AR balance in obesity, and it has been proposed that increased alpha 2-ARs in adipose tissue with or without decreased beta-ARs may contribute mechanistically to the development of increased fat mass. To critically test this hypothesis, adipocyte alpha 2/beta-AR balance was genetically manipulated in mice. Human alpha 2A-ARs were transgenically expressed in the adipose tissue of mice that were either homozygous (-/-) or heterozygous (+/-) for a disrupted beta 3-AR allele. Mice expressing alpha 2-ARs in fat, in the absence of beta 3-ARs (beta 3-AR -/- background), developed high fat diet-induced obesity. Strikingly, this effect was due entirely to adipocyte hyperplasia and required the presence of alpha2-ARs, the absence of beta 3-ARs, and a high fat diet. Of note, obese alpha 2-transgenic beta 3 -/- mice failed to develop insulin resistance, which may reflect the fact that expanded fat mass was due to adipocyte hyperplasia and not adipocyte hypertrophy. In summary, we have demonstrated that increased alpha 2/beta-AR balance in adipocytes promotes obesity by stimulating adipocyte hyperplasia. This study also demonstrates one way in which two genes (alpha 2 and beta 3-AR) and diet interact to influence fat mass.

Energy metabolism in uncoupling protein 3 gene knockout mice

Uncoupling protein 3 (UCP3) is a member of the mitochondrial anion carrier superfamily. Based upon its high homology with UCP1 and its restricted tissue distribution to skeletal muscle and brown adipose tissue, UCP3 has been suggested to play important roles in regulating energy expenditure, body weight, and thermoregulation. Other postulated roles for UCP3 include regulation of fatty acid metabolism, adaptive responses to acute exercise and starvation, and prevention of reactive oxygen species (ROS) formation. To address these questions, we have generated mice lacking UCP3 (UCP3 knockout (KO) mice). Here, we provide evidence that skeletal muscle mitochondria lacking UCP3 are more coupled (i.e. increased state 3/state 4 ratio), indicating that UCP3 has uncoupling activity. In addition, production of ROS is increased in mitochondria lacking UCP3. This study demonstrates that UCP3 has uncoupling activity and that its absence may lead to increased production of ROS. Despite these effects on mitochondrial function, UCP3 does not seem to be required for body weight regulation, exercise tolerance, fatty acid oxidation, or cold-induced thermogenesis. The absence of such phenotypes in UCP3 KO mice could not be attributed to up-regulation of other UCP mRNAs. However, alternative compensatory mechanisms cannot be excluded. The consequence of increased mitochondrial coupling in UCP3 KO mice on metabolism and the possible role of yet unidentified compensatory mechanisms, remains to be determined.

Regulation of skeletal muscle UCP-2 and UCP-3 gene expression by exercise and denervation

The factors that regulate gene expression of uncoupling proteins 2 and 3 (UCP-2 and UCP-3) in skeletal muscle are poorly understood, but both genes are clearly responsive to the metabolic state of the organism. Therefore, we tested the hypothesis that denervation and acute and/or chronic exercise (factors that profoundly affect metabolism) would alter UCP-2 and UCP-3 gene expression. For the denervation studies, the sciatic nerve of rat and mouse hindlimb was sectioned in one leg while the contralateral limb served as control. Northern blot analysis revealed that denervation was associated with a 331% increase (P < 0.001) in UCP-3 mRNA and a 200% increase (P < 0. 01) in UCP-2 mRNA levels in rat mixed gastrocnemius (MG) muscle. In contrast, denervation caused a 53% decrease (P < 0.001) in UCP-3 and a 63% increase (P < 0.01) in UCP-2 mRNA levels in mouse MG. After acute exercise (2-h treadmill running), rat UCP-3 mRNA levels were elevated (vs. sedentary control) 252% (P < 0.0001) in white gastrocnemius and 63% (P < 0.05) in red gastrocnemius muscles, whereas UCP-2 levels were unaffected. To a lesser extent, elevations in UCP-3 mRNA (22%; P < 0.01) and UCP-2 mRNA (55%; P < 0.01) levels were observed after acute exercise in the mouse MG. There were no changes in either UCP-2 or UCP-3 mRNA levels after chronic exercise (9 wk of wheel running). These results indicate that acute exercise and denervation regulate gene expression of skeletal muscle UCPs.

Beta-3 adrenergic receptor agonists cause an increase in gastrointestinal transit time in wild-type mice, but not in mice lacking the beta-3 adrenergic receptor

The effects of beta-3 adrenergic receptor (beta3-AR) agonists on gastrointestinal (GI) motility, as reported by stomach retention and intestinal transit of radiolabelled charcoal, were compared in wild-type (WT) mice and in transgenic mice lacking beta3-AR (beta3-AR[KO]) or having beta3-AR in white and brown adipose tissue only (beta3-AR[WAT+BAT]). After s.c. administration of 3 mg/kg of the selective, rodent specific beta3-AR agonists BRL 35135, CL 316, 243 or ICI 198,157, WT mice exhibited a significant decrease in the extent of movement of radiotracer through the stomach and intestines, indicative of decreased GI motility. These compounds also caused an increase in plasma glycerol levels in the WT mice, suggesting that increased lipolysis in adipose tissue had been evoked. None of these compounds had an effect on GI motility or evoked lipolysis in the beta3-AR[KO] mice. Treatment of WT mice with SR 56811A, a beta3-AR agonist that exhibited a relatively lower affinity for rodent beta3-AR in vitro, did not affect GI motility or plasma glycerol levels in WT or beta3[KO] mice when administered s.c. at 3 mg/kg. Clonidine, an alpha-2 adrenergic receptor agonist, used as a positive control in these GI studies, caused a decrease in GI motility in both WT and beta3-AR[KO] mice. These results are consistent with a postulated role for beta3-AR in regulation of GI motility in the mouse. However, treatment of beta3-AR[WAT+BAT] mice with 3 mg/kg BRL 35135 resulted in elevated plasma glycerol levels, as well as increased stomach retention and decreased intestinal transit of radiotracer. These results suggest that this beta3-AR agonist may exert its effects on the GI tract indirectly, through an unknown signaling mechanism activated by agonism of beta3-AR in adipose tissue.

Differential regulation of uncoupling protein gene homologues in multiple tissues of hibernating ground squirrels

Nonshivering thermogenesis in brown adipose tissue (BAT) provides heat through activation of a mitochondrial uncoupling protein (UCP1), which causes futile electron transport cycles without the production of ATP. Recent discovery of two molecular homologues, UCP2, expressed in multiple tissues, and UCP3, expressed in muscle, has resulted in investigation of their roles in thermoregulatory physiology and energy balance. To determine the expression pattern of Ucp homologues in hibernating mammals, we compared relative mRNA levels of Ucp1, -2, and -3 in BAT, white adipose tissue (WAT), and skeletal muscle of arctic ground squirrels (Spermophilus parryii) hibernating at different ambient and body temperatures, with levels determined in tissues from ground squirrels not in hibernation. Here we report significant increases in mRNA levels for Ucp2 in WAT (1. 6-fold) and Ucp3 in skeletal muscle (3-fold) during hibernation. These results indicate the potential for a role of UCP2 and UCP3 in thermal homeostasis during hibernation and indicate that parallel mechanisms and multiple tissues could be important for nonshivering thermoregulation in mammals.

Mice expressing human but not murine beta3-adrenergic receptors under the control of human gene regulatory elements

Beta-adrenergic receptors (ARs) are expressed predominantly in adipose tissue, and beta3-selective agonists are effective anti-obesity drugs in rodents. Rodent and human beta3-ARs differ with respect to expression in white versus brown adipocytes as well as their ability to be stimulated by beta3-AR-selective agonists. Humans express beta3-AR mRNA abundantly in brown but not white adipocytes, while rodents express beta3-AR mRNA abundantly in both sites. To determine the basis for this difference, we have transgenically introduced 74 kilobases (kb) of human beta3-AR genomic sequence into gene knockout mice lacking beta3-ARs. Importantly, human beta3-AR mRNA was expressed only in brown adipose tissue (BAT) of transgenic mice, with little or no expression being detected in white adipose tissue (WAT), liver, stomach, small intestine, skeletal muscle, and heart. This pattern of expression differed from that observed in mice bearing a murine beta3-AR genomic transgene in which beta3-AR mRNA was expressed in both WAT and BAT, but not in other sites. Furthermore, we have transgenically introduced smaller human constructs containing -14.5 and -0.6 kb of upstream sequence into beta3-AR gene knockout mice. Both -14.5 and -0.6 kb constructs were expressed in BAT but not WAT. Thus, human but not murine cis-regulatory elements direct beta3-AR gene expression preferentially to brown adipocytes. Identification of responsible cis-regulatory element(s) and relevant trans-acting factor(s) should provide insight into mechanisms controlling human beta3-AR gene expression. In addition, the beta3-AR agonist, CGP-12177, stimulated oxygen consumption in mice expressing human but not murine beta3-ARs by 91% compared with only 49% in control beta3-AR gene knockout mice, demonstrating that the human beta3-AR can functionally couple with energy expenditure. These "humanized" mice should assist us in the development of drugs that may become effective anti-obesity agents in humans.

The human uncoupling protein-3 gene. Genomic structure, chromosomal localization, and genetic basis for short and long form transcripts

Uncoupling protein-3 (UCP3) is a recently identified candidate mediator of adaptive thermogenesis in humans. Unlike UCP1 and UCP2, UCP3 is expressed preferentially and at high levels in human skeletal muscle and exists as short and long form transcripts, UCP3S and UCP3L. UCP3S is predicted to encode a protein which lacks the last 37 C-terminal residues of UCP3L. In the present study, we have defined the intron-exon structure for the human UCP3 gene and determined that UCP3S is generated when a cleavage and polyadenylation signal (AATAAA) located in the last intron prematurely terminates message elongation. In addition we have mapped UCP3 to the distal segment of human chromosome 11q13 (between framework markers D11S916 and D11S911), adjacent to UCP2. Of note, UCP2 and UCP3 in both mice and humans colocalize in P1 and BAC genomic clones indicating that these two UCPs are located within 75-150 kilobases of each other and most likely resulted from a gene duplication event. Previous studies have noted that mouse UCP2 maps to a region of chromosome 7 which is coincident with three independently mapped quantitative trait loci for obesity. Our study shows that UCP3 is also coincident with these quantitative trait loci raising the possibility that abnormalities in UCP3 are responsible for obesity in these models.

Beta3-adrenergic receptors on white and brown adipocytes mediate beta3-selective agonist-induced effects on energy expenditure, insulin secretion, and food intake. A study using transgenic and gene knockout mice

beta3-Adrenergic receptors (beta3-ARs) are expressed predominantly on white and brown adipocytes, and acute treatment of mice with CL 316,243, a potent and highly selective beta3-AR agonist, produces a 2-fold increase in energy expenditure, a 50-100-fold increase in insulin levels, and a 40-50% reduction in food intake. Recently, we generated gene knockout mice lacking functional beta3-ARs and demonstrated that each of these responses were mediated exclusively by beta3-ARs. However, the tissue site responsible for producing these actions is unknown. In the present study, genetically engineered mice were created in which beta3-ARs are expressed exclusively in white and brown adipocytes (WAT+BAT-mice), or in brown adipocytes only (BAT-mice). This was accomplished by injecting tissue-specific beta3-AR transgenic constructs into mouse zygotes homozygous for the beta3-AR knockout allele. Control, knockout, WAT+BAT, and BAT-mice were then treated acutely with CL, and the effects on various parameters were assessed. As previously observed, all effects of CL were completely absent in gene knockout mice lacking beta3-ARs. The effects on O2 consumption, insulin secretion, and food intake were completely rescued with transgenic re-expression of beta3-ARs in white and brown adipocytes (WAT+BAT-mice), demonstrating that each of these responses is mediated exclusively by beta3-ARs in white and/or brown adipocytes, and that beta3-ARs in other tissue sites were not required. Importantly, transgenic re-expression of beta3-ARs in brown adipocytes only (BAT-mice) failed to rescue, in any way, CL-mediated effects on insulin levels and food intake and only minimally restored effects on oxygen consumption, indicating that any effect on insulin secretion and food intake, and a full stimulation of oxygen consumption required the presence of beta3-ARs in white adipocytes. The mechanisms by which beta3-AR agonist stimulation of white adipocytes produces these responses are unknown but may involve novel mediators not previously known to effect these processes.

UCP3: an uncoupling protein homologue expressed preferentially and abundantly in skeletal muscle and brown adipose tissue

Uncoupling proteins (UCPs) are inner mitochondrial membrane transporters which dissipate the proton gradient, releasing stored energy as heat. UCP1 is expressed exclusively in brown adipocytes while UCP2 is expressed widely. We now report the molecular cloning of a third uncoupling protein homologue, designated UCP3. At the amino acid level, hUCP3 is 71% identical to hUCP2 and 57% identical to hUCP1. UCP3 is distinguished from UCP1 and UCP2 by its abundant and preferential expression in skeletal muscle in humans, and brown adipose tissue and skeletal muscle in rodents. Since skeletal muscle and brown adipose tissue are believed to be important sites for regulated energy expenditure in humans and rodents, respectively, UCP3 may be an important mediator of adaptive thermogenesis. Since UCP3 is minimally expressed in human heart and other critical organs, it is a promising target for anti-obesity drug development aimed at increasing thermogenesis.

Discovering distinct genes represented in 29,570 clones from infant brain cDNA libraries by applying sequencing by hybridization methodology

To discover all distinct human genes and to determine their patterns of expression across different cell types, developmental stages, and physiological conditions, a procedure is needed for fast, mutual comparison of hundreds of thousands (and perhaps millions) of clones from cDNA libraries, as well as their comparison against data bases of sequenced DNA. In a pilot study, 29,570 clones in duplicate from both original and normalized, directional, infant brain cDNA libraries were hybridized with 107-215 heptamer oligonucleotide probes to obtain oligonucleotide sequence signatures (OSSs). The OSSs were compared and clustered based on mutual similarity into 16,741 clusters, each corresponding to a distinct cDNA. A number of distinct cDNAs were successfully recognized by matching their 107-probe OSSs against GenBank entries, indicating the possibility of sequence recognition with only a few hundred randomly chosen oligomers.