PRDM16 Protein Research Articles

High lipolytic capacity improves cold tolerance in red swamp crayfish (Procambarus clarkii)

Temperature is one of the most prevalent environmental factors that affects the growth and development of organisms. The survival of aquatic animals is closely related to the changes in temperature, low temperature could cause physiological damage even death. In this study, we revealed the regulatory mechanisms of low-temperature stimulation from the transcriptomics in the hepatopancreas of the red swamp crayfish, Procambarus clarkii. Transcriptome sequencing revealed that lipid metabolism pathways were significantly enriched at low temperature. Crayfish improved their cold tolerance by increasing expression levels of thermogenic gene prdm16 and uncoupling protein genes ucp4 and ucp5. Furthermore, lipid and triglyceride content increased significantly in cold-sensitive crayfish, which in turn increased the expression levels of proinflammatory factors (cox2 and tgfβr) and the amount of hepatopancreas bacteria. In addition, low-temperature stimulation could cause more severe damage to cold-sensitive crayfish spermatophores, accompanied by downregulated of spermatozoa viability-related genes such as alp and ldh. Estradiol 17β-dehydrogenase 8-like (17βde8) may contain a critical SNP site at exon 544, the bases of this site were “G” in cold-tolerant crayfish and “A” in cold-sensitive crayfish. Above all, our results reveal that lipid metabolism is the main factor affecting cold tolerance in crayfish and reveal the key loci for cold tolerance, providing a reference for cold tolerance breeding.

Overexpression of PRDM16 improves muscle function after rotator cuff tears

Muscle atrophy, fibrosis, and fatty infiltration are commonly seen in rotator cuff tears (RCTs), which are critical factors that directly determine the clinical outcomes for patients with this injury. Therefore, improving muscle quality after RCT is crucial in improving the clinical outcome of tendon repair. In recent years, it has been discovered that adults have functional beige/brown adipose tissue (BAT) that can secrete batokines to promote muscle growth. PRDM16, a PR-domain-containing protein, was discovered with the ability to determine the brown fat cell fate and stimulate its development. Thus, the goal of this study was to discover the role of PRDM16 in improving muscle function after massive tendon tears using a transgenic mouse model with an elevated level of PRDM16 expression. Transgenic aP2-driven PRDM16-overexpressing mice and C57BL/6J mice underwent unilateral supraspinatus (SS) tendon transection and suprascapular nerve transection (TTDN) as described previously (n=8 in each group). DigiGait was performed to evaluate forelimb function at 6 weeks post the TTDN injury. Bilateral SS muscles, interscapular brown fat, epididymal white fat, and inguinal beige fat were harvested for analysis. The expression of PRDM16 in adipose tissue was detected by Western blot. Masson Trichrome staining was conducted to evaluate the muscle fibrosis, and Oil Red O staining was used to determine the fat infiltration. Muscle fiber type was determined by major histocompatibility complex (MHC) expression via immunostaining. All data were presented in the form of mean±standard deviation. t test and 2-way analysis of variance was performed to determine a statistically significant difference between groups. Significance was considered when P<.05. Western blot data showed an increased expression of PRDM16 protein in both white and brown fat in PRDM16-overexpressing mice compared with wild-type (WT) mice. Even though PRDM16 overexpression had no effect on increasing muscle weight, it significantly improved the forelimbs function with longer brake, stance, and stride time and larger stride length and paw area in mice after RCT. Additionally, PRDM16-overexpressing mice showed no difference in the amount of fibrosis when compared to WT mice; however, they had a significantly reduced area of fatty infiltration. These mice also exhibited abundant MHC-IIx fiber percentage in the supraspinatus muscle after TTDN. Overexpression of PRDM16 significantly improved muscle function and reduced fatty infiltration after rotator cuff tears. Promoting BAT activity is beneficial in improving rotator cuff muscle quality and shoulder function after RCT.

Protein PRDM16 and its importance for adipose tissue (literature review)

Currently, in Russia and in the world, there is an increase in the proportion of overweight and obese people among the population, which contributes to an increase in the number of socially significant diseases. Obesity is associated with the predominance of the proportion of fat mass in the component composition of the body. Based on this, increased attention is paid to a comprehensive study of the functioning of all types of human adipose tissue, which is necessary for the further use of this knowledge in the fight against obesity. This article provides an overview of the literature data on the structure and properties of the PRDM16 gene, the features of its functioning in brown, white and beige adipose tissue. The influence of the PRDM16 gene on the activation of brown adipogenesis and the formation of beige adipocytes in white adipose tissue, which contribute to increased heat production of cells by means of non-contractile thermogenesis and improvement of metabolic parameters of the body, is considered. Data on the role of PRDM16 protein in the treatment of obesity, type 2 diabetes mellitus and other human diseases associated with it are analyzed. The results on the methods of effective activation of brown and beige adipocytes and the use of these methods in the treatment of obesity are presented.

Prdm16 mutation determines sex-specific cardiac metabolism and identifies two novel cardiac metabolic regulators.

Mutation of the PRDM16 gene causes human dilated and non-compaction cardiomyopathy. The PRDM16 protein is a transcriptional regulator that affects cardiac development via Tbx5 and Hand1, thus regulating myocardial structure. The biallelic inactivation of Prdm16 induces severe cardiac dysfunction with post-natal lethality and hypertrophy in mice. The early pathological events that occur upon Prdm16 inactivation have not been explored. This study performed in-depth pathophysiological and molecular analyses of male and female Prdm16csp1/wt mice that carry systemic, monoallelic Prdm16 gene inactivation. We systematically assessed early molecular changes through transcriptomics, proteomics, and metabolomics. Kinetic modelling of cardiac metabolism was performed in silico with CARDIOKIN. Prdm16csp1/wt mice are viable up to 8 months, develop hypoplastic hearts, and diminished systolic performance that is more pronounced in female mice. Prdm16csp1/wt cardiac tissue of both sexes showed reductions in metabolites associated with amino acid as well as glycerol metabolism, glycolysis, and the tricarboxylic acid cycle. Prdm16csp1/wt cardiac tissue revealed diminished glutathione (GSH) and increased inosine monophosphate (IMP) levels indicating oxidative stress and a dysregulated energetics, respectively. An accumulation of triacylglycerides exclusively in male Prdm16csp1/wt hearts suggests a sex-specific metabolic adaptation. Metabolic modelling using CARDIOKIN identified a reduction in fatty acid utilization in males as well as lower glucose utilization in female Prdm16csp1/wt cardiac tissue. On the level of transcripts and protein expression, Prdm16csp1/wt hearts demonstrate an up-regulation of pyridine nucleotide-disulphide oxidoreductase domain 2 (Pyroxd2) and the transcriptional regulator pre-B-cell leukaemia transcription factor interacting protein 1 (Pbxip1). The strongest concordant transcriptional up-regulation was detected for Prdm16 itself, probably through an autoregulatory mechanism. Monoallelic, global Prdm16 mutation diminishes cardiac performance in Prdm16csp1/wt mice. Metabolic alterations and transcriptional dysregulation in Prdm16csp1/wt affect cardiac tissue. Female Prdm16csp1/wt mice develop a more pronounced phenotype, indicating sexual dimorphism at this early pathological window. This study suggests that metabolic dysregulation is an early event in the PRDM16 associated cardiac pathology.

Irisin promotes the browning of white adipocytes tissue by AMPKα1 signaling pathway

The development of white adipose tissue (WAT) browning helps to protect animals from cold conditions and prevent obesity. AMPKα1 has been involved in the process of white adipocytes browning. Although Irisin plays a vital role in the browning of WAT, the detailed regulatory mechanism of Irisin inducing the browning of WAT remains unclear. Herein, we firstly investigated the potential roles of differentiation and Irisin in regulating the browning of 3T3-L1 cells. The results found that they could significantly increase the number of lipid droplets and upregulate the expression levels of UCP1, PGC-1α, PRDM16, and p-AMPKα1. Then we proved the effectiveness of the AMPKα1 signaling pathway in the process of Irisin inducing the browning of 3T3-L1 cells. Compared with si-NC, si-AMPKα1 not only decreased the number of Irisin-induced lipid droplets, but also attenuated the expression of Irisin-induced UCP1, PGC-1α, and PRDM16 protein and mRNA levels in 3T3-L1 cells. Furthermore, the results showed that Irisin increased the positive distribution of UCP1 and PGC-1α, and upregulated the expression of UCP1, PGC-1α, and PRDM16 at both protein and mRNA levels in WAT. Once siRNA treated mice, the facilitation of Irisin on UCP1 and PGC-1α in si-AMPKα1-injected mice was lower than that in si-NC-injected mice. Compared with si-NC, si-AMPKα1 significantly downregulated the expression of UCP1, PGC-1α, and PRDM16 in Irisin-injected mice. Taken together, our results demonstrate that Irisin activates the AMPKα1 pathway to promote the browning of WAT by upregulating the mRNA and protein levels of UCP1, PGC-1α, and PRDM16.

PRDM16, negatively regulated by miR-372-3p, suppresses cell proliferation and invasion in prostate cancer.

Prostate cancer (PCa) is one of the most prevalent malignant tumours. The alternation of microRNAs (miRNAs) expression is associated with prostate cancer progression, whereas its way to influence progression of prostate cancer remains elusive. The expression levels of PRDM16 mRNA and miR-372-3p in PCa cell lines were analysed using qRT-PCR. The protein expression of PRDM16 in PCa cell lines was also analysed using Western blot. CCK-8, wound healing and Transwell assays were applied to examine cell proliferation, migration, and invasion in prostate cancer cells, respectively. Dual-luciferase reporter assay was utilised to validate the interaction between miR-372-3p and PRDM16. In the present study, markedly decreased PRDM16 mRNA and protein expression levels were observed in prostate cancer cells. PRDM16 overexpression hampered cellular proliferation, migration, and invasion, while silencing PRDM16 had the opposite effect. Moreover, miR-372-3p could target the regulation expression of PRDM16. Rescue experiments demonstrated that upregulating miR-372-3p conspicuously restored the inhibitory effect of increased PRDM16 on cell proliferation, migration, and invasion in PCa. Overall, our study clarifies the biological role of miR-372-3p/PRDM16 axis in prostate cancer progression, which may be effective biomarkers for clinical treatment of prostate cancer.

Astragalus polysaccharide regulates brown adipocytes differentiation by miR-6911 targeting Prdm16.

Brown adipose tissue (BAT) is a specialized tissue in mammals related to thermogenesis. The Astragalus polysaccharide (APS) is the major natural active component of Astragalus membranaceus, which has been recognized as one of the most popular herbal medicines worldwide. The role and possible mechanisms of APS on brown adipocytes differentiation is not well defined. Here, we explored the effect of APS on the differentiation of brown adipocytes in C3H10T 1/2 cells. The results showed that APS promoted the differentiation of brown adipocytes and improved insulin sensitivity along with significant increases in the expression of brown adipogenic marker proteins (C/EBPα, C/EBPβ, and PPARγ), thermogenesis marker proteins (UCP1, PRDM16, and PGC-1α), and insulin sensitivity marker protein (GLUT4). Meanwhile, the results showed that the amount of the phosphorylation of insulin receptor substrate 1 (p-IRS1) and phospho-AKT (p-AKT) which are critical factors in the insulin signaling pathway was increased without changing the total amount of IRS and AKT. Furthermore, the results of RNA-seq showed that APS altered the expression profiles of various miRNAs, and among which the expression of miR-6911 as a universal regulatory factor was significantly decreased. Importantly, we found that miR-6911 regulated the differentiation of brown adipocytes by targeting PR domain-containing 16 (Prdm16). In addition, after transfection of miR-6911 mimics, compared with the control and inhibitor group, PRDM16 protein expression significantly decreased, which was accompanied by the decrease of PPARγ, UCP1, and PGC-1α. Collectively, our results indicated that APS regulated brown adipocytes differentiation in C3H10T 1/2 cells via miRNA-6911 targeting Prdm16.

Homeobox A5 and C10 genes modulate adaptation of brown adipose tissue during exercise training in juvenile rats.

What is the central question of this study? Exercise can stimulate brown adipose tissue (BAT) with subsequent increase in uncoupling protein 1 expression and mitochondrial biogenesis. In that case, do BAT-specific Hox genes modify BAT functioning and cause uncoupling protein expression changes due to exercise? What is the main finding and its importance? Exercise enhanced brown adipocyte markers, with significant upregulation of HoxA5 and downregulation of HoxC10 mRNA expression in rat BAT. HoxA5 and HoxC10 are thus likely to play distinct roles in exercise-induced changes in BAT markers during the early postnatal period. These findings provide new insight into the mechanisms underlying exercise-induced changes in BAT function. Brown adipose tissue (BAT) recruitment is involved in increased energy expenditure associated with cold exposure and exercise training. We explored whether exercise training induced changes in expression levels of brown adipocyte-selective factors and Homeobox (Hox) genes during the post-weaning growth period of male Wistar rats. Relative to total body weight, BAT weights alone were lower in exercise-trained (EX) rats compared to sedentary control (SED) rats. mRNA expression of HoxA5 was higher and that of HoxC10 was lower in EX rats than in SED rats, accompanied by both higher citrate synthase activity and protein expression levels for uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor (PPAR) α, and PPARγ-coactivator (PGC)-1α. HoxA5 knockdown with siRNA reduced the expression of PR-domain containing 16 (Prdm16), cell death-inducing DNA fragmentation factor-α-like effector A (Cidea) gene, type 2 deiodinase mRNA, and PRDM16 protein. Comparatively, HoxC10 knockdown with siRNA enhanced mRNA expression of Prdm16, Pparα and Pgc1α and protein expression of UCP1, PPARα and PGC1α in brown adipocytes. The stimulation of brown adipocytes with isoproterenol, a β-adrenoceptor agonist, caused a phenomenon similar to the effect of exercise training on the genes tested: upregulation of HoxA5 mRNA, downregulation of HoxC10 mRNA, and increased protein expression for UCP1 and PGC1α. Collectively, HoxA5 and HoxC10 may have unique functions that contribute to modulating the expression of BAT-selective markers in BAT of juvenile rats during exercise training. The study findings regarding activation and recruitment of BAT during exercise training have implications for anti-obesity management.

3'-Hydroxydaidzein Improves Obesity Through the Induced Browning of Beige Adipose and Modulation of Gut Microbiota in Mice with Obesity Induced by a High-Fat Diet.

Obesity is an important health issue nowadays. 3'-Hydroxydaidzein (OHD) is a metabolite of daidzein (DAI) that can be found in fermented soybean products, such as miso. DAI has been known to affect lipid accumulation, but the effect of OHD on lipid accumulation still needs to be investigated. In this study, we investigated the effects of OHD on mice with obesity induced by a high-fat diet (HFD). The results showed that mice treated with 0.1% OHD (HOHD) significantly reduced their body weight and inguinal fat without altering their food intake compared with the HFD group. The HOHD and DAI groups' hyperlipidemia were alleviated through decreased serum triacylglycerols and total cholesterol levels. The adipocyte sizes in inguinal fat were significantly smaller in the HOHD and DAI groups compared with the HFD group. Both the HOHD and DAI groups had increased PRDM16, C/EBP β, p-p38, SIRT1, PGC1 α, and UCP1 protein expression in their inguinal adipose tissue compared with the HFD group. Moreover, the OHD and DAI groups had significantly lower amounts of Lachnospira and GCA_900066225 compared with the HFD group. Collectively, OHD can ameliorate HFD-induced obesity in mice by stimulating the browning of the white adipose tissue and modulating gut microbiota.

The effect of TGFβ1 on thermogenic markers is dependent on the degree of adipocyte differentiation.

Transforming growth factor β (TGFβ) a multifunctional cytokine is known to regulate cell proliferation, differentiation, migration and survival. Although there is variable expression of modulators of TGFβ action during differentiation, a differential effect on fat cell metabolism at the different stages of adipocyte differentiation was unclear. In the present study, 3T3L1 cells were used as an in vitro model to study the effect of TGFβ on adipogenic and thermogenic markers at various stages of preadipocyte to mature adipocyte differentiation. As in our earlier studies on the effect of TGFβ on CEBP’s, we used a standard differentiation mix, and one with the addition of rosiglitazone. RhTGFβ1 was added to undifferentiated adipocytes (preadipocytes) and to adipocytes at day 0 (commitment stage) as well as day 10 (terminal differentiation). Cellular responses in terms of Pref1, PPARγ, TLE3, PGC1α, PRDM16, UCP1 and UCP2 mRNA levels and selected protein products, were determined. Increases in PPARγ, PRDM16, UCP1 and UCP2 mRNA and decreases in Pref1 are good indicators of successful differentiation. The early addition of rhTGFβ1 during commitment stage decreased PPARγ, PRDM16, TLE3, UCP1 and UCP2 mRNA and decreased PRDM16 protein consistent with our earlier report on the inhibition of CEBP’s by TGFβ and CCN2. The addition of rhTGFβ1 to mature adipocyte at day 10 increased UCP1 mRNA and increased PRDM16 and UCP1 proteins. In the present study, our results suggest that TGFβ1 added late enhances the thermogenic potential of mature cells and causes 3T3L1 cells to differentiate to resemble brown or beige rather than white adipose tissue.

Sirt1 Promotes a Thermogenic Gene Program in Bone Marrow Adipocytes: From Mice to (Wo)Men.

Bone marrow adipose tissue (MAT) is influenced by nutritional cues, and participates in whole body energy metabolism. To investigate the role of Sirtuin1 (Sirt1), a key player in metabolism, in MAT, marrow adiposity was evaluated in inbred 5-month-old 129/Sv Sirt1 haplo-insufficient (Sirt1Δ/+) and wild type (WT) mice. Decreased expression of the thermogenic genes: Prdm16, Pgc1α, Foxc2, Dio2, and β3AR was detected in whole tibiae derived from Sirt1Δ/+ compared to WT female mice. Similarly, decreased expression of Prdm16 and Pgc1α was observed in primary bone marrow mesenchymal stem cell (BM-MSC) cultures obtained from Sirt1Δ/+ compared to WT female mice, suggesting a cell autonomous effect of Sirt1 in BM-MSCs. In vitro, Sirt1 over-expression in the mesenchymal embryonic fibroblast stem cell line C3HT101/2 increased Pgc1α and Prdm16 protein level. Similarly, pharmacologic activation of Sirt1 by SRT3025 increased Foxc2, Pgc1α, Dio2, Tfam, and Cyc1 expression while inhibition of Sirt1 by EX527 down-regulated UCP1 in C3HT101/2 cells. Importantly, in human femoral BM-MSCs obtained from female patients undergoing hip operations for fracture or osteoarthritis, Sirt1 activation by SRT3025 increased PGC1α mRNA and protein level. Blocking sclerostin, an inhibitor of the WNT pathway and a Sirt1 target, by the monoclonal humanized antibody (Sc-AbII), stimulated β3AR, PRDM16, and UCP1 gene expression, and increased PGC1α protein level. These results show that Sirt1 stimulates a thermogenic gene program in marrow adipocytes in mice and humans via PGC1α activation and sclerostin inhibition. The implications of these findings to bone health, hematopoiesis and whole body energy metabolism remain to be investigated.

PO-026 Effects of Different Exercise on the Expression of White Fat Browning Proteins in Growing Rats

Objective The prevention of obesity in children and adolescents can reduce the risk of obesity and various chronic diseases in adulthood. In recent years, it has been found that inducing browning of white fat can regulate energy balance and inhibit fat accumulation .Exercise as a healthy intervention can regulate energy balance by affecting the browning of white fat. However, the effect of exercise on the browning of white fat during the critical period of growth and development is not yet known, and the effect of different exercise methods on the browning of different location of white fat is inconsistent. Therefore, this study intends to explore the effects of different exercise methods on the expression of browning-related proteins of peripheral white adipose tissue and browning-related genes of hypothalamus in growing rats through animal experiments, and to explore the relationship between them.&#x0D; Methods 30 Male, 3-week-old SD rats were randomly divided into three groups, C group: Control group (sedentary, n=10);MD group: moderate-intensity training group (MD group, n=10), and high-intensity intermittent training group (HIIT group, n=10). MD group exercise program: 60% VO2max exercise for 60 minutes, 5 times a week for a total of 4 weeks. HIIT group exercise program: 85% ~ 90% VO2max exercise 6min, 50% VO2max exercise interval 4min, repeated 6 times. 5 times a week for a total of 4 weeks. The exercise intensity was adjusted based on the maximal oxygen uptake measurement every 2 weeks. Three groups of rats were weighed once a week. After the experiment, anesthesia was performed with 10% chloral hydrate 50 mg/Kg (body weight) in the abdominal cavity to rapidly separate the hypothalamus、Perirenal and epididymal fat and put into liquid nitrogen and transfer these to -80°C refrigerator for testing. The expression of POMC, NPY, LEPR and GRP78 mRNA in hypothalamus was determined by RT-PCR. The expression of PRDM16 and UCP1 protein in perirenal white fat was measured by Western Blot.&#x0D; Results 1. The weight of the three groups of rats increased continuously within 4 weeks of exercise intervention. Compared with group C,the weight of group E and group H increased slowly from the second week (p&lt;.05). 2. The increase in absolute weight and relative weight of visceral fat in MD group and HIIT group was significantly lower than that in C group (p&lt;.01); the increase in absolute weight and relative weight of visceral fat in MD group was significantly lower than HIIT group(p&lt;.05).3. Compared with group C, the expression of PRDM16 protein in WAT of the kidneys in group MD was significantly increased (p&lt;.01), and the UCP1 protein expression was significantly increased (p&lt;.01). Compared with group C, there was no significant difference in PRDM16 and UCP1 protein expression in WAT of HIIT group (p&gt;.05). 4. Compared with group C, the expression of NPY mRNA in hypothalamus in group MD was significantly decreased,(p&lt;.01), POMC, LEPR, GRP78 mRNA expression had no significant difference (p&gt;.05); Compared with group C, there was no significant difference in the expression of hypothalamus POMC, NPY，LEPR and GRP78 mRNA in HIIT group (p&gt;.05). 5. There was a negative correlation between the expression of NPYmRNA in hypothalamus and the expression of PRDM16 protein in white fat(p&lt;.01).&#x0D; Conclusions Moderate-intensity exercise for 4 weeks in the growth and development period of rats can decrease NPY expression in hypothalamus of rats and induce white-to-brown phenomena in perirenal adipose tissue ,but not in HIIT.

Role of LncRNA ROR in Ad36-induced browning of human adipose-derived stem cells

Objective To investigate the role of LncRNA ROR in Ad36-induced browning of human adipose-derived stem cells(hADSC). Methods After hADSC was induced by cocktail and Ad36 for 2, 4, 6, and 8 days, Oil red O staining was performed for observing the adipogenic status. The mRNA expressions of LncRNA ROR, uncoupling protein 1(UCP1), and PRDM16 were detected by real- time PCR and the protein expressions of UCP1 and PRDM16 were detected by Western-blot. After LncRNA ROR was knocked down by siRNA, UCP1 and PRDM16 mRNA and protein expression levels in the process of Ad36-induced adipocyte differentiation were detected by real- time PCR and Western-blot. Results Oil red O staining showed that fat droplets in the cocktail-induced group were larger than those in the Ad36-induced group. Compared with the cocktail group, the mRNA expressions of LncRNA ROR, UCP1 and PRDM16, and the protein expressions of UCP1 and PRDM16 in Ad36 group were significantly increased(P<0.05). The mRNA and protein expressions of UCP1 and PRDM16 in LncRNA ROR knockdown group were significantly lower than those in control group(P<0.05). Conclusion In the process of Ad36-induced hADSC differentiation, the up-regulation of LncRNA ROR may stimulate UCP1 and PRDM16 expression, and thus promote the browning of hADSC. (Chin J Endocrinol Metab, 2018, 34: 318-324) Key words: Human adipose-derived stem cells; Browning; Cocktail; Ad36; Long noncoding RNA

Determining the Mechanism by which PRDM16 Maintains the Adult Small Intestinal Epithelium

The intestinal epithelium is a well‐organized tissue that undergoes continuous cell turnover, with most cells being replaced every 4–5 days. PRDM16 is a large zinc‐finger containing transcription factor that, in addition to its well‐studied role in brown/beige adipose, regulates maintenance of neuronal and hematopoietic stem cells. However, the role of PRDM16 in other tissues is not well understood. We find that acute global deletion of Prdm16 in adult mice causes death within ten days. The Prdm16‐deleted mice begin to lose weight and appear weak and lethargic, with visibly distended and pale intestines. Histological analysis shows that PRDM16 is selectively and highly expressed in the intestinal epithelium of the duodenum and jejunum. Apoptotic cells are prevalent in the crypt, particularly in the transit amplifying zone by 3 days after Prdm16 deletion. By 5 days after deletion, intestinal tissue appears disorganized, with an abnormal accumulation of secretory cells in the crypt that express markers of both the goblet and Paneth cell lineages, indicating defects in differentiation. Interestingly, we could detect no obvious defects in Notch signaling. We performed RNA‐seq on isolated crypts to identify candidate signaling pathways that change in the intestine shortly after global knockout of Prdm16. A striking upregulation of P53‐activated apoptotic genes occurs immediately following the disappearance of PRDM16 protein, as well as an induction of Type‐I Interferon signaling. Independent of this, we see marked downregulation of genes involved in metabolic pathways. Studying the effects of PRDM16 ex vivo, we find that enteroid culture recapitulates the phenotypes observed in vivo, with Prdm16 deletion causing induction of apoptosis and a failure of intestinal enteroids to form buds. Further, we show that shRNA mediated knockdown of Prdm16 is sufficient to block the formation of enteroids. Our phenotype is ameliorated but not fully rescued by additional deletion of p53 both in vivo and ex vivo. We are currently focusing on defects in mitochondrial function, which appear to be a second major driver of our intestinal phenotype.Support or Funding InformationNRSA NIDDK F32 DK105743‐03 Pilot Grant NIDDK P30‐DK050306This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

PRDM16 sustains white fat gene expression profile in human adipocytes in direct relation with insulin action

In the present study, we aimed to evaluate the possible role of PRDM16 in human adipocytes and in whole adipose tissue according to obesity and insulin sensitivity. PRDM16 knockdown (KD) had a dual behavior. While KD in preadipocytes led to enhanced gene expression markers of adipocyte differentiation, PRDM16 KD in fully differentiated adipocytes resulted in decreased adipogenic gene expression and insulin action. In line with KD in adipocytes, PRDM16 was positively associated with the expression of several genes involved in adipogenesis, insulin signaling, mitochondrial function and brown adipocyte-related markers in whole adipose tissue from two independent cohorts. PRDM16 was decreased in obese subjects in relation with the decrease of insulin sensitivity [HOMAIR (cohort 1) and M clamp value (cohort 2)]. Rosiglitazone (5 µmol/l) and metformin (5 mmol/l) led to increased PRDM16 mRNA and protein levels in isolated human adipocytes and in whole adipose tissue. In conclusion, PRDM16 might contribute to maintain adipose tissue “white fat” gene expression profile and systemic metabolic homeostasis.

Tyk2 and Stat3 Regulate Brown Adipose Tissue Differentiation and Obesity

Mice lacking the Jak tyrosine kinase member Tyk2 become progressively obese due to aberrant development of Myf5+ brown adipose tissue (BAT). Tyk2 RNA levels in BAT and skeletal muscle, which shares a common progenitor with BAT, are dramatically decreased in mice placed on a high-fat diet and in obese humans. Expression of Tyk2 or the constitutively active form of the transcription factor Stat3 (CAStat3) restores differentiation in Tyk2(-/-) brown preadipocytes. Furthermore, Tyk2(-/-) mice expressing CAStat3 transgene in BAT also show improved BAT development, normal levels of insulin, and significantly lower body weights. Stat3 binds to PRDM16, a master regulator of BAT differentiation, and enhances the stability of PRDM16 protein. These results define Tyk2 and Stat3 as critical determinants of brown fat lineage and suggest that altered levels of Tyk2 are associated with obesity in both rodents and humans.

PPARγ agonists Induce a White-to-Brown Fat Conversion through Stabilization of PRDM16 Protein

Brown adipose tissue dissipates energy through heat and functions as a defense against cold and obesity. PPARγ ligands have been shown to induce the browning of white adipocytes; however, the underlying mechanisms remain unclear. Here, we show that PPARγ ligands require full agonism to induce a brown fat gene program preferentially in subcutaneous white adipose. These effects require expression of PRDM16, a factor that controls the development of classical brown fat. Depletion of PRDM16 blunts the effects of the PPARγ agonist rosiglitazone on the induced brown fat gene program. Conversely, PRDM16 and rosiglitazone synergistically activate the brown fat gene program invivo. This synergy is tightly associated with an increased accumulation of PRDM16 protein, due in large measure to an increase in the half-life of the protein in agonist treated cells. Identifying compounds that stabilize PRDM16 protein may represent a plausible therapeutic pathway for the treatment of obesity and diabetes.

Identification by FISH of 4 novel partner loci of PRDM16 in myeloid malignancies

11037 Background: PRDM16 is a gene located on 1p36.32 that encodes for a zinc finger transcription factor and contains an N-terminal PR domain. It has been shown to be involved in the reciprocal translocation t(1;3)(p36;q21) and more rarely the t(1;21)(p36;q22) which both occur in myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML). These translocations result in the overexpression of a truncated version of the PRDM16 protein that lacks the PR domain. This overexpression might play an important role in the pathogenesis of MDS and AML in blocking myeloid differentiation. This raises the question whether PRDM16 is rearranged with other partner genes and whether its sequences play the most important role in the oncogenic process attributed to those translocations. Methods: We studied 35 myeloid malignancies, 12 lymphoid malignancies and 3 undifferentiated acute leukemias with 1p36 abnormalities by fluorescent in situ hybridization (FISH) with a bacterial artificial chromosomes (BAC) contig containing 50 BAC probes on 1p36. Results: In addition to the known t(1;3)(p36;q21) (11 cases) and t(1;21)(p36;q22) (1 case) involving RPN1 andAML1/RUNX1 respectively in myeloid malignancies, we specifically found PRDM16 to be rearranged in 4 additional translocations : a t(1;12)(p36;p13) in an AML-M4, a t(1;7)(p36;p12) in a MDS, an add(1)(p36) in an AML-M2 and a t(1;2)(p36;p12) in a relapsed AML-M4. We identified the respective candidate partner loci : TEL/ETV6, IKZF1, CDH4 and a non-coding unknown sequence. Conclusions: In our series of 50 cases of hematological malignancies with 1p36 abnormalities, PRDM16 was involved in about 45% of myeloid malignancies, and was never involved in lymphoid malignancies. PRDM16 is supposed to have similar oncogenic properties as MDS1/EVI-1(3q26), another gene encoding for a zinc finger protein and acting as a transcriptional regulatory factor with 2 isoforms. Interestingly, the shortest isoform of MDS/EVI-1, lacking the PR domain, is supposed to have an oncogenic effect due to its translocation-induced upregulation in AML. Further characterization of these new partner genes and functional studies should give us more insight into the pathogenesis of AML and MDS mediated by PRDM16, and the role of its partner genes. No significant financial relationships to disclose.

Brown adipose tissue: the molecular mechanism of its formation

The function of brown adipose tissue (BAT) is to oxidize fat and to dissipate the energy produced as heat, providing a source of heat to the organism. Preadipocytes are stimulated by expression of the PRDM16 gene to differentiate into BAT cells. The PRDM16 protein is greatly enriched in BAT and causes increased expression of mitochondrial genes and greater density of mitochondria. It increases expression of the uncoupling factor UCP1 and thereby causes a large stimulation of uncoupled respiration with resultant heat production, enhanced by cAMP. Recent evidence strongly supports the idea that the PRDM16 gene determines BAT identity.

Regulation of the brown and white fat gene programs through a PRDM16/CtBP transcriptional complex

Brown fat is a specialized tissue that can dissipate energy and counteract obesity through a pattern of gene expression that greatly increases mitochondrial content and uncoupled respiration. PRDM16 is a zinc-finger protein that controls brown fat determination by stimulating brown fat-selective gene expression, while suppressing the expression of genes selective for white fat cells. To determine the mechanisms regulating this switching of gene programs, we purified native PRDM16 protein complexes from fat cells. We show here that the PRDM16 transcriptional holocompex contains C-terminal-binding protein-1 (CtBP-1) and CtBP-2, and this direct interaction selectively mediates the repression of white fat genes. This repression occurs through recruiting a PRDM16/CtBP complex onto the promoters of white fat-specific genes such as resistin, and is abolished in the genetic absence of CtBP-1 and CtBP-2. In turn, recruitment of PPAR-gamma-coactivator-1alpha (PGC-1alpha) and PGC-1beta to the PRDM16 complex displaces CtBP, allowing this complex to powerfully activate brown fat genes, such as PGC-1alpha itself. These data show that the regulated docking of the CtBP proteins on PRDM16 controls the brown and white fat-selective gene programs.