Repeated Oral Administration of Flavan-3-ols Induces Browning in Mice Adipose Tissues through Sympathetic Nerve Activation

We previously found increases in uncoupling protein (Ucp)-1 transcription in brown adipose tissue (BAT) of mice following a single oral dose of flavan 3-ol (FL)s, a fraction of catechins and procyanidins. It was confirmed that these changes were totally reduced by co-treatment of adrenaline blockers. According to these previous results, FLs possibly activate sympathetic nervous system (SNS). In this study, we confirmed the marked increase in urinary catecholamine (CA) s projecting SNS activity following a single dose of 50 mg/kg FLs. In addition, we examined the impact of the repeated administration of 50 mg/kg FLs for 14 days on adipose tissues in mice. In BAT, FLs tended to increase the level of Ucp-1 along with significant increase of thermogenic transcriptome factors expressions, such as peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and PR domain-containing (PRDM)1. Expression of browning markers, CD137 and transmembrane protein (TMEM) 26, in addition to PGC-1α were increased in epididymal adipose (eWAT) by FLs. A multilocular morphology with cell size reduction was shown in the inguinal adipose (iWAT), together with increasing the level of Ucp-1 by FLs. These results exert that FLs induce browning in adipose, and this change is possibly produced by the activation of the SNS.

Combined deletion of PR-domain containing 16 (Prdm16) in cardiomyocyte and non-cardiomyocyte lineages results in spontaneous early-onset lethality and progressive left ventricular dysfunction in mice

Introduction PR-domain containing 16 (Prdm16) has an asymmetric expression pattern in the developing cardiovascular system, including ventricular myocardium, endocardium and arterial endothelial and smooth muscle cell (SMC) layers. Heterozygous PRDM16 mutations in humans have been linked with early-onset cardiomyopathy resulting in heart failure. Myocardial PRDM16-deficiency has been suggested as the culprit for this cardiomyopathy, however embryonic Prdm16 deletion in cardiomyocytes or their progenitors in mice only results in symptomatic cardiac defects upon metabolic stress or ageing. This suggests that Prdm16 loss in other cell types has an important co-contribution in the early heart phenotype seen in patients with causal PRDM16 variants. Purpose To investigate the adjuvant role of non-cardiomyocytes to the heart phenotype caused by Prdm16 deficiency, we used a conditional mouse model in which deletion of Prdm16 occurs in all cells expressing an Sm22-driven Cre recombinase which has a combined activity in cardiomyocyte and non-cardiomyocyte lineages in the heart, including SMCs and pericytes. Methods Mice carrying two Prdm16 alleles with a floxed exon 9 (Prdm16fl/fl) were intercrossed with the Sm22-Cre driver line. Offspring of Sm22Cre+; Prdm16fl/fl and Sm22Cre−; Prdm16fl/fl breeding pairs was monitored for Mendelian inheritance and for signs of (progressive) cardiac dysfunction by echocardiography at 5 and 16 weeks of age. Hearts were isolated and analyzed for RNA expression levels of cardiac stress markers Atrial and Brain Natriuretic Peptide (ANP and BNP) via quantitative RT-PCR and histologically for the appearance of fibrosis through Sirius red-staining. Results Genotyping at 5 weeks of age showed a loss of 60.4% of Sm22Cre+; Prdm16fl/fl offspring. Mice surviving at 5 weeks spontaneously developed signs of left ventricular diastolic and systolic dysfunction, the latter shown by a significantly reduced ejection fraction (EF; 37±3% vs. 61±3% in control Sm22Cre−; Prdm16fl/fl littermates). Cardiac expression levels of ANP and BNP were significantly increased (728-fold and 36-fold, respectively) in Sm22Cre+; Prdm16fl/fl mice which also showed perivascular fibrosis compared to control littermates. At 16 weeks of age, this aberrant cardiac phenotype further progressed (EF: 32±3% vs. 57±4%; ANP: 2,541-fold increase; BNP: 129-fold increase) and in addition to perivascular fibrosis, hearts also showed interstitial fibrosis (Sirius red+ area: 17±2% vs. 3.0±0.4% in control littermates). Conclusion Unlike recently reported mice with a Prdm16 deficiency in cardiomyocytes or their (precursor) lineages, mice with a combined loss of Prdm16 in the cardiomyocytes and certain non-cardiomyocyte lineages feature early mortality and (progressive) signs of severe heart failure. Therefore, Prdm16 expressed by non-cardiomyocytes is indispensable for proper cardiac function and its loss in these cell types co-determines the aberrant cardiac phenotype. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fonds voor Wetenschappelijk Onderzoek Strategic Basic Research pre-doctoral fellowship (1S25817N)KU Leuven Research Coordination grant (C14/19/095)

PRDM12 Is Transcriptionally Active and Required for Nociceptor Function Throughout Life

PR domain-containing member 12 (PRDM12) is a key developmental transcription factor in sensory neuronal specification and survival. Patients with rare deleterious variants in PRDM12 are born with congenital insensitivity to pain (CIP) due to the complete absence of a subtype of peripheral neurons that detect pain. In this paper, we report two additional CIP cases with a novel homozygous PRDM12 variant. To elucidate the function of PRDM12 during mammalian development and adulthood, we generated temporal and spatial conditional mouse models. We find that PRDM12 is expressed throughout the adult nervous system. We observed that loss of PRDM12 during mid-sensory neurogenesis but not in the adult leads to reduced survival. Comparing cellular biophysical nociceptive properties in developmental and adult-onset PRDM12 deletion mouse models, we find that PRDM12 is necessary for proper nociceptive responses throughout life. However, we find that PRDM12 regulates distinct age-dependent transcriptional programs. Together, our results implicate PRDM12 as a viable therapeutic target for specific pain therapies even in adults.

Repeated Oral Administration of Flavan-3-ols Induces Browning in Mice Adipose Tissues Through Sympathetic Nerve Activation

We previously found increases in uncoupling protein (Ucp)-1 transcription in brown adipose tissue (BAT) of mice following a single oral dose of flavan 3-ols (FL), a fraction of catechins and procyanidins. It was confirmed that these changes were totally reduced by co-treatment of adrenaline blockers. According to these previous results, FL possibly activates sympathetic nervous system (SNS). In this study, we confirmed the marked increase in urinary catecholamine (CA) s projecting SNS activity following a single dose of 50 mg/kg FL. In addition, we examined the impact of the repeated administration of 50 mg/kg FL for 14 days on adipose tissues in mice. In BAT, FL tended to increase the level of Ucp-1 along with thermogenic transcriptome factors, such as peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and PR domain-containing (PRDM)1. Transcription of browning markers, such as CD137 and transmembrane protein (TMEM) 26 in addition to PGC-1α were increased in epididymal adipose (eWAT) by FL. A multilocular morphology with cell size reduction was shown in the inguinal adipose (iWAT), together with increasing the level of Ucp-1 following administration of FL. These results suggest that FL produces browning in adipose through activation of the SNS.

Mucosal ribosomal stress-induced PRDM1 promotes chemoresistance via stemness regulation

The majorities of colorectal cancer (CRC) cases are sporadic in origin and a large proportion of etiologies are associated with environmental stress responses. In response to external and internal stress, the ribosome stands sentinel and stress-driven ribosomal dysfunction triggers the cellular decision pathways via transcriptional reprogramming. In the present study, PR domain zinc finger protein (PRDM) 1, a master transcriptional regulator, was found to be closely associated with ribosomal actions in patients with CRC and the murine models. Stress-driven ribosomal dysfunction enhanced PRDM1 levels in intestinal cancer cells, which contributed to their survival and enhanced cancer cell stemness against cancer treatment. Mechanistically, PRDM1 facilitated clustering modulation of insulin-like growth factor (IGF) receptor-associated genes, which supported cancer cell growth and stemness-linked features. Ribosomal dysfunction-responsive PRDM1 facilitated signaling remodeling for the survival of tumor progenitors, providing compelling evidence for the progression of sporadic CRC.

Recessive PRDM13 Mutations Result in Hypogonadotropic Hypogonadism and Cerebellar Hypoplasia

PRDM13 (PR Domain containing 13) is a putative chromatin modifier and transcriptional regulator that functions downstream of the transcription factor PTF1A. Here, we report a novel, recessive syndrome associated with PRDM13 mutation. Patients exhibited intellectual disability, ataxia with cerebellar hypoplasia, scoliosis and delayed puberty with hypogonadotropic hypogonadism (HH). We investigated the development of hypothalamic neurons and the cerebellum in mice homozygous for a Prdm13 mutant allele. Cerebellar hypoplasia was evident, but male gonadal development appeared unaffected in these mutants. As PTF1A has been linked to early GABAergic neuronal cell fate regulation in the spinal cord, we examined GABAergic neuron progenitor development in the hypothalamus and cerebellum. A significant reduction in the number of Kisspeptin neurons in the hypothalamus and PAX2+ progenitors emerging from the cerebellar ventricular zone was observed. The latter was accompanied by ectopic expression of the glutamatergic lineage marker TLX3. Together, these findings identify PRDM13 as a critical regulator of GABAergic cell fate during neurodevelopment, providing a mechanistic explanation for the co-occurrence of HH and cerebellar hypoplasia in this syndrome. To our knowledge, this is the first evidence linking disrupted regulation of Kiss1 neurons to CHH in humans.

Investigation of PRDM10 and PRDM13 Expression in Developing Mouse Embryos by an Optimized PACT-Based Embryo Clearing Method

Recent developments in tissue clearing methods have significantly advanced the three-dimensional analysis of biological structures in whole, intact tissue, providing a greater understanding of spatial relationships and biological circuits. Nonetheless, studies have reported issues with maintaining structural integrity and preventing tissue disintegration, limiting the wide application of these techniques to fragile tissues such as developing embryos. Here, we present an optimized passive tissue clearing technique (PACT)-based embryo clearing method, initial embedding PACT (IMPACT)-Basic, that improves tissue rigidity without compromising optical transparency. We also present IMPACT-Advance, which is specifically optimized for thin slices of mouse embryos past E13.5. We demonstrate proof-of-concept by investigating the expression of two relatively understudied PR domain (PRDM) proteins, PRDM10 and PRDM13, in intact cleared mouse embryos at various stages of development. We observed strong PRDM10 and PRDM13 expression in the developing nervous system and skeletal cartilage, suggesting a functional role for these proteins in these tissues throughout embryogenesis.

OsPRR37 Alternatively Promotes Heading Date Through Suppressing the Expression of Ghd7 in the Japonica Variety Zhonghua 11 under Natural Long-Day Conditions

Heading date is an important agronomic trait of rice (Oryza sativa L.) and is regulated by numerous genes, some of which exhibit functional divergence in a genetic background-dependent manner. Here, we identified a late heading date 7 (lhd7) mutant that flowered later than wild-type Zhonghua 11 (ZH11) under natural long-day (NLD) conditions. Map-based cloning facilitated by the MutMap strategy revealed that LHD7 was on the same locus as OsPRR37 but exhibited a novel function as a promoter of heading date. A single-nucleotide mutation of G-to-A in the coding region caused a substitution of aspartic acid for glycine at site 159 within the pseudo-receiver (PR) domain of OsPRR37. Transcriptional analysis revealed that OsPRR37 suppressed Ghd7 expression in both ZH11 background under NLD conditions and the Zhenshan 97 background under natural short-day conditions. Consistently, the expression of Ehd1, Hd3a and RFT1 was enhanced by OsPRR37 in the ZH11 background. Genetic analysis indicated that the promotion of heading date and reduction in grain yield by OsPRR37 were partially dependent on Ghd7. Further investigation showed that the alternative function of OsPRR37 required an intact Ghd7-related regulatory pathway involving not only its upstream regulators OsGI and PhyB but also its interacting partner Hd1. Our study revealed the distinct role of OsPRR37 in the ZH11 background, which provides a more comprehensive understanding of OsPRR37 function and enriches the theoretical bases for improvement of rice heading date in the future.

AMPKα1 regulates Idh2 transcription through H2B O-GlcNAcylation during brown adipogenesis

AMP-activated protein kinase (AMPK) is indispensable for the development and maintenance of brown adipose tissue (BAT), and its activity is inhibited due to obesity. The isocitrate dehydrogenase 2 (IDH2) is a mitochondrial enzyme responsible for the production of α-ketoglutarate, a key intermediate metabolite integrating multiple metabolic processes. We previously found that AMPKα1 ablation reduced cellular α-ketoglutarate concentration during brown adipocyte differentiation, but the effect of AMPKα1 on Idh2 expression remains undefined. In the present study, mouse C3H10T1/2 cells were transfected with Idh2-CRISPR/Cas9, and induced to brown adipogenesis. Our data suggested that brown adipogenesis was compromised due to IDH2 deficiency in vitro, which was accompanied by down-regulation of PR-domain containing 16. Importantly, the IDH2 content was reduced in brown stromal vascular cells (BSVs) separated from AMPKα1 knockout (KO) BAT, which was associated with lower contents of histone 2B (H2B) O-GlcNAcylation and monoubiquitination. Furthermore, both GlcNAcylated-H2B (S112) and ubiquityl-histone 2B (K120) contents in the Idh2 promoter were decreased in AMPKα1 KO BSVs. Meanwhile, ectopic O-linked N-acetylglucosamine transferase (OGT) expression was positively correlated with Idh2 expression, while OGT (T444A) mutation abolished the regulatory effect of AMPKα1 on Idh2. In vivo, reduced AMPKα1 activity and lower IDH2 abundance were observed in BAT of obese mice when compared with those in control mice. Taken together, our data demonstrated that IDH2 is necessary for brown adipogenesis and that AMPKα1 deficiency attenuates Idh2 expression, which might be by suppressing H2B O-GlcNAcylation modification.