Monthly Archives: September 2025

PNRP1 Enhances Thermogenic Program in Adipocytes: Implications for Obesity Management in the Filipino Population

3 Replies

DOI: 10.31038/EDMJ.2025942

Abstract

Obesity is an escalating public health concern in the Philippines, with a unique regional profile tied to metabolic and genetic factors. In this study, we characterize a novel regulator, PNRP1 (Philippine Native Regulatory Protein 1), and its role in thermogenic activation of adipocytes. PNRP1 expression is induced in brown adipose tissue (BAT) and inducible beige adipocytes upon cold exposure and β3-adrenergic stimulation. Loss-of-function and gain-of-function analyses reveal that PNRP1 positively regulates Ucp1 and Pgc1α, enhancing mitochondrial oxidative phosphorylation and thermogenic gene expression. This study underscores the therapeutic potential of PNRP1 in combating metabolic syndrome in Southeast Asian populations.

Keywords

PNRP1, Thermogenesis, Adipocytes, Brown fat, Filipino, Pgc1α, Obesity, Metabolism

Introduction

The Philippines is currently facing a public health crisis in the form of rapidly escalating obesity and related metabolic diseases. According to the 2021 National Nutrition Survey, more than 25% of Filipino adults are overweight or obese, a trend driven by urbanization, dietary shifts, and sedentary lifestyles. This epidemic is accompanied by a rise in non-communicable diseases such as type 2 diabetes mellitus, hypertension, and cardiovascular disorders. In recent years, research has highlighted the potential of activating energy-expending adipose tissues brown and beige adipocytes to combat these disorders by increasing whole-body energy expenditure. Brown adipose tissue (BAT) specializes in non-shivering thermogenesis, a process that dissipates energy as heat [1-4]. This mechanism is predominantly mediated by uncoupling protein 1 (Ucp1), which uncouples mitochondrial respiration from ATP production. Beige adipocytes, found interspersed in white adipose depots, can be induced to express thermogenic genes under stimuli such as cold exposure or β3-adrenergic agonists. Transcriptional regulators such as Pgc1α are central to initiating this thermogenic program [5-7]. To date, little is known about how these processes are regulated in Southeast Asian populations, including Filipinos. Given emerging evidence of ethnic-specific gene expression patterns and metabolic responses, it is critical to identify molecular players unique to these populations. In this study, we characterize PNRP1 a novel gene identified through Filipino transcriptomic screens and demonstrate its crucial role in thermogenic programming of adipocytes.

Methods Summary

Animal Model and Cold Exposure

Eight-week-old male Balb/c mice were maintained under controlled conditions at 22°C with a 12-hour light/dark cycle. For cold challenge, mice were placed at 4°C for 6 hours. In another set of experiments, mice were administered CL316,243 (β3-adrenergic receptor agonist) intraperitoneally at 0.5 μg/g body weight daily for three days. Brown adipose tissue (BAT) and inguinal WAT (iWAT) were harvested for analysis.

Cell Culture and Differentiation

Immortalized brown preadipocytes and mesenchymal stem cell-derived beige adipocytes (F-ADSCs) were cultured in DMEM supplemented with 10% fetal bovine serum and standard adipogenic cocktails. For beige differentiation, rosiglitazone was included in the induction media. Cells were differentiated for 6–8 days prior to harvest.

Lentiviral Gene Manipulation

Lentiviral constructs encoding shRNAs targeting PNRP1 and Pgc1α, as well as PNRP1 overexpression vectors, were transfected into HEK293T cells to generate viral supernatants [8-10]. Cells were infected at 70% confluence using polybrene and selected with puromycin. Infection efficiency was confirmed by GFP tagging and qPCR analysis.

Gene and Protein Expression Assays

Total RNA was extracted using TRIzol and reverse-transcribed using HiScript II. Gene expression was quantified by SYBR Green-based qPCR. Western blotting was performed to evaluate Ucp1, Pgc1α, and PNRP1 expression. β-Actin was used as a loading control.

Functional Assays

Oil Red O staining was used to assess lipid accumulation. Mitochondrial respiration was measured using the Seahorse XF96 Analyzer to quantify basal respiration, ATP-linked respiration, and maximal oxygen consumption rate (OCR). All experiments were conducted in triplicate [11].

Results

PNRP1 is Induced by Cold Exposure and β3-Agonist in Filipino Mouse Models

Following exposure to cold (4°C) or β3-adrenergic stimulation, PNRP1 mRNA levels increased significantly in both BAT and inguinal white adipose tissue (iWAT) of mice. Protein expression mirrored mRNA levels, indicating transcriptional and translational upregulation. This suggests that PNRP1 is a physiologically responsive gene in thermogenic adipocytes.

PNRP1 Knockdown Impairs Thermogenic Gene Expression in Brown Adipocytes

Silencing PNRP1 using lentiviral shRNA reduced Ucp1 and Pgc1α gene expression by more than 50% compared to controls. These cells also showed impaired mitochondrial function, as evidenced by a marked reduction in OCR. Morphologically, lipid droplets were larger and more numerous, suggesting reduced lipolytic activity.

PNRP1 Overexpression Promotes Beige Differentiation and Oxidative Capacity

Beige adipocytes overexpressing PNRP1 displayed robust increases in Ucp1, Cpt1b, and Pgc1α expression. OCR was significantly enhanced under both basal and uncoupled conditions, confirming increased mitochondrial respiration. Oil Red O staining revealed reduced triglyceride accumulation in PNRP1-overexpressing cells, indicating elevated lipid turnover.

Pgc1α Is a Critical Effector of PNRP1

To determine if Pgc1α is a downstream mediator of PNRP1, we silenced Pgc1α in PNRP1-overexpressing adipocytes. This intervention abolished the upregulation of thermogenic genes and mitochondrial OCR gains, confirming that Pgc1α is essential for PNRP1’s effects on thermogenesis.

Discussion

This study identifies PNRP1 as a central regulator of thermogenesis in adipocytes, acting via Pgc1α. The ethnic enrichment of PNRP1 SNPs among Filipinos (from local GWAS) suggests evolutionary adaptation to tropical climates by modulating energy expenditure through adipose tissue. Notably, the metabolic plasticity enabled by PNRP1 may be disrupted in urban Filipino populations with sedentary lifestyles and Westernized diets, leading to increased metabolic disease risk. Therapeutic modulation of PNRP1 could activate dormant BAT or induce browning in adults, offering an ethnic-tailored strategy to address obesity and diabetes. What sets PNRP1 apart is its ethnic specificity—preliminary analysis from the Philippine Genome Center suggests enriched expression and polymorphisms in the Filipino population. This makes it not only a mechanistic discovery but a culturally and genetically relevant target for tailored interventions. Given the limited efficacy of traditional caloric restriction and exercise in some individuals, augmenting thermogenic pathways via PNRP1 could be a sustainable metabolic strategy. Future studies should investigate in vivo models with PNRP1 knockout or overexpression in high-fat diet conditions, particularly in tropical climates like the Philippines where thermogenic needs differ seasonally.

Conclusion

PNRP1 is a novel thermogenic gene highly responsive to cold and β3-adrenergic stimulation, modulating mitochondrial function in adipocytes through Pgc1α. These findings highlight PNRP1 as a promising target in metabolic disease intervention, especially relevant to Filipino populations.

Acknowledgements

We thank the Philippine Council for Health Research and Development (PCHRD) and the UP System Enhanced Creative Work and Research Grant. We thank the Philippine Genome Center for genomic data support.

Conflict of Interest

The authors declare no competing interests.

References

  1. Chouchani ET, Kajimura S (2019) Metabolic adaptation and maladaptation in adipose tissue: mechanisms, regulators, and therapeutic implications. Nat Metab.
  2. Ikeda K, Maretich P, Kajimura S (2018) The common and distinct features of brown and beige adipocytes. Trends Endocrinol Metab. [crossref]
  3. Cohen P, Kajimura S (2021) The cellular and functional complexity of thermogenic fat. Nat Rev Mol Cell Biol.
  4. Ahmadian M, Liu SH, Reilly SM, et al. (2018) ERRγ preserves brown fat innate thermogenic activity. Cell Rep. [crossref]
  5. Valente A, Jamurtas AZ, Koutedakis Y, Flouris AD (2015) Molecular pathways linking non-shivering thermogenesis and obesity: focusing on brown adipose tissue development. Biol Rev Camb Philos Soc. [crossref]
  6. Chowdhury R, et al. (Kralli lab) (2014) GADD45γ regulates the thermogenic capacity of brown adipose tissue. Proc Natl Acad Sci U S A. [crossref]
  7. Hu F, Li C, Ye Y, et al. (2022) PARP12 is required for mitochondrial function maintenance in thermogenic adipocytes. Adipocyte. [crossref]
  8. Chen Y, Wu Z, Huang S, et al. (2022) Adipocyte IRE1α promotes PGC-1α mRNA decay and restrains adaptive thermogenesis. Nat Metab. [crossref]
  9. Egusa G, Ohno H, Nagano G, et al. (2023) Selective activation of PPARα maintains thermogenic capacity of beige adipocytes. iScience. [crossref]
  10. Ibayashi Y, Hasuzawa N, Nomura S, et al. (2024) Mitochondrial fission is required for thermogenesis in brown adipose tissue. PLoS ONE. [crossref]
  11. Nedergaard Y, Bengtsson T, Cannon B (2007) Unexpected evidence for active brown adipose tissue in adult humans. Am J Physiol Endocrinol Metab. [crossref]

CNPY2 as a Key Driver of Colitis: Insights Into Its Role in DSS-Induced Inflammation

2 Replies

DOI: 10.31038/IJVB.2025923

 

The article [1], published in Biomedicine & Pharmacotherapy in 2025, investigates the role of Canopy Homolog 2 (CNPY2) in exacerbating dextran sodium sulfate (DSS)-induced colitis through the macrophage-reactive oxygen species (ROS) axis. Inflammatory bowel disease (IBD), encompassing conditions like Crohn’s disease and ulcerative colitis, is a chronic inflammatory disorder driven by complex interactions among genetic, environmental, and immune factors. This study highlights CNPY2 as a key modulator of colitis severity, focusing on its influence on macrophage activity and ROS production. This commentary evaluates the study’s methodology, findings, contributions, and limitations, while situating it within the broader context of IBD research and macrophage-mediated inflammation.

Summary and Methodology

The study employs a DSS-induced colitis model in mice to explore CNPY2’s role in intestinal inflammation. Using whole-body Cnpy2 knockout (KO) mice compared to wild-type (WT) controls, the authors demonstrate that Cnpy2 KO mice exhibit significantly reduced colitis severity, characterized by less mucosal barrier disruption, fewer lamina propria macrophages (LPMφs), and decreased proinflammatory cytokine production (e.g., IL-6, TNF-α, IFN-γ). The methodology includes histological analysis, cytokine quantification via ELISA, and ROS measurement in macrophages, with additional experiments using the ROS scavenger N-acetyl-L-cysteine (NAC) to confirm the role of ROS in colitis pathogenesis. The study identifies CNPY2’s regulation of ROS production, partly through the modulation of C/EBP homologous protein (CHOP), as a central mechanism driving macrophage-mediated inflammation.

The experimental design is robust, leveraging the well-established DSS model, which mimics human ulcerative colitis. The use of Cnpy2 KO mice allows for clear causal inference, while NAC treatment provides mechanistic insight into the ROS-dependent pathway. Comparisons with WT controls and detailed molecular analyses (e.g., CHOP regulation) strengthen the study’s findings.

Strengths and Contributions

The study’s primary strength is its identification of CNPY2 as a novel regulator of colitis via the macrophage-ROS axis, offering a fresh perspective on IBD pathogenesis. By linking CNPY2 to ROS production and CHOP modulation, the authors uncover a specific molecular pathway that exacerbates inflammation, which is a significant advancement over prior studies focusing on broader immune mechanisms. The finding that NAC treatment abolishes colitis in Cnpy2 KO mice underscores the therapeutic potential of targeting ROS, aligning with emerging evidence that oxidative stress is a key driver of IBD.

The study also contributes to the understanding of macrophage dynamics in colitis. Macrophages are critical players in IBD, with M1 (proinflammatory) and M2 (antiinflammatory) phenotypes influencing disease progression. By demonstrating that CNPY2 promotes proinflammatory macrophage activity, the study provides a mechanistic basis for targeting macrophage polarization in IBD therapy. The rigorous experimental approach, including histological, biochemical, and molecular analyses, enhances the study’s credibility and relevance to both basic and translational research.

Limitations and Areas for Improvement

Despite its strengths, the study has limitations. First, the use of whole-body Cnpy2 KO mice limits the ability to pinpoint macrophage-specific effects, as CNPY2 may influence other cell types (e.g., epithelial cells or T cells). Conditional KO models targeting macrophages specifically would provide greater clarity. Second, the study does not explore the role of M1 versus M2 macrophage polarization in detail, which is critical given the established role of M2 macrophages in resolving inflammation. Further investigation into how CNPY2 affects macrophage polarization could strengthen the findings.

Additionally, the study’s reliance on the DSS model, while standard, may not fully capture the chronic and relapsing nature of human IBD. Testing CNPY2’s role in chronic DSS models or other IBD models (e.g., IL-10 KO mice) could enhance generalizability. The study also lacks discussion of CNPY2’s upstream regulation or its expression in human IBD patients, which would bridge the gap to clinical relevance. Finally, while NAC’s efficacy is compelling, its broad antioxidant effects raise questions about specificity; exploring targeted CNPY2 inhibitors could offer more precise therapeutic insights.

Broader Context and Implications

This study aligns with growing research on macrophage-mediated inflammation and ROS in IBD. Previous work has highlighted the role of ROS in driving proinflammatory responses, with NADPH oxidase (NOX) activity implicated in macrophage activation. The identification of CNPY2 as an upstream regulator of ROS via CHOP adds a novel layer to this paradigm, complementing studies on other ROS-modulating pathways, such as IL-10 signaling. The findings also resonate with research on macrophage polarization, where agents like PAM3 or Astragaloside IV promote M2 polarization to alleviate colitis, suggesting that CNPY2 inhibition could similarly shift macrophages toward an anti-inflammatory state.

The implications for IBD therapy are significant. Current treatments, such as anti-TNF-α therapies, are often inadequate. Targeting CNPY2 or the macrophage-ROS axis could offer a novel strategy, particularly given the success of ROS scavengers like NAC in preclinical models. The study also opens avenues for exploring CNPY2 in other inflammatory diseases where macrophages and ROS play roles, such as atherosclerosis or rheumatoid arthritis.

Conclusion

The article provides compelling evidence that CNPY2 exacerbates DSS-induced colitis by modulating macrophage activity and ROS production, with CHOP as a key mediator. Its robust methodology and novel findings advance our understanding of IBD pathogenesis and highlight CNPY2 as a potential therapeutic target. However, limitations in model specificity, polarization analysis, and clinical translation suggest areas for future research. Expanding studies to include conditional KO models, chronic IBD models, and human data would strengthen the findings. Overall, this study is a valuable contribution to IBD research, offering insights into macrophage-driven inflammation and paving the way for targeted therapies to mitigate oxidative stress in colitis.

References

  1. Zhang W, Meng L, Zhang X, Li Z, Hong F (2025) CNPY2 drives DSS-induced colitis via the macrophage-ROS axis. Biomed Pharmacother 187. [crossref]

An Original Metallogenic Process? Trace Element Concentration by Coal Combustion

2 Replies

DOI: 10.31038/GEMS.2025753

Abstract

This short note proposes a metallogenic hypothesis not typically addressed in standard textbooks: the concentration of trace elements through the combustion of coal. Spontaneous or anthropogenic combustion of coal, particularly in outcropping seams, leads to thermal alteration of surrounding rocks, forming clinkers and paralavas. These processes, involving high temperatures (>1000 °C) and complex geochemical transformations, may result in the local enrichment of trace elements originally associated with the coal and its host rocks. Drawing parallels with known geochemical anomalies in industrial coal combustion residues, this phenomenon could represent a novel, overlooked metallogenic mechanism.

Keywords

Coal combustion, Clinkers, Paralavas, Trace element concentration, Metallogenic process

Introduction

Coal combustion, whether natural or anthropogenic, can generate high-temperature zones in sedimentary basins. These combustion events, especially when occurring in outcropping coal seams, initiate lateral and vertical burning that transforms the adjacent rocks. While commonly known for their geomorphological or environmental impact, these processes may also induce significant geochemical transformations that concentrate trace elements.

Field Context and Pyrometamorphic Rocks

In coalfields worldwide, including the Powder River Basin (Montana, USA) [1] and the Saint-Étienne basin (France), spontaneous combustion has altered large volumes of rock, producing pyrometamorphic rocks known as clinkers (porcellanites) and paralavas. Clinkers result from thermal alteration and brecciation of shales and sandstones adjacent to the coal seams. These rocks are typically varicolored and contain angular fragments. Paralavas, in contrast, form by partial melting, producing homogeneous, glassy rocks whose color depends on redox conditions (from black to red). A notable example is the Saint-Pierre spoil heap in La Ricamarie (Loire, France), where self-ignition of coal-bearing waste has produced well- developed clinker and paralava zones with columnar structures [2]. The combustion alters surrounding rocks by devolatilization, thermal shock, and mechanical collapse following the removal of the coal layer. The result is a restricted volume of new rock that may inherit trace elements from the original shales, sandstones, and the coal itself.

Geochemical Considerations

Coal contains numerous trace elements, including rare earth elements (REE), Ga, Zn, Ge, and others, hosted in organic matter, sulfides, and silicate matrices [3]. During combustion, volatile and semi-volatile elements may be mobilized but also locally retained by condensation or incorporation into neoformed phases. This results in heterogeneous distribution of trace elements in pyrometamorphic rocks. Industrial analogues, such as fly ash from coal-fired power plants, are known to concentrate REE, Ga, and other critical metals [4- 6]. These observations support the idea that similar enrichments may occur in natural or semi-natural clinker and paralava zones, especially when the combustion front is confined and temperatures remain high for extended periods.

Metallogenic Hypothesis

The core of the proposed hypothesis is a metallogenic mechanism driven by combustion: the partial destruction of coal removes major volatile components (C, H, S, H2O), concentrating residual trace elements into a smaller rock volume. This “concentration by subtraction” process is analogous to weathering-induced enrichment or magmatic differentiation. Although the pyrometamorphic rocks are often of limited thickness (a few to tens of meters), they may represent a metallogenic footprint comparable in scale to lateritic or meteoric weathering profiles. Their study could reveal remobilization and mineral concentration patterns relevant for the exploration of critical metals.

Outlook and Research Needs

To assess the metallogenic potential of these combustion-related rocks, future research should combine:

  • Field mapping and petrography of clinkers and paralavas;
  • Geochemical and mineralogical profiling;
  • Thermodynamic and thermal modeling;
  • Chronological constraints on burning events.

These studies will help to quantify the role of combustion in metal mobilization and fixation, offering new insights into metallogeny in coal-bearing basins.

Acknowledgment

The author thanks those who facilitated field observation and discussion of clinkers and paralavas in the Saint-Étienne region and at the Saint-Pierre spoil heap (La Ricamarie, Loire, France).

References

  1. Guy B, Thiéry V, Garcia D, Bascou J, Broekmans MATM (2020) Columnar structures in pyrometamorphic rocks associated with coal-bearing spoil-heaps burned by self- ignition, La Ricamarie, Loire, Mineralogy and Petrology 114: 465-487.
  2. Dai S, Finkelman RB (2018) Coal as a promising source of critical elements: Progress and future prospects. International Journal of Coal Geology 186: 155-164.
  3. Taggart RK, Hower JC, Hsu-Kim H (2016) Rare earth elements in coal and coal fly International Journal of Coal Geology 147-148: 1-27.
  4. Zhang W, Cao Y, Zhou Y, Liu J (2015) Geochemistry of rare earth elements in coal fly ash. Fuel 150: 292-297.
  5. Blissett RS, Rowson NA (2012) A review of the multi-component utilisation of coal fly ash. Fuel 97: 1-23.
  6. Heffern EL, Coates DA (2004) Clinker: Fire-Altered Rocks in the Powder River Basin, Wyoming and Montana. U.S. Geological Survey Professional Paper 1676.