The Role of Peptide Hormones Discovered in the 21st Century in the Regulation of Adipose Tissue Functions

mHPpred: Accurate identification of peptide hormones using multi-view feature learning

Peptide hormones were first used in medicine in the early 20th century, with the pivotal event being the isolation and purification of insulin in 1921. These hormones are integral to a sophisticated system that emerged early in evolution to regulate growth, development, and homeostasis. They serve as targeted signaling molecules that transfer specific information between cells and organs, ensuring coordinated and precise physiological responses. While experimental methods for identifying peptide hormones present challenges such as low abundance, stability issues, and complexity, computational methods offer promising alternatives. Advances in machine learning and bioinformatics have facilitated the prediction of peptide hormones, further enhancing their therapeutic potential. In this study, we explored three different computational frameworks for peptide hormone identification and determined that the meta-approach was the most suitable. Firstly, we evaluated the discriminative power of 26 feature descriptors using a series of baseline models and identified seven feature descriptors with high predictive potential. Through a systematic approach, we then selected the top 20 performing baseline models and integrated their predicted probabilities to train a meta-model, leveraging the strengths of multiple prediction strategies. Our final light gradient boosting-based meta-model, mHPpred, significantly outperformed the existing method, HOPPred, on both benchmarking and independent datasets. Notably, mHPpred also demonstrated superior performance compared to the hybrid and integrative framework approaches employed in this study. This superiority demonstrates the effectiveness of our multi-view feature learning strategy in capturing discriminative features and providing a more accurate prediction model for peptide hormones. mHPpred is publicly accessible at: https://balalab-skku.org/mHPpred.

Prediction of peptide hormones using an ensemble of machine learning and similarity-based methods

Peptide hormones serve as genome-encoded signal transduction molecules that play essential roles in multicellular organisms, and their dysregulation can lead to various health problems. In this study, we propose a method for predicting hormonal peptides with high accuracy. The dataset used for training, testing, and evaluating our models consisted of 1174 hormonal and 1174 non-hormonal peptide sequences. Initially, we developed similarity-based methods utilizing BLAST and MERCI software. Although these similarity-based methods provided a high probability of correct prediction, they had limitations, such as no hits or prediction of limited sequences. To overcome these limitations, we further developed machine and deep learning-based models. Our logistic regression-based model achieved a maximum AUROC of 0.93 with an accuracy of 86% on an independent/validation dataset. To harness the power of similarity-based and machine learning-based models, we developed an ensemble method that achieved an AUROC of 0.96 with an accuracy of 89.79% and a Matthews correlation coefficient (MCC) of 0.8 on the validation set. To facilitate researchers in predicting and designing hormone peptides, we developed a web-based server called HOPPred. This server offers a unique feature that allows the identification of hormone-associated motifs within hormone peptides. The server can be accessed at: https://webs.iiitd.edu.in/raghava/hoppred/.

Adropin Predicts Asymptomatic Heart Failure in Patients with Type 2 Diabetes Mellitus Independent of the Levels of Natriuretic Peptides

In patients with type 2 diabetes mellitus (T2DM), asymptomatic adverse cardiac remodeling plays a pivotal role in the development of heart failure (HF). Patients with T2DM often have low or near-normal levels of natriuretic peptides, including N-terminal brain natriuretic peptide (NT-proBNP), which have been inconclusive in predicting the transition from asymptomatic adverse cardiac remodeling to HF with preserved ejection fraction (HFpEF). The aim of this study was to elucidate the predictive ability of adropin for HFpEF depending on the circulating levels of NT-proBNP. We prospectively enrolled 561 T2DM patients (glycated hemoglobin < 6.9%) with echocardiographic evidence of structural cardiac abnormalities and left ventricular ejection fractions >50%. All patients underwent B-mode transthoracic echocardiographic and Doppler examinations. Circulating biomarkers, i.e., NT-proBNP and adropin, were assessed at baseline. All individuals were divided into two groups according to the presence of low levels (<125 pmol/mL; n = 162) or elevated levels (≥125 pmol/mL; n = 399) of NT-proBNP. Patients with known asymptomatic adverse cardiac remodeling and elevated NT-proBNP were classified as having asymptomatic HFpEF. A multivariate logistic regression showed that low serum levels of adropin (<3.5 ng/mL), its combination with any level of NT-proBNP, and use of SGLT2 inhibitors were independent predictors of HFpEF. However, low levels of adropin significantly increased the predictive ability of NT-proBNP for asymptomatic HFpEF in patients with T2DM, even though the concentrations of NT-proBNP were low, while adropin added discriminatory value to all concentrations of NT-proBNP. In conclusion, low levels of adropin significantly increase the predictive ability of NT-proBNP for asymptomatic HFpEF in patients with T2DM.

Potential relationships between apelin and metabolic-associated indices in transition dairy cows

Metabolic disorders pose significant challenges in transition dairy cows. Numerous parameters have been investigated in this context, and apelin has recently emerged as a potential metabolic indicator. Accordingly, this study aimed to assess the associations between this hormone and other metabolic parameters. Twenty-two adult Holstein-Friesian dairy cows, 21 days before their expected calving date, were selected for blood sampling and serum separation at four time points: 21 and 10 days before calving and 10 and 21 days after parturition. Serum concentrations of apelin, leptin, insulin, cortisol, T3, T4, non-esterified fatty acids, glucose, total protein, albumin, globulin, aspartate aminotransferase, alanine transaminase, triglycerides, cholesterol, high, low and very low-density lipoproteins, total, direct and indirect bilirubin were measured in these samples. Surrogate indices for insulin resistance, body condition score, and milk production were also evaluated. Throughout the transition period, a significant increase in apelin levels was observed. Various models were employed to identify associations between apelin and the studied metabolic parameters. Notably, significant correlations between apelin and Leptin, Insulin, Cortisol, T3, T4, NEFA, Cholesterol, LDL, VLDL, Total Protein, Albumin, Globulin, Total Bilirubin, Direct Bilirubin and Indirect Bilirubin were observed, with some being immediate while others developed over time. These findings indicate a mutual influence between apelin and specific metabolic indices. Changes in any component of the metabolic profile at one stage can lead to alterations in apelin levels in subsequent stages. The correlations uncovered between apelin and other components of the metabolic profile in transitioning dairy cows offer valuable insights, contributing to a better understanding of the potential effects of apelin on the studied indicators and vice versa.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

Comprehensive expression analysis of hormone-like substances in the subcutaneous adipose tissue of the common bottlenose dolphin Tursiops truncatus

Marine mammals possess a specific subcutaneous fat layer called blubber that not only insulates and stores energy but also secretes bioactive substances. However, our understanding of its role as a secretory organ in cetaceans is incomplete. To exhaustively explore the hormone-like substances produced in dolphin subcutaneous adipose tissue, we performed seasonal blubber biopsies from captive female common bottlenose dolphins (Tursiops truncatus; N = 8, n = 32) and analyzed gene expression via transcriptomics. Analysis of 186 hormone-like substances revealed the expression of 58 substances involved in regulating energy metabolism, tissue growth/differentiation, vascular regulation, immunity, and ion/mineral homeostasis. Adiponectin was the most abundantly expressed gene, followed by angiopoietin protein like 4 and insulin-like growth factor 2. To investigate the endocrine/secretory responses of subcutaneous adipose tissue to the surrounding temperature, we subsequently compared the mean expression levels of the genes during the colder and warmer seasons. In the colder season, molecules associated with appetite suppression, vasodilation, and tissue proliferation were relatively highly expressed. In contrast, warmer seasons enhanced the expression of substances involved in tissue remodeling, immunity, metabolism, and vasoconstriction. These findings suggest that dolphin blubber may function as an active secretory organ involved in the regulation of metabolism, appetite, and tissue reorganization in response to changes in the surrounding environment, providing a basis for elucidating the function of hormone-like substances in group-specific evolved subcutaneous adipose tissue.

The Levels of Phoenixin-14 and Phoenixin-20 in Patients with Type 2 Diabetes Mellitus

BACKGROUND

New pathogenesis-related early detection markers are needed to prevent Type 2 Diabetes Mellitus (T2DM).

OBJECTIVE

We aimed to determine phoenixin (PNX)-14 and PNX-20 levels in T2DM patients and investigate their relationship with diabetes.

METHODS

36 T2DM patients and 36 healthy controls were included in the study, and PNX-14 and PNX-20 levels in blood samples taken from the groups were measured by ELISA method.

RESULTS

Patients' serum PNX-14 and PNX-20 levels were statistically significantly lower than in controls (p <0.001). A negative correlation was detected between PNX-14 and BMI, fasting blood sugar, HbA1c%, and HOMA-IR. A negative correlation was found between PNX-20 and BMI, fasting insulin and glucose, HbA1c%, and HO-MA-IR. A positive correlation was noticed between PNX-14 and PNX-20 levels. In ROC analyses, PNX-14 and PNX-20 performed almost equally in predicting T2DM. In predicting T2DM, the area under the ROC curve for PNX-14 was 0.874 (cutoff value 413.4 ng/L, sensitivity 89 %, specificity 72%), and for PNX-20 was 0.858 (cutoff value 228.7 ng/L, sensitivity 80 %, specificity 83 %).

CONCLUSION

This study shows that serum PNX measurement may have a high level of evidence in predicting T2DM. PNX, related to pathogenesis, may be useful in diagnosing T2DM and other information to support clinical decision-making.

Special Issue: Lipid Metabolism, Adipogenesis and Fat Tissue Metabolism: Gene Regulation

Lipid metabolism is pivotal in controlling energy homeostasis [...].

Deorphanizing Peptides Using Structure Prediction

Many endogenous peptides rely on signaling pathways to exert their function, but identifying their cognate receptors remains a challenging problem. We investigate the use of AlphaFold-Multimer complex structure prediction together with transmembrane topology prediction for peptide deorphanization. We find that AlphaFold's confidence metrics have strong performance for prioritizing true peptide-receptor interactions. In a library of 1112 human receptors, the method ranks true receptors in the top percentile on average for 11 benchmark peptide-receptor pairs.

Protective Effect of N-Acetylcysteine Against Aluminum-Induced Kidney Tissue Damage in Rats

Aluminum (AL) is an important nephrotoxic agent with a high daily exposure rate and property of accumulation in tissues. This study aimed to investigate the potential protective efficacy of N-acetylcysteine (NAC) against AL exposure-induced nephrotoxicity in rats. Twenty-eight rats were randomly divided into 4 groups as control, N-acetylcysteine group (NC), AL, and AL + NC, with an equal number of rats in each group (n = 7). No application was made to the control group. A total of 150 mg/kg/day NAC was administered to the NC group and 30 mg/kg/day AL was administered to the AL group intraperitoneally (i.p.). The AL + NC group received 30 mg/kg/day AL and 150 mg/kg/day NAC i.p. Biochemical parameters in blood serum and histopathological changes in kidney tissue, oxidative stress parameters, spexin (SPX), and apoptotic protein levels were examined after 15 days. Histopathological changes, biochemical parameters, oxidative stress parameters, and apoptotic protein levels were significantly irregular in the AL group compared to the control group. Moreover, SPX levels increased in the AL group. However, NAC treatment regulated AL exposure-related changes in the AL + NC group. NAC treatment may have a prophylactic effect against nephrotoxicity due to AL exposure. SPX may play a role in AL-induced nephrotoxicity.

Neuropeptide B promotes differentiation of rodent white preadipocytes into mature adipocytes

Neuropeptide B (NPB) modulates energy homeostasis and metabolism through activation of NPBWR1 and NPBWR2 in humans and NPBWR1 in rodents. Recently, we reported that NPB promotes adipogenesis in rat brown preadipocytes. In the present study, we evaluated the effects of NPB on proliferation and differentiation into mature adipocytes of white rat preadipocytes and 3T3-L1 cells. We found the expression of NPBWR1 and NPB on mRNA and protein level in rat white preadipocytes and 3T3-L1 cells. NPB increased expression of mRNA and protein production of adipogenic genes (PPARγ, C/EBPβ, CEBPα and FABP4) in rat preadipocytes and 3T3-L1 cells during the differentiation process. Furthermore, NPB stimulated lipid accumulation in rat preadipocytes and 3T3-L1 cells. In addition, we found that NPB promotes phosphorylation of p38 kinase in rat preadipocytes and 3T3-L1 cells. NPB failed to stimulate expression of proadipogenic genes in the presence of p38 inhibitor. NPB failed to modulate viability and proliferation of rat preadipocytes and 3T3-L1 cells. Taken together, we report that NPB promotes differentiation of rodent preadipocytes via p38-dependent mechanism. NPB does not modulate viability and proliferation of rat preadipocytes and 3T3-L1 cells.

The Emerging Role of Epigenetics in Metabolism and Endocrinology

Each cell in a multicellular organism has its own phenotype despite sharing the same genome. Epigenetics is a somatic, heritable pattern of gene expression or cellular phenotype mediated by structural changes in chromatin that occur without altering the DNA sequence. Epigenetic modification is an important factor in determining the level and timing of gene expression in response to endogenous and exogenous stimuli. There is also growing evidence concerning the interaction between epigenetics and metabolism. Accordingly, several enzymes that consume vital metabolites as substrates or cofactors are used during the catalysis of epigenetic modification. Therefore, altered metabolism might lead to diseases and pathogenesis, including endocrine disorders and cancer. In addition, it has been demonstrated that epigenetic modification influences the endocrine system and immune response-related pathways. In this regard, epigenetic modification may impact the levels of hormones that are important in regulating growth, development, reproduction, energy balance, and metabolism. Altering the function of the endocrine system has negative health consequences. Furthermore, endocrine disruptors (EDC) have a significant impact on the endocrine system, causing the abnormal functioning of hormones and their receptors, resulting in various diseases and disorders. Overall, this review focuses on the impact of epigenetics on the endocrine system and its interaction with metabolism.

Cord Blood Levels of Spexin, Leptin, and Visfatin in Term Infants Born Small, Appropriate, and Large for Gestational Age and Their Association with Newborn Anthropometric Measurements

OBJECTIVE

Children born small for gestational age (SGA) are at risk of future obesity and associated comorbidities. Therefore the identification of risk factors and novel biomarkers which are associated with this risk are needed for early detection and to improve preventive strategies. Spexin (SPX), a novel neuropeptide that is involved in the regulation of obesity and fat metabolism, is a candidate biomarker for predicting obesity and related comorbidities at an early age. The aim of this study was to investigate serum levels of SPX in term infants born small, appropriate, and large for gestational age (LGA) and its association with newborn anthropometric measurements.

METHODS

One hundred and twenty term newborn babies classified as SGA, appropriate for gestational age (AGA), or LGA and their mothers were included. SPX, leptin and visfatin were measured in cord blood and maternal serum by enzyme-linked immunosorbent assay.

RESULTS

Fifty-six (46.7%) neonates were girls and 64 (53.3%) were boys. The mean birth weight was 3170.70±663 g, birth length was 48.9±2.79 cm, and head circumference was 34.5±1.67 cm. Birth weights, lengths, and head circumferences of the neonates in the SGA, AGA, and LGA groups were significantly different. Cord blood SPX and leptin levels in the SGA groups were significantly lower than those of both the LGA and AGA groups. Cord blood visfatin levels were significantly lower in the AGA group than the LGA and SGA groups. Maternal SPX levels of SGA babies were significantly lower than those of the mothers in both the LGA and AGA groups, but no significant difference was observed between the SGA and LGA groups. Maternal visfatin levels of the AGA babies were significantly higher than the maternal levels of SGA and LGA groups. There was no difference in terms of maternal leptin levels. Cord blood SPX and leptin levels were positively correlated with birth weight, length and head circumference. Birth weight increased significantly in line with maternal pregestational body mass index.

CONCLUSION

The lowest SPX levels were found in the SGA babies and cord SPX level was significantly correlated with newborn length, weight, and head circumference.

New evidence for SPX2 in regulating the brain-pituitary reproductive axis of half-smooth tongue sole (Cynoglossus semilaevis)

Spexin (SPX) is an evolutionarily conserved neuropeptide, which was first identified in human proteome by data mining. Two orthologs (SPX1 and SPX2) are present in some non-mammalian species, including teleosts. It has been demonstrated that SPX1 is involved in reproduction and food intake, whereas the functional role of SPX2 is still absent in any vertebrate. The aim of the current study was to evaluate the actions of intraperitoneal injection of endogenous SPX2 peptide on the expression levels of some key reproductive genes of the brain-pituitary axis in half-smooth tongue sole. Our data showed an inhibitory action of SPX2 on brain gnih, spx1, tac3 and pituitary gthα, lhβ mRNA levels. However, SPX2 had no significant effect on brain gnihr, gnrh2, gnrh3, kiss2, kiss2r, spx2 expression or pituitary gh expression. On the other hand, SPX2 induced an increase in pituitary fshβ expression. Taken together, our results provide initial evidence for the involvement of SPX2 in the regulation of reproduction in vertebrates, which is in accordance with previous studies on SPX1.

Spexin: Its role, regulation, and therapeutic potential in the hypothalamus

Spexin is the most recently discovered member of the galanin/kisspeptin/spexin family of peptides. This 14-amino acid peptide is highly conserved and is implicated in homeostatic functions including, but not limited to, metabolism, energy homeostasis, and reproduction. Spexin is expressed by neurons in the hypothalamus, which coordinate energy homeostasis and reproduction. Critically, levels of spexin appear to be altered in disorders related to energy homeostasis and reproduction, such as obesity, diabetes, and polycystic ovarian syndrome. In this review, we discuss the evidence for the involvement of spexin in the hypothalamic control of energy homeostasis and reproduction. The anorexigenic properties of spexin have been attributed to its effects on the energy-regulating neuropeptide Y/agouti-related peptide neurons and proopiomelanocortin neurons. While the role of spexin in reproduction remains unclear, there is evidence that gonadotropin-releasing hormone expressing neurons may produce and respond to spexin. Furthermore, we discuss the disorders and concomitant treatments, which have been reported to alter spexin expression, as well as the underlying signaling mechanisms that may be involved. Finally, we discuss the biochemical basis of spexin, its interaction with its cognate receptors, and how this information can be adapted to develop therapeutics for disorders related to the alteration of energy homeostasis and reproduction.

Changes in MOTS-c Level in the Blood of Pregnant Women with Metabolic Disorders

Simple Summary

Metabolic relationships between mother and child are currently some of the most studied in the context of maternal imprinting. This is particularly important in the context of metabolic diseases as well as newly discovered peptides, proteins, and biologically active substances produced in the bodies of a mother and child. One of them is MOTS-c, which belongs to the group of mitochondria-derived peptides (MDP). The first reports show that it plays an important metabolic role in carbohydrate–lipid metabolism. We decided to investigate the concentration changes in MOTS-c levels in maternal and umbilical cord blood at delivery in healthy, obese, and hypothyroidism subjects. We found changes in MOTS-c levels depending on the metabolic condition of mothers.

Abstract

MOTS-c peptide is a member of the group of mitochondria-derived peptides (MDP). It is a product of the open reading frame in the 12S RNA gene. Due to its features and functions in the body, this peptide is classified as a hormone. The first publications indicated that this hormone improves insulin sensitivity and lowers body weight in obese animals. This suggests that it may be an important peptide in maintaining the body’s energy homeostasis. The aim of our work was to investigate the potential role of MOTS-c peptide during pregnancy, which is a condition prone to metabolic disorders. The research covered healthy, obese women and women with thyroid disorders. The obtained results indicated an increase in the concentration of MOTS-c in the blood of mothers and newborns in the obese group as compared to the healthy control group and a corresponding decrease in the concentration of this peptide in mothers and newborns in the group with hypothyroidism compared to the obese group. Moreover, we also observed a strong positive correlation between the concentration of MOTS-c in maternal blood and in umbilical cord blood. In summary, the MOTS-c peptide shows changes in blood concentration in various physiological states and may, in the future, become an important tool in the fight against metabolic diseases such as obesity or type 2 diabetes.

The Role of Neuropeptide B and Its Receptors in Controlling Appetite, Metabolism, and Energy Homeostasis

Neuropeptide B (NPB) is a peptide hormone that was initially described in 2002. In humans, the biological effects of NPB depend on the activation of two G protein-coupled receptors, NPBWR1 (GPR7) and NPBWR2 (GPR8), and, in rodents, NPBWR1. NPB and its receptors are expressed in the central nervous system (CNS) and in peripheral tissues. NPB is also present in the circulation. In the CNS, NPB modulates appetite, reproduction, pain, anxiety, and emotions. In the peripheral tissues, NPB controls secretion of adrenal hormones, pancreatic beta cells, and various functions of adipose tissue. Experimental downregulation of either NPB or NPBWR1 leads to adiposity. Here, we review the literature with regard to NPB-dependent control of metabolism and energy homeostasis.