Identification of Isthmin1 in the small annual fish, Nothobranchius guentheri, as a novel biomarker of aging and its potential rejuvenation activity

Identification of Isthmin-1 in common carp (Cyprinus carpio L.) and the effects on glucose metabolism in vivo and in vitro

Isthmin-1 (Ism1) plays roles in glucose uptake in mammals as an adipokine. To investigate its role in the glucose metabolism of common carp (Cyprinus carpio. L), the Ism1 sequence was cloned, and its expression and distribution in tissues were detected. In addition, we prepared and purified the recombinant Ism1 protein using the E. coli expression system and assessed changes in the expression of key genes related to glucose metabolism through both in vivo injection experiments and primary hepatocyte experiments in vitro. The results revealed that the open reading frame of Ism1 was 1377 bp long, encoding 458 amino acids. Similarity analysis indicated that Ism1 exhibited a close evolutionary relationship with goldfish (Carassius auratus), sharing 98.35% amino acid similarity. Ism1 was expressed in all tissues of common carp, with the highest level observed in the heart, followed by the gill, head kidney, and hepatopancreas. Distinct patterns of Ism1 expression were identified during the oral glucose tolerance test and long-term high-carbohydrate and high-fat diet feeding experiments. In vivo studies demonstrated that the serum glucose concentration was reduced on treatment with Ism1, accompanied by a significant upregulation of mRNA levels for gk, hk, and pfk genes in hepatopancreas; conversely pepck and g6pase mRNA levels were significantly downregulated in the hepatopancreas under these conditions as well. Furthermore, our primary hepatocyte experiment confirmed that Ism1 could inhibit pepck and g6pase mRNA expression, while promoting gk, hk, and pfk mRNA expression levels. In conclusion, Ism1, in common carp, could participate in the glucose metabolism, which provides essential information for future studies on the function of Ism1.

Localization of Calretinin, Parvalbumin, and S100 Protein in Nothobranchius guentheri Retina: A Suitable Model for the Retina Aging

Calcium-binding proteins (CaBPs) are members of a heterogeneous family of proteins able to buffer intracellular Ca2+ ion concentration. CaBPs are expressed in the central and peripheral nervous system, including a subpopulation of retinal neurons. Since neurons expressing different CaBPs show different susceptibility to degeneration, it could be hypothesized that they are not just markers of different neuronal subpopulations, but that they might be crucial in survival. CaBPs' ability to buffer Ca2+ cytoplasmatic concentration makes them able to defend against a toxic increase in intracellular calcium that can lead to neurodegenerative processes, including those related to aging. An emergent model for aging studies is the annual killifish belonging to the Nothobranchius genus, thanks to its short lifespan. Members of this genus, such as Nothobranchius guentheri, show a retinal stratigraphy similar to that of other actinopterygian fishes and humans. However, according to our knowledge, CaBPs' occurrence and distribution in the retina of N. guentheri have never been investigated before. Therefore, the present study aimed to localize Calretinin N-18, Parvalbumin, and S100 protein (S100p) in the N. guentheri retina with immunohistochemistry methods. The results of the present investigation demonstrate for the first time the occurrence of Calretinin N-18, Parvalbumin, and S100p in N. guentheri retina and, consequently, the potential key role of these CaBPs in the biology of the retinal cells. Hence, the suitability of N. guentheri as a model to study the changes in CaBPs' expression patterns during neurodegenerative processes affecting the retina related both to disease and aging can be assumed.

Advances in research of biological functions of Isthmin-1

Isthmin-1 (ISM1) was initially thought to be a brain secretory factor, but with the development of technical means of research and the refinement of animal models, numerous studies have shown that this molecule is expressed in multiple tissues, suggesting that it may have multiple biological functions. As a factor that regulates growth and development, ISM1 is expressed in different animals with spatial and temporal variability and can coordinate the normal development of multiple organs. Recent studies have found that under the dependence of a non-insulin pathway, ISM1 can lower blood glucose, inhibit insulin-regulated lipid synthesis, promote protein synthesis, and affect the body's glucolipid and protein metabolism. In addition, ISM1 plays an important role in cancer development by promoting apoptosis and anti-angiogenesis, and by regulating multiple inflammatory pathways to influence the body's immune response. The purpose of this paper is to summarize relevant research results from recent years and to describe the key features of the biological functions of ISM1. We aimed to provide a theoretical basis for the study of ISM1 related diseases, and potential therapeutic strategies. The main biological functions of ISM1. Current studies on the biological functions of ISM1 focus on growth and development, metabolism, and anticancer treatment. During embryonic development, ISM1 is dynamically expressed in the zebrafish, African clawed frog, chick, mouse, and human, is associated with craniofacial malformations, abnormal heart localization, and hematopoietic dysfunction. ISM1 plays an important role in regulating glucose metabolism, lipid metabolism, and protein metabolism in the body. ISM1 affects cancer development by regulating cellular autophagy, angiogenesis, and the immune microenvironment.

Glomerular filtration rate in patients with type 2 diabetes mellitus: is serum isthmin-1 level a possible link?

INTRODUCTION

Isthmin-1 (Ism-1) is a novel adipokine. However, little is known regarding the association between Ism-1 and type 2 diabetes mellitus (T2DM). This study aimed to investigate the relationship between serum Ism-1 levels and glomerular filtration rate (GFR) in patients with T2DM.

RESEARCH DESIGN AND METHODS

A total of 209 patients with T2DM were recruited into this retrospective study. Clinical data were collected. Fasting blood samples were collected for serum Ism-1 testing using ELISA kits. Based on the estimated glomerular filtration rate (eGFR), participants were divided into the normal eGFR group (n=167) and the decreased eGFR group (n=42). The relationship between Ism-1 and eGFR was assessed using linear and binary logistic regression analyses. Receiver operating characteristic (ROC) curve analysis was employed to examine the predictive efficacy of Ism-1 for distinguishing patients with eGFR <60 mL/min/1.73 m2.

RESULTS

Compared with patients with normal eGFR, serum Ism-1 levels were increased in patients with decreased eGFR (p<0.001). Serum Ism-1 levels were negatively correlated with eGFR in patients with T2DM even after multiple adjustments (p<0.001). For each 0.1 ng/mL increment of Ism-1, the odds of having an eGFR <60 mL/min/1.73 m2 increased by 54.5% (OR=1.545; p<0.001) in patients with T2DM. ROC analysis showed that higher serum Ism-1 levels (>1.297 ng/mL) had predictive efficacy in patients with eGFR <60 mL/min/1.73 m2, with an area under the curve of 0.908.

CONCLUSIONS

Serum Ism-1 levels were inversely associated with eGFR, and high Ism-1 levels may be used as a potential biomarker for predicting kidney function impairment in patients with T2DM.

Serum Isthmin-1 Was Increased in Type 2 Diabetic Patients but Not in Diabetic Sensorimotor Peripheral Neuropathy

Purpose

This study aimed to investigate the relationship between serum isthmin-1 (ISM1) and type 2 diabetes mellitus (T2DM), and the alteration of serum ISM1 level in both diabetic sensorimotor peripheral neuropathy (DSPN) and diabetic adults with obesity.

Patients and Methods

We recruited 180 participants (120 T2DM and 60 controls) in the cross-sectional study. First, we compared the serum ISM1 concentration in diabetic patients and non-diabetic controls. Secondly, according to DSPN, patients were divided into DSPN and non-DSPN groups. Last, patients were categorized as lean T2DM (15 males, 15 females), overweight T2DM (35 males, 19 females), and obese T2DM groups (23 males, 13 females) according to gender and body mass index (BMI). All participants were collected with clinical characteristics and biochemical profiles. Serum ISM1 was detected in all subjects by ELISA.

Results

Higher serum ISM1 [7.78 ng/mL (IQR: 6.33-9.06) vs 5.22 (3.86-6.04), P <0.001] was observed in diabetic patients compared to non-diabetic controls. Binary logistic regression analysis showed that serum ISM1 was a risk factor for type 2 diabetes after adjustment (OR=4.218, 95% CI: 1.843-9.653, P=0.001). Compared to the non-DSPN group, serum ISM1 level was not changed significantly in patients who suffered from DSPN. Diabetic females with obesity had lower level of serum ISM1 (7.10±1.29 ng/mL) when compared to the lean T2DM (8.42±1.36 ng/mL, P <0.05) and the overweight T2DM (8.33±1.27 ng/mL, P <0.05). However, serum ISM1 was not changed significantly in male groups or all patients together.

Conclusion

Serum ISM1 was a risk factor for type 2 diabetes, and it was associated with diabetic adults with obesity while there was sexual dimorphism. However, serum ISM1 levels were not correlated with DSPN.

Dietary intake of microplastics impairs digestive performance, induces hepatic dysfunction, and shortens lifespan in the annual fish Nothobranchius guentheri

Microplastics (MPs) are ubiquitous in aquatic and terrestrial ecosystem, increasingly becoming a serious concern of human health. Many studies have explored the biological effects of MPs on animal and plant life in recent years. However, information regarding the effects of MPs on aging and lifespan is completely lacking in vertebrate species to date. Here we first confirm the bioavailability of MPs by oral delivery in the annual fish N. guentheri. We then show for the first time that administration of MPs not only shortens the lifespan but also accelerates the development of age-related biomarkers in N. guentheri. We also demonstrate that administration of MPs induces oxidative stress, suppresses antioxidant enzymes, reduces digestive enzymes, and causes hepatic dysfunction. Therefore, we propose that administration of MPs reduces lifespan of N. guentheri via induction of both suppressed antioxidant system and digestive disturbance as well as hepatic damage. Our results also suggest that smaller MPs appear more toxic to digestion, metabolism and growth of animals.

Ferroptotic Potency of ISM1 Expression in the Drug-Induced Alzheimer's Disease-Like Phenotype Under the Influence of Betulin

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by two main pathological mechanisms, mostly hyperphosphorylated tau and amyloid-β toxicity. Although many studies focus on these basic mechanisms, ferroptosis draws attention as an important pathway responsible for neurodegeneration in AD. There is no definitive treatment for AD but alternative phytochemicals to drugs come into prominence. Betulin is usually obtained from the birch tree. It is an abundant triterpene and has a high antioxidant capacity. Isthmin-1 (ISM1) is a secreted adipokine.

OBJECTIVE

In this study, we investigated the potential treatment of AD in the ferroptosis-ISM1-betulin triangle.

METHODS

For this, we created an AD model with okadaic acid (200 ng/kg)) in 36 Wistar albino male rats and treated with betulin (20 mg/kg/day, i.p). We evaluated ISM1 gene expression, iron accumulation, and total oxidative metabolism parameters (TAS, TOS, OSI) in hippocampal tissue. We analyzed cognitive recovery in AD with Morris Water Maze Test and general locomotor activity, explore, and anti-anxiolytic effect with Open Field Test.

RESULTS

We compared the obtained data with metabolic and genetic results. In conclusion, betulin may have a role in neuronal ferroptotic mechanisms by reducing iron accumulation by ISM1 regulation.

CONCLUSIONS

Betulin may have a role in neuronal ferroptotic mechanisms by reducing iron accumulation by ISM1 regulation. Although this study suggests the corrective effect of betulin and ISM1 on cognitive gain and anxiety, it is the first study to show the total antioxidant capacity of betulin in AD.

Isthmin-A Multifaceted Protein Family

Isthmin (ISM) is a secreted protein family with two members, namely ISM1 and ISM2, both containing a TSR1 domain followed by an AMOP domain. Its broad expression pattern suggests diverse functions in developmental and physiological processes. Over the past few years, multiple studies have focused on the functional analysis of the ISM protein family in several events, including angiogenesis, metabolism, organ homeostasis, immunity, craniofacial development, and cancer. Even though ISM was identified two decades ago, we are still short of understanding the roles of the ISM protein family in embryonic development and other pathological processes. To address the role of ISM, functional studies have begun but unresolved issues remain. To elucidate the regulatory mechanism of ISM, it is crucial to determine its interactions with other ligands and receptors that lead to the activation of downstream signalling pathways. This review provides a perspective on the gene organization and evolution of the ISM family, their links with developmental and physiological functions, and key questions for the future.

Polystyrene microplastic ingestion induces the damage in digestive gland of Amphioctopus fangsiao at the physiological, inflammatory, metabolome and transcriptomic levels

Microplastics are ubiquitous in the aquatic and terrestrial ecosystem, increasingly becoming a serious concern for aquatic organism health. However, information regarding the effects of microplastics on cephalopods is remain limited to date. Amphioctopus fangsiao, an important economic species in cephalopods, can serve as a potential indicator of environmental pollution due to its short life expectancy and high metabolic rates. Here, to explore the toxic effects during the microplastic stress response, we analyzed the growth performance, histopathological damage, oxidative stress biomarkers, metabolomic and transcriptomic response in digestive gland of A. fangsiao under different concentrations (0, 100 and 1000 μg/L) of commercial polystyrene microplastics (MPS) exposure (5 μm, sphere) for 21 days. The results showed that MPS exerted a huge influence on the growth performance of A. fangsiao. The oxidative stress and inflammation in digestive gland of A. fangsiao were also detected after exposure to MPS. In addition, most of the altered metabolites observed in the metabolic analysis were related to inflammation, oxidative stress and glucolipid metabolism. Transcriptome analysis detected the differentially expressed genes (DEGs) and the significantly enriched KEGG pathways associated with glycolipid metabolism, inflammation and DNA damage. Collectively, our results indicate that excessive environmental microplastic exposure will cause toxicity damage and then initiate the detoxification mechanism in A. fangsiao digestive gland to maintain homeostasis. This study revealed that microplastic can cause adverse consequences on cephalopods, providing novel insights into the toxicological effect of microplastic exposure.

Multifaceted Nothobranchius

Annual killifish of the genus Nothobranchius are seeing a rapid increase in scientific interest over the years. A variety of aspects surrounding the egg-laying Cyprinodontiformes is being extensively studied, including their aging. Inhabiting drying water bodies of Africa rarely allows survival through more than one rainy season for the Nothobranchius populations. Therefore, there is no lifespan-related bias in natural selection, which has ultimately led to the decreased efficiency of DNA repair system. Aging of the Nothobranchius species is studied both under normal conditions and under the influence of potential geroprotectors, as well as genetic modifications. Most biogerontological studies are conducted using the species Nothobranchius furzeri (GRZ isolate), which has a lifespan of 3 to 7 months. However, the list of model species of Nothobranchius is considerably wider, and the range of advanced research areas with their participation extends far beyond gerontology. This review summarizes the most interesting and promising topics developing in the studies of the fish of Nothobranchius genus. Both classical studies related to lifespan control and rather new ones are discussed, including mechanisms of diapause, challenges of systematics and phylogeny, evolution of sex determination mechanisms, changes in chromosome count, occurrence of multiple repeated DNA sequences in the genome, cognitive and behavioral features and social stratification, as well as methodological difficulties in working with Nothobranchius.

Serum isthmin-1 levels are positively and independently correlated with albuminuria in patients with type 2 diabetes mellitus

INTRODUCTION

Isthmin-1 (Ism-1), as a novel adipokine, plays a role in glucose homeostasis and lipid metabolism. However, the relationship between Ism-1 and type 2 diabetes mellitus (T2DM) remains unclear. This study aims to investigate the association of serum Ism-1 levels with albuminuria and insulin resistance in patients with T2DM and preserved renal function.

RESEARCH DESIGN AND METHODS

A total of 150 patients with T2DM were recruited. The presence of albuminuria was evaluated by urinary albumin:creatinine ratio (UACR) in first morning urine sample. Serum Ism-1 levels were tested by ELISA. Homeostasis model assessments were used to evaluate insulin resistance. Binary logistic regression and multivariable linear regression analyses were used to assess the association of serum Ism-1 levels with albuminuria. Multivariable linear regression analyses were performed to explore the correlation of serum Ism-1 levels with insulin resistance.

RESULTS

Compared with the normal-albuminuria and microalbuminuria groups, serum Ism-1 levels were significantly higher in the macroalbuminuria group (p<0.01). Binary logistic regression analyses showed that serum Ism-1 was positively associated with odds of albuminuria even after multiple adjustments (OR=4.766, p=0.013). Serum Ism-1 was positively associated with log10-transformed UACR (β=0.625, p<0.001). However, the associations between serum Ism-1 levels and insulin resistance were not observed in patients with T2DM.

CONCLUSIONS

Serum Ism-1 levels were positively and independently correlated with the severity of albuminuria in patients with T2DM but not with insulin resistance.

Administration of krill oil extends lifespan of fish Nothobranchius guentheri via enhancement of antioxidant system and suppression of NF-κB pathway

Krill oil (KO) extracted from Antarctic krill (Euphausia superba) mainly comprises phospholipids and triglycerides. KO has been shown to prolong the median lifespan of the nematode Caenorhabditis elegans, but to shorten the lifespan of long-lived F1 mice; therefore, it remains controversial over the life-extending property of KO. In this study, we clearly demonstrated that dietary intake of KO extended both the mean and maximum lifespans of aged male Nothobranchius guentheri (p < 0.05), reduced the accumulation of lipofuscin (LF) (p < 0.05) in the gills and senescence-associated β-galactosidase (SA-β-Gal) (p < 0.05) in the caudal fins, and lowered the levels of protein oxidation (p < 0.05), lipid peroxidation (p < 0.01), and reactive oxygen species (ROS) (p < 0.01) in the muscles and livers, indicating that KO possesses rejuvenation and anti-aging activity. We also showed that KO enhanced the activities of antioxidant enzymes catalase (CAT) (p < 0.05), superoxide dismutase (SOD) (p < 0.05), and glutathione peroxidase (GPX) (p < 0.05) in aged male N. guentheri. In addition, KO administration effectively reversed histological lesions including inflammatory cell infiltration and structural collapse in the muscles and livers of aged N. guentheri and suppressed the nuclear factor kappa-B (NF-κB) signaling pathway (p < 0.05), a master regulator of inflammation. Altogether, our study indicates that KO has anti-aging and rejuvenation property. It also suggests that KO exerts its anti-aging and rejuvenation effects via enhancement of the antioxidant system and suppression of the NF-κB signaling pathway.

A brief overview about the adipokine: Isthmin-1

Isthmin-1 is a secreted protein with multiple capability; however, it truly attracts our attention since the definition as an adipokine in 2021, which exerts indispensable roles in various pathophysiological processes through the endocrine or autocrine manners. In this review, we summarize recent knowledge of isthmin-1, including its distribution, structure, receptor and potential function.