Zebrafish Ism1 is a novel antiviral factor that positively regulates antiviral immune responses

Gene expression profiling of peripheral blood in patients with steroid-induced osteonecrosis of the femoral head

Aim: Steroid-induced osteonecrosis of the femoral head (SONFH) is a severe complication following glucocorticoid therapy. This study aimed to identify the differential mRNA expression and investigate the molecular mechanisms of SONFH. Materials & methods: RNA sequencing was performed in eight SONFH patients, five non-SONFH patients and five healthy individuals. Results: A total of 1555, 3997 and 5276 differentially expressed mRNAs existed between the following combinations: SONFH versus non-SONFH, SONFH versus healthy subjects and non-SONFH versus healthy subjects. Increased ISM1 expression might contribute to a high risk of SONFH through antiangiogenesis. Decreased FOLR3 expression might affect the metabolism of homocysteine, leading to avascular necrosis of the femoral head. KCNJ2, which plays a pivotal role in regulating bone development, was also deregulated. Conclusion: ISM1, FOLR3 and KCNJ2 might be related to the occurrence of SONFH.

The paracrine isthmin1 transcriptionally regulated by C/EBPβ exacerbates pulmonary vascular leakage in murine sepsis

It is known that pulmonary vascular leakage, a key pathological feature of sepsis-induced lung injury, is largely regulated by perivascular cells. However, the underlying mechanisms have not been fully uncovered. In the present study, we aimed to evaluate the role of isthmin1, a secretory protein originating from alveolar epithelium, in the pulmonary vascular leakage during sepsis and to investigate the regulatory mechanisms of isthmin1 gene transcription. We observed an elevated isthmin1 gene expression in the pulmonary tissue of septic mice induced by cecal ligation and puncture (CLP), as well as in primary murine alveolar type II epithelial cells (ATII) exposed to lipopolysaccharide (LPS). Furthermore, we confirmed that isthmin1 derived from ATII contributes to pulmonary vascular leakage during sepsis. Specifically, adenovirus-mediated isthmin1 disruption in ATII led to a significant attenuation of the increased pulmonary microvascular endothelial cell (PMVEC) hyperpermeability in a PMVEC/ATII coculture system when exposed to LPS. In addition, adeno-associated virus 9 (AAV9)-mediated knockdown of isthmin1 in the alveolar epithelium of septic mice significantly attenuated pulmonary vascular leakage. Finally, mechanistic studies unveiled that nuclear transcription factor CCAAT/enhancer binding protein (C/EBP)β participates in isthmin1 gene activation by binding directly to the cis-regulatory element of isthmin1 locus and may contribute to isthmin1 upregulation during sepsis. Collectively, the present study highlighted the impact of the paracrine protein isthmin1, derived from ATII, on the exacerbation of pulmonary vascular permeability in sepsis and revealed a new regulatory mechanism for isthmin1 gene transcription.NEW & NOTEWORTHY This article addresses the role of the alveolar epithelial-secreted protein isthmin1 on the exacerbation of pulmonary vascular permeability in sepsis and identified nuclear factor CCAAT/enhancer binding protein (C/EBP)β as a new regulator of isthmin1 gene transcription. Targeting the C/EBPβ-isthmin1 regulatory axis on the alveolar side would be of great value in the treatment of pulmonary vascular leakage and lung injury induced by sepsis.

Isthmin: A multifunctional secretion protein

Isthmin is a polypeptide secreted by adipocytes that was first detected in Xenopus gastrula embryos. Recent studies have focused on the biological functions of isthmin in growth and development, angiogenesis, and metabolism. Distinct spatiotemporal expression of isthmin-1 (ISM-1) was observed during growth and development. ISM-1 plays an important role in the occurrence and development of cancer by regulating cell proliferation, migration, angiogenesis, and immune microenvironments. Moreover, ISM-1, as a newly identified insulin-like adipokine, increases adipocyte glucose uptake and inhibits hepatic lipid synthesis. However, the biological function of ISM-1 remains largely unknown. In this review, we highlight the structure and physiological functions of isthmin and explore its application potential, contributing to a better understanding of its function and providing prevention and treatment strategies for various diseases.

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.

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.

Phosphoproteomic mapping reveals distinct signaling actions and activation of muscle protein synthesis by Isthmin-1

The secreted protein isthmin-1 (Ism1) mitigates diabetes by increasing adipocyte and skeletal muscle glucose uptake by activating the PI3K-Akt pathway. However, while both Ism1 and insulin converge on these common targets, Ism1 has distinct cellular actions suggesting divergence in downstream intracellular signaling pathways. To understand the biological complexity of Ism1 signaling, we performed phosphoproteomic analysis after acute exposure, revealing overlapping and distinct pathways of Ism1 and insulin. We identify a 53% overlap between Ism1 and insulin signaling and Ism1-mediated phosphoproteome-wide alterations in ~450 proteins that are not shared with insulin. Interestingly, we find several unknown phosphorylation sites on proteins related to protein translation, mTOR pathway, and, unexpectedly, muscle function in the Ism1 signaling network. Physiologically, Ism1 ablation in mice results in altered proteostasis, including lower muscle protein levels under fed and fasted conditions, reduced amino acid incorporation into proteins, and reduced phosphorylation of the key protein synthesis effectors Akt and downstream mTORC1 targets. As metabolic disorders such as diabetes are associated with accelerated loss of skeletal muscle protein content, these studies define a non-canonical mechanism by which this antidiabetic circulating protein controls muscle biology.

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.

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

Isthmin 1 (Ism1) has been shown to play roles in multiple biological processes including morphogenesis, hematopoiesis, antiviral immune response and suppression of tumor growth. However, it remains unknown if it plays any role in aging process. Here we showed for the first time that Ism1 was a new age-related biomarker, which decreased with age in fish, mice and humans. Interestingly, Ism1 was also useful to measure the "rejuvenated" age of fish Nothobranchius guentheri reversed by salidroside treatment and temperature reduction, providing additional evidence that Ism1 was an aging biomarker. In addition, we clearly showed that dietary intake of recombinant Ism1 had little effects on the body length and weight of aging N. guentheri, but it retarded the onset of age-related biomarkers and prolonged both the maximum and median lifespan of the fish. We also showed that Ism1 exerted its rejuvenation activity via the enhancement of antioxidant system. Collectively, our results indicate that Ism1 is not only is a novel biomarker of aging but also a potential rejuvenation factor capable of reversing aging of N. guentheri.