Insulin Substrate Receptor (IRS) proteins in normal and malignant hematopoiesis

Outer Membrane Vesicles Released from Garlic Exosome-like Nanoparticles (GaELNs) Train Gut Bacteria that Reverses Type 2 Diabetes via the Gut-Brain Axis

Gut microbiota function has numerous effects on humans and the diet humans consume has emerged as a pivotal determinant of gut microbiota function. Here, a new concept that gut microbiota can be trained by diet-derived exosome-like nanoparticles (ELNs) to release healthy outer membrane vesicles (OMVs) is introduced. Specifically, OMVs released from garlic ELN (GaELNs) trained human gut Akkermansia muciniphila (A. muciniphila) can reverse high-fat diet-induced type 2 diabetes (T2DM) in mice. Oral administration of OMVs released from GaELNs trained A. muciniphila can traffick to the brain where they are taken up by microglial cells, resulting in inhibition of high-fat diet-induced brain inflammation. GaELNs treatment increases the levels of OMV Amuc-1100, P9, and phosphatidylcholines. Increasing the levels of Amuc-1100 and P9 leads to increasing the GLP-1 plasma level. Increasing the levels of phosphatidylcholines is required for inhibition of cGas and STING-mediated inflammation and GLP-1R crosstalk with the insulin pathway that leads to increasing expression of Insulin Receptor Substrate (IRS1 and IRS2) on OMV targeted cells. These findings reveal a molecular mechanism whereby OMVs from plant nanoparticle-trained gut bacteria regulate genes expressed in the brain, and have implications for the treatment of brain dysfunction caused by a metabolic syndrome.

NT157 exhibits antineoplastic effects by targeting IRS and STAT3/5 signaling in multiple myeloma

Multiple myeloma (MM) is a prevalent hematological malignancy with high recurrence and no definitive cure. The current study revisits the role of the IGF1/IGF1R axis in MM, introducing a novel inhibitor, NT157. The IGF1/IGF1R pathway is pivotal in MM, influencing cell survival, proliferation, and migration and impacting patient survival outcomes. NT157 targets intracellular proteins such as IRS and STAT proteins and demonstrates antineoplastic potential in hematological malignancies and solid tumors. In the present study, we assessed IGF1R signaling-related gene expression in MM patients and healthy donors, unveiling significant distinctions. MM cell lines displayed varying expression patterns of IGF1R-related proteins. A gene dependence analysis indicated the importance of targeting receptor and intracellular elements over autocrine IGF1. NT157 exhibited inhibitory effects on MM cell viability, clonal growth, cell cycle progression, and survival. Moreover, NT157 reduced IRS2 expression and STAT3, STAT5, and RPS6 activation and modulated oncogenes and tumor suppressors, fostering a tumor-suppressive molecular profile. In summary, our study demonstrates that the IGF1/IGF1R/IRS signaling axis is differentially activated in MM cells and the NT157's capacity to modulate crucial molecular targets, promoting antiproliferative effects and apoptosis in MM cells. NT157 may offer a multifaceted approach to enhance MM therapy.

Obesity and Leukemia: Biological Mechanisms, Perspectives, and Challenges

PURPOSE OF REVIEW

To examine the epidemiological data on obesity and leukemia; evaluate the effect of obesity on leukemia outcomes in childhood acute lymphoblastic leukemia (ALL) survivors; assess the potential mechanisms through which obesity may increase the risk of leukemia; and provide the effects of obesity management on leukemia. Preventive (diet, physical exercise, obesity pharmacotherapy, bariatric surgery) measures, repurposing drugs, candidate therapeutic agents targeting oncogenic pathways of obesity and insulin resistance in leukemia as well as challenges of the COVID-19 pandemic are also discussed.

RECENT FINDINGS

Obesity has been implicated in the development of 13 cancers, such as breast, endometrial, colon, renal, esophageal cancers, and multiple myeloma. Leukemia is estimated to account for approximately 2.5% and 3.1% of all new cancer incidence and mortality, respectively, while it represents the most frequent cancer in children younger than 5 years. Current evidence indicates that obesity may have an impact on the risk of leukemia. Increased birthweight may be associated with the development of childhood leukemia. Obesity is also associated with worse outcomes and increased mortality in leukemic patients. However, there are several limitations and challenges in meta-analyses and epidemiological studies. In addition, weight gain may occur in a substantial number of childhood ALL survivors while the majority of studies have documented an increased risk of relapse and mortality among patients with childhood ALL and obesity. The main pathophysiological pathways linking obesity to leukemia include bone marrow adipose tissue; hormones such as insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. Obesity represents a risk factor for leukemia, being among the only known risk factors that could be prevented or modified through weight loss, healthy diet, and physical exercise. Pharmacological interventions, repurposing drugs used for cardiometabolic comorbidities, and bariatric surgery may be recommended for leukemia and obesity-related cancer prevention.

Protein O-GlcNAcylation: The sweet hub in liver metabolic flexibility from a (patho)physiological perspective

O-GlcNAcylation is a dynamic, reversible and atypical O-glycosylation that regulates various cellular physiological processes via conformation, stabilisation, localisation, chaperone interaction or activity of target proteins. The O-GlcNAcylation cycle is precisely controlled by collaboration between O-GlcNAc transferase and O-GlcNAcase. Uridine-diphosphate-N-acetylglucosamine, the sole donor of O-GlcNAcylation produced by the hexosamine biosynthesis pathway, is controlled by the input of glucose, glutamine, acetyl coenzyme A and uridine triphosphate, making it a sensor of the fluctuation of molecules, making O-GlcNAcylation a pivotal nutrient sensor for the metabolism of carbohydrates, amino acids, lipids and nucleotides. O-GlcNAcylation, particularly prevalent in liver, is the core hub for controlling systemic glucose homeostasis due to its nutritional sensitivity and precise spatiotemporal regulation of insulin signal transduction. The pathology of various liver diseases has highlighted hepatic metabolic disorder and dysfunction, and abnormal O-GlcNAcylation also plays a specific pathological role in these processes. Therefore, this review describes the unique features of O-GlcNAcylation and its dynamic homeostasis maintenance. Additionally, it explains the underlying nutritional sensitivity of O-GlcNAcylation and discusses its mechanism of spatiotemporal modulation of insulin signal transduction and liver metabolic homeostasis during the fasting and feeding cycle. This review emphasises the pathophysiological implications of O-GlcNAcylation in nonalcoholic fatty liver disease, nonalcoholic steatohepatitis and hepatic fibrosis, and focuses on the adverse effects of hyper O-GlcNAcylation on liver cancer progression and metabolic reprogramming.

Phosphorylation Codes in IRS-1 and IRS-2 Are Associated with the Activation/Inhibition of Insulin Canonical Signaling Pathways

Insulin receptor substrates 1 and 2 (IRS-1 and IRS-2) are signaling adaptor proteins that participate in canonical pathways, where insulin cascade activation occurs, as well as in non-canonical pathways, in which phosphorylation of substrates is carried out by a diverse array of receptors including integrins, cytokines, steroid hormones, and others. IRS proteins are subject to a spectrum of post-translational modifications essential for their activation, encompassing phosphorylation events in distinct tyrosine, serine, and threonine residues. Tyrosine residue phosphorylation is intricately linked to the activation of the insulin receptor cascade and its interaction with SH2 domains within a spectrum of proteins, including PI3K. Conversely, serine residue phosphorylation assumes a different function, serving to attenuate the effects of insulin. In this review, we have identified over 50 serine residues within IRS-1 that have been reported to undergo phosphorylation orchestrated by a spectrum of kinases, thereby engendering the activation or inhibition of different signaling pathways. Furthermore, we delineate the phosphorylation of over 10 distinct tyrosine residues at IRS-1 or IRS-2 in response to insulin, a process essential for signal transduction and the subsequent activation of PI3K.

Monoamine oxidase mediated oxidative stress: a potential molecular and biochemical crux in the pathogenesis of obesity

Obesity has become a global health concern with an increasing prevalence as years pass by but the researchers have not come to a consensus on the exact pathophysiological mechanism underlying this disease. In the past three decades, Monoamine Oxidases (MAO), has come into limelight for a possible involvement in orchestrating the genesis of obesity but the exact mechanism is not well elucidated. MAO is essentially an enzyme involved in the catabolism of neurotransmitters and other biogenic amines to form a corresponding aldehyde, hydrogen peroxide (H2O2) and ammonia. This review aims to highlight the repercussions of MAO's catabolic activity on the redox balance, carbohydrate metabolism and lipid metabolism of adipocytes which ultimately leads to obesity. The H2O2 produced by these enzymes seems to be the culprit causing oxidative stress in pre-adipocytes and goes on to mimic insulin's activity independent of its presence via the Protein Kinase B Pathway facilitating glucose influx. The H2O2 activates Sterol regulatory-element binding protein-1c and peroxisome proliferator activated receptor gamma crucial for encoding enzymes like fatty acid synthase, acetyl CoA carboxylase 1, Adenosine triphosphate-citrate lyase, phosphoenol pyruvate carboxykinase etc., which helps promoting lipogenesis at the same time inhibits lipolysis. More reactive oxygen species production occurs via NADPH Oxidases enzymes and is also able activate Nuclear Factor kappa B leading to inflammation in the adipocyte microenvironment. This chronic inflammation is the seed for insulin resistance.

The strategic involvement of IRS in cancer progression

Insulin Receptor Substrate (IRS), an intracellular molecule devoid of an intrinsic kinase activity, is activated upon binding to IR which thereby works as a scaffold, organizing all signaling complexes and initiating the signaling process downstream. The level of IRS proteins and their stability in the cell is mostly maintained through the phosphorylation status of their tyrosine and serine residues. IRS is positively regulated by phosphorylation of its Tyr residues whereas a Ser residue phosphorylation attenuates it, although there exist some exceptions as well. Other post-translational modifications like O-linked glycosylation, N-linked glycosylation and acetylation also play a prominent role in IRS regulation. Since the discovery of the Warburg effect, people have been curious to find out all possible signaling networks and molecules that could lead to cancer and no doubt, the insulin signaling pathway is identified as one such pathway, which is highly deregulated in cancers. Eminent studies reveal that IRS is a pertinent regulator of cancer and is highly overexpressed in the five most commonly occurring cancers namely- Prostate, Ovarian, Breast, Colon and Lung cancers. IRS1 and IRS2 family members are actively involved in the progression, invasion and metastasis of these cancers. Recently, less studied IRS4 has also emerged as a contributor in ovarian, breast, colorectal and lung cancer, but no such studies related to IRS4 are found in Prostate cancer. The involvement of other IRS family members in cancer is still undiscovered and so paves the way for further exploration. This review is a time-lapse study of IRSs in the context of cancer done over the past two decades and it highlights all the major discoveries made till date, in these cancers from the perspective of IRS.

The inverse association between DNA gaps and HbA1c levels in type 2 diabetes mellitus

Naturally occurring DNA gaps have been observed in eukaryotic DNA, including DNA in nondividing cells. These DNA gaps are found less frequently in chronologically aging yeast, chemically induced senescence cells, naturally aged rats, D-galactose-induced aging model rats, and older people. These gaps function to protect DNA from damage, so we named them youth-associated genomic stabilization DNA gaps (youth-DNA-gaps). Type 2 diabetes mellitus (type 2 DM) is characterized by an early aging phenotype. Here, we explored the correlation between youth-DNA-gaps and the severity of type 2 DM. Here, we investigated youth-DNA-gaps in white blood cells from normal controls, pre-DM, and type 2 DM patients. We found significantly decreased youth-DNA-gap numbers in the type 2 DM patients compared to normal controls (P = 0.0377, P = 0.0018 adjusted age). In the type 2 DM group, youth-DNA-gaps correlate directly with HbA1c levels. (r = - 0.3027, P = 0.0023). Decreased youth-DNA-gap numbers were observed in patients with type 2 DM and associated with increased HbA1c levels. Therefore, the decrease in youth-DNA-gaps is associated with the molecular pathogenesis of high blood glucose levels. Furthermore, youth-DNA-gap number is another marker that could be used to determine the severity of type 2 DM.

Decreased Alu methylation in type 2 diabetes mellitus patients increases HbA1c levels

INTRODUCTION

Alu hypomethylation is a common epigenetic process that promotes genomic instability with aging phenotypes, which leads to type 2 diabetes mellitus (type 2 DM). Previously, our results showed significantly decreased Alu methylation levels in type 2 DM patients. In this study, we aimed to investigate the longitudinal changes in Alu methylation levels in these patients.

RESULTS

We observed significantly decreased Alu methylation levels in type 2 DM patients compared with normal (p = 0.0462). Moreover, our findings demonstrated changes in Alu hypomethylation over a follow-up period within the same individuals (p < 0.0001). A reduction in Alu methylation was found in patients with increasing HbA1c levels (p = 0.0013) and directly correlated with increased HbA1c levels in type 2 DM patients (r = -0.2273, p = 0.0387).

CONCLUSIONS

Alu methylation in type 2 DM patients progressively decreases with increasing HbA1c levels. This observation suggests a potential association between Alu hypomethylation and the underlying molecular mechanisms of elevated blood glucose. Furthermore, monitoring Alu methylation levels may serve as a valuable biomarker for assessing the clinical outcomes of type 2 DM.

Crosstalk between the mTOR and Hippo pathways

Cell behavior changes in response to multiple stimuli, such as growth factors, nutrients, and cell density. The mechanistic target of the rapamycin (mTOR) pathway is activated by growth factors and nutrient stimuli to regulate cell growth and autophagy, whereas the Hippo pathway has negative effects on cell proliferation and tissue growth in response to cell density, DNA damage, and hormonal signals. These two signaling pathways must be precisely regulated and integrated for proper cell behavior. This integrative mechanism is not completely understood; nevertheless, recent studies have suggested that components of the mTOR and Hippo pathways interact with each other. Herein, as per contemporary knowledge, we review the molecular mechanisms of the interaction between the mTOR and Hippo pathways in mammals and Drosophila. Moreover, we discuss the advantage of this interaction in terms of tissue growth and nutrient consumption.

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

Regulation of erythroid differentiation in K562 cells by the EPAS1-IRS2 axis under hypoxic conditions

Red blood cells (RBCs) produced in vitro have the potential to alleviate the worldwide demand for blood transfusion. Hematopoietic cell differentiation and proliferation are triggered by numerous cellular physiological processes, including low oxygen concentration (<5%). In addition, hypoxia inducible factor 2α (HIF-2α) and insulin receptor substrate 2 (IRS2) were found to be involved in the progression of erythroid differentiation. However, the function of the HIF-2α-IRS2 axis in the progression of erythropoiesis is not yet fully understood. Therefore, we used an in vitro model of erythropoiesis generated from K562 cells transduced with shEPAS1 at 5% O₂ in the presence or absence of the IRS2 inhibitor NT157. We observed that erythroid differentiation was accelerated in K562 cells by hypoxia. Conversely, knockdown of EPAS1 expression reduced IRS2 expression and erythroid differentiation. Intriguingly, inhibition of IRS2 could impair the progression of hypoxia-induced erythropoiesis without affecting EPAS1 expression. These findings indicated that the EPAS1-IRS2 axis may be a crucial pathway that regulates erythropoiesis and that drugs targeting this pathway may become promising agents for promoting erythroid differentiation.

LINC00638 promotes the progression of non-small cell lung cancer by regulating the miR-541-3p/IRS1/PI3K/Akt axis

Background

Preceding works reveal the function of long non-coding RNAs (abbreviated to lncRNAs) during non-small cell lung cancer (NSCLC) evolvement. We explored the profile and biological functions of the lncRNA LINC00638 in NSCLC.

Methods

Reverse transcription-quantitative PCR examined LINC00638 level in NSCLC and corresponding non-tumor tissues, human normal lung epithelial cells BEAS-2B, and NSCLC cells (NCI-H460, HCC-827, A549, H1299, H1975, H460). The gain- and loss-of-function assay of LINC00638 ascertained its function in modulating the proliferation, apoptosis, and invasion of NSCLC cells (HCC-827 and H460). Bioinformatics analysis investigated the underlying mechanisms. Dual luciferase reporter gene and RNA immunoprecipitation (RIP) checked the interactions between LINC00638 and microRNA (miR)-541-3p, miR-541-3p and insulin receptor substrate 1 (IRS1).

Results

LINC00638 was upregulated in NSCLC tissues by contrast to the profiles found in the corresponding non-tumor normal tissues, as well as in NSCLC cells vis-à-vis BEAS-2B cells. LINC00638 upregulation pertained to the poorer survival rates of NSCLC patients. Overexpressing LINC00638 augmented NSCLC cells' proliferation, growth, migration, and invasion but inhibited their apoptosis, while down-regulating LINC00638 led to the opposite. miR-541-3p might be an underlying target of LINC00638, which targeted IRS1, inhibited NSCLC progression, and reversed the carcinogenic effects of LINC00638. Mechanistically, LINC00638/miR-541-3p regulated the IRS1/phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Repressing IRS1/2 using its inhibitor NT157 repressed LINC00638-mediated oncogenic effects.

Conclusion

LINC00638 may function as an oncogene in NSCLC by modulating the miR-541-3p/IRS1/PI3K/Akt axis.

Far-western Blotting Detection of the Binding of Insulin Receptor Substrate to the Insulin Receptor

Far-western blotting, derived from the western blot, has been used to detect interactions between proteins in vitro, such as receptor-ligand interactions. The insulin signaling pathway plays a critical role in the regulation of both metabolism and cell growth. The binding of the insulin receptor substrate (IRS) to the insulin receptor is essential for the propagation of downstream signaling after the activation of the insulin receptor by insulin. Here, we describe a step-by-step far-western blotting protocol for determining the binding of IRS to the insulin receptor.

Structural Consequences of IRS-2 nsSNPs and Implication for Insulin Receptor Substrate-2 Protein Stability

Single-Nucleotide Polymorphisms (SNPs) are common genetic variations implicated in human diseases. The non-synonymous SNPs (nsSNPs) affect the proteins' structures and their molecular interactions with other interacting proteins during the accomplishment of biochemical processes. This ultimately causes proteins functional perturbation and disease phenotypes. The Insulin receptor substrate-2 (IRS-2) protein promotes glucose absorption and participates in the biological regulation of glucose metabolism and energy production. Several IRS-2 SNPs are reported in association with type 2 diabetes and obesity in human populations. However, there are no comprehensive reports about the protein structural consequences of these nsSNPs. Keeping in view the pathophysiological consequences of the IRS-2 nsSNPs, we designed the current study to understand their possible structural impact on coding protein. The prioritized list of the deleterious IRS-2 nsSNPs was acquired from multiple bioinformatics resources, including VEP (SIFT, PolyPhen, and Condel), PROVEAN, SNPs&GO, PMut, and SNAP2. The protein structure stability assessment of these nsSNPs was performed by MuPro and I-Mutant-3.0 servers via structural modeling approaches. The atomic-level structural and molecular dynamics (MD) impact of these nsSNPs were examined using GROMACS 2019.2 software package. The analyses initially predicted 8 high-risk nsSNPs located in the highly conserved regions of IRS-2. The MD simulation analysis eventually prioritized the N232Y, R218C, and R104H nsSNPs that predicted to significantly compromise the structure stability and may affect the biological function of IRS-2. These nsSNPs are predicted as high-risk candidates for diabetes and obesity. The validation of protein structural impact of these shortlisted nsSNPs may provide biochemical insight into the IRS-2-mediated type-2 diabetes.

Insulin Receptor Substrate 1 Signaling Inhibits Foxp3 Expression and Suppressive Functions in Treg Cells through the mTORC1 Pathway

Regulatory T (Treg) cells play an important role in immune homeostasis by inhibiting cells within the innate and adaptive immune systems; therefore, the stability and immunosuppressive function of Treg cells need to be maintained. In this study, we found that the expression of insulin receptor substrate 1 (IRS1) by Treg cells was lower than that by conventional CD4 T cells. IRS1-overexpressing Treg cells showed the downregulated expression of FOXP3, as well as Treg signature markers CD25 and CTLA4. IRS1-overexpressing Treg cells also showed diminished immunosuppressive functions in an in vitro suppression assay. Moreover, IRS1-overexpressing Treg cells were unable to suppress the pathogenic effects of conventional T cells in a transfer-induced colitis model. IRS1 activated the mTORC1 signaling pathway, a negative regulator of Treg cells. Moreover, IRS1 destabilized Treg cells by upregulating the expression of IFN-γ and Glut1. Thus, IRS1 acts as a negative regulator of Treg cells by downregulating the expression of FOXP3 and disrupting stability.

Nutrient sensing, signaling transduction, and autophagy in podocyte injury: implications for kidney disease

Podocytes are terminally differentiated epithelial cells of the renal glomerular tuft and these highly specialized cells are essential for the integrity of the slit diaphragm. The biological function of podocytes is primarily based on a complex ramified structure that requires sufficient nutrients and a large supply of energy in support of their unique structure and function in the glomeruli. Of note, the dysregulation of nutrient signaling and energy metabolic pathways in podocytes has been associated with a range of kidney diseases i.e., diabetic nephropathy. Therefore, nutrient-related and energy metabolic signaling pathways are critical to maintaining podocyte homeostasis and the pathogenesis of podocyte injury. Recently, a growing body of evidence has indicated that nutrient starvation induces autophagy, which suggests crosstalk between nutritional signaling with the modulation of autophagy for podocytes to adapt to nutrient deprivation. In this review, the current knowledge and advancement in the understanding of nutrient sensing, signaling, and autophagy in the podocyte biology, injury, and pathogenesis of kidney diseases is summarized. Based on the existing findings, the implications and perspective to target these signaling pathways and autophagy in podocytes during the development of novel preventive and therapeutic strategies in patients with podocyte injury-associated kidney diseases are discussed.

Integrin β2 and β3: Two plasmatocyte markers deepen our understanding of the development of plasmatocytes in the silkworm Bombyx mori

Insect hemocytes play important biological roles at developmental stages, metamorphosis, and innate immunity. As one of the most abundant cell types, plasmatocytes can participate in various innate immune responses, especially in encapsulation and node formation. Here, 2 molecular markers of plasmatocytes, consisting of integrin β2 and β3, were identified and used to understand the development of plasmatocytes. Plasmatocytes are widely distributed in the hematopoietic system, including circulating hemolymph and hematopoietic organs (HPOs). HPOs constantly release plasmatocytes with high proliferative activity in vitro; removal of HPOs leads to a dramatic reduction in the circulating plasmatocytes, and the remaining plasmatocytes gradually lose their ability to proliferate in vivo. Our results demonstrated that the release of plasmatocytes from HPOs is regulated by insulin-mediated signals and their downstream pathways, including PI3K/Akt and MAPK/Erk signals. The insulin/PI3K/Akt signaling pathway can significantly irritate the hematopoiesis, and its inhibitor LY294002 could inhibit the hemocytes discharged from HPOs. While the insulin/MAPK/Erk signaling pathway plays a negative regulatory role, inhibiting its activity with U0126 can markedly promote the discharge of plasmatocytes from HPOs. Our results indicate that the circulating plasmatocytes are mainly generated and discharged by HPOs. This process is co-regulated by the PI3K/Akt and MAPK/Erk signals in an antagonistic manner to adjust the dynamic balance of the hemocytes. These findings can enhance our understanding of insect hematopoiesis.

The Role of Insulin Receptor Substrate Proteins in Bronchopulmonary Dysplasia and Asthma: New Potential Perspectives

Insulin receptor substrates (IRSs) are proteins that are involved in signaling through the insulin receptor (IR) and insulin-like growth factor (IGFR). They can also interact with other receptors including growth factor receptors. Thus, they represent a critical node for the transduction and regulation of multiple signaling pathways in response to extracellular stimuli. In addition, IRSs play a central role in processes such as inflammation, growth, metabolism, and proliferation. Previous studies have highlighted the role of IRS proteins in lung diseases, in particular asthma. Further, the members of the IRS family are the common proteins of the insulin growth factor signaling cascade involved in lung development and disrupted in bronchopulmonary dysplasia (BPD). However, there is no study focusing on the relationship between IRS proteins and BPD yet. Unfortunately, there is still a significant gap in knowledge in this field. Thus, in this review, we aimed to summarize the current knowledge with the major goal of exploring the possible roles of IRS in BPD and asthma to foster new perspectives for further investigations.

Prognostic role of IRS-4 in the survival of patients with pancreatic cancer

Pancreatic cancer is a malignancy of rising incidence, especially in developed countries due to causes such as sedentary lifestyles, tobacco smoking and ultraprocessed high fat and high sugar diets, amongst others. It is in fact the 7th cause of cancer-related deaths worldwide, and, in the following years, it is expected to climb upwards to 2nd position, after lung cancer. This is because it may have an asymptomatic course, and when it becomes evident it is in advanced stages, accompanied by metastasis generally. For this reason, survival rates are so low and, even in the few successful cases there is a high possibility of recurrence. Identifying new molecular biomarkers is arising as a highly useful tool for pancreatic cancer clinical management, although much research and work remain to be done in this field. Thus, the present study aims to analyze a series of molecules (IRS-4, Rb1, Ki-67 y COX-2) as candidates for prognosis and survival by immunohistochemistry techniques. Additionally, a 60-month longitudinal surveillance program was conducted, associated with diverse clinical parameters. Kaplan-Meier curves estimating the time of survival according to tumoral expression of those molecules denoted a low cumulative survival rate. Importantly, we observed that high levels of IRS-4 were significantly associated with a bad prognosis of the disease, increasing 160 times the mortality risk. In this way, our research showed a relevant value of these biomarkers in pancreatic cancer patients' survival, opening a pathway for future research areas designed to inhibit these components.

CirRNA circFAM126A Exerts Oncogenic Functions in NSCLC to Upregulate IRS2

Non-small cell lung cancer (NSCLC) is a common histological subtype of lung cancer, which occupies 80-85% of the proportion in all lung cancer cases. Therefore, this study was designed to clarify the role and underlying molecular mechanisms of circFAM126A in NSCLC. The real-time quantitative polymerase chain reaction (RT-qPCR) assay was conducted to assess circFAM126A, FAM126A, miR-613, and IRS2 expression in NSCLC tissues and cells. The proliferation ability of cells was measured by MTT, EdU, and colony-forming assays. The flow cytometry assay was performed to evaluate cell cycle distribution and apoptosis of NSCLC cells. The migration and invasion were determined by wound healing and transwell matrigel assays, respectively. The interaction relationship between miR-613 and circFAM126A or IRS2 was analyzed by dual-luciferase reporter and RNA pull-down assays. Tumorigenesis in nude mice was conducted to clarify the functional roles of circFAM126A inhibition in vivo. CircFAM126A was obviously overexpressed in NSCLC tissues and cells when compared with controls. The loss-of-functional experiments suggested that knockdown of circFAM126A suppressed proliferation, migration and invasion, as well as caused apoptosis and cell cycle arrest in NSCLC cells, which was abolished by silencing of miR-613. In addition, IRS2 was a target gene of miR-613. Overexpression of miR-613 exerted carcinoma inhibitor role in NSCLC by inhibition of IRS2 expression. Consistently, the silencing of circFAM126A also functioned anti-tumorigenic roles in nude mice in vivo. Mechanistically, circFAM126A could function as a miRNA sponge for miR-613 to regulate the expression of IRS2, thereby regulating proliferation, migration, invasion, apoptosis, and cell cycle arrest in NSCLC cells.

YiQi YangYin Decoction Attenuates Nonalcoholic Fatty Liver Disease in Type 2 Diabetes Rats

Background

YiQi YangYin Decoction (YQ) is a modern Chinese formula composed by the guidance of traditional Chinese medicine theory, which consists of nine traditional Chinese medicines and is applied to treat type 2 diabetes mellitus (T2DM) with nonalcoholic fatty liver in clinic in China for more than a decade. This study aims to evaluate the antidiabetes and lipid-lowering effect of YQ and explore the possible mechanisms of this action.

Methods

T2DM rat models were established and given YQ at three different doses for three weeks. Tissues, including pancreas islet and liver, and blood serum were collected. The levels of fasting blood glucose (FBG), fasting insulin (Fins), lipid index, such as total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL), and hepatic function index such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in serum were measured. Pancreas islet damage and liver damage were observed by hematoxylin and eosin staining. The glycogen content and lipid accumulation in liver were determined by periodic acid-Schiff (PAS) staining and Oil Red O staining. The expression levels of insulin receptor substrate 2 (IRS-2), phosphatidylinositol 3 kinase-associated p85alpha (PI3K p85α), AKT, and Glucose Transporter 2 (Glut4) in pancreas islet and AMP-activated protein kinase alpha (AMPKα), sterol regulatory element-binding protein 1c (SREBP1c), acetyl-CoA carboxylase (ACC1), and peroxisome proliferator-activated receptor-α (PPARα) in liver were determined by western blotting. The relative expressions of ACC1, fatty acid synthase (FAS), stearoyl-CoA desaturase 1 (SCD1), carnitine palmityl transferase-1 (CPT-1), and SREBP-1 mRNA were detected by qRT-PCR.

Results

After administering YiQi for three weeks, the levels of fast blood glucose, fasting insulin, TC, TG, LDL, ALT, AST, and ALP were significantly decreased, while HDL significantly increased compared with the model group. YQ could obviously attenuate pancreatic damage and improve islet α- and ß-cell survival compared with the model group. Furthermore, YQ could attenuate hepatic damage caused by lipid accumulation, decrease the content of lipid, and increase the hepatic glycogen content, compared with the model group. In addition, YQ remarkably elevated the proteins expression of p-PI3K, p-AKT, and GLUT4 in pancreas islet and elevated the proteins expression of p-PI3K, p-AKT, GLUT4, p-AMPK, SREBP1, and PPARα and inhibited the expression of p-ACC1 in liver. Besides, YQ reduced the relative expression of ACC1, FAS, SERBP-1c, and SCD mRNA along with the decreased production of CPT-1 mRNA.

Conclusions

YQ could attenuate type 2 diabetes mellitus by improving islet α- and ß-cells via IRS-2/AKT/GLUT4 pathway and nonalcoholic fatty liver by ameliorating lipid accumulation via AMPK/PPARα/SREBP1/ACC1 pathway.

IRS4 promotes the progression of non-small cell lung cancer and confers resistance to EGFR-TKI through the activation of PI3K/Akt and Ras-MAPK pathways

IRS4 is a member of the insulin receptor substrate (IRS) protein family. It acts as a cytoplasmic adaptor protein, integrating and transmitting signals from receptor protein tyrosine kinases to the intracellular environment. IRS4 can induce mammary tumorigenesis and is usually overexpressed in non-small cell lung cancer (NSCLC). However, little is known about the role of IRS4 in the development and progression of lung cancer. In this study, we show that IRS4 knockout suppresses the proliferation, colony formation, migration, and invasion of A549 lung cancer cells, as well as tumor growth in a nude mouse xenograft model. In contrast, stable expression of IRS4 showed the opposite effects. As expected, IRS4 was found to activate the PI3K/Akt and Ras-MAPK pathways, and we also showed that IRS4 depletion significantly enhanced the sensitivity of EGFR tyrosine kinase inhibitor (EGFR-TKI)-resistant cells to gefitinib. Taken together, these results show that IRS4 promotes NSCLC progression and may represent a potential therapeutic target for EGFR-TKI-resistant NSCLC.

Effect of l-carnitine on cardiotoxicity and apoptosis induced by imatinib through PDGF/ PPARγ /MAPK pathways

A tyrosine kinase inhibitor Imatinib (IM) is used in the treatment of different varieties of cancers. The current study was designed to explore the beneficial role of l-carnitine against IM-induced cardiotoxicity in rats. Male albino rats received IM (40 mg/kg, i.p.) either alone or/in combination with l-carnitine (100 mg/kg, i.p.) for 7 days. IM increased serum inflammatory cytokines, concomitant with activation of cardiac MAPK, α-SMA, malondialdehyde (MDA) and nitric oxide(NO), decreased cardiac peroxisome proliferator-activated receptor-γ (PPAR-γ) level, superoxide dismutase (SOD) activity, and glutathione (GSH) content. The expression levels of Bcl-2 and PDGF were significantly decreased, while the expression levels of CTGF and BAX were significantly increased in the IM group. The l-carnitine treatment successfully protected the heart as indicated by the improvement of the biochemical and histopathological parameters. l-carnitine didn't affect the serum concentration of IM and increased intracellular concentration in the combination-treated group as measured by the mass spectrometer. Conclusion: l-carnitine abrogated IM-induced cardiac damage and apoptosis via PDGF/PPARγ/MAPK pathways.

Effects of Heshouwuyin on gene expression of the insulin/IGF signalling pathway in rat testis and spermatogenic cells

CONTEXT

The Chinese herbal formula Heshouwu decoction (Heshouwuyin) has protective effects on testicular function in aging male rats, but the mechanism is unknown.

OBJECTIVE

This study investigated whether Heshouwuyin affects the testicular function of aging rats by regulating the insulin/IGF signalling pathway.

MATERIALS AND METHODS

Sixteen-month-old male Wistar rats in the Heshouwuyin group and the natural-aging group were orally administered Heshouwuyin granules (0.056 g/kg) or equivalent normal saline for 60 d. The testicular tissue of 12-month-old male Wistar rats was removed as a young control group (n = 10). The testicular tissue and spermatogenic cells were studied.

RESULTS

The immunofluorescence results revealed that the insulin receptor (INSR)- (0.056 ± 0.00548), insulin receptor substrate 1(IRS1)- (0.251 ± 0.031), IRS2 (0.230 ± 0.019)- and insulin-like growth factor 1 (IGF1)-positive cell rate (0.33 ± 0.04) in the aging group was higher than that in the young control group (0.116 ± 0.011, 0.401 ± 0.0256, 0.427 ± 0.031, 0.56 ± 0.031; p < 0.01), and the IGF-binding protein 3 (IGFBP3)-positive cell rate (0.42 ± 0.024) was lower than that (0.06 ± 0.027) in the young group (p < 0.01). The intervention of Heshouwuyin reversed the above phenomena. The qPCR and immunoblot results were consistent with those of the immunofluorescence. The same results were obtained in spermatogenic cells.

CONCLUSIONS

Our research shows that Heshouwuyin can regulate the insulin/IGF signalling pathway to improve testicular function, and provides an experimental basis for further clinical use.

AAV delivery of shRNA against IRS1 in GABAergic neurons in rat hippocampus impairs spatial memory in females and male rats

Brain insulin resistance is a major factor leading to impaired cognitive function and it is considered as the onset of Alzheimer´s disease. Insulin resistance is intimately linked to inflammatory conditions, many studies have revealed how pro-inflammatory cytokines lead to insulin resistance, by inhibiting IRS1 function. Thus, the dysfunction of insulin signaling is concomitant with inflammatory biomarkers. However, the specific effect of IRS1 impaired function in otherwise healthy brain has not been dissected out. So, we decided in our study, to study the specific role of IRS1 in the hippocampus, in the absence of comorbidities. To that end, shRNA against rat and human IRS1 was designed and tested in cultured HEK cells to evaluate mRNA levels and specificity. The best candidate sequence was encapsulated in an AAV vector (strain DJ8) under the control of the cytomegalovirus promoter and together with the green fluorescent protein gene as a reporter. AAV-CMV-shIRS1-EGFP and control AAV-CMV-EGFP were inoculated into the dorsal hippocampus of female and male Wistar rats. One month later, animals undertook a battery of behavioral paradigms evaluating spatial and social memory and anxiety. Our results suggest that females displayed increased susceptibility to AAV-shIRS1 in the novel recognition object paradigm; whereas both females and males show impaired performance in the T maze when infected with AAV-shIRS1 compared to control. Anxiety parameters were not affected by AAV-shIRS1 infection. We observed specific fluorescence within the hilum of the dentate gyrus, in immuno-characterized parvalbumin and somatostatin neurons. AAV DJ8 did not enter astrocytes. Intense green fibers were found in the fornix, mammillary bodies, and in the medial septum indicating that hippocampal efferent had been efficiently targeted by the AAV DJ8 infection. We observed that AAV-shIRS1 reduced significantly synaptophysin labeling in hippocampal-septal projections compared to controls. These results support that, small alterations in the insulin/IGF1 pathway in specific hippocampal circuitries can underlie alterations in synaptic plasticity and affect behavior, in the absence of inflammatory conditions.

Circ_0000003 promotes the proliferation and metastasis of non-small cell lung cancer cells via miR-338-3p/insulin receptor substrate 2

Background: Circular RNAs (circRNAs) play a pivotal regulatory role in a variety of tumors.Nevertheless, the detailed function of circ_0000003 in non-small cell lung cancer (NSCLC) and its regulatory mechanism remain elusive.Methods: RT-PCR was carried out to detect the expressions of circ_0000003, miR-338-3p and insulin receptor substrate 2 (IRS2)in NSCLC tissues. Besides, western blot was done to monitor IRS2 expression in NSCLC cells. The correlation between circ_0000003 and clinicopathologic characteristics of NSCLC patients was analyzed as well.CCK8 and BrdUassays were used to monitor cell proliferation; flow cytometry was used to detect apoptosis; and transwell assay was conducted to detect its migration and invasion.Moreover, dual luciferase reporter gene assay was done to verify the targeting relationship between circ_0000003 and miR-338-3p.Additionally, the effect of circ_0000003 on the growth of NSCLC cells in vivo was evaluated by tumorigenesis assay in nude mice.Results: The expression of circ_0000003 was significantly high in NSCLC tissues and cell lines, and its high expression level was notably correlated with lymph node metastasis andTNM staging.In vitro experiments showed that overexpression of circ_0000003 facilitated the proliferation, migration, invasion and inhibited the apoptosis of NSCLC cells, while the knockdown of circ_0000003 had the opposite effect.In vivo experiments revealed that knockdown of circ_0000003 impeded tumor growth and metastasis. Further, the underlying mechanism showed that circ_0000003 functioned as endogenous competitive RNA and directly targeted miR-338-3p to positively regulated IRS2 expression.Conclusion: Circ_0000003 promotes the proliferation and metastasis of NSCLC cells via modulating miR-338-3p/IRS2 axis.

Night-Shift Work Duration and Risk of Colorectal Cancer According to IRS1 and IRS2 Expression

BACKGROUND

We hypothesized that the risk of colorectal cancer in night-shift workers might be different according to insulin receptor substrate status.

METHODS

Among 77,470 eligible women having night work assessed in the Nurses' Health Study, we documented a total of 1,397 colorectal cancer cases, of which 304 or 308 had available data on IRS1 and IRS2, respectively. We used duplication-method Cox proportional hazards regression analysis for competing risks to calculate HRs and 95% confidence intervals (CI) for each colorectal cancer subtype. We measured tumor IRS1 or IRS2 expression by immunohistochemistry (IHC).

RESULTS

Compared with women who never worked night shifts, those working ≥15 years night shifts had a marginal trend of increased overall risk of colorectal cancer (P _trend = 0.06; multivariable HR = 1.20; 95% CI, 0.99-1.45). Longer duration of night-shift work was associated with a higher risk of IRS2-positive tumors (multivariable HR = 2.69; 95% CI, 1.48-4.89; P _trend = 0.001, ≥15 years night shifts vs. never) but not with IRS2-negative tumors (multivariable HR = 0.90; 95% CI, 0.54-1.51; P _trend = 0.72; P _{heterogeneity} for IRS2 = 0.008). Similarly, the corresponding multivariable HRs were 1.81 for IRS1-positive tumors (95% CI, 0.94-3.48; P _trend = 0.06) and 1.13 for IRS1-negative tumors (95% CI, 0.71-1.80; P _trend = 0.56; P _{heterogeneity} for IRS1 = 0.02).

CONCLUSIONS

Our molecular pathologic epidemiology data suggest a potential role of IRS in mediating carcinogenesis induced by night-shift work.

IMPACT

Although these findings need validation, rotating night shift might increase colorectal cancer risk in women with abnormal insulin receptor pathways.

Advances in understanding the mechanisms of evasive and innate resistance to mTOR inhibition in cancer cells

The development of drug-resistance by neoplastic cells is recognized as a major cause of targeted therapy failure and disease progression. The mechanistic (previously mammalian) target of rapamycin (mTOR) is a highly conserved Ser/Thr kinase that acts as the catalytic subunit of two structurally and functionally distinct large multiprotein complexes, referred to as mTOR complex 1 (mTORC1) and mTORC2. Both mTORC1 and mTORC2 play key roles in a variety of healthy cell types/tissues by regulating physiological anabolic and catabolic processes in response to external cues. However, a body of evidence identified aberrant activation of mTOR signaling as a common event in many human tumors. Therefore, mTOR is an attractive target for therapeutic targeting in cancer and this fact has driven the development of numerous mTOR inhibitors, several of which have progressed to clinical trials. Nevertheless, mTOR inhibitors have met with a very limited success as anticancer therapeutics. Among other reasons, this failure was initially ascribed to the activation of several compensatory signaling pathways that dampen the efficacy of mTOR inhibitors. The discovery of these regulatory feedback mechanisms greatly contributed to a better understanding of cancer cell resistance to mTOR targeting agents. However, over the last few years, other mechanisms of resistance have emerged, including epigenetic alterations, compensatory metabolism rewiring and the occurrence of mTOR mutations. In this article, we provide the reader with an updated overview of the mechanisms that could explain resistance of cancer cells to the various classes of mTOR inhibitors.