Circulating PANDER concentration is associated with increased HbA1c and fasting blood glucose in Type 2 diabetic subjects

The role of PANDER and its interplay with IL-6 in the regulation of GLP-1 secretion

Glucose-like peptide-1 (GLP-1) is a vital hormone in the intestines that regulates glucose metabolism. Although pancreatic-derived factor (PANDER) overexpression is known to suppress GLP-1, the underlying mechanisms are unclear. Our study aims to uncover how PANDER influences GLP-1 synthesis and secretion. We established a PANDER overexpression model in STC-1 intestinal cells, confirming its inhibitory effect on GLP-1 secretion. This effect was reversed in PANDER-knockout cells. Additionally, a negative correlation between PANDER and GLP-1 was observed in patients with a history of gestational diabetes. Subsequently, through whole transcriptome gene sequencing in PANDER-overexpressed STC-1 cells, we discovered that the activation of IL-6 and its related STAT3 signaling pathway was significantly inhibited, and this finding was validated by Western blotting and quantitative reverse transcription PCR. Finally, rescue experiments confirmed that the IL-6-related STAT3/Akt/GSK3β/β-catenin signaling pathway mediates the negative regulatory effect of PANDER on GLP-1. Taken together, our data identify IL-6 as a bridge connecting PANDER and GLP-1 in the STC-1 cells, demonstrating potential therapeutic targets for diabetes treatment by targeting the PANDER-IL-6-GLP-1 axis.

Relationship between Cytokines and Metabolic Syndrome Components: Role of Pancreatic-Derived Factor, Interleukin-37, and Tumor Necrosis Factor-α in Metabolic Syndrome Patients

The metabolic syndrome (MetS) is a serious public health issue that affects people all over the world. Notably, insulin resistance, prothrombotic activity, and inflammatory state are associated with MetS. This study aims to explore the relationship between cytokines and tumor necrosis factor-α (TNF-α), pancreatic-derived factor (PANDER), and interleukin (IL-)-37 and the accumulation of MetS components. Eligible participants were divided into four groups as follows: group 1, patients with dyslipidemia; group 2, patients with dyslipidemia and obesity; group 3, patients with dyslipidemia, obesity, and hypertension; and group 4, patients with dyslipidemia, obesity, hypertension, and hyperglycemia. This study exhibited that serum levels of TNF-α and PANDER were significantly elevated (P < 0.001) in the MetS groups, while IL-37 level and IL-37 mRNA expression were significantly decreased (P < 0.001) relative to healthy controls. Moreover, this study has revealed significant correlations (P < 0.001) between MetS components and TNF-α, PANDER, and IL-37 levels in MetS patients. The aforementioned results suggested the association between the proinflammatory cytokine (TNF-α and PANDER) and anti-inflammatory cytokine (IL-37) with the accumulation of MetS components. Hence, the overall outcome indicated that PANDER and IL-37 may be considered novel biomarkers associated with increased risk of MetS and can be used as a promising therapeutic target in preventing, ameliorating, and treating metabolic disorders.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12291-022-01079-z.

Inter-organ crosstalk during development and progression of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by tissue-specific insulin resistance and pancreatic β-cell dysfunction, which result from the interplay of local abnormalities within different tissues and systemic dysregulation of tissue crosstalk. The main local mechanisms comprise metabolic (lipid) signalling, altered mitochondrial metabolism with oxidative stress, endoplasmic reticulum stress and local inflammation. While the role of endocrine dysregulation in T2DM pathogenesis is well established, other forms of inter-organ crosstalk deserve closer investigation to better understand the multifactorial transition from normoglycaemia to hyperglycaemia. This narrative Review addresses the impact of certain tissue-specific messenger systems, such as metabolites, peptides and proteins and microRNAs, their secretion patterns and possible alternative transport mechanisms, such as extracellular vesicles (exosomes). The focus is on the effects of these messengers on distant organs during the development of T2DM and progression to its complications. Starting from the adipose tissue as a major organ relevant to T2DM pathophysiology, the discussion is expanded to other key tissues, such as skeletal muscle, liver, the endocrine pancreas and the intestine. Subsequently, this Review also sheds light on the potential of multimarker panels derived from these biomarkers and related multi-omics for the prediction of risk and progression of T2DM, novel diabetes mellitus subtypes and/or endotypes and T2DM-related complications.

The cytokine FAM3B/PANDER is an FGFR ligand that promotes posterior development in Xenopus

How distinct body regions form along the anterior–posterior axis in vertebrate embryos is a fascinating and incompletely understood developmental process. FAM3B/PANDER is a secreted protein involved in glucose metabolism and type 2 diabetes pathogenesis in mammals, but its receptor has been unknown. Here, we report that FAM3B binds to transmembrane fibroblast growth factor receptors (FGFRs) and activates their downstream signaling pathway. In frog embryos, gain-of-function of FAM3B impairs head development and induces ectopic tail-like structures, whereas loss-of-function of FAM3B promotes head development. FGFR is required downstream of FAM3B for head-to-tail patterning. Our results reveal that FAM3B functions by activating the FGFR pathway in frog embryos and mammalian cells and shed light on its possible role in human diseases.

Fibroblast growth factor (FGF)/extracellular signal-regulated kinase (ERK) signaling plays a crucial role in anterior–posterior (A–P) axial patterning of vertebrate embryos by promoting posterior development. In our screens for novel developmental regulators in Xenopus embryos, we identified Fam3b as a secreted factor regulated in ectodermal explants. Family with sequence similarity 3 member B (FAM3B)/PANDER (pancreatic-derived factor) is a cytokine involved in glucose metabolism, type 2 diabetes, and cancer in mammals. However, the molecular mechanism of FAM3B action in these processes remains poorly understood, largely because its receptor is still unidentified. Here we uncover an unexpected role of FAM3B acting as a FGF receptor (FGFR) ligand in Xenopus embryos. fam3b messenger RNA (mRNA) is initially expressed maternally and uniformly in the early Xenopus embryo and then in the epidermis at neurula stages. Overexpression of Xenopus fam3b mRNA inhibited cephalic structures and induced ectopic tail-like structures. Recombinant human FAM3B protein was purified readily from transfected tissue culture cells and, when injected into the blastocoele cavity, also caused outgrowth of tail-like structures at the expense of anterior structures, indicating FGF-like activity. Depletion of fam3b by specific antisense morpholino oligonucleotides in Xenopus resulted in macrocephaly in tailbud tadpoles, rescuable by FAM3B protein. Mechanistically, FAM3B protein bound to FGFR and activated the downstream ERK signaling in an FGFR-dependent manner. In Xenopus embryos, FGFR activity was required epistatically downstream of Fam3b to mediate its promotion of posterior cell fates. Our findings define a FAM3B/FGFR/ERK-signaling pathway that is required for axial patterning in Xenopus embryos and may provide molecular insights into FAM3B-associated human diseases.

FAM3B (PANDER) functions as a co-activator of FOXO1 to promote gluconeogenesis in hepatocytes

FAM3B, also known as PANcreatic DERived factor (PANDER), promotes gluconeogenesis and lipogenesis in hepatocytes. However, the underlying mechanism(s) still remains largely unclear. This study determined the mechanism of PANDER-induced FOXO1 activation in hepatocytes. In mouse livers and cultured hepatocytes, PANDER protein is located in both the cytoplasm and nucleus. Nuclear PANDER distribution was increased in the livers of obese mice. In cultured mouse and human hepatocytes, PANDER was co-localized with FOXO1 in the nucleus. PANDER directly interacted with FOXO1 in mouse and human hepatocytes. PANDER overexpression enhanced PANDER-FOXO1 interaction, and detained FOXO1 in the nucleus upon insulin stimulation in hepatocytes. With the increase in PANDER-FOXO1 interaction, PANDER overexpression upregulated the expression of gluconeogenic genes and promoted gluconeogenesis in both human and mouse hepatocytes. Luciferase reporter assays further revealed that PANDER augmented the transcriptional activity of FOXO1 on gluconeogenic genes. Moreover, PANDER overexpression also interfered the binding of AS1842856, a specific FOXO1 inhibitor, with FOXO1, and impaired its inhibitory effects on gluconeogenic gene expression and gluconeogenesis in hepatocytes. siRNA mediated-silencing of FOXO1 inhibited PANDER-promoted gluconeogenic gene expression and glucose production in hepatocytes. In conclusion, PANDER protein is abundantly present in the nucleus, where it functions as a new co-activator of FOXO1 to induce gluconeogenic gene expression in hepatocytes.