Hepatic carbohydrate and lipid metabolism is strictly regulated by hormones such as insulin, glucagon, cortisol, and adrenaline, dynamically adapting to diet and stress. Metabolic zonation, a key feature of liver function, has been studied for decades. It refers to the spatial arrangement of hepatocytes with distinct metabolic roles along the portal-to-central vein axis, shaped by nutrient and oxygen gradients, as well as signaling molecules. However, traditional methods have struggled to reveal the spatial regulation of gene expression and signaling within these zones. Recent advances in single-cell and spatial omics technologies now allow detailed analysis of gene expression, signaling pathways, and cell-cell interactions with spatial resolution, providing new insights beyond classical models. Metabolic zonation research is rapidly advancing, and the concept of immune zonation, describing the spatial distribution of immune cells, has gained attention for its role in liver metabolism. These findings have improved our understanding of metabolic changes in conditions like fatty liver disease and diabetes. However, many questions remain, including the dynamic effects of diet and hormones and disease-related alterations. This review summarizes past and recent findings on metabolic zonation, explores the role of immune zonation and hormonal regulation, and discusses the latest technologies and future challenges.

Hypercalcemia, a common electrolyte imbalance, requires accurate differential diagnosis to guide appropriate management. PTH-dependent hypercalcemia, predominantly caused by primary hyperparathyroidism (PHPT) and rarely by familial hypocalciuric hypercalcemia (FHH)—mainly due to heterozygous loss-of-function mutations in the CASR gene encoding the calcium-sensing receptor (CaSR)—now includes acquired hypocalciuric hypercalcemia (AHH) as an emerging disease entity. Initially identified as analogous to FHH, AHH was characterized by blocking antibodies targeting the CaSR. However, our research has identified unique autoantibodies, termed biased antibodies, that paradoxically regulate signaling by enhancing Gq activity while suppressing Gi activity. Investigating their mechanisms has not only provided insights into specific treatments for AHH but also suggested novel activation mechanisms and binding sites of the CaSR, offering a fresh perspective on the regulation of PTH secretion. In clinical practice, recognizing AHH is crucial. A key diagnostic feature is fluctuating serum calcium levels, making a wait-and-see approach viable for mild hypercalcemia. Conversely, hypercalcemic crises necessitate immediate diagnostic and therapeutic interventions. The most important diagnostic clue to differentiate AHH from PHPT is hypermagnesemia. Additionally, AHH is less likely to involve AVP resistance (i.e., nephrogenic diabetes insipidus) and acute kidney injury (AKI), owing to preserved medullary hyperosmolarity and minimal interference with AVP signaling. Finally, a relatively low PTH level serves as another distinguishing feature. Based on these observations, we propose a novel diagnostic guide for PTH-dependent hypercalcemia. We anticipate that this guide will help identify previously undiagnosed AHH cases in routine practice, enabling timely and effective management of this rare condition.

The parathyroid glands (PTGs) regulate calcium metabolism by secreting parathyroid hormone (PTH). Patients with hypoparathyroidism require lifelong replacement therapy, which is associated with risks of chronic kidney disease, bone fractures, and a reduced quality of life. Generating PTGs from pluripotent stem cells (PSCs) offers a potential regenerative therapy for this condition. This review first explains PTG organogenesis, followed by an overview of both in vitro and in vivo approaches to PTG generation. In vitro studies have successfully induced PTH-expressing parathyroid cells from human PSCs. However, challenges remain, particularly in achieving sufficient PTH secretion and functional efficacy in vivo. Meanwhile, an in vivo organ generation technique known as blastocyst complementation has successfully produced functional PTGs in rodents. However, whether this technology can be applied using human PSCs and animal embryos remains unclear. Pluripotent stem cell-derived PTGs hold promise for both clinical applications and basic research, but further advancements will be necessary to overcome existing challenges in this field.

Glucose-dependent insulinotropic polypeptide (GIP) is secreted by enteroendocrine K cells, primarily located in the upper small intestine, in response to food intake and plays a significant role in the postprandial regulation of nutrient metabolism. Although the importance of GIP in metabolic regulation has long been recognized, progress in developing GIP as a therapeutic target has been limited. However, the GIP/GIP receptor (GIPR) axis has garnered increasing attention in recent years. Emerging evidence suggests that dual GIP/GLP-1 receptor agonists and triple GIP/GLP-1/glucagon receptor agonists provide beneficial metabolic effects in individuals with type 2 diabetes and obesity. In this review, we outline the physiological roles of GIP, detailing the mechanisms of GIP secretion from K cells in response to macronutrients, its actions on key target organs involved in metabolic regulation, and ongoing developments in its therapeutic applications.

Hypopituitarism, characterized by reduced secretion of pituitary hormones, profoundly impacts systemic metabolic homeostasis and quality of life. Its etiology ranges from congenital anomalies in pituitary development to acquired conditions involving inflammation and autoimmune processes. Despite advances in understanding its pathogenesis, diagnostic challenges persist, particularly in cases with complex extra-pituitary manifestations or novel genetic variations. Congenital hypopituitarism often stems from disruptions in transcription factors and signaling pathways critical for pituitary organogenesis. Emerging studies employing next-generation sequencing and developmental biology techniques have revealed new genetic loci and mechanisms implicated in combined pituitary hormone deficiency. However, the pathogenesis of most congenital cases remains elusive, underscoring the need for functional and phenotypic analyses of novel variants. Acquired hypopituitarism, frequently associated with pituitary tumors or systemic diseases, has also been increasingly linked to autoimmune mechanisms. Notably, the concept of paraneoplastic autoimmune hypophysitis has emerged, highlighting malignancy-driven immune responses as a novel etiological framework. Investigations into immune checkpoint inhibitor-related hypophysitis and anti-PIT-1 hypophysitis exemplify the intricate interplay between tumor immunity and endocrine dysfunction, suggesting shared mechanisms involving ectopic antigen expression and autoimmunity. This review synthesizes recent insights into the genetic, developmental, and immunological underpinnings of hypopituitarism. By exploring both congenital and acquired etiologies, we aim to bridge gaps in the current understanding of this complex disorder and provide a foundation for improved diagnostic and therapeutic strategies. Future perspectives emphasize the integration of advanced genetic tools, deeper exploration of tumor-immunity interactions, and a heightened focus on extra-pituitary phenotypes to refine clinical practice and enhance patient outcomes.