The integrity and permeability of epithelial and endothelial barriers depend on the formation of tight junctions, adherens junctions, and a junction-associated cytoskeleton. The establishment of this junction–cytoskeletal module relies on the correct folding and oligomerization of its protein components. Molecular chaperones are known regulators of protein folding and complex formation in different cellular compartments. Mammalian cells possess an elaborate chaperone network consisting of several hundred chaperones and co-chaperones. Only a small part of this network has been linked, however, to the regulation of intercellular adhesions, and the systematic analysis of chaperone functions at epithelial and endothelial barriers is lacking. This review describes the functions and mechanisms of the chaperone-assisted regulation of intercellular junctions. The major focus of this review is on heat shock protein chaperones, their co-chaperones, and chaperonins since these molecules are the focus of the majority of the articles published on the chaperone-mediated control of tissue barriers. This review discusses the roles of chaperones in the regulation of the steady-state integrity of epithelial and vascular barriers as well as the disruption of these barriers by pathogenic factors and extracellular stressors. Since cytoskeletal coupling is essential for junctional integrity and remodeling, chaperone-assisted assembly of the actomyosin cytoskeleton is also discussed.

Intestinal epithelial barrier integrity is essential for human health, and its disruption induces and exacerbates intestinal inflammatory disorders. While the epithelial cytoskeleton is critical for maintaining gut barrier-integrity, the role of septins — a family of GTP-binding, cytoskeletal proteins — is largely unknown. This highlights an important knowledge gap, as dysfunction of septins, and specifically septin 9 (SEPT9), is associated with intestinal pathologies. We determined that SEPT9 localizes to the apical junctions of intestinal epithelial cells (IECs), overlapping with both tight and adherens junctions. IEC-specific ablation of SEPT9 in mice resulted in leaky gut, due to mislocalization of junctional proteins, and increased susceptibility to experimental colitis. Consistently, SEPT9 expression was significantly reduced in intestinal mucosa of patients with inflammatory bowel disease (IBD). Using affinity-purification mass spectrometry, super-resolution imaging, and genetic KO, we determined that SEPT9 interacts with and is necessary to recruit nonmuscle myosin IIC (NMIIC) to the IEC perijunctional actomyosin belt. Loss of NMIIC also caused IEC barrier disruption. In summary, SEPT9 regulates intestinal barrier integrity by supporting the assembly of tight and adherens junctions through NMIIC recruitment to the actomyosin belt. The septin cytoskeleton safeguards the intestinal mucosa during acute inflammation, and its disruption in IBD suggests a loss of this protective function.

Background/Objectives: Patients with chronic kidney disease (CKD) frequently experience upper gastrointestinal (GI) symptoms such as epigastric discomfort, nausea, vomiting, and early satiety. These symptoms can contribute to malabsorption and intermittent dehydration, ultimately accelerating the decline of residual renal function. However, they are often attributed to electrolyte imbalances or fluid overload, and the possibility of underlying gastroparesis is frequently overlooked by both patients and caregivers. This study aimed to provide new insights into the relationship between CKD and gastroparesis through a dual, population-based retrospective analysis that incorporated both inpatient and outpatient data. Methods: From the National Inpatient Sample (NIS) database, 3,579,372 patients diagnosed with gastroparesis, with or without CKD, were identified. From the TriNetX database, 6,263,251 patients presenting to ambulatory clinics with a chief complaint of nausea and vomiting were included. In both datasets, gastroparesis was defined using ICD-10-CM codes. Results: In the inpatient cohort, the prevalence of gastroparesis increased in proportion to CKD severity, with the highest likelihood observed in advanced stages compared to patients without CKD. An increased risk of gastroparesis was also observed in the outpatient CKD cohort from an independent TriNetX database, while the severity-dependent phenotype was not consistent. However, after rigorous propensity score matching, advanced CKD remained significantly associated with higher odds of gastroparesis, with the greatest risk observed in patients with end-stage renal disease (ESRD). Conclusions: These findings, validated across two large and independent datasets representing both inpatient and outpatient populations, demonstrate a consistent association between CKD severity and gastroparesis. They highlight the importance of routine screening and early management of gastroparesis in patients with advanced CKD to improve outcomes and reduce disease burden for CKD patients with sign of early satiety or dyspepsia.