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T follicular helper (Tfh) cells are essential for the development of germinal center B cells and high-affinity antibody-producing B cells in humans and mice. Here, we identify the guanine nucleotide exchange factor (GEF) Rin-like (Rinl) as a negative regulator of Tfh generation. Loss of Rinl leads to an increase of Tfh in aging, upon in vivo immunization and acute LCMV Armstrong infection in mice, and in human CD4+ T cell in vitro cultures. Mechanistically, adoptive transfer experiments using WT and Rinl-KO naïve CD4+ T cells unraveled T cell-intrinsic GEF-dependent functions of Rinl. Further, Rinl regulates CD28 internalization and signaling, thereby shaping CD4+ T cell activation and differentiation. Thus, our results identify the GEF Rinl as a negative regulator of global Tfh differentiation in an immunological context and species-independent manner, and furthermore, connect Rinl with CD28 internalization and signaling pathways in CD4+ T cells, demonstrating for the first time the importance of endocytic processes for Tfh differentiation.
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http://dx.doi.org/10.1084/jem.20221466 | DOI Listing |
World J Urol
September 2025
Department of Pharmacology, Faculty of Medical Sciences, University of Campinas (UNICAMP), Campinas, Sao Paulo, Brazil.
Purpose: To evaluate the impact of MRP inhibition by MK571 on prostate hypercontractility in diet-induced obesity, based on the hypothesis that this intervention enhances intracellular cAMP and cGMP signaling.
Methods: Adult C57BL/6 mice were divided into three groups: (i) lean, (ii) obese, and (iii) obese + MK571 (5 mg/kg/day, 14 days). The prostate was isolated for immunohistochemistry, biochemistry and functional assays.
Allergol Immunopathol (Madr)
September 2025
Department of Respiratory and Critical Care Medicine, the Wenzhou Central Hospital and Dingli Clinical Institute of Wenzhou Medical University, Wenzhou, Zhejiang, China.
Background: Acute lung injury (ALI) is a critical clinical condition with high mortality, necessitating the development of more effective therapeutic strategies. Rho Guanine nucleotide dissociation inhibitor (GDP) beta (ARHGDIB) has been shown to exert protective effects against noxious stimuli in various disease models.
Objective: In this study, we investigated whether ARHGDIB knockdown had a protective effect on lipopolysaccharide (LPS)-induced injury in alveolar epithelial cells and elucidated its underlying molecular mechanisms.
J Cell Biol
October 2025
Cell and Systems Biology Program, Hospital for Sick Children, Toronto, Canada.
Mitochondria continually undergo fission to maintain their network and health. Nascent fission sites are marked by the ER, which facilitates actin polymerization to drive calcium flux into the mitochondrion and constrict the inner mitochondrial membrane. Septins are a major eukaryotic cytoskeleton component that forms filaments that can both directly and indirectly modulate other cytoskeleton components, including actin.
View Article and Find Full Text PDFFront Endocrinol (Lausanne)
September 2025
Pediatric Endocrinology Department, Obesity, Endocrine and Metabolism Center, King Fahd Medical City, Riyadh, Saudi Arabia.
McCune-Albright syndrome (MAS) is a rare genetic disorder characterized by a triad of café-au-lait spots, fibrous dysplasia, and hyperfunctioning endocrinopathies, resulting from a mosaic mutation in the guanine nucleotide-binding protein (GNAS) gene. This case report presents the long-term follow-up of an eight-year-old girl diagnosed with MAS, who first presented at 22 months of age with skin pigmentation, hyperthyroidism, and precocious puberty, later developing additional features such as fibrous dysplasia and growth hormone excess. This complex presentation of MAS-featuring more than two hyperfunctioning endocrinopathies along with fibrous dysplasia-has rarely been described in the literature.
View Article and Find Full Text PDFBiology (Basel)
August 2025
Department of Oral Biology, The Dental College of Georgia, Augusta University, Augusta, GA 30912, USA.
The retina is highly sensitive to oxygen and blood supply, and hypoxia plays a key role in retinal diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). Müller glial cells, which are essential for retinal homeostasis, respond to injury and hypoxia with reactive gliosis, characterized by the upregulation of the glial fibrillary acidic protein (GFAP) and vimentin, cellular hypertrophy, and extracellular matrix changes, which can impair retinal function and repair. The retinal pigment epithelium (RPE) supports photoreceptors, forms part of the blood-retinal barrier, and protects against oxidative stress; its dysfunction contributes to retinal degenerative diseases such as AMD, retinitis pigmentosa (RP), and Stargardt disease (SD).
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