Biology subjects

Kamijo, K.

Publications and source records attributed to Kamijo, K..

3 recordsLinked to original sources

bioRxiv2026

Loss of stromal VEGFR2 protects against ischemic acute kidney injury by preserving the renal microvasculature

Injury to the renal microvasculature, particularly the peritubular capillaries, is a defining feature of ischemic acute kidney injury (AKI). Vascular endothelial growth factor receptor 2 (VEGFR2) signaling is a central regulator of endothelial cell survival, proliferation, migration, and vascular remodeling. Although VEGFR2 has been extensively studied in endothelial cells, accumulating evidence suggests that it is also expressed in non-endothelial cell populations, where it may regulate tissue-specific responses to injury. Here, using publicly available single-cell or single-nucleus RNA sequencing data from human and mouse kidneys, we identified VEGFR2 expression in renal stromal populations. Immunostaining further detected phosphorylated VEGFR2 in the renal stroma of mouse kidneys. To determine the functional role of stromal VEGFR2, we utilized renal stroma-specific Vegfr2 KO mice. Stromal VegfR2 deletion attenuated kidney injury after renal ischemia/reperfusion injury (IRI), as evidenced by reduced tubular injury, preservation of renal blood flow, decreased endothelial oxidative stress, and maintenance of the renal microvasculature. Stromal Vegfr2-deficient kidneys also exhibited increased Angpt1 and Tek levels, enhanced endothelial ERK activation, and preserved endothelial adherent junctions. Taken together, these findings reveal an unexpected role for VEGFR2 in the renal stromal lineage and highlight stromal-endothelial communication as a potential therapeutic target for preserving microvascular integrity after ischemic AKI.

pathology↗

bioRxiv2025

Reliable Detection of SGLT2 Protein through Knockout-based Antibody Characterization and Optimized Procedures

IntroductionSodium-glucose cotransporter 2 (SGLT2) is a key mediator of renal glucose reabsorption. Its pharmacological inhibition exerts cardio- and reno-protective benefits. Despite widespread clinical interest, reliable detection of SGLT2 protein remains challenging due to concerns regarding the specificity of available antibodies. MethodsThis study assessed the specificity of eight commercially available anti-SGLT2 antibodies by immunohistochemistry and Western blotting. Genetically engineered Sglt2-deficient mice and rats, generated via clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technology, were employed as definitive negative controls. Additionally, human kidney tissues, including renal cell carcinoma samples, were analyzed. ResultsAmong the antibodies tested, few exhibited robust specificity, characterized by substantial immunostaining with minimal background in wild-type kidney tissues and complete absence of staining in Sglt2-deficient samples. In renal cell carcinoma samples, a validated antibody detected SGLT2 immunostaining in proximal tubules of non-tumor regions but not in tumor areas. Subcellular localization studies revealed that SGLT2 was enriched within proximal tubular microvilli, partially overlapping with its co-factor PDZK1IP1 (MAP17). LRP2 (megalin) and NHE3 were placed at the microvillar base and did not colocalize with SGLT2. Western blotting identified a specific SGLT2 band at approximately 55 kDa in kidney lysates using several antibodies under optimized procedures. This band was shifted to approximately 45 kDa after enzymatic removal of N-linked glycans. One antibody detected a weak band at the same molecular mass even in kidney lysates from Sglt2-deficient rodents. ConclusionsConsiderable variability exists in the specificity of commercially available anti-SGLT2 antibodies. Only a limited number of antibodies are suitable for reliable detection of SGLT2 in rodent and human samples. Rigorous antibody characterization, including the use of knockout controls and optimized experimental conditions, is essential to ensure reproducibility and prevent misinterpretation in studies investigating the biological and pathophysiological roles of SGLT2.

molecular biology↗

bioRxiv2018

A genetically encoded probe for imaging HA-tagged protein translation, localization, and dynamics in living cells and animals

To expand the toolbox of imaging in living cells, we have engineered a new single chain variable fragment (scFv) that binds the classic linear HA epitope with high affinity and specificity in vivo. The resulting probe, which we call the HA frankenbody, is capable of lighting up in multiple colors HA-tagged nuclear, cytoplasmic, and membrane proteins in diverse living cell types. The HA frankenbody also enables state-of-the-art single-molecule experiments, which we demonstrate by tracking single mRNA translation dynamics in living U2OS cells and neurons. In combination with the SunTag, we track two mRNA species simultaneously to demonstrate comparative single-molecule studies of translation can now be done with genetically encoded tools alone. Finally, we use the HA frankenbody to precisely quantify the expression of HA tagged proteins in developing zebrafish embryos. The versatility of the HA frankenbody makes it a powerful new tool for imaging protein dynamics in vivo.\n\nOne-sentence summaryA genetically encodable intracellular single-chain variable fragment that selectively binds the HA epitope (YPYDVPDYA) with high affinity in living cells and organisms can be used to quantify HA-tagged protein translation, localization, and dynamics.

cell biology↗