Association of TRPV5, CASR, and CALCR genetic variants with kidney stone disease susceptibility in Egyptians through main effects and gene–gene interactions

miR-148b-5p regulates hypercalciuria and calcium-containing nephrolithiasis

Calcium-containing stones represent the most common form of kidney calculi, frequently linked to idiopathic hypercalciuria, though their precise pathogenesis remains elusive. This research aimed to elucidate the molecular mechanisms involved by employing urinary exosomal microRNAs as proxies for renal tissue analysis. Elevated miR-148b-5p levels were observed in exosomes derived from patients with kidney stones. Systemic administration of miR-148b-5p in rat models resulted in heightened urinary calcium excretion, whereas its inhibition reduced stone formation. RNA immunoprecipitation combined with deep sequencing identified miR-148b-5p as a suppressor of calcitonin receptor (Calcr) expression, thereby promoting urinary calcium excretion and stone formation. Mice deficient in Calcr in distal epithelial cells demonstrated elevated urinary calcium excretion and renal calcification. Mechanistically, miR-148b-5p regulated Calcr through the circRNA-83536/miR-24-3p signaling pathway. Human kidney tissue samples corroborated these results. In summary, miR-148b-5p regulates the formation of calcium-containing kidney stones via the circRNA-83536/miR-24-3p/Calcr axis, presenting a potential target for novel therapeutic interventions to prevent calcium nephrolithiasis.

Ca2+-sensing receptor-TRP channel-mediated Ca2+ signaling: Functional diversity and pharmacological complexity

The Ca2+-sensing receptor (CaSR) is a G-protein-coupled receptor activated by elevated concentrations of extracellular Ca2+, and was initially known for its regulation of parathyroid hormone (PTH) release. Ubiquitous expression of CaSR in different tissues and organs was later noted and CaSR participation in various physiological functions was demonstrated. Accumulating evidence has suggested that CaSR functionally interacts with transient receptor potential (TRP) channels, which are mostly non-selective cation channels involved in sensing temperature, pain and stress. This review describes the interactions of CaSR with TRP channels in diverse cell types to trigger a variety of biological responses. CaSR has been known to interact with different types of G proteins. Possible involvements of G proteins, other signaling and scaffolding protein intermediates in CaSR-TRP interaction are discussed. In addition, an attempt will be made to extend the current understanding of biased agonism of CaSR.

CALCR exacerbates renal cell carcinoma progression via stabilizing CD44

The calcitonin receptor (CALCR) is an essential protein for maintaining calcium homeostasis and has been reported to be upregulated in numerous cancers. However, the molecular role of CALCR in renal cell carcinoma (RCC) is not well understood. In this study, we identified the overexpression of CALCR in RCC using human tissue chip by immunohistochemical (IHC) staining, which was associated with a poor prognosis. Functionally, CALCR depletion inhibited RCC cell proliferation and migration, and induced cell apoptosis and cycle arrest. CALCR is also essential for in vivo tumor formation. Mechanistically, we demonstrated that CALCR could directly bind to CD44, preventing CD44 protein degradation and thereby upregulating CD44 expression. Moreover, a deficiency in CD44 significantly attenuated the promoting role of CALCR on RCC cell proliferation, migration and anti-apoptosis capacities. Collectively, CALCR exacerbates RCC progression via stabilizing CD44, offering a fundamental basis for considering CALCR as a potential therapeutic target for RCC patients.

Targeting TRP channels: recent advances in structure, ligand binding, and molecular mechanisms

Transient receptor potential (TRP) channels are a large and diverse family of transmembrane ion channels that are widely expressed, have important physiological roles, and are associated with many human diseases. These proteins are actively pursued as promising drug targets, benefitting greatly from advances in structural and mechanistic studies of TRP channels. At the same time, the complex, polymodal activation and regulation of TRP channels have presented formidable challenges. In this short review, we summarize recent progresses toward understanding the structural basis of TRP channel function, as well as potential ligand binding sites that could be targeted for therapeutics. A particular focus is on the current understanding of the molecular mechanisms of TRP channel activation and regulation, where many fundamental questions remain unanswered. We believe that a deeper understanding of the functional mechanisms of TRP channels will be critical and likely transformative toward developing successful therapeutic strategies targeting these exciting proteins. This endeavor will require concerted efforts from computation, structural biology, medicinal chemistry, electrophysiology, pharmacology, drug safety and clinical studies.