Cav 3.2 T-type calcium channel regulates mouse platelet activation and arterial thrombosis

Thymidine phosphorylase participates in platelet activation and promotes inflammation in rheumatoid arthritis

The elevated risk of cardiovascular disease (CVD) associated with inflammatory rheumatic diseases has long been recognized. Patients with established rheumatoid arthritis (RA) have a higher mortality rate compared to the general population due to abnormal platelet activation. Thymidine phosphorylase (TYMP) plays a crucial role in platelet activation and thrombosis, following bridging the link between RA and CVD. Data from Gene Expression Omnibus (GEO) database exhibited that TYMP levels were highly expressed in synovial tissues, immune cells, and whole blood of RA patients especially those with high levels of inflammation. Platelet count (PLT) and plateletcrit (PCT) were positively correlated with the severity of inflammation in rheumatoid arthritis while platelet distribution width (PDW) and mean platelet volume (MPV) were adverse. Levels of CD62P and TYMP in platelets of patients with active RA were significantly elevated compared to patients in the inactive phase. In vivo experiments showed that reducing TYMP expression levels of platelets could relieve inflammation in Adjuvant-Induced Arthritis (AIA) mice. Platelet activation was significantly elevated in AIA model mice, along with increased levels of intracellular calcium (Ca2+), reactive oxygen species (ROS), and decreased Mitochondrial Membrane Potential (ΔΨm). However, treatment with Tipiracil hydrochloride (TPI) or the utilization of Tymp-/- mice reversed these effects. In vitro stimulation of wild type (WT) mouse platelets with tumor necrosis factor-alpha (TNF-α) promoted platelet activation, elevated levels of intracellular Ca2+as well as ROS while decreased ΔΨm. Platelets of WT mice treated with TPI or platelets of Tymp-/- mice exhibited the adverse results. Our study illustrates the vital role of TYMP in promoting RA inflammation and platelet activation, suggesting that TYMP may be a potential therapeutic target for RA.

T-Type Voltage-Gated Calcium Channels: Potential Regulators of Smooth Muscle Contractility

Emerging evidence has indicated a possible link between attenuation of contractility in aortic smooth muscle cells and pathogenesis of aortic dissection, as revealed through comprehensive, multi-omic analyses of familial thoracic aortic aneurysm and dissection models. While L-type voltage-gated calcium channels have been extensively investigated for their roles in smooth muscle contraction, more recent investigations have suggested that downregulation of T-type voltage-gated calcium channels, rather than their L-type counterparts, may be more closely associated with impaired contractility observed in vascular smooth muscle cells. This review provides a detailed examination of T-type voltage-gated calcium channels, highlighting their structure, electrophysiology, biophysics, expression patterns, functional roles, and potential mechanisms through which their downregulation may contribute to reduced contractile function. Furthermore, the application of multi-omic approaches in investigating calcium channels is discussed.

The T-Type Calcium Channel CACNA1H is Required for Smooth Muscle Cytoskeletal Organization During Tracheal Tubulogenesis

Abnormalities of tracheal smooth muscle (SM) formation are associated with several clinical disorders including tracheal stenosis and tracheomalacia. However, the cellular and molecular mechanisms underlying tracheal SM formation remain poorly understood. Here, it is shown that the T-type calcium channel CACNA1H is a novel regulator of tracheal SM formation and contraction. Cacna1h in an ethylnitrosourea forward genetic screen for regulators of respiratory disease using the mouse as a model is identified. Cacna1h mutants exhibit tracheal stenosis, disorganized SM and compromised tracheal contraction. CACNA1H is essential to maintain actin polymerization, which is required for tracheal SM organization and tube formation. This process appears to be partially mediated through activation of the actin regulator RhoA, as pharmacological increase of RhoA activity ameliorates the Cacna1h-mutant trachea phenotypes. Analysis of human tracheal tissues indicates that a decrease in CACNA1H protein levels is associated with congenital tracheostenosis. These results provide insight into the role for the T-type calcium channel in cytoskeletal organization and SM formation during tracheal tube formation and suggest novel targets for congenital tracheostenosis intervention.

Iron deficiency anemia and platelet dysfunction: A comprehensive analysis of the underlying mechanisms

AIMS

This research aimed to study the changes in platelet function and their underlying mechanisms in iron deficiency anemia.

MAIN METHODS

Initially, we evaluated platelet function in an IDA mice model. Due to the inability to accurately reduce intracellular Fe2+ concentrations, we investigated the impact of Fe2+ on platelet function by introducing varying concentrations of Fe2+. To probe the underlying mechanism, we simultaneously examined the dynamics of calcium in the cytosol, and integrin αIIbβ3 activation in Fe2+-treated platelets. Ferroptosis inhibitors Lip-1 and Fer-1 were applied to determine whether ferroptosis was involved in this process.

KEY FINDINGS

Our study revealed that platelet function was suppressed in IDA mice. Fe2+ concentration-dependently facilitated platelet activation and function in vitro. Mechanistically, Fe2+ promoted calcium mobilization, integrin αIIbβ3 activation, and its downstream outside-in signaling. Additionally, we also demonstrated that ferroptosis might play a role in this process.

SIGNIFICANCE

Our data suggest an association between iron and platelet activation, with iron deficiency resulting in impaired platelet function, while high concentrations of Fe2+ contribute to platelet activation and function by promoting calcium mobilization, αIIbβ3 activation, and ferroptosis.

The T-type calcium channelosome

T-type calcium channels perform crucial physiological roles across a wide spectrum of tissues, spanning both neuronal and non-neuronal system. For instance, they serve as pivotal regulators of neuronal excitability, contribute to cardiac pacemaking, and mediate the secretion of hormones. These functions significantly hinge upon the intricate interplay of T-type channels with interacting proteins that modulate their expression and function at the plasma membrane. In this review, we offer a panoramic exploration of the current knowledge surrounding these T-type channel interactors, and spotlight certain aspects of their potential for drug-based therapeutic intervention.