Selective inhibition of neuronal Cav3.3 T-type calcium channels by TAT-based channel peptide

CaV3.3 T-type calcium channels contribute to carboplatin resistance in retinoblastoma

Carboplatin resistance in retinoblastoma, an aggressive pediatric intraocular tumor, remains a major clinical challenge in treatment. This study elucidates the role of T-type calcium channels in carboplatin resistance using human retinoblastoma Y79 cells. We generated carboplatin-resistant Y79 (Y79CR) cells and characterized their electrophysiological properties. Patch-clamp recordings revealed a subpopulation of enlarged Y79CR cells (i.e., giant cells) with hyperpolarized resting membrane potentials, reduced input resistance, and increased T-type calcium currents. Quantitative RT-PCR analysis confirmed upregulation of CaV3.3 mRNA in Y79CR cells, identifying CaV3.3 as the predominant channel mediating these currents. Pharmacological inhibition of CaV3.3 using ML218 and TAT-C3P attenuated the sustained currents and partially restored carboplatin sensitivity, as evidenced by decreased IC50 values in Y79CR cells. These findings demonstrate a critical role for T-type calcium channels, particularly CaV3.3, in mediating chemoresistance in retinoblastoma. Our results suggest that targeting these channels may provide a potential strategy to enhance the efficacy of carboplatin-based therapy in retinoblastoma treatment.

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 L-type calcium channel CaV1.3: A potential target for cancer therapy

Cancer remains a prominent cause to life expectancy, and targeted cancer therapy stands as a pivotal approach in contemporary therapy. Calcium (Ca2+) signalling plays a multifaceted role in cancer progression, such as proliferation, invasion and distant metastasis. Otherwise, it also exerts an important influence on the efficacy of clinical treatment, including cancer therapy resistance. In this review we discuss the role of the L-type calcium channel CaV1.3 (calcium voltage-gated channel subunit alpha1 D) in different types of cancers, highlighting its potential as a therapeutic target for certain cancer types. The development of selective blockers of the CaV1.3 channel has been of great interest and is expected to be a new option for the treatment of cancers such as prostate cancer and endometrial cancer. We present the pharmacological properties of CaV1.3 and the current status of selective blocker development, and analyse the challenges and possible directions for breakthroughs in the development of tailored medicines.

CaV3.3 Channelopathies

CaV3.3 is the third member of the low-voltage-activated calcium channel family and the last to be recognized as disease gene. Previously, CACNA1I, the gene encoding CaV3.3, had been described as schizophrenia risk gene. More recently, de novo missense mutations in CACNA1I were identified in patients with variable degrees of neurodevelopmental disease with and without epilepsy. Their functional characterization indicated gain-of-function effects resulting in increased calcium load and hyperexcitability of neurons expressing CaV3.3. The amino acids mutated in the CaV3.3 disease variants are located in the vicinity of the channel's activation gate and thus are classified as gate-modifying channelopathy mutations. A persistent calcium leak during rest and prolonged calcium spikes due to increased voltage sensitivity of activation and slowed kinetics of channel inactivation, respectively, may be causal for the neurodevelopmental defects. The prominent expression of CaV3.3 in thalamic reticular nucleus neurons and its essential role in generating the rhythmic thalamocortical network activity are consistent with a role of the mutated channels in the etiology of epileptic seizures and thus suggest T-type channel blockers as a viable treatment option.

TET1 involved in bisphenol A induced TM3 Leydig cell toxicity by regulating Cav3.3 hydroxymethylation

Bisphenol A (BPA), an important environmental pollutant, is known to damage reproductive development. However, the underlying epigenetic mechanism in Leydig cells during BPA exposure has not been explored in detail. In this study, TM3 Leydig cells were treated with BPA (0, 20, 40 and 80 μM) for 72 h. The differentially expressed TET1 cell model was constructed to explore the mechanism of BPA-induced cytotoxicity. Results showed that BPA exposure significantly inhibited cell viability and increased apoptosis of TM3 Leydig cells. Meanwhile, the mRNA of TET1, Cav3.2 and Cav3.3 decreased significantly with the increase of BPA exposure. Importantly, TET1 significantly promoted proliferation of TM3 Leydig cells and inhibited apoptosis. Differentially expressed TET1 significantly affected BPA-induced toxicity in TM3 Leydig cells. Notably, TET1 elevated the mRNA levels of Cav3.2 and Cav3.3. MeDIP and hMeDIP confirmed that TET1 regulated the expression of Cav3.3 through DNA hydroxymethylation. Our study firstly presented that TET1 participated in BPA-induced toxicity in TM3 Leydig cells through regulating Cav3.3 hydroxymethylation modification. These findings suggest that TET1 acts as a potential epigenetic marker for reproductive toxicity induced by BPA exposure and may provide a new direction for the research on male reproductive damage.

Trigeminal neuropathic pain is alleviated by inhibition of Cav3.3 T-type calcium channels in mice

In this brief report, we demonstrate that the Cav3.3 T-type voltage-gated calcium channel subtype is involved in our FRICT-ION model of chronic trigeminal neuropathic pain. We first showed that the Cacna1i gene encoding Cav3.3 is significantly upregulated in whole trigeminal ganglia of FRICT-ION mice compared to controls at week 10 post-injury. We confirmed protein upregulation of Cav3.3 compared to controls using Western blot analysis of whole trigeminal ganglia tissues. Finally, we demonstrated that intraperitoneal injection of a selective TAT-based Cav3.3 blocking peptide in FRICT-ION mice significantly reduces Cav3.3 protein expression at the peak anti-allodynic effect (4 hrs post-injection) of the attenuated neuropathic pain behavior. We also suggest that blockade of Cav3.3 may be more effective in attenuating trigeminal neuropathic pain in female than male FRICT-ION mice. Therefore, blocking or attenuating Cav3.3 function may be an effective strategy for the treatment of trigeminal neuropathic pain.