Identification and functional characterization of ion channels in CD34(+) hematopoietic stem cells from human peripheral blood

The role and mechanism of vascular wall cell ion channels in vascular fibrosis remodeling

Fibrosis is usually the final pathological state of many chronic inflammatory diseases and may lead to organ malfunction. Excessive deposition of extracellular matrix (ECM) molecules is a characteristic of most fibrotic tissues. The blood vessel wall contains three layers of membrane structure, including the intima, which is composed of endothelial cells; the media, which is composed of smooth muscle cells; and the adventitia, which is formed by the interaction of connective tissue and fibroblasts. The occurrence and progression of vascular remodeling are closely associated with cardiovascular diseases, and vascular remodeling can alter the original structure and function of the blood vessel. Dysregulation of the composition of the extracellular matrix in blood vessels leads to the continuous advancement of vascular stiffening and fibrosis. Vascular fibrosis reaction leads to excessive deposition of the extracellular matrix in the vascular adventitia, reduces vessel compliance, and ultimately alters key aspects of vascular biomechanics. The pathogenesis of fibrosis in the vasculature and strategies for its reversal have become interesting and important challenges. Ion channels are widely expressed in the cardiovascular system; they regulate blood pressure, maintain cardiovascular function homeostasis, and play important roles in ion transport, cell differentiation, proliferation. In blood vessels, different types of ion channels in fibroblasts, smooth muscle cells and endothelial cells may be relevant mediators of the development of fibrosis in organs or tissues. This review discusses the known roles of ion channels in vascular fibrosis remodeling and discusses potential therapeutic targets for regulating remodeling and repair after vascular injury.

Distribution and Assembly of TRP Ion Channels

In the last several decades, a large family of ion channels have been identified and studied intensively as cellular sensors for diverse physical and/or chemical stimuli. Named transient receptor potential (TRP) channels, they play critical roles in various aspects of cellular physiology. A large number of human hereditary diseases are found to be linked to TRP channel mutations, and their dysregulations lead to acute or chronical health problems. As TRP channels are named and categorized mostly based on sequence homology rather than functional similarities, they exhibit substantial functional diversity. Rapid advances in TRP channel study have been made in recent years and reported in a vast body of literature; a summary of the latest advancements becomes necessary. This chapter offers an overview of current understandings of TRP channel distribution and subunit assembly.

Pathophysiological role of calcium channels and transporters in the multiple myeloma

Multiple myeloma (MM) is a common malignant tumor of plasma cells. Despite several treatment approaches in the past two decades, MM remains an aggressive and incurable disease in dire need of new treatment strategies. Approximately 70–80% of patients with MM have myeloma bone disease (MBD), often accompanied by pathological fractures and hypercalcemia, which seriously affect the prognosis of the patients. Calcium channels and transporters can mediate Ca²⁺ balance inside and outside of the membrane, indicating that they may be closely related to the prognosis of MM. Therefore, this review focuses on the roles of some critical calcium channels and transporters in MM prognosis, which located in the plasma membrane, endoplasmic reticulum and mitochondria. The goal of this review is to facilitate the identification of new targets for the treatment and prognosis of MM.

TRPV2: A Cancer Biomarker and Potential Therapeutic Target

The Transient Receptor Potential Vanilloid type-2 (TRPV2) channel exhibits oncogenicity in different types of cancers. TRPV2 is implicated in signaling pathways that mediate cell survival, proliferation, and metastasis. In leukemia and bladder cancer, the oncogenic activity of TRPV2 was linked to alteration of its expression profile. In multiple myeloma patients, TRPV2 overexpression correlated with bone tissue damage and poor prognosis. In prostate cancer, TRPV2 overexpression was associated with the castration-resistant phenotype and metastasis. Loss or inactivation of TRPV2 promoted glioblastoma cell proliferation and increased resistance to CD95-induced apoptotic cell death. TRPV2 overexpression was associated with high relapse-free survival in triple-negative breast cancer, whereas the opposite was found in patients with esophageal squamous cell carcinoma or gastric cancer. Another link was found between TRPV2 expression and either drug-induced cytotoxicity or stemness of liver cancer. Overall, these findings validate TRPV2 as a prime candidate for cancer biomarker and future therapeutic target.

Therapeutic effects of coronary granulocyte colony-stimulating factor on rats with chronic ischemic heart disease

Background

The aim of this study was to evaluate the therapeutic effects of coronary granulocyte colony-stimulating factor (G-CSF) on rats with chronic ischemic heart disease (CIHD).

Methods

Thirty healthy rats were randomly divided into control, subcutaneous and intracoronary G-CSF injection groups (n = 10) after the CIHD model was established. Left ventricular ejection fraction (LVEF), myocardial injury area, myocardial perfusion area and viable myocardium were observed by coronary angiography, dual-isotopic myocardial imaging and first-pass delayed myocardial perfusion magnetic resonance imaging (MRI) before modeling as well as 2 and 4 weeks after surgery.

Results

The peak times of peripheral blood and subcutaneous G-CSF levels were 3 and 5 days after mobilization, respectively. The peripheral blood CD34+/CD133+ cell ratio of subcutaneous or intracoronary G-CSF injection group significantly exceeded that of the control group (P < 0.05). The distal stenosis degrees of target lesions in subcutaneous and intracoronary G-CSF injection groups were significantly lower than that of the control group (P < 0.05). Compared with the situation before mobilization, LVEF was significantly improved after 2 weeks in intracoronary and subcutaneous G-CSF injection groups (P < 0.01). Their infarcted myocardial areas were reduced, the left ventricular remodeling was relieved, the percentage of viable myocardium was increased, angiogenesis was promoted and cardiomyocyte apoptosis was inhibited.

Conclusion

Intracoronary G-CSF injection is safe and effective as subcutaneous injection, improving the cardiac function of CIHD rats.

Conditioned Medium from Canine Amniotic Membrane-Derived Mesenchymal Stem Cells Improved Dog Sperm Post-Thaw Quality-Related Parameters

Simple Summary

Mesenchymal stem cells and their derivatives are used in clinical studies for their anti-apoptotic, anti-oxidant, immunomodulatory, and regenerative properties. Their use in reproductive medicine is increasing as they have been proved to be beneficial for infertility treatment. Mesenchymal stem cells can secrete factors that influence biological processes in target tissues or cells; these factors are either directly secreted by the cells or mediated through their derivatives. Although the amniotic membrane is easy to obtain and is a good source of stem cells, clinical trials using amniotic membrane-derived mesenchymal stem cells are still uncommon, especially in reproductive medicine or artificial reproductive technologies. The objective of the present study was to demonstrate the effects of conditioned medium prepared from amniotic membrane-derived stem cells on dog sperm cryopreservation. Our results showed that 10% of the conditioned medium enhanced the quality-related parameters of frozen–thawed sperm cells because of the presence of antioxidants and growth factors in the medium, which probably protected spermatozoa during the freeze–thaw process. These results suggest that conditioned media prepared from amniotic membrane-derived mesenchymal stem cells might have clinical applications in assisted reproductive technologies.

Abstract

This study investigated the effects of conditioned medium (CM) from canine amniotic membrane-derived MSCs (cAMSCs) on dog sperm cryopreservation. For this purpose, flow cytometry analysis was performed to characterize cAMSCs. The CM prepared from cAMSCs was subjected to proteomic analysis for the identification of proteins present in the medium. Sperm samples were treated with freezing medium supplemented with 0%, 5%, 10%, and 15% of the CM, and kinetic parameters were evaluated after 4–6 h of chilling at 4 °C to select the best concentration before proceeding to cryopreservation. Quality-related parameters of frozen–thawed sperm were investigated, including motility; kinetic parameters; viability; integrity of the plasma membrane, chromatin, and acrosome; and mitochondrial activity. The results showed that 10% of the CM significantly enhanced motility, viability, mitochondrial activity, and membrane integrity (p < 0.05); however, the analysis of chromatin and acrosome integrity showed no significant differences between the treatment and control groups. Therefore, we concluded that the addition of 10% CM derived from cAMSC in the freezing medium protected dog sperm during the cryopreservation process.

Altered expression and functional role of ion channels in leukemia: bench to bedside

Leukemic cells' (LCs) survival, proliferation, activation, differentiation, and invasiveness/migration can be mediated through the function of cation and anion channels that are involved in volume regulation, polarization, cytoskeleton, and extracellular matrix reorganization. This study will review the expression of ion channels in LCs and their possible function in leukemia progression. We searched relevant literature by a PubMed (2002-2019) of English-language literature using the terms "ion channels", "leukemia", "proliferation", "differentiation", "apoptosis", and "migration". Altered expression and dysfunction of ion channels can have a strong impact on hematopoietic cell and LCs physiology and signaling, which contributes to the vital processes such as proliferation, differentiation, and apoptosis. Indeed, it can be stated that changing expression of ion channels can affect the onset and progression as well as clinical features and therapeutic responses of leukemia via inducing the maintenance of LCs. Since ion channels are membrane proteins, they can be easily accessible in LCs for understanding their influence on leukemia progression. On the other hand, ion channels can be new potential targets for chemotherapeutic agents, which may open a novel clinical and pharmaceutical field in leukemia therapy.

Calcium channels and cancer stem cells

Cancer stem cells (CSC's) have emerged as a key area of investigation due to associations with cancer development and treatment resistance, related to their ability to remain quiescent, self-renew and terminally differentiate. Targeting CSC's in addition to the tumour bulk could ensure complete removal of the cancer, lessening the risk of relapse and improving patient survival. Understanding the mechanisms supporting the functions of CSC's is essential to highlight targets for the development of therapeutic strategies. Changes in intracellular calcium through calcium channel activity is fundamental for integral cellular processes such as proliferation, migration, differentiation and survival in a range of cell types, under both normal and pathological conditions. Here in we highlight how calcium channels represent a key mechanism involved in CSC function. It is clear that expression and or function of a number of channels involved in calcium entry and intracellular store release are altered in CSC's. Correlating with aberrant proliferation, self-renewal and differentiation, which in turn promoted cancer progression and treatment resistance. Research outlined has demonstrated that targeting altered calcium channels in CSC populations can reduce their stem properties and induce terminal differentiation, sensitising them to existing cancer treatments. Overall this highlights calcium channels as emerging novel targets for CSC therapies.

Immune aspects of the bi-directional neuroimmune facilitator TRPV1

A rapidly growing area of interest in biomedical science involves the reciprocal crosstalk between the sensory nervous and immune systems. Both of these systems are highly integrated, detecting potential environmental harms and restoring homeostasis. Many different cytokines, receptors, neuropeptides, and other proteins are involved in this bidirectional communication that are common to both systems. One such family of proteins includes the transient receptor potential vanilloid (TRPV) proteins. Though much progress has been made in understanding TRPV proteins in the nervous system, their functions in the immune system are not well elucidated. Hence, further understanding their role in the peripheral immune system and as regulators of neuroimmunity is critical for evaluating their potential as therapeutic targets for numerous inflammatory disorders, cancers, and other disease states. Here, we focus on the latest advancements in understanding TRPV1 and TRPV2's roles in the immune system, TRPV1 in neuroimmunity, and TRPV1's potential involvement in anti-tumor therapy.

Niche Extracellular Matrix Components and Their Influence on HSC

Maintenance of hematopoietic stem cells (HSC) takes place in a highly specialized microenvironment within the bone marrow. Technological improvements, especially in the field of in vivo imaging, have helped unravel the complexity of the niche microenvironment and have completely changed the classical concept from what was previously believed to be a static supportive platform, to a dynamic microenvironment tightly regulating HSC homeostasis through the complex interplay between diverse cell types, secreted factors, extracellular matrix molecules, and the expression of different transmembrane receptors. To add to the complexity, non-protein based metabolites have also been recognized as a component of the bone marrow niche. The objective of this review is to discuss the current understanding on how the different extracellular matrix components of the niche regulate HSC fate, both during embryonic development and in adulthood. Special attention will be provided to the description of non-protein metabolites, such as lipids and metal ions, which contribute to the regulation of HSC behavior. J. Cell. Biochem. 118: 1984-1993, 2017. © 2017 Wiley Periodicals, Inc.

Increased expression of transient receptor potential canonical 6 (TRPC6) in differentiating human megakaryocytes

Members of the transient receptor potential (TRP) family of cation conducting channels are found in several tissues and cell types where they have different physiological functions. The canonical TRP channel 6 (TRPC6) is present on the platelet membrane and appears to participate in calcium influx during platelet activation. However, limited information is available on the importance of TRPC channels in megakaryocytes (MKs), the precursor cells of platelets. We determined the mRNA and protein expression of TRPC family members and investigated the role of TRPC6 for proliferation and differentiation of human MKs derived from CD34+ progenitor cells. TRPC6 transcripts were highly expressed during the differentiation of MKs and TRPC6 protein was detectable in MK cytoplasm by confocal staining. TRPC6 channel activity was modulated by pharmacological approaches using flufenamic acid (FFA) for activation and SKF96365 for inhibition. Upon FFA stimulation in MKs, an increase in intracellular calcium was observed, which was blocked by SKF96365 at 10 µM concentration. Incubation of MKs with SKF96365 resulted in a reduction in thrombopoietin-stimulated cell proliferation. Our results suggest a role of TRPC6 in calcium homeostasis during MK development, particularly for cell proliferation.

Loss of TRPV2 Homeostatic Control of Cell Proliferation Drives Tumor Progression

Herein we evaluate the involvement of the TRPV2 channel, belonging to the Transient Receptor Potential Vanilloid channel family (TRPVs), in development and progression of different tumor types. In normal cells, the activation of TRPV2 channels by growth factors, hormones, and endocannabinoids induces a translocation of the receptor from the endosomal compartment to the plasma membrane, which results in abrogation of cell proliferation and induction of cell death. Consequently, loss or inactivation of TRPV2 signaling (e.g., glioblastomas), induces unchecked proliferation, resistance to apoptotic signals and increased resistance to CD95-induced apoptotic cell death. On the other hand, in prostate cancer cells, Ca2+-dependent activation of TRPV2 induced by lysophospholipids increases the invasion of tumor cells. In addition, the progression of prostate cancer to the castration-resistant phenotype is characterized by de novo TRPV2 expression, with higher TRPV2 transcript levels in patients with metastatic cancer. Finally, TRPV2 functional expression in tumor cells can also depend on the presence of alternative splice variants of TRPV2 mRNA that act as dominant-negative mutant of wild-type TRPV2 channels, by inhibiting its trafficking and translocation to the plasma membrane. In conclusion, as TRP channels are altered in human cancers, and their blockage impair tumor progression, they appear to be a very promising targets for early diagnosis and chemotherapy.

TRPV2

Transient receptor potential vanilloid type 2, TRPV2, is a calcium-permeable cation channel belonging to the TRPV channel family. This channel is activated by heat (>52 °C), various ligands, and mechanical stresses. In most of the cells, a large portion of TRPV2 is located in the endoplasmic reticulum under unstimulated conditions. Upon stimulation of the cells with phosphatidylinositol 3-kinase-activating ligands, TRPV2 is translocated to the plasma membrane and functions as a cation channel. Mechanical stress may also induce translocation of TRPV2 to the plasma membrane. The expression of TRPV2 is high in some types of cells including neurons, neuroendocrine cells, immune cells involved in innate immunity, and certain types of cancer cells. TRPV2 may modulate various cellular functions in these cells.

hERG potassium channel blockage by scorpion toxin BmKKx2 enhances erythroid differentiation of human leukemia cells K562

BACKGROUND

The hERG potassium channel can modulate the proliferation of the chronic myelogenous leukemic K562 cells, and its role in the erythroid differentiation of K562 cells still remains unclear.

PRINCIPAL FINDINGS

The hERG potassium channel blockage by a new 36-residue scorpion toxin BmKKx2, a potent hERG channel blocker with IC50 of 6.7 ± 1.7 nM, enhanced the erythroid differentiation of K562 cells. The mean values of GPA (CD235a) fluorescence intensity in the group of K562 cells pretreated by the toxin for 24 h and followed by cytosine arabinoside (Ara-C) treatment for 72 h were about 2-fold stronger than those of K562 cells induced by Ara-C alone. Such unique role of hERG potassium channel was also supported by the evidence that the effect of the toxin BmKKx2 on cell differentiation was nullified in hERG-deficient cell lines. During the K562 cell differentiation, BmKKx2 could also suppress the expression of hERG channels at both mRNA and protein levels. Besides the function of differentiation enhancement, BmKKx2 was also found to promote the differentiation-dependent apoptosis during the differentiation process of K562 cells. In addition, the blockage of hERG potassium channel by toxin BmKKx2 was able to decrease the intracellular Ca(2+) concentration during the K562 cell differentiation, providing an insight into the mechanism of hERG potassium channel regulating this cellular process.

CONCLUSIONS/SIGNIFICANCE

Our results revealed scorpion toxin BmKKx2 could enhance the erythroid differentiation of leukemic K562 cells via inhibiting hERG potassium channel currents. These findings would not only accelerate the functional research of hERG channel in different leukemic cells, but also present the prospects of natural scorpion toxins as anti-leukemic drugs.

The role of transient receptor potential vanilloid type-2 ion channels in innate and adaptive immune responses

The transient receptor potential vanilloid type-2 (TRPV2), belonging to the transient receptor potential channel family, is a specialized ion channel expressed in human and other mammalian immune cells. This channel has been found to be expressed in CD34(+) hematopoietic stem cells, where its cytosolic Ca(2) (+) activity is crucial for stem/progenitor cell cycle progression, growth, and differentiation. In innate immune cells, TRPV2 is expressed in granulocytes, macrophages, and monocytes where it stimulates fMet-Leu-Phe migration, zymosan-, immunoglobulin G-, and complement-mediated phagocytosis, and lipopolysaccharide-induced tumor necrosis factor-alpha and interleukin-6 production. In mast cells, activation of TRPV2 allows intracellular Ca(2) (+) ions flux, thus stimulating protein kinase A-dependent degranulation. In addition, TRPV2 is highly expressed in CD56(+) natural killer cells. TRPV2 orchestrates Ca(2) (+) signal in T cell activation, proliferation, and effector functions. Moreover, messenger RNA for TRPV2 are expressed in CD4(+) and CD8(+) T lymphocytes. Finally, TRPV2 is expressed in CD19(+) B lymphocytes where it regulates Ca(2) (+) release during B cell development and activation. Overall, the specific expression of TRPV2 in immune cells suggests a role in immune-mediated diseases and offers new potential targets for immunomodulation.

Ion channels in hematopoietic and mesenchymal stem cells

Hematopoietic stem cells (HSCs) reside in bone marrow niches and give rise to hematopoietic precursor cells (HPCs). These have more restricted lineage potential and eventually differentiate into specific blood cell types. Bone marrow also contains mesenchymal stromal cells (MSCs), which present multilineage differentiation potential toward mesodermal cell types. In bone marrow niches, stem cell interaction with the extracellular matrix is mediated by integrin receptors. Ion channels regulate cell proliferation and differentiation by controlling intracellular Ca(2+), cell volume, release of growth factors, and so forth. Although little evidence is available about the ion channel roles in true HSCs, increasing information is available about HPCs and MSCs, which present a complex pattern of K(+) channel expression. K(+) channels cooperate with Ca(2+) and Cl(-) channels in regulating calcium entry and cell volume during mitosis. Other K(+) channels modulate the integrin-dependent interaction between leukemic progenitor cells and the niche stroma. These channels can also regulate leukemia cell interaction with MSCs, which also involves integrin receptors and affects the MSC-mediated protection from chemotherapy. Ligand-gated channels are also implicated in these processes. Nicotinic acetylcholine receptors regulate cell proliferation and migration in HSCs and MSCs and may be implicated in the harmful effects of smoking.

The KCNE Tango - How KCNE1 Interacts with Kv7.1

The classical tango is a dance characterized by a 2/4 or 4/4 rhythm in which the partners dance in a coordinated way, allowing dynamic contact. There is a surprising similarity between the tango and how KCNE β-subunits "dance" to the fast rhythm of the cell with their partners from the Kv channel family. The five KCNE β-subunits interact with several members of the Kv channels, thereby modifying channel gating via the interaction of their single transmembrane-spanning segment, the extracellular amino terminus, and/or the intracellular carboxy terminus with the Kv α-subunit. Best studied is the molecular basis of interactions between KCNE1 and Kv7.1, which, together, supposedly form the native cardiac I(Ks) channel. Here we review the current knowledge about functional and molecular interactions of KCNE1 with Kv7.1 and try to summarize and interpret the tango of the KCNEs.