Calcium Binding Proteins

Anatomical and neurochemical organization of the dorsal, lumbar precerebellar and sacral precerebellar nuclei in the human spinal cord

BACKGROUND AND PURPOSE

The dorsal nucleus (Clarke's nucleus, D), lumbar precerebellar nucleus (LPrCb), and sacral precerebellar nucleus (Stilling's sacral nucleus, SPrCb) are precerebellar nuclei of the spinal cord. This study investigates the cytoarchitecture and neurochemical organization of the D, LPrCb, and SPrCb nuclei in the human spinal cord.

MATERIAL AND METHODS

Using Nissl staining and immunohistochemistry for markers including calbindin (Cb), calretinin (Cr), parvalbumin (Pv), choline acetyltransferase (ChAT), glutamic acid decarboxylase (GAD 65/67), and vesicular glutamate transporter 1 (VGLUT1), we analyzed sections from T1-T12, L1-L5, and S1-Co1 segments of a human spinal cord.

RESULTS

Our findings reveal a diverse range of neuron sizes and morphologies within these nuclei, with multipolar neurons being predominant. The immunohistochemical analysis showed distinct neurochemical characteristics, with varying densities of the markers across the D, LPrCb, and SPrCb.

CONCLUSION

This study provides the first detailed characterization of these nuclei in the human spinal cord, highlighting their intricate organization and suggesting potential functional similarities. The comprehensive understanding of the neurochemical profiles of these nuclei lays the groundwork for future research into their roles in motor coordination and their involvement in neurodegenerative diseases. Our findings underscore the importance of further investigation into the pathological changes occurring within the precerebellar nuclei to advance treatment and prevention strategies for related neurological disorders.

Impact of sodium alginate hydrogel containing bacteriophage peptides that specifically bind to the EtCab protein on the inhibition of Eimeria tenella infection

Avian coccidiosis, caused by the protozoan Eimeria, leads to significant economic losses for the poultry industry. In this study, bacteriophages that specifically bind to the calcium-binding protein (EtCab) of Eimeria tenella were selected using a biopanning process with a pIII phage display library. The recombinant EtCab protein served as the ligand in this selection process. The binding ability of target phages to the EtCab protein or E. tenella sporozoites was evaluated. The role of peptides corresponding to target phages in inhibiting the invasion of E. tenella sporozoites into cells was analysed using flow cytometry. Subsequently, the phages were encapsulated in sodium alginate to protect them from degradation in gastric fluid, which has a low pH value. Chickens were orally administered both microencapsulated and non-microencapsulated phages, and the protective effects against E. tenella infection were assessed. The binding mechanism of these peptides to the EtCab protein was investigated through in silico analysis. The results indicated that three specific phages (Y, G, and V) could bind effectively to recombinant EtCab protein as well as to sporozoite proteins. All three peptides, particularly Y and G, demonstrated significant inhibition of sporozoite invasion into cells in vitro. Additionally, oral administration of the encapsulated phages Y and G provided a higher level of protection against Eimeria infection compared to encapsulated phage V and the unencapsulated phages. Molecular docking studies revealed that three peptides, particularly Y and G, efficiently bind to the EtCab protein through hydrogen bonds. This study provides a reference for developing small molecular drugs targeting coccidiosis.

Calcium Signalling in Neurological Disorders, with Insights from Miniature Fluorescence Microscopy

Neurological disorders (NDs), such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and schizophrenia, represent a complex and multifaceted health challenge that affects millions of people around the world. Growing evidence suggests that disrupted neuronal calcium signalling contributes to the pathophysiology of NDs. Additionally, calcium functions as a ubiquitous second messenger involved in diverse cellular processes, from synaptic activity to intercellular communication, making it a potential therapeutic target. Recently, the development of the miniature fluorescence microscope (miniscope) enabled simultaneous recording of the spatiotemporal calcium activity from large neuronal ensembles in unrestrained animals, providing a novel method for studying NDs. In this review, we discuss the abnormalities observed in calcium signalling and its potential as a therapeutic target for NDs. Additionally, we highlight recent studies that utilise miniscope technology to investigate the alterations in calcium dynamics associated with NDs.

Calcium-binding protein TgpCaBP regulates calcium storage of the zoonotic parasite Toxoplasma gondii

Toxoplasma gondii, the causative parasite of toxoplasmosis, is an apicomplexan parasite that infects warm-blooded mammals. The ability of the calcium-binding proteins (CBPs) to transport large amounts of Ca2+ appears to be critical for the biological activity of T. gondii. However, the functions of some members of the CBP family have not yet been deciphered. Here, we characterized a putative CBP of T. gondii, TgpCaBP (TGME49_229480), which is composed of four EF-hand motifs with Ca2+-binding capability. TgpCaBP was localized in the cytosol and ER of T. gondii, and parasites lacking the TgpCaBP gene exhibited diminished abilities in cell invasion, intracellular growth, egress, and motility. These phenomena were due to the abnormalities in intracellular Ca2+ efflux and ER Ca2+ storage, and the reduction in motility was associated with a decrease in the discharge of secretory proteins. Therefore, we propose that TgpCaBP is a Ca2+ transporter and signaling molecule involved in Ca2+ regulation and parasitization in the hosts.IMPORTANCECa2+ signaling is essential in the development of T. gondii. In this study, we identified a calcium-binding protein in T. gondii, named TgpCaBP, which actively regulates intracellular Ca2+ levels in the parasite. Deletion of the gene coding for TgpCaBP caused serious deficits in the parasite's ability to maintain a stable intracellular calcium environment, which also impaired the secretory protein discharged from the parasite, and its capacity of gliding motility, cell invasion, intracellular growth, and egress from host cells. In summary, we have identified a novel calcium-binding protein, TgpCaBP, in the zoonotic parasite T. gondii, which is a potential therapeutic target for toxoplasmosis.

Calcium influx: An essential process by which α-Synuclein regulates morphology of erythrocytes

INTRODUCTION

Morphological abnormalities of erythrocytes/red blood cells (RBCs), e.g., increased acanthocytes, in Parkinson's disease (PD) have been reported previously, although the underlying mechanisms remain to be characterized. In this study, the potential roles of α-synuclein (α-syn), a protein critically involved in PD and highly abundant in RBCs, were studied in PD patients as well as in a PD mouse model.

METHODS

Transgenic [PAC-Tg (SNCAA53T), A53T] mice overexpressing A53T mutant α-syn and SNCA knockout mice were employed to characterize the effect of α-syn on RBC morphology. In addition to A53T and SNCA knockout mice, the morphology of RBCs of PD patients was also examined using scanning electron microscopy. The potential roles of α-syn were further investigated in cultured RBCs and mice.

RESULTS

Morphological abnormalities of RBCs and increased accumulation of aggregated α-syn on the RBC membrane were observed in PD patients. A similar phenomenon was also observed in A53T mice. Furthermore, while mice lacking α-syn expression showed a lower proportion of acanthocytes, treating RBCs derived from SNCA knockout mice with aggregated α-syn resulted in a higher percentage of acanthocytes. In a follow-up proteomic investigation, several major classes of proteins were identified as α-syn-associated proteins on the RBC membrane, seven of which were calcium-binding proteins. Applying aggregated α-syn to the RBC membrane directly induced extracellular calcium influx along with morphological changes; both observations were adequately reversed by blocking calcium influx.

CONCLUSIONS

This study demonstrated that α-syn plays a critical role in PD-associated morphological abnormalities of RBCs, at least partially via a process mediated by extracellular calcium influx.

The amygdaloid body of the family Delphinidae: a morphological study of its central nucleus through calbindin-D28k

Introduction

The amygdala is a noticeable bilateral structure in the medial temporal lobe and it is composed of at least 13 different nuclei and cortical areas, subdivided into the deep nuclei, the superficial nuclei, and the remaining nuclei which contain the central nucleus (CeA). CeA mediates the behavioral and physiological responses associated with fear and anxiety through pituitary-adrenal responses by modulating the liberation of the hypothalamic Corticotropin Releasing Factor/Hormone.

Methods

Five dolphins of three different species, belonging to the family Delphinidae (three striped dolphins, one common dolphin, and one Atlantic spotted dolphin), were used for this study. For a precise overview of the CeA's structure, thionine staining and the immunoperoxidase method using calbindin D-28k were employed.

Results

CeA extended mainly dorsal to the lateral nucleus and ventral to the striatum. It was medial to the internal capsule and lateral to the optic tract and the medial nucleus of the amygdala.

Discussion

The dolphin amygdaloid complex resembles that of primates, including the subdivision, volume, and location of the CeA.

S100Z is expressed in a lateral subpopulation of olfactory receptor neurons in the main olfactory system of Xenopus laevis

In contrast to other S100 protein members, the function of S100 calcium-binding protein Z (S100Z) remains largely uncharacterized. It is expressed in the olfactory epithelium of fish, and it is closely associated with the vomeronasal organ (VNO) in mammals. In this study, we analyzed the expression pattern of S100Z in the olfactory system of the anuran amphibian Xenopus laevis. Using immunohistochemistry in whole mount and slice preparations of the larval olfactory system, we found exclusive S100Z expression in a subpopulation of olfactory receptor neurons (ORNs) of the main olfactory epithelium (MOE). S100Z expression was not co-localized with TP63 and cytokeratin type II, ruling out basal cell and supporting cell identity. The distribution of S100Z-expressing ORNs was laterally biased, and their average number was significantly increased in the lateral half of the olfactory epithelium. The axons of S100Z-positive neurons projected exclusively into the lateral and intermediate glomerular clusters of the main olfactory bulb (OB). Even after metamorphic restructuring of the olfactory system, S100Z expression was restricted to a neuronal subpopulation of the MOE, which was then located in the newly formed middle cavity. An axonal projection into the ventro-lateral OB persisted also in postmetamorphic frogs. In summary, S100Z is exclusively associated with the main olfactory system in the amphibian Xenopus and not with the VNO as in mammals, despite the presence of a separate accessory olfactory system in both classes.

Dysregulation of calcium homeostasis in cancer and its role in chemoresistance

Globally, cancer, as a major public health concern, poses a severe threat to people's well-being. Advanced and specialized therapies can now cure the majority of people with early-stage cancer. However, emerging resistance to traditional and novel chemotherapeutic drugs remains a serious issue in clinical medicine. Chemoresistance often leads to cancer recurrence, metastasis, and increased mortality, accounting for 90% of chemotherapy failures. Thus, it is important to understand the molecular mechanisms of chemoresistance and find novel therapeutic approaches for cancer treatment. Among the several factors responsible for chemoresistance, calcium (Ca2+) dysregulation plays a significant role in cancer progression and chemoresistance. Therefore, targeting this derailed Ca2+ signalling for cancer therapy has become an emerging research area. Of note, the Ca2+ signal and its proteins are a multifaceted and potent tool by which cells achieve specific outcomes. Depending on cell survival needs, Ca2+ is either upregulated or downregulated in both chemosensitive and chemoresistant cancer cells. Consequently, the appropriate treatment should be selected based on Ca2+ signalling dysregulation. This review discusses the role of Ca2+ in cancer cells and the targeting of Ca2+ channels, pumps, and exchangers. Furthermore, we have emphasised the role of Ca2+ in chemoresistance and therapeutic strategies. In conclusion, targeting Ca2+ signalling is a multifaceted process. Methods such as site-specific drug delivery, target-based drug-designing, and targeting two or more Ca2+ proteins simultaneously may be explored; however, further clinical studies are essential to validate Ca2+ blockers' anti-cancer efficacy.

Calcium-based biomaterials: Unveiling features and expanding applications in osteosarcoma treatment

Calcium, an indispensable element in bone tissues, plays a crucial role in various cellular processes involved in cancer progression. Its ubiquitous yet spatially distinct distribution in the body presents an opportunity to target calcium homeostasis as a novel strategies for cancer treatment, with specific advantages in osteosarcoma therapy. In this comprehensive review, we retrospect the calcium biology intersected with cancer progression, highlight the unveiling features of calcium-based biomaterials in regulating both bone homeostasis and cancer development. We also provide an overview of recent breakthroughs in cancer therapy that leverage calcium biomaterials, showcasing their potential to serve as versatile, customizable platforms for osteosarcoma treatment and as reservoirs for supporting bone reconstruction.

Calcium-binding protein parvalbumin in the spinal cord and dorsal root ganglia

Parvalbumin is one of the calcium-binding proteins. In the spinal cord, it is mainly expressed in inhibitory neurons; in the dorsal root ganglia, it is expressed in proprioceptive neurons. In contrast to in the brain, weak systematization of parvalbumin-expressing neurons occurs in the spinal cord. The aim of this paper is to provide a systematic review of parvalbumin-expressing neuronal populations throughout the spinal cord and the dorsal root ganglia of mammals, regarding their mapping, co-expression with some functional markers. The data reviewed are mostly concerning rodentia species because they are predominantly presented in literature.

Clonorchis sinensis calcium-binding protein Cs16 causes acute hepatic injury possibly by reprogramming the metabolic pathway of bone marrow-derived monocytes

Introduction

Clonorchis sinensis infection results in various complications in the liver and biliary systems and is a neglected tropical disease in Eastern Asia. In this study, we report that C. sinensis calcium-binding protein Cs16 activates host immune cells and induces immunopathology in liver.

Methods

Immunohistochemistry was used to detect the localization of Cs16 in C. sinensis adult worms. ELISA was used to detect the serum levels of anti-Cs16 IgG antibody in infected humans and mice. Bile duct injection model was used to figure out the role of Cs16 in vivo. RT-qPCR and ELISA were used to detect the cytokine production from Cs16-treated BMMs in vitro. Seahorse assay was used to detect the metabolic pathway of Cs16-treated BMMs in vitro.

Result

Cs16 localizes in the tegument and gut of C. sinensis. Humans and mice with C. sinensis infection exhibited increased levels of anti-Cs16-specific antibody. Using the bile duct injection technique, we found that Cs16 induced obvious inflammation and hepatic necrosis in vivo. Cs16 treatment caused the upregulation of inflammatory cytokines in innate immune cells. Moreover, Cs16-treated monocytes relied more on the glycolytic metabolic pathway.

Discussion

Our findings suggest that Cs16 is a potential pathogenic factor derived from C. sinensis adult worm. By reprogramming the metabolic pathway of innate immune cells, Cs16 triggers pro-inflammatory responses in the liver, and therefore, Cs16 is a potential target for the prevention and treatment of clonorchiasis.

Triple enzymatic immunochemistry for interneuron populations in postmortem human cerebral cortex

Immunostaining is an antibody-based tool used to visualize proteins in tissue. Enzymes or fluorochromes conjugated to antibodies are used to detect proteins of interests. Fluorescent immunostaining can be used in human tissue, however due to the high autofluorescence of non-perfused human tissue, enzymatic immunostaining is better suited. Enzymes produce a colored product that is detectable by light microscopes. Here we describe a successful triple immunochemistry protocol to enzymatically label three distinct populations of interneurons (Parvalbumin+, Calbindin+, and Calretinin + interneurons) in non-perfused formalin fixed human brain cerebral cortex. Signal was achieved using a combination of horseradish peroxidase (HRP) and Alkaline Phosphatase (AP) enzymes and color was generated using the insoluble chromogens: 3,3'- Diaminobenzidine (DAB, Brown), Vector Blue (Blue), and Vector VIP (Pink). There were no noticeable background and minimal signal overlap between the different colors. We were able to successfully stain human cortical tissue and distinguish morphological properties of the three interneuron (IN) populations.

Elucidating the Role of a Calcium-Binding Loop in an x-Prolyl Aminodipeptidase from Lb. helveticus

Prolyl aminodipeptidase (PepX) is an α/β hydrolase that cleaves at penultimate N-terminal prolyl peptide bonds. The crystal structure of PepX from Lactobacillus helveticus exhibits a calcium-binding loop within the catalytic domain. The calcium-binding sequence of xDxDxDGxxD within this loop is highly conserved in PepX proteins among lactic acid bacteria, but its purpose remains unknown. Enzyme activity is not significantly affected in the presence of the metal chelator ethylenediaminetetraacetic acid (EDTA), nor in the presence of excess calcium ions. To eliminate calcium binding, D196A and D194A/D196A mutations were constructed within the conserved calcium-binding sequence motif. Enzyme activity and stability of the D196A mutant were comparable to the wild-type enzyme by colorimetric kinetic assays and protein thermal shift assays. However, the D194A/D196A mutant was inactive though it retained native-like structure and thermal stability, contradicting the EDTA and calcium titration results. This suggests calcium binding to PepX may be essential for activity.

Molecular identification of a novel antimicrobial peptide in giant Triton snail Charonia tritonis: mRNA profiles for tissues and its potential antibacterial activity

Antimicrobial peptides (AMPs) play an important role in innate immunity against microorganisms. AMPs is an effective antibacterial agent, and the chances of causing pathogens to develop is very low. However, there is little information about AMPs in the giant Triton snail Charonia tritonis. In this research, an antimicrobial peptide gene (termed Ct-20534) was identified in C. tritonis. The open reading frame of Ct-20534 is 381 bp in size and it encodes a basic peptide precursor containing 126 amino acids. Ct-20534 gene was found to be expressed in all five tissues examined by real-time fluorescence quantitative PCR (qPCR), but the highest expression was found in the proboscis. This is the first report that antibacterial peptides have been found in C. tritonis, and it has been proved that Ct-20534 has antibacterial activity against Gram-positive bacteria and Gram-negative bacteria, among which the activity of Staphylococcus aureus is most significantly inhibited, this suggests that the newly discovered antimicrobial peptides in C. tritonis may play an important role in the immune system and bacterial resistance of C. tritonis. This study presents the discovery of a newly identified antibacterial peptide from C. tritonis, with its structural properties fully characterized and potent antibacterial activity confirmed. The results provide essential fundamental data for the development of preventive and therapeutic measures against aquatic animal diseases, which in turn can promote the sustainable and stable growth of the aquaculture industry and create economic benefits. Additionally, this research lays the foundation for future development of novel anti-infective drugs.

Calcineurin Signalling in Astrocytes: From Pathology to Physiology and Control of Neuronal Functions

Calcineurin (CaN), a Ca²⁺/calmodulin-activated serine/threonine phosphatase, acts as a Ca²⁺-sensitive switch regulating cellular functions through protein dephosphorylation and activation of gene transcription. In astrocytes, the principal homeostatic cells in the CNS, over-activation of CaN is known to drive pathological transcriptional remodelling, associated with neuroinflammation in diseases such as Alzheimer's disease, epilepsy and brain trauma. Recent reports suggest that, in physiological conditions, the activity of CaN in astrocytes is transcription-independent and is required for maintenance of basal protein synthesis rate and activation of astrocytic Na⁺/K⁺ pump thereby contributing to neuronal functions such as neuronal excitability and memory formation. In this contribution we overview the role of Ca²⁺ and CaN signalling in astroglial pathophysiology focusing on the emerging physiological role of CaN in astrocytes. We propose a model for the context-dependent switch of CaN activity from the post-transcriptional regulation of cell proteostasis in healthy astrocytes to the CaN-dependent transcriptional activation in neuroinflammation-associated diseases.

New progress with calcium-binding protein S100A16 in digestive system disease

INTRODUCTION

This review summarizes and analyzes the abnormal expression and mechanism of S100A16 in digestive system diseases, which is expected to provide new ideas and methods for adjuvant treatment and prognosis evaluation of digestive system diseases.

AREAS COVERED

Based on original publications found in database systems (PubMed, Cochrane), we introduce the mechanism and research progress of S100A16 in digestive system tumors, inflammatory bowel disease and fatty liver.

EXPERT OPINION

S100A16 is closely related to the proliferation, migration, and invasion of digestive system tumor cells. Further, it plays an important role in inflammatory bowel disease and fatty liver.

Proteomics Evaluation of Semen of Clinically Healthy Beagle-Breed Dogs

The objectives of the present work were to evaluate the semen of dogs by means of proteomics methods and to compare with proteomics results of the blood of the animals, in order to increase available knowledge on the topic and present relevant reference values for semen samples. Semen samples were collected from five Beagle-breed dogs. Reproductive assessment of the animals by means of clinical, ultrasonographic and seminological examinations confirmed their reproductive health. The sperm-rich fraction and the prostatic fraction of semen were processed for proteomics evaluation. LC-MS/MS analysis was performed by means of a LTQ Orbitrap Elite system. The technology combines high separation capacity and strong qualitative ability of proteins in biological samples that require deep proteome coverage. Protein classification was performed based on their functional annotations using Gene Ontology (GO). In blood plasma, semen sperm-rich fraction, and semen prostatic fraction, 59, 42 and 43 proteins, respectively, were detected. Two proteins were identified simultaneously in plasma and the semen sperm-rich fraction, 11 proteins in plasma and the semen prostatic fraction, and three proteins in the semen sperm-rich and prostatic fractions. In semen samples, most proteins were related to cell organization and biogenesis, metabolic processes or transport of ions and molecules. Most proteins were located in the cell membrane, the cytosol or the nucleus. Finally, most proteins performed functions related to binding or enzyme regulation. There were no differences between the semen sperm-rich fraction and prostatic fractions in terms of the clustering of proteins. In conclusion, a baseline reference for proteins in the semen of Beagle-breed dogs is provided. These proteins are involved mostly in supporting spermatozoan maturation, survival and motility, enhancing the reproductive performance of male animals. There appears potential for the proteomics examination of semen to become a tool in semen evaluation. This analysis may potentially identify biomarkers for reproductive disorders. This can be particularly useful in stud animals, also given its advantage as a non-invasive method.

Neurochemical atlas of the cat spinal cord

The spinal cord is a complex heterogeneous structure, which provides multiple vital functions. The precise surgical access to the spinal regions of interest requires precise schemes for the spinal cord structure and the spatial relation between the spinal cord and the vertebrae. One way to obtain such information is a combined anatomical and morphological spinal cord atlas. One of the widely used models for the investigation of spinal cord functions is a cat. We create a single cell-resolution spinal cord atlas of the cat using a variety of neurochemical markers [antibodies to NeuN, choline acetyltransferase, calbindin 28 kDa, calretinin, parvalbumin, and non-phosphorylated heavy-chain neurofilaments (SMI-32 antibody)] allowing to visualize several spinal neuronal populations. In parallel, we present a map of the spatial relation between the spinal cord and the vertebrae for the entire length of the spinal cord.

Scaffolding protein functional sites using deep learning

The binding and catalytic functions of proteins are generally mediated by a small number of functional residues held in place by the overall protein structure. Here, we describe deep learning approaches for scaffolding such functional sites without needing to prespecify the fold or secondary structure of the scaffold. The first approach, "constrained hallucination," optimizes sequences such that their predicted structures contain the desired functional site. The second approach, "inpainting," starts from the functional site and fills in additional sequence and structure to create a viable protein scaffold in a single forward pass through a specifically trained RoseTTAFold network. We use these two methods to design candidate immunogens, receptor traps, metalloproteins, enzymes, and protein-binding proteins and validate the designs using a combination of in silico and experimental tests.

Transcriptome profile of spleen tissues from locally-adapted Kenyan pigs (Sus scrofa) experimentally infected with three varying doses of a highly virulent African swine fever virus genotype IX isolate: Ken12/busia.1 (ken-1033)

Background

African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs resulting in up to 100% mortality rates caused by the ASF virus (ASFV). The locally-adapted pigs in South-western Kenya have been reported to be resilient to disease and harsh climatic conditions and tolerate ASF; however, the mechanisms by which this tolerance is sustained remain largely unknown. We evaluated the gene expression patterns in spleen tissues of these locally-adapted pigs in response to varying infective doses of ASFV to elucidate the virus-host interaction dynamics.

Methods

Locally adapted pigs (n = 14) were experimentally infected with a high dose (1x10⁶HAD₅₀), medium dose (1x10⁴HAD₅₀), and low dose (1x10²HAD₅₀) of the highly virulent genotype IX ASFV Ken12/busia.1 (Ken-1033) isolate diluted in PBS and followed through the course of infection for 29 days. The in vivo pig host and ASFV pathogen gene expression in spleen tissues from 10 pigs (including three from each infective group and one uninfected control) were analyzed in a dual-RNASeq fashion. We compared gene expression between three varying doses in the host and pathogen by contrasting experiment groups against the naïve control.

Results

A total of 4954 differentially expressed genes (DEGs) were detected after ASFV Ken12/1 infection, including 3055, 1771, and 128 DEGs in the high, medium, and low doses, respectively. Gene ontology and KEGG pathway analysis showed that the DEGs were enriched for genes involved in the innate immune response, inflammatory response, autophagy, and apoptosis in lethal dose groups. The surviving low dose group suppressed genes in pathways of physiopathological importance. We found a strong association between severe ASF pathogenesis in the high and medium dose groups with upregulation of proinflammatory cytokines and immunomodulation of cytokine expression possibly induced by overproduction of prostaglandin E synthase (4-fold; p < 0.05) or through downregulation of expression of M1-activating receptors, signal transductors, and transcription factors. The host-pathogen interaction resulted in induction of expression of immune-suppressive cytokines (IL-27), inactivation of autophagy and apoptosis through up-regulation of NUPR1 [5.7-fold (high dose) and 5.1-fold (medium dose) [p < 0.05] and IL7R expression. We detected repression of genes involved in MHC class II antigen processing and presentation, such as cathepsins, SLA-DQB1, SLA-DOB, SLA-DMB, SLA-DRA, and SLA-DQA in the medium and high dose groups. Additionally, the host-pathogen interaction activated the CD8⁺ cytotoxicity and neutrophil machinery by increasing the expression of neutrophils/CD8⁺ T effector cell-recruiting chemokines (CCL2, CXCL2, CXCL10, CCL23, CCL4, CXCL8, and CXCL13) in the lethal high and medium dose groups. The recovered pigs infected with ASFV at a low dose significantly repressed the expression of CXCL10, averting induction of T lymphocyte apoptosis and FUNDC1 that suppressed neutrophilia.

Conclusions

We provide the first in vivo gene expression profile data from locally-adapted pigs from south-western Kenya following experimental infection with a highly virulent ASFV genotype IX isolate at varying doses that mimic acute and mild disease. Our study showed that the locally-adapted pigs induced the expression of genes associated with tolerance to infection and repression of genes involved in inflammation at varying levels depending upon the ASFV dose administered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08754-8.

Proteomic Analysis of Chicken Chorioallantoic Membrane (CAM) during Embryonic Development Provides Functional Insight

In oviparous animals, the egg contains all resources required for embryonic development. The chorioallantoic membrane (CAM) is a placenta-like structure produced by the embryo for acid-base balance, respiration, and calcium solubilization from the eggshell for bone mineralization. The CAM is a valuable in vivo model in cancer research for development of drug delivery systems and has been used to study tissue grafts, tumor metastasis, toxicology, angiogenesis, and assessment of bacterial invasion. However, the protein constituents involved in different CAM functions are poorly understood. Therefore, we have characterized the CAM proteome at two stages of development (ED12 and ED19) and assessed the contribution of the embryonic blood serum (EBS) proteome to identify CAM-unique proteins. LC/MS/MS-based proteomics allowed the identification of 1470, 1445, and 791 proteins in CAM (ED12), CAM (ED19), and EBS, respectively. In total, 1796 unique proteins were identified. Of these, 175 (ED12), 177 (ED19), and 105 (EBS) were specific to these stages/compartments. This study attributed specific CAM protein constituents to functions such as calcium ion transport, gas exchange, vasculature development, and chemical protection against invading pathogens. Defining the complex nature of the CAM proteome provides a crucial basis to expand its biomedical applications for pharmaceutical and cancer research.

The Functional Characterization of GCaMP3.0 Variants Specifically Targeted to Subcellular Domains

Calcium (Ca²⁺) ions play a pivotal role in physiology and cellular signaling. The intracellular Ca²⁺ concentration ([Ca²⁺]_i) is about three orders of magnitude lower than the extracellular concentration, resulting in a steep transmembrane concentration gradient. Thus, the spatial and the temporal dynamics of [Ca²⁺]_i are ideally suited to modulate Ca²⁺-mediated cellular responses to external signals. A variety of highly sophisticated methods have been developed to gain insight into cellular Ca²⁺ dynamics. In addition to electrophysiological measurements and the application of synthetic dyes that change their fluorescent properties upon interaction with Ca²⁺, the introduction and the ongoing development of genetically encoded Ca²⁺ indicators (GECI) opened a new era to study Ca²⁺-driven processes in living cells and organisms. Here, we have focused on one well-established GECI, i.e., GCaMP3.0. We have systematically modified the protein with sequence motifs, allowing localization of the sensor in the nucleus, in the mitochondrial matrix, at the mitochondrial outer membrane, and at the plasma membrane. The individual variants and a cytosolic version of GCaMP3.0 were overexpressed and purified from E. coli cells to study their biophysical properties in solution. All versions were examined to monitor Ca²⁺ signaling in stably transfected cell lines and in primary cortical neurons transduced with recombinant Adeno-associated viruses (rAAV). In this comparative study, we provide evidence for a robust approach to reliably trace Ca²⁺ signals at the (sub)-cellular level with pronounced temporal resolution.

The Interaction Between Non-Coding RNAs and Calcium Binding Proteins

Calcium binding proteins (CBP) are a group of proteins mediating the effects of calcium on cellular functions. These proteins can regulate calcium levels inside the cells and contribute in several cellular functions through transporting this ion across cell membranes or decoding related signals. Recent studies have shown that several non-coding RNAs interact with CBPs to affect their expression or activity. The interactions between these transcripts and CBPs have implications in the pathoetiology of human disorders, including both neoplastic and non-neoplastic conditions. In the current review, we describe the interactions between three classes of non-coding RNAs (long non-coding RNAs, circular RNAs, and microRNAs) and a number of CBPs, particularly CAB39, S100A1, S100A4, S100A7 and S100P. This kind of interaction has been verified in different pathological contexts such as drug-induced cardiotoxicity, osteoblasts cytotoxicity, acute lung injury, myocardial ischemia/reperfusion injury, proliferative diabetic retinopathy, glomerulonephritis, as well as a wide array of neoplastic conditions.

Targeted Activation of GPCR-Mediated Ca2+ Signaling Drives Enhanced Cartilage-Like Matrix Formation

Intracellular calcium ([Ca²⁺]_i) signaling is a critical regulator of chondrogenesis, chondrocyte differentiation, and cartilage development. Calcium (Ca²⁺) signaling is known to direct processes that govern chondrocyte gene expression, protein synthesis, cytoskeletal remodeling, and cell fate. Control of chondrocyte/chondroprogenitor Ca²⁺ signaling has been attempted through mechanical and/or pharmacological activation of endogenous Ca²⁺ signaling transducers; however, such approaches can lack specificity and/or precision regarding Ca²⁺ activation mechanisms. Synthetic signaling platforms permitting precise and selective Ca²⁺ signal transduction can improve dissection of the roles that [Ca²⁺]_i signaling play in chondrocyte behavior. One such platform is the chemogenetic hM3Dq DREADD (designer receptor exclusively activated by designer drugs) that activates [Ca²⁺]_i signaling via the Gα_q-PLCβ-IP₃-ER pathway upon clozapine N-oxide (CNO) administration. We previously demonstrated hM3Dq's ability to precisely and synthetically initiate robust [Ca²⁺]_i transients and oscillatory [Ca²⁺]_i signaling in chondrocyte-like ATDC5 cells. Here, we investigate the effects that long-term CNO stimulatory culture have on hM3Dq [Ca²⁺]_i signaling dynamics, proliferation, and protein deposition in 2D ATDC5 cultures. Long-term culturing under repeated CNO stimulation modified the temporal dynamics of hM3Dq [Ca²⁺]_i signaling, increased cell proliferation, and enhanced matrix production in a CNO dose- and frequency-dependent manner, and triggered the formation of cell condensations that developed aligned, anisotropic neotissue structures rich in cartilaginous proteoglycans and collagens, all in the absence of differentiation inducers. This study demonstrated Gα_q-GPCR-mediated [Ca²⁺]_i signaling involvement in chondroprogenitor proliferation and cartilage-like matrix production, and established hM3Dq as a powerful tool for elucidating the role of GPCR-mediated Ca²⁺ signaling in chondrogenesis and chondrocyte differentiation.

Mangifera indica (Mango): A Promising Medicinal Plant for Breast Cancer Therapy and Understanding Its Potential Mechanisms of Action

Globally, breast cancer is the most common cancer type and is one of the most significant causes of deaths in women. To date, multiple clinical interventions have been applied, including surgical resection, radiotherapy, endocrine therapy, targeted therapy and chemotherapy. However, 1) the lack of therapeutic options for metastatic breast cancer, 2) resistance to drug therapy and 3) the lack of more selective therapy for triple-negative breast cancer are some of the major challenges in tackling breast cancer. Given the safe nature of natural products, numerous studies have focused on their anti-cancer potentials. Mangifera indica, commonly known as mango, represents one of the most extensively investigated natural sources. In this review, we provide a comprehensive overview of M. indica extracts (bark, kernel, leaves, peel and pulp) and phytochemicals (mangiferin, norathyriol, gallotannins, gallic acid, pyrogallol, methyl gallate and quercetin) reported for in vitro and in vivo anti-breast cancer activities and their underlying mechanisms based on relevant literature from several scientific databases, including PubMed, Scopus and Google Scholar till date. Overall, the in vitro findings suggest that M. indica extracts and/or phytochemicals inhibit breast cancer cell growth, proliferation, migration and invasion as well as trigger apoptosis and cell cycle arrest. In vivo results demonstrated that there was a reduction in breast tumor xenograft growth. Several potential mechanisms underlying the anti-breast cancer activities have been reported, which include modulation of oxidative status, receptors, signalling pathways, miRNA expression, enzymes and cell cycle regulators. To further explore this medicinal plant against breast cancer, future research directions are addressed. The outcomes of the review revealed that M. indica extracts and their phytochemicals may have potential benefits in the management of breast cancer in women. However, to validate its utility in the creation of innovative and potent therapeutic agents to treat breast cancer, more dedicated research, especially clinical studies are needed to explore the anti-breast cancer potentials of M. indica extracts and their phytochemicals.

Postnatal Cytoarchitecture and Neurochemical Hippocampal Dysfunction in Down Syndrome

Although the prenatal hippocampus displays deficits in cellular proliferation/migration and volume, which are later associated with memory deficits, little is known about the effects of trisomy 21 on postnatal hippocampal cellular development in Down syndrome (DS). We examined postnatal hippocampal neuronal profiles from autopsies of DS and neurotypical (NTD) neonates born at 38-weeks’-gestation up to children 3 years of age using antibodies against non-phosphorylated (SMI-32) and phosphorylated (SMI-34) neurofilament, calbindin D-_28k (Calb), calretinin (Calr), parvalbumin (Parv), doublecortin (DCX) and Ki-67, as well as amyloid precursor protein (APP), amyloid beta (Aβ) and phosphorylated tau (p-tau). Although the distribution of SMI-32-immunoreactive (-ir) hippocampal neurons was similar at all ages in both groups, pyramidal cell apical and basal dendrites were intensely stained in NTD cases. A greater reduction in the number of DCX-ir cells was observed in the hippocampal granule cell layer in DS. Although the distribution of Calb-ir neurons was similar between the youngest and oldest NTD and DS cases, Parv-ir was not detected. Conversely, Calr-ir cells and fibers were observed at all ages in DS, while NTD cases displayed mainly Calr-ir fibers. Hippocampal APP/Aβ-ir diffuse-like plaques were seen in DS and NTD. By contrast, no Aβ_1–42 or p-tau profiles were observed. These findings suggest that deficits in hippocampal neurogenesis and pyramidal cell maturation and increased Calr immunoreactivity during early postnatal life contribute to cognitive impairment in DS.

Cellular Calcium Levels Influenced by NCA-2 Impact Circadian Period Determination in Neurospora

Intracellular calcium signaling has been implicated in the control of a variety of circadian processes in animals and plants, but its role in microbial clocks has remained largely cryptic. To examine the role of intracellular Ca²⁺ in the Neurospora clock, we screened mutants with knockouts of calcium transporter genes and identified a gene encoding a calcium exporter, nca-2, uniquely as having significant period effects. The loss of NCA-2 results in an increase in the cytosolic calcium level, and this leads to hyper-phosphorylation of core clock components, FRQ and WC-1, and a short period, as measured by both the core oscillator and the overt clock. Genetic analyses showed that mutations in certain frq phospho-sites and in Ca²⁺-calmodulin-dependent kinase 2 (camk-2) are epistatic to nca-2 in controlling the pace of the oscillator. These data are consistent with a model in which elevated intracellular Ca²⁺ leads to the increased activity of CAMK-2, leading to enhanced FRQ phosphorylation, accelerated closure of the circadian feedback loop, and a shortened circadian period length. At a mechanistic level, some CAMKs undergo more auto-phosphorylations in the Δnca-2 mutant, consistent with high calcium levels in the Δnca-2 mutant influencing the enzymatic activities of CAMKs. NCA-2 interacts with multiple proteins, including CSP-6, a protein known to be required for circadian output. Most importantly, the expression of nca-2 is circadian clock-controlled at both the transcriptional and translational levels, and this in combination with the period effects seen in strains lacking NCA-2 firmly places calcium signaling within the larger circadian system, where it acts as both an input to and an output from the core clock.

Mg(II) and Ca(II) Microsolvation by Ammonia: Born-Oppenheimer Molecular Dynamics Studies

We report the structural and energetic features of the Mg²⁺ and Ca²⁺ cations in ammonia microsolvation environments. Born-Oppenhemier molecular dynamics studies are carried out for [Mg(NH₃)_n]²⁺ and [Ca(NH₃)_n]²⁺ clusters with n = 2, 3, 4, 6, 8, 20, and 27 at 300 K based on hybrid density functional theory calculations. We determine binding energies per ammonia molecule and the metal cation solvation patterns as a function of the number of molecules. The general trend for Mg²⁺ is that the Mg-N distances increase as a function of n until the first solvation shell is populated by six ammonia molecules, and then the distances slightly decrease while CN = 6 does not change. For Ca²⁺, the first solvation shell at room temperature is populated by eight ammonia molecules for clusters with more than one solvation shell, leading to a different structure from that of [Ca(NH₃)₆]²⁺ hexamine. The evaporation of NH₃ molecules was found at 300 K only for Mg²⁺ clusters with n ≥ 10; this was not the case for Ca²⁺ clusters. Vibrational spectra are obtained for all of the clusters, and the evolution of the main features is discussed. EXAFS spectra are also presented for the [Mg(NH₃)₂₇(NH₃)₂₇]²⁺ and [Ca(NH₃)₂₇]²⁺ clusters, which yield valuable data to be compared with experimental data in the liquid phase, as previously done for the aqueous solvation of these dications.

New Approach for Untangling the Role of Uncommon Calcium-Binding Proteins in the Central Nervous System

Although Ca²⁺ ion plays an essential role in cellular physiology, calcium-binding proteins (CaBPs) were long used for mainly as immunohistochemical markers of specific cell types in different regions of the central nervous system. They are a heterogeneous and wide-ranging group of proteins. Their function was studied intensively in the last two decades and a tremendous amount of information was gathered about them. Girard et al. compiled a comprehensive list of the gene-expression profiles of the entire EF-hand gene superfamily in the murine brain. We selected from this database those CaBPs which are related to information processing and/or neuronal signalling, have a Ca²⁺-buffer activity, Ca²⁺-sensor activity, modulator of Ca²⁺-channel activity, or a yet unknown function. In this way we created a gene function-based selection of the CaBPs. We cross-referenced these findings with publicly available, high-quality RNA-sequencing and in situ hybridization databases (Human Protein Atlas (HPA), Brain RNA-seq database and Allen Brain Atlas integrated into the HPA) and created gene expression heat maps of the regional and cell type-specific expression levels of the selected CaBPs. This represents a useful tool to predict and investigate different expression patterns and functions of the less-known CaBPs of the central nervous system.

Expression of recombinant Schistosoma japonicum protein rSjE16 and its effects on LX-2 cells in vitro

Objective

The activation of hepatic stellate cells (HSCs) is a key event in schistosome-induced liver fibrosis. Previous studies have shown that soluble egg antigens and the recombinant P40 protein from Schistosoma japonicum eggs inhibit HSC activation. In the present study, we observed the direct effect of the S. japonicum recombinant (r)SjE16 protein on HSCs.

Methods

The sequence of SjE16 was analyzed by bioinformatics. Then western blotting, quantitative PCR, and MTT assays were performed to observe the effects of rSjE16 on HSCs.

Results

The SjE16 protein has no signal peptide or transmembrane region. rSjE16 significantly inhibited expression levels of α-smooth muscle actin and collagen I protein in LX-2 cells. rSjE16 also significantly increased the expression levels of interleukin (IL)-6 and IL-8, and enhanced the expression of matrix metalloproteinase (MMP)-2, MMP-9, and peroxisome proliferator-activated receptor-γ in LX-2 cells. LX-2 cell viability was not inhibited by rSjE16.

Conclusion

rSjE16 may be involved in the progression of HSC activation via a complex molecular mechanism, which requires further study to fully understand.

A comparative study on fabrication techniques of gelable bone matrix derived from porcine tibia

Recently, several types of native tissues have been enzymatically digested to prepare hydrogels that have natural-mimic extracellular matrix (ECM) proteins, architecture, and biologic activities. However, the residual detergents and salts remaining in the hydrogel may cause some undesirable effects on compatibility, functionality, and bioactivity of the material. In this study, we enzymatically digested the demineralized and decellularized bone matrix (DDBM) and adopted two common methods that included dialysis against distilled water and acetone precipitation for sample desalting. Efficiency in salt removal, protein preservation, gelation ability, and in vivo biocompatibility and function were compared to the DDBM digest without a desalting treatment. After lyophilization, the dialyzed, precipitated, and non-desalted DDBM digests all exhibited cotton-like texture and were water-soluble; however, only the precipitated DDBM digest could be gelled. We also found that the method of acetone precipitation could effectively remove salt from the DDBM digest while preserving of multiple proteins from the native bone and internal porous structure. A total of 57 proteins were identified by mass spectrometry in the precipitated DDBM digest and the majority of these proteins are critical to overall protein assembly, scaffold structure and stability, and cell-activities. Additionally, the precipitated DDBM digest possessed enhanced biocompatibility and osteointegration in repairing a cranial bone defect in Sprague-Dawley (SD) rat. In conclusion, the soluble, biodegradable, and biocompatible natures of the precipitated DDBM digest allow its usage in bone tissue engineering as a protein carrier because of its resemblance to native bone-like protein composite and operative flexibility.

Evolution of Matrix Gla and Bone Gla Protein Genes in Jawed Vertebrates

Matrix Gla protein (Mgp) and bone Gla protein (Bgp) are vitamin-K dependent proteins that bind calcium in their γ-carboxylated versions in mammals. They are recognized as positive (Bgp) or negative (Mgp and Bgp) regulators of biomineralization in a number of tissues, including skeletal tissues of bony vertebrates. The Mgp/Bgp gene family is poorly known in cartilaginous fishes, which precludes the understanding of the evolution of the biomineralization toolkit at the emergence of jawed vertebrates. Here we took advantage of recently released genomic and transcriptomic data in cartilaginous fishes and described the genomic loci and gene expression patterns of the Mgp/Bgp gene family. We identified three genes, Mgp1, Mgp2, and Bgp, in cartilaginous fishes instead of the single previously reported Mgp gene. We describe their genomic loci, resulting in a dynamic evolutionary scenario for this gene family including several events of local (tandem) duplications, but also of translocation events, along jawed vertebrate evolution. We describe the expression patterns of Mgp1, Mgp2, and Bgp in embryonic stages covering organogenesis in the small-spotted catshark Scyliorhinus canicula and present a comparative analysis with Mgp/Bgp family members previously described in bony vertebrates, highlighting ancestral features such as early embryonic, soft tissues, and neuronal expressions, but also derived features of cartilaginous fishes such as expression in fin supporting fibers. Our results support an ancestral function of Mgp in skeletal mineralization and a later derived function of Bgp in skeletal development that may be related to the divergence of bony vertebrates.

Mitochondrial Calcification

One of the most fascinating aspects of mitochondria is their remarkable ability to accumulate and store large amounts of calcium in the presence of phosphate leading to mitochondrial calcification. In this paper, we briefly address the mechanisms that regulate mitochondrial calcium homeostasis followed by the extensive review on the formation and characterization of intramitochondrial calcium phosphate granules leading to mitochondrial calcification and its relevance to physiological and pathological calcifications of body tissues.

Domain-wise differentiation of Mycobacterium tuberculosis H37 Rv hypothetical proteins: A roadmap to discover bacterial survival potentials

Proteomic information revealed approximately 3,923 proteins in Mycobacterium tuberculosis H₃₇ Rv genome of which around ∼25% of proteins are hypothetical proteins (HPs). The present work comprises computational approaches to identify and characterize the HPs of M. tuberculosis that symbolize the putative target for rationale development of a drug or antituberculosis strategy. Proteins were primarily classified based on motif and domain information, which were further analyzed for the presence of virulence factors (VFs), determination of localization, and signal peptide/enzymatic cleavage sites. 863 HPs were found, and 599 HPs were finalized based on motifs, that is, GTP (525), Trx (47), SAM (14), PE-PGRS (5), and CBD (8). 80 HPs contain virulence factor (VF), 24 HPs localized in membrane region, and 4 HPs contain signal peptide/enzymatic cleavage sites. The overall parametric study finalizes four HPs Rv0679c, Rv0906, Rv3627c, and Rv3811 that also comprise GTPase domain. Structure prediction, structure-based function prediction, molecular docking and mutation analysis of selected proteins were done. Docking studies revealed that GTP and GTPase inhibitor (mac0182344) were docked with all four proteins with high affinities. In silico point mutation studies showed that substitution of aspartate with glycine within a GTPase motif showed the largest decrease in stability and pH differentiation also affects protein's stability. This analysis thus fixes a roadmap in the direction of finding potential target of this bacterium for drug development and enlightens the efficacy of GTP as a major regulator of Mycobacterial cellular pathways.

Calcium signaling: breast cancer's approach to manipulation of cellular circuitry

Calcium is a versatile element that participates in cell signaling for a wide range of cell processes such as death, cell cycle, division, migration, invasion, metabolism, differentiation, autophagy, transcription, and others. Specificity of calcium in each of these processes is achieved through modulation of intracellular calcium concentrations by changing the characteristics (amplitude/frequency modulation) or location (spatial modulation) of the signal. Breast cancer utilizes calcium signaling as an advantage for survival and progression. This review integrates evidence showing that increases in expression of calcium channels, GPCRs, pumps, effectors, and enzymes, as well as resulting intracellular calcium signals, lead to high calcium and/or an elevated calcium- mobilizing capacity necessary for malignant functions such as migratory, invasive, proliferative, tumorigenic, or metastatic capacities.

Disturbances in Calcium Homeostasis Promotes Skeletal Muscle Atrophy: Lessons From Ventilator-Induced Diaphragm Wasting

Mechanical ventilation (MV) is often a life-saving intervention for patients in respiratory failure. Unfortunately, a common and undesired consequence of prolonged MV is the development of diaphragmatic atrophy and contractile dysfunction. This MV-induced diaphragmatic weakness is commonly labeled “ventilator-induced diaphragm dysfunction” (VIDD). VIDD is an important clinical problem because diaphragmatic weakness is a major risk factor for the failure to wean patients from MV; this inability to remove patients from ventilator support results in prolonged hospitalization and increased morbidity and mortality. Although several processes contribute to the development of VIDD, it is clear that oxidative stress leading to the rapid activation of proteases is a primary contributor. While all major proteolytic systems likely contribute to VIDD, emerging evidence reveals that activation of the calcium-activated protease calpain plays a required role. This review highlights the signaling pathways leading to VIDD with a focus on the cellular events that promote increased cytosolic calcium levels and the subsequent activation of calpain within diaphragm muscle fibers. In particular, we discuss the emerging evidence that increased mitochondrial production of reactive oxygen species promotes oxidation of the ryanodine receptor/calcium release channel, resulting in calcium release from the sarcoplasmic reticulum, accelerated proteolysis, and VIDD. We conclude with a discussion of important and unanswered questions associated with disturbances in calcium homeostasis in diaphragm muscle fibers during prolonged MV.

Coordination between Cell Motility and Cell Cycle Progression in Keratinocyte Sheets via Cell-Cell Adhesion and Rac1

Regulations of cell motility and proliferation are essential for epithelial development and homeostasis. However, it is not fully understood how these cellular activities are coordinated in epithelial collectives. In this study, we find that keratinocyte sheets exhibit time-dependent coordination of collective cell movement and cell cycle progression after seeding cells. Cell movement and cell cycle progression are coordinately promoted by Rac1 in the “early phase” (earlier than ∼30 h after seeding cells), which is not abrogated by increasing the initial cell density to a saturated level. The Rac1 activity is gradually attenuated in the “late phase” (later than ∼30 h after seeding cells), leading to arrests in cell motility and cell cycle. Intact adherens junctions are required for normal coordination between cell movement and cell cycle progression in both early and late phases. Our results unveil a novel basis for integrating motile and proliferative behaviors of epithelial collectives.

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Cell motility and cell cycle progression in keratinocyte sheets are temporally coordinated

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Rac1 promotes both cell motility and cell cycle progression in keratinocyte sheets

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Arrest of cell motility and cell cycle is associated with Rac1 deactivation

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Adherens junction is required for coordinating cell motility and cell cycle

Calcium Channels in Adult Brain Neural Stem Cells and in Glioblastoma Stem Cells

The brain of adult mammals, including humans, contains neural stem cells (NSCs) located within specific niches of which the ventricular-subventricular zone (V-SVZ) is the largest one. Under physiological conditions, NSCs proliferate, self-renew and produce new neurons and glial cells. Several recent studies established that oncogenic mutations in adult NSCs of the V-SVZ are responsible for the emergence of malignant primary brain tumors called glioblastoma. These aggressive tumors contain a small subpopulation of cells, the glioblastoma stem cells (GSCs), that are endowed with proliferative and self-renewal abilities like NSCs from which they may arise. GSCs are thus considered as the cells that initiate and sustain tumor growth and, because of their resistance to current treatments, provoke tumor relapse. A growing body of studies supports that Ca²⁺ signaling controls a variety of processes in NSCs and GSCs. Ca²⁺ is a ubiquitous second messenger whose fluctuations of its intracellular concentrations are handled by channels, pumps, exchangers, and Ca²⁺ binding proteins. The concerted action of the Ca²⁺ toolkit components encodes specific Ca²⁺ signals with defined spatio-temporal characteristics that determine the cellular responses. In this review, after a general overview of the adult brain NSCs and GSCs, we focus on the multiple roles of the Ca²⁺ toolkit in NSCs and discuss how GSCs hijack these mechanisms to promote tumor growth. Extensive knowledge of the role of the Ca²⁺ toolkit in the management of essential functions in healthy and pathological stem cells of the adult brain should help to identify promising targets for clinical applications.

Calbindin-D28K, parvalbumin, and calretinin in young and aged human locus coeruleus

Certain neuronal populations, including basal forebrain cholinergic neurons (BFCN) and noradrenergic neurons of the locus coeruleus (LC), are selectively vulnerable to pathology and loss early in the course of aging and Alzheimer's disease (AD). Human BFCN show substantial loss of the calcium-binding protein (CBP), calbindin-D28K (CB), during normal aging, which is associated with formation of neurofibrillary tangles and BFCN loss in AD. Here we determined if, similar to the BFCN, LC neurons contain CB or the other 2 ubiquitous CBPs parvalbumin and calretinin, and whether these proteins display an age-related loss from LC neurons. Immunostaining for CBP and tyrosine hydroxylase, a marker of catecholaminergic neurons, was used in sections from the LC of young and aged human brains. Parvalbumin and calretinin immunoreactivities were completely absent from human LC neurons. A subpopulation of LC neurons (~10%) contained CB immunoreactivity. Quantitative analysis revealed no age-related loss of CB from LC neurons. Thus, unlike the BFCN, age-related loss of CB does not figure prominently in the selective vulnerability of LC neurons to degeneration in AD.

Aspartate Residues in a Forisome-Forming SEO Protein Are Critical for Protein Body Assembly and Ca2+ Responsiveness

Forisomes are protein bodies known exclusively from sieve elements of legumes. Forisomes contribute to the regulation of phloem transport due to their unique Ca2+-controlled, reversible swelling. The assembly of forisomes from sieve element occlusion (SEO) protein monomers in developing sieve elements and the mechanism(s) of Ca2+-dependent forisome contractility are poorly understood because the amino acid sequences of SEO proteins lack conventional protein-protein interaction and Ca2+-binding motifs. We selected amino acids potentially responsible for forisome-specific functions by analyzing SEO protein sequences in comparison to those of the widely distributed SEO-related (SEOR), or SEOR proteins. SEOR proteins resemble SEO proteins closely but lack any Ca2+ responsiveness. We exchanged identified candidate residues by directed mutagenesis of the Medicago truncatula SEO1 gene, expressed the mutated genes in yeast (Saccharomyces cerevisiae) and studied the structural and functional phenotypes of the forisome-like bodies that formed in the transgenic cells. We identified three aspartate residues critical for Ca2+ responsiveness and two more that were required for forisome-like bodies to assemble. The phenotypes observed further suggested that Ca2+-controlled and pH-inducible swelling effects in forisome-like bodies proceeded by different yet interacting mechanisms. Finally, we observed a previously unknown surface striation in native forisomes and in recombinant forisome-like bodies that could serve as an indicator of successful forisome assembly. To conclude, this study defines a promising path to the elucidation of the so-far elusive molecular mechanisms of forisome assembly and Ca2+-dependent contractility.

Calcium Permeable Channels in Cancer Hallmarks

Cancer, the second cause of death worldwide, is characterized by several common criteria, known as the “cancer hallmarks” such as unrestrained cell proliferation, cell death resistance, angiogenesis, invasion and metastasis. Calcium permeable channels are proteins present in external and internal biological membranes, diffusing Ca²⁺ ions down their electrochemical gradient. Numerous physiological functions are mediated by calcium channels, ranging from intracellular calcium homeostasis to sensory transduction. Consequently, calcium channels play important roles in human physiology and it is not a surprise the increasing number of evidences connecting calcium channels disorders with tumor cells growth, survival and migration. Multiple studies suggest that calcium signals are augmented in various cancer cell types, contributing to cancer hallmarks. This review focuses in the role of calcium permeable channels signaling in cancer with special attention to the mechanisms behind the remodeling of the calcium signals. Transient Receptor Potential (TRP) channels and Store Operated Channels (SOC) are the main extracellular Ca²⁺ source in the plasma membrane of non-excitable cells, while inositol trisphosphate receptors (IP₃R) are the main channels releasing Ca²⁺ from the endoplasmic reticulum (ER). Alterations in the function and/or expression of these calcium channels, as wells as, the calcium buffering by mitochondria affect intracellular calcium homeostasis and signaling, contributing to the transformation of normal cells into their tumor counterparts. Several compounds reported to counteract several cancer hallmarks also modulate the activity and/or the expression of these channels including non-steroidal anti-inflammatory drugs (NSAIDs) like sulindac and aspirin, and inhibitors of polyamine biosynthesis, like difluoromethylornithine (DFMO). The possible role of the calcium permeable channels targeted by these compounds in cancer and their action mechanism will be discussed also in the review.

HSI-II Gene Cluster of Pseudomonas syringae pv. tomato DC3000 Encodes a Functional Type VI Secretion System Required for Interbacterial Competition

The type VI secretion system (T6SS) is a widespread bacterial nanoweapon used for delivery of toxic proteins into cell targets and contributes to virulence, anti-inflammatory processes, and interbacterial competition. In the model phytopathogenic bacterium Pseudomonas syringae pv. tomato (Pst) DC3000, two T6SS gene clusters, HSI-I and HSI-II, were identified, but their functions remain unclear. We previously reported that hcp2, located in HSI-II, is involved in competition with enterobacteria and yeast. Here, we demonstrated that interbacterial competition of Pst DC3000 against several Gram-negative plant-associated bacteria requires mainly HSI-II activity. By means of a systematic approach using in-frame deletion mutants for each gene in the HSI-II cluster, we identified genes indispensable for Hcp2 expression, Hcp2 secretion and interbacterial competition ability. Deletion of PSPTO_5413 only affected growth in interbacterial competition assays but not Hcp2 secretion, which suggests that PSPTO_5413 might be a putative effector. Moreover, PSPTO_5424, encoding a putative σ⁵⁴-dependent transcriptional regulator, positively regulated the expression of all three operons in HSI-II. Our discovery that the HSI-II gene cluster gives Pst DC3000 the ability to compete with other plant-associated bacteria could help in understanding a possible mechanism of how phytopathogenic bacteria maintain their ecological niches.

ER-luminal [Ca2+] regulation of InsP3 receptor gating mediated by an ER-luminal peripheral Ca2+-binding protein

Modulating cytoplasmic Ca2+ concentration ([Ca2+]i) by endoplasmic reticulum (ER)-localized inositol 1,4,5-trisphosphate receptor (InsP3R) Ca2+-release channels is a universal signaling pathway that regulates numerous cell-physiological processes. Whereas much is known regarding regulation of InsP3R activity by cytoplasmic ligands and processes, its regulation by ER-luminal Ca2+ concentration ([Ca2+]ER) is poorly understood and controversial. We discovered that the InsP3R is regulated by a peripheral membrane-associated ER-luminal protein that strongly inhibits the channel in the presence of high, physiological [Ca2+]ER. The widely-expressed Ca2+-binding protein annexin A1 (ANXA1) is present in the nuclear envelope lumen and, through interaction with a luminal region of the channel, can modify high-[Ca2+]ER inhibition of InsP3R activity. Genetic knockdown of ANXA1 expression enhanced global and local elementary InsP3-mediated Ca2+ signaling events. Thus, [Ca2+]ER is a major regulator of InsP3R channel activity and InsP3R-mediated [Ca2+]i signaling in cells by controlling an interaction of the channel with a peripheral membrane-associated Ca2+-binding protein, likely ANXA1.

The mystery of mitochondria-ER contact sites in physiology and pathology: A cancer perspective

Mitochondria-associated membranes (MAM), physical platforms that enable communication between mitochondria and the endoplasmic reticulum (ER), are enriched with many proteins and enzymes involved in several crucial cellular processes, such as calcium (Ca²⁺) homeostasis, lipid synthesis and trafficking, autophagy and reactive oxygen species (ROS) production. Accumulating studies indicate that tumor suppressors and oncogenes are present at these intimate contacts between mitochondria and the ER, where they influence Ca²⁺ flux between mitochondria and the ER or affect lipid homeostasis at MAM, consequently impacting cell metabolism and cell fate. Understanding these fundamental roles of mitochondria-ER contact sites as important domains for tumor suppressors and oncogenes can support the search for new and more precise anticancer therapies. In the present review, we summarize the current understanding of basic MAM biology, composition and function and discuss the possible role of MAM-resident oncogenes and tumor suppressors.

Polymorphisms in CRYBB2 encoding βB2-crystallin are associated with antisaccade performance and memory function

βB2-crystallin (gene symbol: Crybb2/CRYBB2) was first described as a structural protein of the ocular lens before it was detected in various brain regions of the mouse, including the hippocampus and the cerebral cortex. Mutations in the mouse Crybb2 gene lead to alterations of sensorimotor gating measured as prepulse inhibition (PPI) and reduced hippocampal size, combined with an altered number of parvalbumin-positive GABAergic interneurons. Decreased PPI and alterations of parvalbumin-positive interneurons are also endophenotypes that typically occur in schizophrenia. To verify the results found in mice, we genotyped 27 single nucleotide polymorphisms (SNPs) within the CRYBB2 gene and its flanking regions and investigated different schizophrenia typical endophenotypes in a sample of 510 schizophrenia patients and 1322 healthy controls. In the case-control study, no association with schizophrenia was found. However, 3 of the 4 investigated haplotype blocks indicated a decreased CRYBB2 mRNA expression. Two of these blocks were associated with poorer antisaccade task performance and altered working memory-linked functional magnetic resonance imaging signals. For the two haplotypes associated with antisaccade performance, suggestive evidence was found with visual memory and in addition, haplotype block 4 showed a nominally significant association with reduced sensorimotor gating, measured as P50 ratio. These results were not schizophrenia-specific, but could be detected in a combined sample of patients and healthy controls. This is the first study to demonstrate the importance of βB2-crystallin for antisaccade performance and memory function in humans and therefore provides implications for βB2-crystallin function in the human brain.

Hemispheric asymmetry of calbindin-positive neurons is associated with successful song imitation

The plasticity that facilitates learning during critical (sensitive) periods in development is tightly regulated by inhibitory neurons. Song acquisition in birds is one example of a learning process that occurs during a sensitive period early in development. Sensory experience with a song 'tutor' during this sensitive period prunes excitatory and inhibitory synapses in the song production nucleus HVC (proper noun). Neurons in the caudomedial nidopallium (NCM), a secondary auditory region, lose their tutor song selectivity when gamma-aminobutyric acid (GABA) signaling is blocked. Given the importance of inhibition in the song learning process, we investigated whether individual differences in learning outcomes can be explained by the distribution of specific populations of (mostly) inhibitory neurons in HVC and NCM. We measured the densities of distinct neuronal populations (defined by their expression of the calcium-binding proteins calbindin, calretinin, and parvalbumin) in these two regions. We found that lateralization of calbindin-positive neurons was related to successful song learning: good learners were characterized by hemispheric asymmetry of calbindin-positive neurons in the medial NCM (fewer CB+ neurons in the left hemisphere), whereas poor learners did not show any asymmetry. In contrast, the density of all three neuronal populations in HVC did not differ between good and poor learners. These findings not only identify a specific (presumably) inhibitory cell type (calbindin-expressing neurons) that is related to song learning, but also emphasize the role of hemispheric asymmetry in auditory memory formation.

Structures and functions of penta-EF-hand calcium-binding proteins and their interacting partners: enigmatic relationships between ALG-2 and calpain-7

The penta-EF-hand (PEF) protein family includes ALG-2 (gene name, PDCD6) and its paralogs as well as classical calpain family members. ALG-2 is a prototypic PEF protein that is widely distributed in eukaryotes and interacts with a variety of proteins in a Ca²⁺-dependent manner. Mammalian ALG-2 and its interacting partners have various modulatory roles including roles in cell death, signal transduction, membrane repair, ER-to-Golgi vesicular transport, and RNA processing. Some ALG-2-interacting proteins are key factors that function in the endosomal sorting complex required for transport (ESCRT) system. On the other hand, mammalian calpain-7 (CAPN7) lacks the PEF domain but contains two microtubule-interacting and trafficking (MIT) domains in tandem. CAPN7 interacts with a subset of ESCRT-III proteins through the MIT domains and regulates EGF receptor downregulation. Structures and functions of ALG-2 and those of its interacting partners as well as relationships with the calpain family are reviewed in this article.