Physiology and pathophysiology of the interstitial cell of Cajal: from bench to bedside. I. Functional development and plasticity of interstitial cells of Cajal networks

Interstitial cells of Cajal (ICC) are the pacemaker cells in gastrointestinal (GI) muscles. They also mediate or transduce inputs from enteric motor nerves to the smooth muscle syncytium. What is known about functional roles of ICC comes from developmental studies based on the discovery that ICC express c-kit. Functional development of ICC networks depends on signaling via the Kit receptor pathway. Immunohistochemical studies using Kit antibodies have expanded our knowledge about the ICC phenotype, the structure of ICC networks, the interactions of ICC with other cells within the tunica muscularis, and the loss of ICC in some motility disorders. Manipulating Kit signaling with reagents to block the receptor or downstream signaling pathways or by using mutant mice in which Kit or its ligand, stem cell factor, are defective has allowed novel studies of the development of these cells within the tunica muscularis and also allowed the study of specific functions of different classes of ICC in several regions of the GI tract. This article examines the role of ICC in GI motility, focusing on the functional development and maintenance of ICC networks in the GI tract and the phenotypic changes that can occur when the Kit signaling pathway is disrupted.     

Physiology and pathophysiology of the interstitial cells of Cajal: from bench to bedside. IV. Genetic and animal models of GI motility disorders caused by loss of interstitial cells of Cajal

Several human motility disorders have been shown to be associated with loss or defects in interstitial cells of Cajal (ICC) networks. Because tissue samples for these studies were taken from patients with well-advanced motility problems, it is difficult to determine whether the loss of ICC is a cause or a consequence of the disease process. To establish the cause-and-effect relationship of ICC loss in motility disorders, it may be feasible to use animal models in which ICC are lost as motility dysfunction develops. Several models with defects in ICC networks have been developed, and these include animals with defects in the Kit signaling pathway (e.g., white-spotting mutants that have defects in Kit receptors; steel mutants that have mutations in stem cell factor, the ligand for Kit; and animals that are chronically treated with reagents that block Kit or downstream signaling proteins). ICC do not die when Kit signaling is blocked, rather, they redifferentiate into a smooth muscle-like phenotype. Diabetic animals (NOD/LtJ mice), animals with chronic bowel obstruction, and inflammatory bowel models also have defects in ICC networks that have been associated with motility disorders. By studying these models with molecular and genomic techniques it may be possible to determine the signals that cause loss of ICC and find ways of restoring ICC to dysfunctional tissues. This article discusses recent progress in the utilization of animal models to study the consequences of losing ICC on the development of motility disorders.     

Physiology and pathophysiology of the interstitial cells of Cajal: from bench to bedside. VI. Pathogenesis and therapeutic approaches to human gastric dysrhythmias

This review describes recent advances in our knowledge about the pathogenesis and therapeutic approaches to human gastric dysrhythmias. A number of clinical conditions has been found to be associated with gastric slow-wave rhythm disturbances that may relate to the induction of nausea and vomiting. Human and animal studies indicate that multiple neurohumoral factors are involved in the generation of gastric dysrhythmias. Antral distension and increased intestinal delivery of lipids may cause slow-wave disruption and development of nausea. This may be mediated by cholinergic and serotonergic pathways. Similarly, progesterone and estrogen may also disrupt gastric slow-wave rhythm in susceptible individuals. Prostaglandin overproduction in gastric smooth muscle appears to mediate slow-wave disruption in diabetes and with tobacco smoking. On the other hand, central cholinergic pathways play an important role in the genesis of gastric dysrhythmias associated with motion sickness. This may be mediated by vasopressin released from the pituitary. Although it is difficult to ascribe with certainty a causative role of slow-wave rhythm disturbances in the genesis of nausea and vomiting, the search has begun for novel antiemetic therapies based on their abilities to ablate or prevent gastric dysrhythmia formation. This includes the use of prostaglandin synthesis inhibitors, central muscarinic receptor antagonists, and dopamine receptor antagonists. Finally direct gastric electrical stimulation using a surgically implanted neurostimulator has shown promise in reducing emesis in patients with gastroparesis and gastric dysrhythmias.     

Dendritic cells: On the move from bench to bedside.

As dendritic cells increasingly become the adjuvant of choice in new approaches to cancer immunotherapy, a degree of protocol standardization is required to aid future large-scale clinical trials.     

无绿藻的研究进展:从基础到临床

无绿藻是一种直径约3 ～ 30 μm的单细胞生物,广泛存在于自然界和动物体表及体内,属于条件致病性真菌.目前主要通过直接镜检、真菌培养、组织病理学检查及分子生物学等手段对无绿藻进行鉴定.现已发现无绿藻属包括五个种,其中对人有致病性的仅为中型无绿藻基因型2、小型无绿藻和P.blaschkeae,其致病机制可能与外伤和免疫力低下有关.随着研究的深入,越来越多的无绿藻病被临床确诊.根据不同的类型及其临床表现,对无绿藻病的治疗也有所区别.为了提高对无绿藻这一条件真菌及其致病性的认识,该文对其生物学特性、鉴定方法、致病性、临床表现等研究进展做一简要综述.     

The transition from bench to bedside: lessons learned in the creation of a new T-cell product for the clinic

While the technology of translational research is sometimes considered a poor relation to 'basic science', it has become a central focus of work to turn exciting new concepts into practical therapies. Here we use the example of selective T-cell depletion of allografted lymphocytes to illustrate the problems of scale-up, reproducibility, sterility, safety and regulatory concerns encountered during the bench to bedside process.     

Familial adenomatous polyposis: from bedside to bench and vice versa. A tribute to the somatic cell geneticist P. Meera Khan.

Familial adenomatous polyposis (FAP) is characterized by the presence of numerous adenomatous polyps in the colorectum, as well as an autosomal dominant mode of inheritance. This syndrome will inevitably lead to colorectal cancer when left untreated, and it is estimated that 1% of all colorectal cancer cases are due to it. Over the past 20 years molecular genetic studies on FAP patients have laid down the basis for the elucidation of the genetic phenomena that ultimately result in the development of colorectal cancer. Professor P. Meera Khan was one of the leading authorities in the world of molecular genetics of colorectal cancer in general and of FAP in particular. His scientific contributions from the pre-DNA era up to the recent implementation of molecular genetic research in daily clinical practice have helped revolutionize our approach and management of FAP patients and their relatives.     

Alterations of the interstitial cells of Cajal and the microstructure of the gastrointestinal tract in KIT distal kinase mutant mice

The development and maintenance of interstitial cells of Cajal (ICC) are closely associated with SCF/KIT signal activity. In this study, we evaluate the distribution of ICC in KIT distal kinase domain mutant mice (Wads) and determine whether the loss-of-function mutations in KIT easily lead to gastrointestinal (GI) disorders. ICC were examined by anti-KIT immunohistochemistry and western blotting. The GI microstructure of wild-type (WT) and Wads mice in normal intestines and incomplete intestinal obstruction was evaluated by hematoxylin and eosin staining. The results in Wads^m/m mice were as follows. Myenteric ICC were obviously decreased in the stomach and colon and were totally absent in the small intestine. Intramuscular ICC were nearly absent in the stomach and irregularly distributed in the colon. Moreover, the smooth muscle thickness of the small intestine was increased 1.3-fold in Wads^m/m, compared to WT and Wads^m/+ mice and the diameter of the intestinal lumen was also enlarged in Wads^m/m mice. When constructing an incomplete intestinal obstruction model, the extent of distention involved was greater in Wads mice (1.6-fold in Wads^m/+ mice and 1.8-fold in Wads^m/m mice vs. WT mice). Meanwhile, the intestinal lumen expansion and decrease in ICC were more pronounced in Wads mice than in WT mice. Our results suggest that the KIT distal kinase domain mutation leads to an ICC loss in a subtype and location-specific pattern in Wads^m/m mice. The injury of the KIT signaling in mutant mice results in more serious pathological manifestations after being exposed to pathogenic factors.     

The tale of soluble receptors and binding proteins: from bench to bedside

Our approach of isolating proteins from a rich source of human proteins by ligand-affinity-chromatography enabled rapid and efficient isolation of not only soluble receptors corresponding to cell-associated receptors, but also independent binding-proteins and associated enzymes. No other approach would yield the latter. During the early 80's we prepared the tools and the infrastructure that enabled the subsequent 20 years of achievements. Thus we described eight soluble receptors (R) and binding proteins (BP) for various cytokines including the IL-6R, IFN-γR, TNFRI, TNFRII, LDLR, IFN-/βR, IL-18BP and IL-32BP identified as Proteinase 3. The isolation of the soluble IFN-/β receptor led to the cloning of its long sought cell surface ligand binding counterpart. We have established the concept that soluble receptors and binding proteins are normal constituents of body fluids in healthy individuals and that the levels of these biomarkers are modulated in various pathological situations. Each of these proteins contributed to basic science, one of them serves as a basis for therapy and some others are in various stages of clinical development.     

Serotonin fiber innervation of cerebellar cell suspensions intraparenchymally grafted to the cerebellum ofpcd mutant mice

One aspect of integration of implanted neurons into the neuronal circuitry of a defective host brain is the re-establishment of a host-to-graft afferent innervation. We addressed this issue by using the adult cerebellum of Purkinje cell degeneration (pcd) mutant mice, which lack virtually all Purkinje cells after postnatal day (P) 45. Purkinje cells constitute one of the cerebellar cell types being innervated by axons of raphé serotonin (5-HT) neurons. In normal mice, 5-HT-immunoreactive fibers are distributed to all cerebellar folia. Following Purkinje cell loss inpcd mice, cerebellar 5-HT-immunoreactive fibers persist. Cerebellar cell suspensions were prepared from embryonic day (E) 11–13 normal mouse embryos and were intraparenchymally grafted into the cerebellum ofpcd mutants either directly or after pre-treatment with 5, 7-dihydroxytryptamine (5,7-DHT) to selectively remove 5-HT cells of donor origin. The state of Purkinje cells and 5-HT axons was monitored in alternate sections by 28-kDa Ca²⁺-binding protein (CaBP) and 5-HT immunocytochemistry, respectively. Serotonin-immunoreactive axons were seen in the grafts from 5 to 32 days after transplantation. In some of the grafts which had not been pre-treated with 5,7-DHT, a small number of 5-HT-immunoreactive cell bodies was found, indicating that part of the 5-HT fiber innervation of the graft could actually derive from donor cells. On the other hand, in grafts pre-treated with 5,7-DHT, no 5-HT cell bodies were seen in the grafted cerebellum; 5-HT fibre innervation of the grafts occurred, but it appeared to be slightly less robust compared to situations of co-grafted 5-HT cell bodies. These findings suggest that host 5-HT fibers are able to provide afferent innervation to donor cerebellar tissue; the presence of co-grafted 5-HT cells may augment such an innervation.Special issue dedicated to Dr. Morris H. Aprison.     

Somatic hypermutation of immunoglobulin genes: lessons from proliferating cell nuclear antigenK164R mutant mice

Proliferating cell nuclear antigen (PCNA) encircles DNA as a ring-shaped homotrimer and, by tethering DNA polymerases to their template, PCNA serves as a critical replication factor. In contrast to high-fidelity DNA polymerases, the activation of low-fidelity translesion synthesis (TLS) DNA polymerases seems to require damage-inducible monoubiquitylation (Ub) of PCNA at lysine residue 164 (PCNA-Ub). TLS polymerases can tolerate DNA damage, i.e. they can replicate across DNA lesions. The lack of proofreading activity, however, renders TLS highly mutagenic. The advantage is that B cells use mutagenic TLS to introduce somatic mutations in immunoglobulin (Ig) genes to generate high-affinity antibodies. Given the critical role of PCNA-Ub in activating TLS and the role of TLS in establishing somatic mutations in immunoglobulin genes, we analysed the mutation spectrum of somatically mutated immunoglobulin genes in B cells from PCNA^K164R knock-in mice. A 10-fold reduction in A/T mutations is associated with a compensatory increase in G/C mutations—a phenotype similar to Polη and mismatch repair-deficient B cells. Mismatch recognition, PCNA-Ub and Polη probably act within one pathway to establish the majority of mutations at template A/T. Equally relevant, the G/C mutator(s) seems largely independent of PCNA^K164 modification.     

RNA-based gene therapy for the treatment and prevention of HIV: from bench to bedside

Gene therapy is considered a feasible approach for the treatment and prevention of HIV/AIDS. Targeting both viral genes and host dependency factors can interfere with the viral lifecycle and prevent viral replication. A number of approaches have been taken to target these genes, including ribozymes, aptamers, and RNAi based therapies. A number of these therapies are now beginning to make their way into clinical trials and providing proof of principle that gene therapy is a safe and realistic option for treating HIV. Here, we focus on those therapies that have progressed along the pipeline to preclinical and clinical testing.     

Molecular physiology and pathophysiology of tight junctions I. Tight junction structure and function: lessons from mutant animals and proteins

Tight junctions form the major paracellular barrier in epithelial tissues. Barrier-sealing properties are quite variable among cell types in terms of electrical resistance, solute and water flux, and charge selectivity. A molecular explanation for this variability appears closer following identification of the transmembrane proteins occludin and members of the claudin multigene family. For example, the human phenotype of mutations in claudin-16 suggests that it creates a channel that allows magnesium to diffuse through renal tight junctions. Similarly, a mouse knockout of claudin-11 reveals its role in formation of tight junctions in myelin and between Sertoli cells in testis. The study of other claudins is expected to elucidate their contributions to creating junction structure and physiology in all epithelial tissues.     

Direct and indirect innervation of smooth muscle cells of rat stomach,with special reference to the interstitial cells of Cajal

Interstitial cells of Cajal in the circular (ICC-CM) and longitudinal (ICC-LM) muscle layer of the rat gastric antrum and their innervation were studied ultrastructurally. Both ICC-CM and ICC-LM are characterized by many mitochondria, rough and smooth endoplasmic reticulum, caveolae, and formation of gap junctions with each other and with muscle cells, though ICC-LM tend to show more variable cytoplasmic features depending on section profiles. Close contacts between nerve terminals and both ICC-CM and ICC-LM are observed. These possible synaptic structures are characterized by: (1) accumulation of synaptic vesicles in nerve varicosities, (2) a narrow gap (about 20 nm) between pre- and postjunctional membranes, (3) lack of a basal lamina between pre- and postjunctional membranes, and (4) the presence of an electron-dense lining on the inner aspect of prejunctional membranes. Almost the same characteristics are observed between the nerve terminals and the muscle cells of both circular and longitudinal muscle layers of the same specimens. Therefore, we conclude that the smooth muscle cells of both circular and longitudinal layers of the rat antrum are directly and indirectly innervated via ICC. Their functional significance is discussed.     

Translating preclinical findings of (endothelial) progenitor cell mobilization into the clinic; from bedside to bench and back

It is generally accepted that angiogenesis plays a major role in tumor growth and numerous targeting agents directed against angiogenesis pathways have been developed and approved for clinical use. In the past years the concept of angiogenesis has developed into a multi-faceted process in which, besides local activation and division of endothelial cells, bone marrow derived progenitor cells (BMDPCs) contribute to neovascularization. A multitude of preclinical and clinical data indicates that the release of BMDPCs influences the response to certain anti-cancer modalities. In this review we provide an overview of all the preclinical and clinical studies contributing to this hypothesis and translate these findings to the clinic by pointing out the clinical implications these findings might have. The recent insight in the mechanism of a systemic host response, in response to various treatment modalities has shed new light on the mechanism of tumor regrowth, early recurrence and metastasis formation during or after treatment. This provides various new targets for therapy which can be used to improve conventional chemotherapy. Furthermore it provides a potential explanation why bevacizumab selectively enhances the effectiveness of only certain types of chemotherapy.     

Accessory oculomotor nuclei of man. II. The interstitial nucleus of Cajal: a Nissl and Golgi study.

The interstitial nucleus of Cajal (INC) is an important premotor centre related to the control of eye and head movements. The aim of the present research was to draw a detailed picture of the cytoarchitecture of the human INC, in particular taking into consideration the morphological features of the neurons and their functional implications. Within the neuronal population, two groups of cells were identified: one group (the most substantial) was made up of small and medium-sized neurons showing different soma shapes and both light and moderate basophilia. The second group consisted of a limited number (about 25%) of large cells dispersed throughout the whole INC, showing polygonal soma and intense basophilia. The hypothesis that these large cells represent a different cellular population inside the INC is advanced. On the basis of the dendritic emergence pattern, two types of cells were identified: multipolar and fusiform cells. The multipolar cells (59%) had small to large nerve cell bodies giving off 2-3 dendrites radiating in all directions. Dendrites and axons were often seen spreading outside the INC. The fusiform cells were small or medium sized and two dendrites emerged from the opposite poles of their elongated perikaryon. Their dendrites and axons always lay inside the INC. The fusiform cells were interpreted as neurons carrying out a mainly local integrative function, while the multipolar cells could also probably carry out an important projective role. The structural data reported are in agreement with the functional studies indicating the INC as both an integrative and a projective center.     

Remarkable features of tiny RNA molecules: Highlights of revolutionary discoveries on the path from the bench to bedside

The August 15, 2008 issue of Cell Cycle presents a breakthrough collection of papers including original Reports, Perspectives and Review articles that highlight revolutionary discoveries of remarkable regulatory features and biological functions of microRNAs and other small non-coding RNA molecules. Recognized as legitimate components of human genomes some eight years ago, microRNAs emerged as “master” regulators of life and death pathways and disease and health states which often appear to take precedents over phenotypically-relevant regulatory networks defined by the central dogma.¹ A compelling experimentally-supported case in support of this concept is presented by Susana Gonzalez, David G. Pisano and Manuel Serrano in a Report describing mechanistic principles of chromatin remodeling guided by siRNAs and miRNAs.² The Perspective by Pitto et al. summarizes evidence supporting the idea that microRNAs are integral components of the gene regulatory networks.³ Three papers of the Spotlight on microRNA section edited by Frank J. Slack overview the rapidly growing microRNA and cancer field (Medina and Slack), highlight aspects of functional integration of microRNAs into oncogenic and tumor suppressor pathways (Craig D. Lotterman, Oliver A. Kent and Joshua T. Mendell) and discuss lessons from microRNA mutants in worms, flies and mice (Peter Smibert and Eric C. Lai).^4-6 Novel experimental evidence of the important role of microRNA pathway aberrations in cancer are presented in the Report by Dmitri Lodygin and colleagues which describes discovery of inactivation of miR-34a by aberrant CpG methylation in multiple types of cancer.⁷ Finally, a disease phenocode hypothesis revealing sequence homology-driven association between disease-linked SNPs, microRNAs, and mRNAs of protein-coding genes is presented in the Report by Gennadi V. Glinsky.⁸ Initial experimental validation of this idea in a disease state genomic context of 15 major human disorders, namely bipolar disease; rheumatoid arthritis; coronary artery disease; Crohn's disease; type 1 diabetes; type 2 diabetes; hypertension; ankylosing spondylitis; Graves' disease (autoimmune thyroid disease); multiple sclerosis; breast cancer; prostate cancer; systemic lupus erythematosus; vitiligo-associated multiple autoimmune disease; and ulcerative colitis, identifies KPNA1 gene and other principal components of the nuclear import pathway as potential critical targets across large spectrum of human pathological conditions.⁸ We are confident that this unique collection of papers will be of interest to the broad scientific audience outside of an immediate microRNA field and extending to translational and clinical science.

References

1. Glinsky GV. Phenotype-defining functions of multiple non-coding RNA pathways. Cell Cycle 2008 7:1630-9.2. Susana Gonzalez, David G. Pisano and Manuel Serrano. Mechanistic principles of chromatin remodeling guided by siRNAs and miRNAs. Cell Cycle 2008; 7:In this issue.3. Letizia Pitto, Andrea Ripoli, Federico Cremisi and Giuseppe Rainaldi. microRNA(interference) networks are embedded in the gene regulatory networks. Cell Cycle 2008; 7:In this issue.4. Pedro P. Medina and Frank J. Slack. MicroRNAs and cancer: An overview. Cell Cycle 2008; 7: In this issue.5. Craig D. Lotterman, Oliver A. Kent and Joshua T. Mendell. Functional integration of microRNAs into oncogenic and tumor suppressor pathways. Cell Cycle 2008; 7: In this issue.6. Peter Smibert and Eric C. Lai. Lessons from microRNA mutants in worms, flies and mice. Cell Cycle 2008; 7: In this issue.7. Dmitri Lodygin, Valery Tarasov, Alexey Epanchintsev, Carola Berking, Tatjana Knyazeva, Henrike Körner, Piotr Knyazev, Joachim Diebold and Heiko Hermeking. Inactivation of miR-34a by aberrant CpG methylation in multiple types of cancer. Cell Cycle 2008; 7: In this issue.8. Gennadi Glinsky. An SNP-guided microRNA map of fifteen common human disorders identifies a consensus disease phenocode aiming at principal components of the nuclear import pathway. Cell Cycle 2008; 7: In this issue.