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Physiological Reviews Oct 2012Stem cell factor (SCF) is a dimeric molecule that exerts its biological functions by binding to and activating the receptor tyrosine kinase c-Kit. Activation of c-Kit... (Review)
Review
Stem cell factor (SCF) is a dimeric molecule that exerts its biological functions by binding to and activating the receptor tyrosine kinase c-Kit. Activation of c-Kit leads to its autophosphorylation and initiation of signal transduction. Signaling proteins are recruited to activated c-Kit by certain interaction domains (e.g., SH2 and PTB) that specifically bind to phosphorylated tyrosine residues in the intracellular region of c-Kit. Activation of c-Kit signaling has been found to mediate cell survival, migration, and proliferation depending on the cell type. Signaling from c-Kit is crucial for normal hematopoiesis, pigmentation, fertility, gut movement, and some aspects of the nervous system. Deregulated c-Kit kinase activity has been found in a number of pathological conditions, including cancer and allergy. The observation that gain-of-function mutations in c-Kit can promote tumor formation and progression has stimulated the development of therapeutics agents targeting this receptor, e.g., the clinically used inhibitor imatinib mesylate. Also other clinically used multiselective kinase inhibitors, for instance, sorafenib and sunitinib, have c-Kit included in their range of targets. Furthermore, loss-of-function mutations in c-Kit have been observed and shown to give rise to a condition called piebaldism. This review provides a summary of our current knowledge regarding structural and functional aspects of c-Kit signaling both under normal and pathological conditions, as well as advances in the development of low-molecular-weight molecules inhibiting c-Kit function.
Topics: Animals; Cell Survival; Humans; Phosphorylation; Proto-Oncogene Proteins c-kit; Signal Transduction; Stem Cell Factor
PubMed: 23073628
DOI: 10.1152/physrev.00046.2011 -
Pastoralism : Research, Policy and... 2017Animal breeds are the diverse outcome of the thousands-year-long process of livestock domestication. Many of these breeds are piebald, resulting from the artificial...
Animal breeds are the diverse outcome of the thousands-year-long process of livestock domestication. Many of these breeds are piebald, resulting from the artificial selection by pastoralists of animals bearing a genetic condition known as leucism, and selected for their productive, behavioural, or aesthetical traits. Piebald dromedary camels have not been studied or discussed before, and their same existence is often overlooked. Based on fieldwork in Western Sahara, direct observations across Northern and East Africa and the Middle East, and a literature review, we address the morphological and behavioural traits, geographical distribution, taxonomy, and material and cultural importance of piebald (painted) camels. They are a hundreds-year-old camel breed used for caravans, as mounts, and for aesthetical and cultural reasons across Sudan, Niger, Mali, Mauritania, Western Sahara, and Morocco. While they are increasingly bred out of a pastoral context for tourism and entertainment in the Canary Islands, mainland Europe, and the USA, in part of their original African range, piebald camels are under threat due to wars, droughts, and demise of pastoral livelihoods. More research is needed about these 'beautiful and dignified' animals.
PubMed: 32269746
DOI: 10.1186/s13570-017-0075-3 -
Gastroenterology Nov 2020Hirschsprung disease (HSCR) is a life-threatening birth defect in which the distal colon is devoid of enteric neural ganglia. HSCR is treated by surgical removal of...
BACKGROUND & AIMS
Hirschsprung disease (HSCR) is a life-threatening birth defect in which the distal colon is devoid of enteric neural ganglia. HSCR is treated by surgical removal of aganglionic bowel, but many children continue to have severe problems after surgery. We studied whether administration of glial cell derived neurotrophic factor (GDNF) induces enteric nervous system regeneration in mouse models of HSCR.
METHODS
We performed studies with four mouse models of HSCR: Holstein (Hol, a model for trisomy 21-associated HSCR), TashT (TashT, a model for male-biased HSCR), Piebald-lethal (Ednrb, a model for EDNRB mutation-associated HSCR), and Ret (with aganglionosis induced by mycophenolate). Mice were given rectal enemas containing GDNF or saline (control) from postnatal days 4 through 8. We measured survival times of mice, and colon tissues were analyzed by histology, immunofluorescence, and immunoblots. Neural ganglia regeneration and structure, bowel motility, epithelial permeability, muscle thickness, and neutrophil infiltration were studied in colon tissues and in mice. Stool samples were collected, and microbiomes were analyzed by 16S rRNA gene sequencing. Time-lapse imaging and genetic cell-lineage tracing were used to identify a source of GDNF-targeted neural progenitors. Human aganglionic colon explants from children with HSCR were cultured with GDNF and evaluated for neurogenesis.
RESULTS
GDNF significantly prolonged mean survival times of Hol mice, Ednrb mice, and male TashT mice, compared with control mice, but not Ret mice (which had mycophenolate toxicity). Mice given GDNF developed neurons and glia in distal bowel tissues that were aganglionic in control mice, had a significant increase in colon motility, and had significant decreases in epithelial permeability, muscle thickness, and neutrophil density. We observed dysbiosis in fecal samples from Hol mice compared with feces from wild-type mice; fecal microbiomes of mice given GDNF were similar to those of wild-type mice except for Bacteroides. Exogenous luminal GDNF penetrated aganglionic colon epithelium of Hol mice, inducing production of endogenous GDNF, and new enteric neurons and glia appeared to arise from Schwann cells within extrinsic nerves. GDNF application to cultured explants of human aganglionic bowel induced proliferation of Schwann cells and formation of new neurons.
CONCLUSIONS
GDNF prolonged survival, induced enteric neurogenesis, and improved colon structure and function in 3 mouse models of HSCR. Application of GDNF to cultured explants of aganglionic bowel from children with HSCR induced proliferation of Schwann cells and formation of new neurons. GDNF might be developed for treatment of HSCR.
Topics: Animals; Colon; Disease Models, Animal; Dysbiosis; Enteric Nervous System; Gastrointestinal Microbiome; Gastrointestinal Motility; Glial Cell Line-Derived Neurotrophic Factor; Hirschsprung Disease; Humans; Intestinal Absorption; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Transgenic; Nerve Regeneration; Neural Stem Cells; Neurogenesis; Permeability; Recovery of Function; Schwann Cells; Tissue Culture Techniques
PubMed: 32687927
DOI: 10.1053/j.gastro.2020.07.018 -
Indian Journal of Dermatology,... 2018
Topics: Diagnosis, Differential; Hair Diseases; Hemochromatosis; Humans; Melanocytes; Melanosis; Piebaldism; Pigmentation Disorders
PubMed: 30147109
DOI: 10.4103/ijdvl.IJDVL_451_18 -
Dermatology Online Journal Dec 2005A 46-year-old man presented with a history of a congenital pigment disorder. On physical examination hypopigmented and depigmented patches were present on the...
A 46-year-old man presented with a history of a congenital pigment disorder. On physical examination hypopigmented and depigmented patches were present on the mid-forehead, anterior chest, and extremities. He also had loss of pigment of the medial eyebrows and a white forelock. The patient has a family history of a similar congenital pigment disorder, the pattern of which is indicative of the autosomal dominant disorder piebaldism.
Topics: Humans; Male; Middle Aged; Piebaldism; Skin
PubMed: 16403390
DOI: No ID Found -
Scandinavian Journal of Immunology Jun 2021Griscelli syndrome (GS) is a rare autosomal recessive disease with characteristic pigment distribution, and there are currently 3 types according to the underlying... (Meta-Analysis)
Meta-Analysis Review
Griscelli syndrome (GS) is a rare autosomal recessive disease with characteristic pigment distribution, and there are currently 3 types according to the underlying genetic defect and clinical features. We present the case of a girl born from consanguineous parents who presented with predominant neurologic symptoms, silvery hair and granulomatous skin lesions. Cerebral magnetic resonance revealed diffuse white matter lesions, and central nervous system (CNS) lymphocytic infiltration was suspected. The patient underwent haematopoietic stem cell transplantation with graft failure and autologous reconstitution. She developed elevated liver enzyme with a cholestatic pattern. Multiple liver biopsies revealed centrilobular cholestasis and unspecific portal inflammation that improved with immunomodulatory treatment. She was revealed to have an impaired cytotoxicity in NK cells and a decreased expression of RAB27A. However, no variants were found in the gene. All types of GS present with pigment dilution and irregular pigment clumps that can be seen through light microscopy in hair and skin biopsy. Dermic granulomas and immunodeficiency with infectious and HLH predisposition have been described in GS type 2 (GS2). Neurologic alterations might be seen in GS type 1 (GS1) and GS type 2 (GS2), due to different mechanisms. GS1 presents with neurologic impairment secondary to myosin Va role in neuronal development and synapsis. Meanwhile, GS2 can present with neurologic impairment secondary to SNC HLH. Clinical features and cytotoxicity might aid in differentiating GS1 and GS2, especially since treatment differs.
Topics: Biomarkers; Biopsy; Disease Management; Disease Susceptibility; Genetic Predisposition to Disease; Hearing Loss, Sensorineural; Humans; Lymphohistiocytosis, Hemophagocytic; Mutation; Phenotype; Piebaldism; Pigmentation Disorders; Primary Immunodeficiency Diseases; Prognosis
PubMed: 33660295
DOI: 10.1111/sji.13034 -
The Journal of Investigative Dermatology May 2006Mice transgenic for the Kit Val620Ala mutation, which in humans has been associated with progressive piebaldism, exhibit dominant white spotting but show no evidence of...
Mice transgenic for the Kit Val620Ala mutation, which in humans has been associated with progressive piebaldism, exhibit dominant white spotting but show no evidence of progressive depigmentation. These results are consistent with the previous hypothesis that progressive piebaldism might result from digenic inheritance, of the KIT(V620A) mutation that causes piebaldism and a second, unknown locus that causes progressive depigmentation.
Topics: Animals; Humans; Mice; Mice, Transgenic; Mutation; Piebaldism; Pigmentation Disorders; Proto-Oncogene Proteins c-kit
PubMed: 16619012
DOI: 10.1038/sj.jid.5700220 -
Donor to recipient ratios in the surgical treatment of vitiligo and piebaldism: a systematic review.Journal of the European Academy of... May 2021Stabilized vitiligo resistant to conventional therapy (e.g. segmental vitiligo) and piebaldism lesions can be treated with autologous cellular grafting techniques, such...
Stabilized vitiligo resistant to conventional therapy (e.g. segmental vitiligo) and piebaldism lesions can be treated with autologous cellular grafting techniques, such as non-cultured cell suspension transplantation (NCST) and cultured melanocyte transplantation (CMT). These methods are preferred when treating larger surface areas due to the small amount of donor skin needed. However, the donor to recipient expansion ratios and outcomes reported in studies with cellular grafting vary widely, and to date, no overview or guideline exists on the optimal ratio. The aim of our study was to obtain an overview of the various expansion ratios used in cellular grafting and to identify whether expansion ratios affect repigmentation and colour match. We performed a systematic literature search in MEDLINE and EMBASE to review clinical studies that reported the expansion ratio and repigmentation after cellular grafting. We included 31 eligible clinical studies with 1591 patients in total. Our study provides an overview of various expansion ratios used in cellular grafting for vitiligo and piebaldism, which varied from 1:1 up to 1:100. We found expansion ratios between 1:1 and 1:10 for studies investigating NCST and from 1:20 to 1:100 in studies evaluating CMT. Pooled analyses of studies with the same expansion ratio and repigmentation thresholds showed that when using the lowest (1:3) expansion ratio, the proportion of lesions achieving >50% or >75% repigmentation after NCST was significantly better than when using the highest (1:10) expansion ratio (χ P = 0.000 and χ P = 0.006, respectively). Less than half of our included studies stated the colour match between different expansion ratios, and results were variable. In conclusion, the results of our study indicate that higher expansion ratios lead to lower repigmentation percentages after NCST treatment. This should be taken into consideration while determining which expansion ratio to use for treating a patient.
Topics: Humans; Melanocytes; Piebaldism; Skin Pigmentation; Skin Transplantation; Transplantation, Autologous; Treatment Outcome; Vitiligo
PubMed: 33428279
DOI: 10.1111/jdv.17108 -
Frontiers in Veterinary Science 2015Although deafness can be acquired throughout an animal's life from a variety of causes, hereditary deafness, especially congenital hereditary deafness, is a significant... (Review)
Review
Although deafness can be acquired throughout an animal's life from a variety of causes, hereditary deafness, especially congenital hereditary deafness, is a significant problem in several species. Extensive reviews exist of the genetics of deafness in humans and mice, but not for deafness in domestic animals. Hereditary deafness in many species and breeds is associated with loci for white pigmentation, where the cochlear pathology is cochleo-saccular. In other cases, there is no pigmentation association and the cochlear pathology is neuroepithelial. Late onset hereditary deafness has recently been identified in dogs and may be present but not yet recognized in other species. Few genes responsible for deafness have been identified in animals, but progress has been made for identifying genes responsible for the associated pigmentation phenotypes. Across species, the genes identified with deafness or white pigmentation patterns include MITF, PMEL, KIT, EDNRB, CDH23, TYR, and TRPM1 in dog, cat, horse, cow, pig, sheep, ferret, mink, camelid, and rabbit. Multiple causative genes are present in some species. Significant work remains in many cases to identify specific chromosomal deafness genes so that DNA testing can be used to identify carriers of the mutated genes and thereby reduce deafness prevalence.
PubMed: 26664958
DOI: 10.3389/fvets.2015.00029