scholarly journals Sphingomyelin suppresses Hedgehog signaling by restricting cholesterol accessibility at the ciliary membrane

2019 ◽  
Author(s):  
Maia Kinnebrew ◽  
Ellen J. Iverson ◽  
Bhaven B. Patel ◽  
Ganesh V. Pusapati ◽  
Jennifer H. Kong ◽  
...  
Keyword(s):  
Hedgehog Signaling ◽  
Direct Interaction ◽  
Subcellular Location ◽  
Signaling System ◽  
Ciliary Membrane ◽  
Cellular Processes ◽  
Cholesterol Levels ◽  
Collateral Effects ◽  
Patched 1 ◽  
Hedgehog Signal

AbstractTransmission of the Hedgehog signal across the plasma membrane by Smoothened is proposed to be triggered by its direct interaction with cholesterol. But how is cholesterol, an abundant lipid, regulated tightly enough to control a signaling system that can cause birth defects and cancer? Using toxin-based sensors that distinguish between distinct pools of cholesterol, we find here that Smoothened activation and Hedgehog signaling are driven by a biochemically defined fraction of membrane cholesterol, termed accessible cholesterol. Increasing accessible cholesterol levels by depletion of sphingomyelin, which sequesters cholesterol in complexes, potentiates Hedgehog signaling. By inactivating the transporter-like protein Patched 1, Hedgehog ligands trigger an increase in cholesterol accessibility in the ciliary membrane, the subcellular location for Smoothened signaling. Thus, compartmentalization of Hedgehog signaling in the primary cilium may allow cholesterol accessibility to be used as a second messenger to mediate the communication between Patched 1 and Smoothened, without causing collateral effects on other cellular processes.

scholarly journals Cholesterol accessibility at the ciliary membrane controls hedgehog signaling

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Maia Kinnebrew ◽  
Ellen J Iverson ◽  
Bhaven B Patel ◽  
Ganesh V Pusapati ◽  
Jennifer H Kong ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Birth Defects ◽  
Hedgehog Signaling ◽  
Signal Transmission ◽  
Membrane Cholesterol ◽  
Signaling Proteins ◽  
Signaling System ◽  
Ciliary Membrane ◽  
Patched 1 ◽  
Hedgehog Signal

Previously we proposed that transmission of the hedgehog signal across the plasma membrane by Smoothened is triggered by its interaction with cholesterol (Luchetti et al., 2016). But how is cholesterol, an abundant lipid, regulated tightly enough to control a signaling system that can cause birth defects and cancer? Using toxin-based sensors that distinguish between distinct pools of cholesterol, we find that Smoothened activation and hedgehog signaling are driven by a biochemically-defined, small fraction of membrane cholesterol, termed accessible cholesterol. Increasing cholesterol accessibility by depletion of sphingomyelin, which sequesters cholesterol in complexes, amplifies hedgehog signaling. Hedgehog ligands increase cholesterol accessibility in the membrane of the primary cilium by inactivating the transporter-like protein Patched 1. Trapping this accessible cholesterol blocks hedgehog signal transmission across the membrane. Our work shows that the organization of cholesterol in the ciliary membrane can be modified by extracellular ligands to control the activity of cilia-localized signaling proteins.

scholarly journals Patched 1 reduces the accessibility of cholesterol in the outer leaflet of membranes

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maia Kinnebrew ◽  
Giovanni Luchetti ◽  
Ria Sircar ◽  
Sara Frigui ◽  
Lucrezia Vittoria Viti ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Sonic Hedgehog ◽  
Hedgehog Signaling ◽  
Live Cells ◽  
Transport Activity ◽  
Outer Leaflet ◽  
Cholesterol Levels ◽  
Patched 1 ◽  
Potassium Gradient ◽  
Kinetics Of

A long-standing mystery in vertebrate Hedgehog signaling is how Patched 1 (PTCH1), the receptor for Hedgehog ligands, inhibits the activity of Smoothened, the protein that transmits the signal across the membrane. We previously proposed (Kinnebrew et al., 2019) that PTCH1 inhibits Smoothened by depleting accessible cholesterol from the ciliary membrane. To directly test the effect of PTCH1 on accessible cholesterol, we measured the transport activity of PTCH1 using an imaging-based assay to follow the kinetics of cholesterol extraction from the plasma membrane of live cells by methyl-β-cyclodextrin. PTCH1 depletes accessible cholesterol in the outer leaflet of the membrane in a manner regulated by its ligand Sonic Hedgehog and the transmembrane potassium gradient. We propose that PTCH1 moves cholesterol from the outer to the inner leaflet of the membrane in exchange for potassium ion export. Our results show that proteins can change accessible cholesterol levels in membranes to regulate signaling reaction.

scholarly journals Trafficking to the primary cilium membrane

2017 ◽  
Vol 28 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Saikat Mukhopadhyay ◽  
Hemant B. Badgandi ◽  
Sun-hee Hwang ◽  
Bandarigoda Somatilaka ◽  
Issei S. Shimada ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Signaling Pathways ◽  
Primary Cilium ◽  
Hedgehog Signaling ◽  
Diffusion Barriers ◽  
Disease Pathogenesis ◽  
Ciliary Membrane ◽  
Multiple Organs ◽  
Sensory Reception

The primary cilium has been found to be associated with a number of cellular signaling pathways, such as vertebrate hedgehog signaling, and implicated in the pathogenesis of diseases affecting multiple organs, including the neural tube, kidney, and brain. The primary cilium is the site where a subset of the cell's membrane proteins is enriched. However, pathways that target and concentrate membrane proteins in cilia are not well understood. Processes determining the level of proteins in the ciliary membrane include entry into the compartment, removal, and retention by diffusion barriers such as the transition zone. Proteins that are concentrated in the ciliary membrane are also localized to other cellular sites. Thus it is critical to determine the particular role for ciliary compartmentalization in sensory reception and signaling pathways. Here we provide a brief overview of our current understanding of compartmentalization of proteins in the ciliary membrane and the dynamics of trafficking into and out of the cilium. We also discuss major unanswered questions regarding the role that defects in ciliary compartmentalization might play in disease pathogenesis. Understanding the trafficking mechanisms that underlie the role of ciliary compartmentalization in signaling might provide unique approaches for intervention in progressive ciliopathies.

scholarly journals Roles of the Primary Cilium Component Polaris in Synchondrosis Development

2009 ◽  
Vol 88 (6) ◽  
pp. 545-550 ◽  
Author(s):  
T. Ochiai ◽  
M. Nagayama ◽  
T. Nakamura ◽  
T. Morrison ◽  
D. Pilchak ◽  
...  
Keyword(s):  
Primary Cilium ◽  
Hedgehog Signaling ◽  
Primary Cilia ◽  
Cranial Base ◽  
Indian Hedgehog ◽  
Intramembranous Ossification ◽  
Endochondral Bone ◽  
Chondrocyte Maturation ◽  
Mouse Mutants ◽  
Patched 1

Primary cilia regulate several developmental processes and mediate hedgehog signaling. To study their roles in cranial base development, we created conditional mouse mutants deficient in Polaris, a critical primary cilium component, in cartilage. Mutant post-natal cranial bases were deformed, and their synchondrosis growth plates were disorganized. Expression of Indian hedgehog, Patched-1, collagen X, and MMP-13 was reduced and accompanied by decreases in endochondral bone. Interestingly, there was excessive intramembranous ossification along the perichondrium, accompanied by excessive Patched-1 expression, suggesting that Ihh distribution was wider and responsible for such excessive response. Indeed, expression of heparan sulfate proteoglycans (HS-PGs), normally involved in restricting hedgehog distribution, was barely detectable in mutant synchondroses. Analyses of the data provides further evidence for the essential roles of primary cilia and hedgehog signaling in cranial base development and chondrocyte maturation, and point to a close interdependence between cilia and HS-PGs to delimit targets of hedgehog action in synchondroses.

scholarly journals Icariin Promote Stem Cells Regeneration and Repair Acinar Cells in L-arginine / Radiation -Inducing Chronic Pancreatitis in Rats

Dose-Response ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 155932582097081
Author(s):  
Enas M. Moustafa ◽  
Fatma S. M. Moawed ◽  
Gehan R. Abdel-Hamid
Keyword(s):  
Chronic Pancreatitis ◽  
Hedgehog Signaling ◽  
Histopathological Examination ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Myeloperoxidase Activity ◽  
Significant Amelioration ◽  
Gli 1 ◽  
Patched 1

Objective: Chronic Pancreatitis (CP) is a multifactorial disease. It was characterized by severe inflammation and acinar cell destruction. Thus, the present study was initiated to evaluating the ability of bone marrow-based mesenchymal stem cell (MSCs) combined with Icariin to restore and regenerate acinar cells in the pancreas of rats suffering chronic pancreatitis. Methods: Chronic pancreatitis was induced in rats via both L-arginine plus radiation, repeated L-arginine injection (2.5g/Kg body-weight, 1, 4,7,10,13,16,19 days), then, on day 21, rats were exposed to a single dose of gamma-radiation (6 Gy), which exacerbate injury of pancreatic acinar cells. One day after irradiation, rats were treated with either MSCs (1 × 107 /rat, once, tail vein injection) labeled PKH26 fluorescent linker dye and/or Icariin (100 mg/Kg, daily, orally) for 8 weeks. Results: Icariin promotes MSCs proliferation boosting its productivity in vitro. MSCs, and/or icariin treatments has regulated molecular factors TGF-β/PDGF and promoted the regeneration of pancreatic tissues by releasing PDX-1 and MafA involved in the recruitment of stem/progenitor cell in the tissue, and confirmed by histopathological examination. Moreover, a significant decrease in IL-8 and TNF-α cytokines with significant amelioration of myeloperoxidase activity were noted. As well as, reduction in MCP-1 and collagen type-1 levels along with Hedgehog signaling down-regulating expression in such cells, Patched-1, Smoothened, and GLi-1. Conclusion: The potent bioactive therapeutic Icariin combined with MSCs induces a significantly greater improvement, compared to each therapy alone.

scholarly journals The Functional State of Hormone-Sensitive Adenylyl Cyclase Signaling System in Diabetes Mellitus

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Alexander O. Shpakov ◽  
Kira V. Derkach
Keyword(s):  
Diabetes Mellitus ◽  
Adenylyl Cyclase ◽  
Functional State ◽  
Signaling System ◽  
Signaling Systems ◽  
Biochemical Processes ◽  
Cellular Processes ◽  
Polypeptide Hormones ◽  
Hormone Sensitive

Diabetes mellitus (DM) induces a large number of diseases of the nervous, cardiovascular, and some other systems of the organism. One of the main causes of the diseases is the changes in the functional activity of hormonal signaling systems which lead to the alterations and abnormalities of the cellular processes and contribute to triggering and developing many DM complications. The key role in the control of physiological and biochemical processes belongs to the adenylyl cyclase (AC) signaling system, sensitive to biogenic amines and polypeptide hormones. The review is devoted to the changes in the GPCR-G protein-AC system in the brain, heart, skeletal muscles, liver, and the adipose tissue in experimental and human DM of the types 1 and 2 and also to the role of the changes in AC signaling in the pathogenesis and etiology of DM and its complications. It is shown that the changes of the functional state of hormone-sensitive AC system are dependent to a large extent on the type and duration of DM and in experimental DM on the model of the disease. The degree of alterations and abnormalities of AC signaling pathways correlates very well with the severity of DM and its complications.

Precholesterol Sterols Accumulate in Lipid Rafts of Patients with Smith-Lemli-Opitz Syndrome and X-Linked Dominant Chondrodysplasia Punctata

2008 ◽  
Vol 11 (2) ◽  
pp. 128-132 ◽  
Author(s):  
Dinesh Rakheja ◽  
Richard L. Boriack
Keyword(s):  
Lipid Rafts ◽  
Hedgehog Signaling ◽  
Cholesterol Biosynthesis ◽  
Membrane Lipid ◽  
Chondrodysplasia Punctata ◽  
Autopsy Material ◽  
Cholesterol Levels ◽  
Abnormal Accumulation ◽  
Hedgehog Proteins ◽  
Opitz Syndrome

Systemic fetal dysmorphogenesis in disorders of postsqualene cholesterol biosynthesis is thought to be caused by disruption of Hedgehog signaling. Because precholesterol sterols such as 7-dehydrocholesterol and lathosterol can replace cholesterol in the activation of Hedgehog proteins, it is currently believed that cholesterol deficiency-related Hedgehog signaling block occurs further downstream, probably at the level of Smoothened. Experimentally, such a block in Hedgehog signaling occurs at sterol levels of <40 μg/mg protein. Recently, we studied autopsy material from 2 infants with fatal cholesterol biosynthetic disorders (Smith-Lemli-Opitz syndrome and X-linked dominant chondrodysplasia punctata) in which the hepatic cholesterol levels were far greater. In this study, we demonstrate abnormal accumulation of sterol precursors of cholesterol in membrane lipid rafts (detergent resistance membranes) prepared from liver tissues of these 2 infants: 8-dehydrocholesterol and 7-dehydrocholesterol in lipid rafts of the infant with Smith-Lemli-Opitz syndrome and cholest-8(9)-ene-3β-ol in lipid rafts of the infant with X-linked dominant chondrodysplasia punctata. We suggest that such alterations in the lipid raft sterol environment may affect the biology of cells and the development of fetuses with cholesterol biosynthetic disorders.

scholarly journals Application of the Subtractive Genomics and Molecular Docking Analysis for the Identification of Novel Putative Drug Targets against Salmonella enterica subsp. enterica serovar Poona

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Tanvir Hossain ◽  
Mohammad Kamruzzaman ◽  
Talita Zahin Choudhury ◽  
Hamida Nooreen Mahmood ◽  
A. H. M. Nurun Nabi ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Salmonella Enterica ◽  
Drug Targets ◽  
Subcellular Location ◽  
Essential Genes ◽  
Scoring Functions ◽  
Essential Proteins ◽  
Cellular Processes ◽  
Subtractive Genomics ◽  
Resistance Patterns

The emergence of novel pathogenic strains with increased antibacterial resistance patterns poses a significant threat to the management of infectious diseases. In this study, we aimed at utilizing the subtractive genomic approach to identify novel drug targets against Salmonella enterica subsp. enterica serovar Poona strain ATCC BAA-1673. We employed in silico bioinformatics tools to subtract the strain-specific paralogous and host-specific homologous sequences from the bacterial proteome. The sorted proteome was further refined to identify the essential genes in the pathogenic bacterium using the database of essential genes (DEG). We carried out metabolic pathway and subcellular location analysis of the essential proteins of the pathogen to elucidate the involvement of these proteins in important cellular processes. We found 52 unique essential proteins in the target proteome that could be utilized as novel targets to design newer drugs. Further, we investigated these proteins in the DrugBank databases and 11 of the unique essential proteins showed druggability according to the FDA approved drug bank databases with diverse broad-spectrum property. Molecular docking analyses of the novel druggable targets with the drugs were carried out by AutoDock Vina option based on scoring functions. The results showed promising candidates for novel drugs against Salmonella infections.

scholarly journals Defects in mouse mammary gland development caused by conditional haploinsufficiency of Patched-1

Development ◽  
1999 ◽  
Vol 126 (22) ◽  
pp. 5181-5193 ◽  
Author(s):  
M.T. Lewis ◽  
S. Ross ◽  
P.A. Strickland ◽  
C.W. Sugnet ◽  
E. Jimenez ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Hedgehog Signaling ◽  
Morphological Changes ◽  
Receptor Gene ◽  
Mammary Development ◽  
Developmental Defect ◽  
Developmentally Regulated ◽  
Tissue Interactions ◽  
Pregnancy And Lactation ◽  
Patched 1

In vertebrates, the hedgehog family of cell signaling proteins and associated downstream network components play an essential role in mediating tissue interactions during development and organogenesis. Loss-of-function or misexpression mutation of hedgehog network components can cause birth defects, skin cancer and other tumors. The mammary gland is a specialized skin derivative requiring epithelial-epithelial and epithelial-stromal tissue interactions similar to those required for development of other organs, where these interactions are often controlled by hedgehog signaling. We have investigated the role of the Patched-1 (Ptc1) hedgehog receptor gene in mammary development and neoplasia. Haploinsufficiency at the Ptc1 locus results in severe histological defects in ductal structure, and minor morphological changes in terminal end buds in heterozygous postpubescent virgin animals. Defects are mainly ductal hyperplasias and dysplasias characterized by multilayered ductal walls and dissociated cells impacting ductal lumens. This phenotype is 100% penetrant. Remarkably, defects are reverted during late pregnancy and lactation but return upon involution and gland remodeling. Whole mammary gland transplants into athymic mice demonstrates that the observed dysplasias reflect an intrisic developmental defect within the gland. However, Ptc1-induced epithelial dysplasias are not stable upon transplantation into a wild-type epithelium-free fat pad, suggesting stromal (or epithelial and stromal) function of Ptc1. Mammary expression of Ptc1 mRNA is both epithelial and stromal and is developmentally regulated. Phenotypic reversion correlates with developmentally regulated and enhanced expression of Indian hedgehog (Ihh) during pregnancy and lactation. Data demonstrate a critical mammary role for at least one component of the hedgehog signaling network and suggest that Ihh is the primary hedgehog gene active in the gland.

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