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Epsilon Cell
Epsilon cells (ε-cells) are one of the five types of endocrine cells found in regions of the pancreas called Islets of Langerhans. Epsilon cells produce the hormone ghrelin that induces hunger. They were first discovered in mice. In humans, these cells compose less than 1% of all islet cells. They are connected by tight junctions that allow impermeability to water-soluble compounds. Discovery Researchers investigating pancreatic islets in mice compared normal mice pancreatic tissue during development to that of knockout mice. They found that a normal mouse pancreas includes a population of ghrelin-producing cells. Before further investigation took place, it was thought that '' Nkx2.2'' and '' Pax4'' genes promote cell differentiation of β-cells, but in their absence they instead form ε-cells. This was later confirmed by the findings that in the absence of both ''Nkx2.2'' and ''Pax4'' genes, β-cells fail to form and are replaced by ε-cells. Overall, the findings were that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Islets Of Langerhans
The pancreatic islets or islets of Langerhans are the regions of the pancreas that contain its endocrine (hormone-producing) cells, discovered in 1869 by Germans, German pathological anatomist Paul Langerhans. The pancreatic islets constitute 1–2% of the pancreas volume and receive 10–15% of its blood flow. The pancreatic islets are arranged in density routes throughout the human pancreas, and are important in the metabolism of glucose. Structure There are about 1 million islets distributed throughout the pancreas of a healthy adult human, each of which measures an average of about 0.2 mm in diameter.:928 Each islet is separated from the surrounding pancreatic tissue by a thin fibrous connective tissue capsule which is continuous with the fibrous connective tissue that is interwoven throughout the rest of the pancreas.:928 Microanatomy Hormones produced in the pancreatic islets are secreted directly into the blood flow by (at least) five types of cells. In rat islets, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Gestation
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but can also occur through assisted reproductive technology procedures. A pregnancy may end in a live birth, a miscarriage, an induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP), a span known as the gestational age. This is just over nine months. Counting by fertilization age, the length is about 38 weeks. Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; implantation occurs on average 8–9 days after fertilization. An ''embryo'' is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term ''fetus'' is used until birth. Signs and sym ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interferon-gamma Receptor
The interferon-gamma receptor (IFNGR) protein complex is the heterodimer of two chains: IFNGR1 and IFNGR2. It binds interferon-γ, the sole member of interferon type II. Structure and function The human interferon-gamma receptor complex consists the heterodimer of two chains: IFNGR1 and IFNGR2. In unstimulated cells, these subunits are not preassociated with each other but rather associate through their intracellular domains with inactive forms of specific Janus family kinases (Jak1 and Jak2). Jak1 and Jak2 constitutively associate with IFNGR1 and IFNGR2, respectively. Binding of IFN-γ to IFNGR1 induces the rapid dimerization of IFNGR1 chains, thereby forming a site that is recognized by the extracellular domain of IFNGR2. The ligand-induced assembly of the complete receptor complex contains two IFNGR1 and two IFNGR2 subunits, which bring into close juxtaposition the intracellular domains of these proteins together with the inactive Jak1 and Jak2 kinases that they ass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gpcr
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. Coupling with G proteins, they are called seven-transmembrane receptors because they pass through the cell membrane seven times. Text was copied from this source, which is available under Attribution 2.5 Generic (CC BY 2.5) license. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. G protein-coupled receptors are found only in eukaryotes, including yeast, choanoflagellates, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Fatty Acid Receptor 3
Free fatty acid receptor 3 (FFA3) is a G-protein coupled receptor that in humans is encoded by the ''FFAR3'' gene. Animal studies Knockout mouse studies have implicated FFAR3 in diabetes, colitis, hypertension and asthma. However, discrepancies between the pathways activated by FFAR3 agonists in human cells and the equivalent murine counterparts have been observed. Heteromerization FFAR3 may interact with FFAR2 to form a FFAR2-FFAR3 receptor heteromer with signalling that is distinct from the parent homomers. See also * Free fatty acid receptor The free fatty acid receptor is a G-protein coupled receptor which binds free fatty acids. There are four variants of the receptor, each encoded by a separate gene ( FFAR1, FFAR2, FFAR3, FFAR4). Preliminary findings suggest that FFAR2 and ... References Further reading * * * * * G protein-coupled receptors {{transmembranereceptor-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoptosis
Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses between 50 and 70 billion cells each day due to apoptosis. For an average human child between eight and fourteen years old, approximately twenty to thirty billion cells die per day. In contrast to necrosis, which is a form of traumatic cell death that results from acute cellular injury, apoptosis is a highly regulated and controlled process that confers advantages during an organism's life cycle. For example, the separation of fingers and toes in a developing human embryo occurs because cells between the digits undergo apoptosis. Unlike necrosis, apoptosis produces cell fragments called apopt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Defensin 1
Beta-defensin 1 is a protein that in humans is encoded by the ''DEFB1'' gene. Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Members of the defensin family are highly similar in protein sequence. This gene encodes defensin, beta 1, an antimicrobial peptide implicated in the resistance of epithelial surfaces to microbial colonization. This gene maps in close proximity to defensin family member defensin, alpha 1, and has been implicated in the pathogenesis of cystic fibrosis. Single-nucleotide polymorphisms in the ''DEFB1'' gene were associated with plasma kynurenine concentrations in major depressive disorder patients in a genome-wide association study In genomics, a genome-wide association study (GWA study, or GWAS), also known as whole genome association study (WGA study, or WGAS), is an observational study of a genome-wide set of genetic variants in different individuals to see if any varian .... References Further reading * * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ACSL1
Long-chain-fatty-acid—CoA ligase 1 is an enzyme that in humans is encoded by the ''ACSL1'' gene. Structure Gene The ACSL1 gene is located on the 4th chromosome, with its specific location being 4q35.1. The gene contains 28 exons. The protein encoded by this gene is an isozyme of the long-chain fatty-acid-coenzyme A ligase family. Although differing in substrate specificity, subcellular localization, and tissue distribution, all isozymes of this family convert free long-chain fatty acids into fatty acyl-CoA esters, and thereby play a key role in lipid biosynthesis and fatty acid degradation. In melanocytic cells ACSL1 gene expression may be regulated by MITF. Function The protein encoded by this gene is an isozyme of the long-chain fatty-acid-coenzyme A ligase family. Although differing in substrate specificity, subcellular localization, and tissue distribution, all isozymes of this family convert free long-chain fatty acids into fatty acyl-CoA esters, and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesenchyme
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every organ in the developing embryo. Vertebrates Structure Mesenchyme is characterized morphologically by a prominent ground substance matrix containing a loose aggregate of reticular fibers and unspecialized mesenchymal stem cells. Mesenchymal cells can migrate easily (in contrast to epithelial cells, which lack mobility), are organized into closely adherent sheets, and are polarized in an apical-basal orientation. Development The mesenchyme originates from the mesoderm. From the mesoderm, the mesenchyme appears as an embryologically primitive "soup". This "soup" exists as a combination of the mesenchymal cells plus serous fluid plus the many different tissue proteins. Serous fluid is typically stocked with the many serous elements, su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAX6
Paired box protein Pax-6, also known as aniridia type II protein (AN2) or oculorhombin, is a protein that in humans is encoded by the ''PAX6'' gene. Function PAX6 is a member of the Pax gene family which is responsible for carrying the genetic information that will encode the Pax-6 protein. It acts as a "master control" gene for the development of eyes and other sensory organs, certain neural and epidermal tissues as well as other homologous structures, usually derived from ectodermal tissues. However, it has been recognized that a suite of genes is necessary for eye development, and therefore the term of "master control" gene may be inaccurate. Pax-6 is expressed as a transcription factor when neural ectoderm receives a combination of weak Sonic hedgehog (SHH) and strong TGF-Beta signaling gradients. Expression is first seen in the forebrain, hindbrain, head ectoderm and spinal cord followed by later expression in midbrain. This transcription factor is most noted for its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NKX6-1
Homeobox protein Nkx-6.1 is a protein that in humans is encoded by the ''NKX6-1'' gene. Function In the pancreas, NKX6.1 is required for the development of beta cell Beta cells (β-cells) are a type of cell found in pancreatic islets that synthesize and secrete insulin and amylin. Beta cells make up 50–70% of the cells in human islets. In patients with Type 1 diabetes, beta-cell mass and function are dim ...s and is a potent bifunctional transcription regulator that binds to AT-rich sequences within the promoter region of target genes. References Further reading * * * * * * {{gene-4-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISL1
Insulin gene enhancer protein ISL-1 is a protein that in humans is encoded by the ''ISL1'' gene. Function This gene encodes a transcription factor containing two N-terminal LIM domains and one C-terminal homeodomain. The encoded protein plays an important role in the embryogenesis of pancreatic islets of Langerhans. In mouse embryos, a deficiency of this gene results in failure to undergo neural tube motor neuron differentiation. Interactions ISL1 has been shown to interact with Estrogen receptor alpha. Role in cardiac development ISL1 is a marker for cardiac progenitors of the secondary heart field (SHF) which includes the right ventricle and the outflow tract. The biological function of ISL1 is demonstrated through ISL1 mutant mice and chick embryos that have altered cell proliferation, survival, and migration of cardiogenic precursors and severe cardiac defects. More recently it has been defined as a marker for a cardiac progenitor cell lineage that is capable of di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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