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Tissues, and Stem Cells
Terms in this set (120)
The building blocks of multicellular organisms with different structure and functions
Different kind of tissues
Muscular, nervous, epithelial, and connective
How does the hierarchy of cells go?
Specialized cells covering the outside, as well as internal cavities. Main functions involve protection, secretion, and absorption. E.g. skin
Cells in these tissue performs to provide efficient muscle movement, provide contractile strength and resistance from tensile and compressive forces. 3 types: cardiac, skeletal, and smooth.
Cells have specialized function and structure to provide structural support and cell to cell communication. Bone, blood, tendons, and adipose tissues.
Cells are specialized in carrying out functions via electrical and chemical signals. E.g. nerve cells or neurons
Cells are surrounded by:
What is the ECM made of?
Protein, glycoaminoglycan, and glycoconjugate
Functions of ECM
Forming an essential support structure, controlling communication between cells, segregating tissues, and regulating cell processes such as growth, migration, and differentiation.
Over 40 different genes express collagen. Supports structure and function of different tissues. Chief protein in bones, tendons, and skins.
Precursor of collagen
Helps convert procollagen to collagen
Matrix proteases utilize:
Spindle-shaped cells that form connective tissue proper
Influence collagen fiber alignment and the collagen fibers to in turn distribute the fibroblasts.
Changes in the number and phenotype of fibroblasts is associated with:
Asthma, COPD, idiopathic pulmonary fibrosis
Fibroblasts in bone
Connects ECM to intracellullar actin cytoskeleton, with help of fibronectin.
Heterodimers, composed of alpha and beta subunits.
Other functions of integrins:
Catch and release mechanisms, sense extracellular signaling and induces intracellular signal transduction. Drives ECM binding.
Cells response to force on integrin-mediated adhesions by:
Remodeling the ECM
Leukocyte trafficking to sites of injury or infection are:
Tightly regulated by the leukocyte adhesion cascade
Distinct adhesive interactions between endothelial cells and leukocytes and signaling mechanisms contribute to:
The temporal and spatial fine-tuning of the leukocyte adhesion cascade
Leukocytes adhesion deficiency type I:
A syndrome associated with frequent microbial infections, is caused by a mutation on subunit of Beta2 integrins (CD18glycoprotein)
Integrins are also:
Associated with various cancers
They resist compression while collagen provides the tensile strength to resist stretching. Found in connective tissue.
What are proteoglycans made of?
Made of negatively charged polysaccharide chains called glycosaminoglycans (GAGs) with repeating disaccharide units.
Functions of proteoglycans
Important roles in physiology, biomechanical function of tendons, ligaments, and cardiovascular system
GAGs link to ______ to give rise to ______
Protein moiety, proteoglycans
Example of GAGs
Hyaluronan: only GAG synthesized in a free form
GAGs are strongly
Hydrophilic. Act as space fillers.
PGs can be classified into 3 groups:
Extracellularly secreted, associated with cell surface, and intracellular
Hyalectans (aggrecan, versican, Neurocan, and brevican)
Cell surface PGs
Syndecans, Betaglycan, Phospacan, and Glypican
Fxn of extracellular PGs
Load bearing capacity, cell adhesion, migration and inflammation
Fxn of cell surface PGs
Binding to growth factors, dictates morphogen gradient, modulates cellular interactions, control of tumor growth
Fxn of intracellular PGs
Binds and modulates the bioactivity of several inflammatory mediators, chemokines, cytokines, and growth factors. Found in chondrocytes, smooth muscle cells, and endothelial cells.
Cell- cell junctions
Link cells to each other in tissue, regulate homeostasis, cell proliferation, and migration
Cell-cell junction deficiency:
Wide range of tissue abnormalities that disrupts homeostasis and is common in genetic abnormalities and cancers.
Cell-cell junctions are involved in
Adhesions and gap junctions
Encircles each cell, forming a proteinaceous seal that regulates the diffusion of ions and solutes between cells
Two kinds of tight junction cells
Claudin and occludin
Claudin and occludin
Bind directly to cytoplasmic adaptor proteins that in turn bind to actin cytoskeleton.
What regulates the tight junction
Actin turnover and actomyocin contraction
Tight junctions play a role in:
A beltlike junctional complex composed of cadherins that attaches a band of actin to the plasma membrane.
Membrane-spanning proteins that link cells together, requires Ca+2 to function, binds to alpha and beta catenin forming tertiary complexes
Immunoglobulin like adhesion molecule, forms Ca2+ independent cell-cell adhesions.
Function of adherens junction
Cell-cell adhesion, regulates actin cytoskeleton, establishes a hub for cell signaling and regulation of gene transcription.
Facilitate epithelial tube or vesicle formation
Compromise of transmembrane cadherins of two subtypes. Highly ordered structure and exhibit Ca-independent hyperadhesion
Two subtypes of desmosome
Desmoglein (Dsg) and Desmocollin (Dsc)
Desmosomes are common in
Epithelia that need to withstand abrasion connecting to the keratin filaments of these cells
Desmosomes are found in:
Cardiac muscle, bladder, GI mucosa
Connect the epithelial cells to the basal lamina.
Integrins play an important role in:
Painful due to the firm attachment of the underlying connective tissue.
Directly connect the cytoplasm of two cells, which allows various molecules, ions, and electrical impulses to directly pass through a regulated gate between cells
Gap junctions contain:
Protein complexes called connexons
Gap junction channels are:
Voltage gated and can display multiple voltage-dependent conductance states
Epithelial sheets are:
Polarized and rest on the basal lamina.
Tight junctions make:
Epithelial cells leakproof and separate its apical and basolateral surfaces
Bind epithelial cells robustly to one another and to the basal lamina
Gap junctions allow:
Cytosolic inorganic ions and small molecules to pass from cell to cell
Different types of epithelial tissues
Squamous, cuboidal, columnar, transitional
Stability of tissue organization includes:
Cellular communication, selective cell adhesion, and cell memory.
Cellular communication includes:
Cytokines, neurotransmitters, hormones, expresses markers recognized by macrophages
Selective cell adhesion includes:
Different cells express different adhesion molecules, and homophilic binding
Cell memory includes:
Cells remember what cell types to form, genetic as well as epigenetic marks are preserved.
Tissue renewal rates:
Terminally differentiated cells forming tissues require replacement at regular intervals
Tissues reserve a set of :
Precursor cells that has the capacity to divide into specialized cells, they are transcriptionally regulated to form only the tissue related specialized cells.
Hematopoietic stem cells in bone marrow:
Given rise in both short-lived and long-lived differentiated blood cells.
During G1 phase of cell cycle________
Each cell makes a key decision, whether to continue through another cycle and divide OR to remain in a nondividing state either temporarily or permanently.
What could cause a cell to go to G0?
Lack of mitogens, antiproliferation signals, telomere damage
Restriction point in S
Regulates G1 to S phase, blocks cell cycle progression unless nutrient and mitogens are present. Checks size, nutrients, external signals, and DNA integrity.
Quiescent (inactive) stage
What cells are permanently in G0?
What cells rarely divide?
Mature cardiac muscles
Timeline of embryo development
Oocyte is fertilized by sperm (day 0), zygote divides to form two cell embryo (day 1), 16 cells stage called morula (day 3) (totipotent), becomes independent. Cavity of blastocyst is completed (day 5), first observable sign of cellular differentiation. Day-5 blastocysts are used to derive ES cell culture.
Inner cell mass from blastocyst and cultured (pluripotent stem cells)
5-cell stage is implanted in the wall of the uterus
Stem cell factors:
Capacity of self renewal, produce daughters that proliferate and differentiate, can make precursor cells
Stem cells depend on:
Local environment cues called stem cell niches
Stem cells niches
Created by tissue cells and the ECM, gives cues to stem cells
Whole, under the right conditions, they can generate a viable embryo (including support tissues, such as a placenta)
Many, can general all different types of cells in the body
Several, stems cells that can give rise to several different types of specialized cells
Stem cells can be used:
To repair lost or damaged tissues
What are the drawbacks to stem cells?
Immune rejection and ethical concerns
Human embryonic stem cells have been derived primarily from:
Blastocysts created by IVF for assisted reproduction that were no longer needed
Embryonic germ cells
Cell are derived from primordial germ cells, found in the gonadal ridge.
Embryonic germ cells can:
Differentiate into endoderm, mesoderm, and ectoderm germ layers
Epidermal stem cells
Multipotential, committed to stem cells to contribute to both renewal and regeneration. Reside in the basal layer of epidermis. Can give rise to hair follicle cells
Hematopoietic stem cells
Helps form blood and immune cells, found in the bone marrow, peripheral blood, or umbilical cord blood. Can mobilize from the blood marrow to circulating blood, and can undergo apoptosis.
Hematopoietic stems cells can:
Be used with leukemia, lymphoma, and inherited blood disorders
Bone marrow stromal cells
Mesenchymal stem cell, can form colonies
Bone marrow stromal cell functions
Provide physical environment in which the HSC differentiation, generate cartilage, bone, fat, and myocytes.
MSC treatment for:
DM, CHF, liver disease, stroke damage, spinal cord injury, and lung cancer (Not FDA approved), treatment in MI and osteogenesis imperfecta
Pluripotent stem cells can come from:
Blastocyte or human source
Neural progenitors, skin progenitors
Hematopoietic, mesenchymal, and cardiac progenitors
Pancreas, Liver, and lung progenitors
Acts a niche factor to maintin stem cells in self-renewing state.
Wnt protein serves to promote:
Proliferation of stem cells and precursor cells at the base of each intestinal crypt
Cells in the crypt can also:
Secrete signals to inhibit Wnt signaling
Orchestrate the pluripotency process by controlling the expression of subsets of genes expressed by pluripotent blastula cells
Morphogenesis, embryonic development, stem cell differentiation, immune regulation, wound healing, and inflammation.
Embryonic developmental processes, mature tissues, keratincyte, and wound healing processes
Induce neuron survival, cartilage cells, and activate osteocytes
Stimulated formation of blood vessels
Immunomodulatory proteins that regulate growth, differentiation and activation, haematopoietic systems during immune response
Secreted by mesenchymal cells, regulates cell growth, motility, and morphogensis by activated tyrosine kinase signaling cascade
Induced pluripotent stem cells
Cells that have been engineered in the lab by converting tissue-specific cells, such as skin cells, into cells that behave like embryonic stem cells
Induced pluripotent stem cells can be induced by
3-4 transcription factors Oct4, Sox2, Klf4, and cMyc
Drawbacks of induced pluripotent stem cells
Low conversion rate and safety issues
Stem cell therapy can be used in:
Treatment of leukemia, lymphoma, multiple myeloma, neuroblastoma, immune deficiency disease, metabolic disease
Risk of bone marrow transplant
Increased susceptibility to infection, anemia, graft failure, respiratory distress, excess fluid, which can lead to pneumonia and liver dysfunction. Acute vs. graft vs. host disease
Tiny, self-organized 3D tissue culture that are derived from stem cells, helps with understanding development and disease pathology. Can help with personalized medicine development and drug discovery. Similar to IPSC
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