Lecture A9 Flashcards
physiological characteristics of adipocytes
-insulin sensitive
-lipid storage of TAG
-secretion of endocrine hormones
adipocytes are insulin sensitive to control ______
energy production and storage
TAG stands for _____
triacylglycerol
adipocytes are what type of cell?
fat cells
adipocytes maintain homeostasis between ____
lipolysis and lipogenesis
Three types of adipocytes
-white adipocyte
-brown adipocyte
-beige adipocyte
both white and brown adipocyte differentiation share _____
key features
master adipogenic regulator example
-peroxisome proliferator-activated receptor-y (PPAR-y)
adipogenic stimuli activates what?
-signaling pathways that coordinate TF and promote SC commitment to adipogenic fate
commitment to and stability of adipocyte differentiation requires _____
extensive epigenomic modifications
adipocyte generation (general)
fibroblastlike precursor cell –> adipocyte precursor cell accumulates lipid droplets –> fat cell
adipocyte proliferation is regulated by ____ (3)
dietary, micro-environmental and hormonal cues
New adipocytes are formed via the _____ and ___ of resident ______
-proliferation
-differentiation
-adipocyte precursor cells
adipocytes are formed and enlarge as needed for _____
story of excess dietary energy
Obesity (def.)
the excessive accumulation of body fat
obesity is a consequence of
-persistent energy intake that exceeds energy expenditure
obesity leads to the ____ and ____ of adipocytes
-hyperplasia
-hypertrophy
Hyperplasia (def.)
increase in number
Hypertrophy (def.)
increase in size
Hyperplasia of adipocytes involves ______
commitment and differentiation of stem cells/preadipocytes (vascular stroma)
Adipocytes can also dedifferentiate when? and redifferentiate when? in mothers.
1)pregnancy
2) Lactation & Involution (uterus shrink in size)
When pregnant, adipocytes start to _____
de-differentiate (become pre-adipocytes)
When lactating, adipocytes are now mostly _____ and start to _____
-pre-adipocytes
-re-diiferentiate
most common fat cell is ____
white adipocytes
white adipocyte function?
used to store energy in the form of fat
white adipocytes are found where? (7)
-subcutaneous (under skin)
-intra-abdominal
-epicardial (in the heart)
-gonadol
-gluteal
-bone marrow
-intramuscular
white adipocyte morphology
spherical
white adipocyte cell composition (4)
-single lipid droplet
-few mitochondria
-flattened peripheral nucleus
-little endoplasmic reticulum
brown adipocyte function?
converts chemical energy to heat to protect against cold weather without shivering (non-shivering thermogenesis)
brown adipocyte are found where? (5)
-interscapular
-paravertebral
-perirenal
-cervical
-supraclavicular
brown adipocyte morphology
-elliptical (oval)
-smaller than white adipocyte
brown adipocyte cell composition (3)
-multiple small lipid droplets
-large number of mitochondria
-oval central nucleus
beige adipocyte (def.)
immature cell in white fat tissue that matures to burn fat
beige adipocyte function
thermogenic potential
beige adipocyte localization
-found in white adipose tissue with appropriate stimuli
beige adipocyte morphology
spherical
beige adipocyte cell composition
-mitochondria appear after stimulation
-uniocular morphology but small lipid droplets after stimulation
WAT stands for _____
white adipose tissue
BAT stands for _____
brown adipose tissue
types of WAT
-visceral WAT
-subcutaneous WAT
visceral WAT examples
-perirenal
-retroperitoneal
-omental
-mesentric
subcutaneous WAT examples
-abdominal
-gluteal
-femoral
visceral WAT function
-energy storage and various adipokine secretion
visceral WAT is correlated with ____
-high incidence of metabolic disorders
subcutaneous WAT function
-insulating layer, energy storage and various adipokine secretion
subcutaneous WAT is correlated with ____
-low incidence of metabolic disorders
breakdown of fat and release of free fatty acids into bloodstream from adipocytes is stimulated by ______
nerves releasing norepinephrine
cLD stands for ___
central lipid droplet
LDM stands for ____
lipid droplets
regulation of lipolysis and thermogenesis in brown adipocytes pathway
1) B3-AR (receptor) is activated by noradrenaline which causes release of cAMP
2)cAMP activates PKA (protein kinase A)
3) PKA activates HSL (hormone-sensitive lipase), ATGL (Adipose triglyceride lipase) and perilipins on the surface of lipid droplets
4)lipases break down lipid droplets to make free-fatty acids (FFA)
5) FFA enters mitochondria to be broken down to make heat
Perilipins reside on ____ and regulate _____
-surface of lipid droplets
-lipases
Adipocytes can be formed from two different lineages: _______
-resident mesenchymal cells in the stromal-vascular fraction of adipose tissue
-hematopoietic progenitors that reside in bone marrow
mesenchymal precursors + MYF5 TF = ____
BAT adipocyte precursor
mesenchymal precursors + (no MYF5 TF) = ____
WAT adipocyte precursor
WAT adipocyte precursor forms ____
white adipocyte, beige adipocyte
BAT adipocyte precursor forms ____
-brown adipocyte
endothelial precursor forms this adipocyte?
white & brown adipocyte
muscle satellite cell forms this adipocyte?
brown adipocyte
MYF5 transcription factor also acts as _____
muscle regulatory factor (MRF)
mesenchymal stem cells that form (pre-)adipocytes don’t receive ______
WNT signals
pre-adipocytes that form adipocytes don’t receive _____
WNT signals
adipogenic stimuli activates _____ which activates _______ which _____
-C/EBPδ/β
-PPARγ & C/EBPa
-turns on adipocyte genes
PPARγ stands for ______
-Peroxisome proliferator -activatedreceptor
PPARγ is a ______. It is highly expressed in ______
-nuclear receptor with fatty acids as their activating cofactor
-adipose tissues
“Master regulator” of adipogenesis is _____
PPARγ
C/EBPδ/β stands for ______
CCAAT-enhancer-binding protein
C/EBPδ/β is a ______
bZip protein
C/EBPδ/β is at the crossroads between ______
proliferation and differentiation
early adipogenesis has these TF: _____
C/EBPδ
C/EBPβ
mature adipocyte has these TF: _____
C/EBPa
C/EBPβ
PPARγ
genes activate in early adipogenesis has this element: _____
C/EBP-Response Element
PRDM16 (PR/SET Domain 16) function
transcription factor that promotes formation of brown adipocytes
brown adipocyte precursors
-myf-5 precursor (muscle precursor)
-pre-adipocyte
PR domain of PRDM16 contains ______
- a ZNF-C2H2 – Zinc Finger DNA binding domain
Suppressing PRDM16 in brown adipose cells causes them to______
- change into myocytes
Genes like _____ encode proteins that are needed in BAT cells
Ucp1, Cidea and Elovl3
