Week 6 Flashcards
(11 cards)
Bipotential Gonad (+ Paramesonephric Duct)
- Y-Chromosome Present (SRY/TDF) –> Testis (androgen): male genitalia
- Y-Chromosome Absent –> Ovary (female genitalia)
Gametes fuse at fertilization –> diploid zygote
Fertilization
Gametes fuse into diploid zygote
> DNA insert via HR into ICM of blastocyst from ES cell line –> select –> reimplant into foster mother
> Egg –> rotational cleavage –> 4-cell –> morula –> tight junction in compacted morula –> grow in mature blastocyst with 64-200 cell stage and ICM –> cross with heterozygote to identify AOI
Embryo Development and Cell Differentiation
- Function: Treat Disease, prevent cancer, and replace bad cells
- 64-200 cell stage blastocyst: (in to out)
> ICM: ESC here –> all human cells
> Blastococel: cavity filled with fluid around ICM
> Trophectoderm: derives trophoblast (placental embryo); surrounds everything else
Stem Cells (Overview)
- Unspecialized –> indefinite renewal
2. Can be induced –> specialized/differentiate
ESC
From ICM of embryo –> specialized
ASC
- Somatic tissue only (undifferentiated in other tissues self-renew into cells specialized in one type of cell it originates from, usually)
- Difficult to obtain (neuronal), but blood SC can be obtained from BM cells
BSC
- From multipotent hemapoietic SC progenitor –> lymphoid/myeloid progenitor –> thymus T-cells/eosinophils
- X-irradiation kills BC + newly injected BM colonize donor hema-tissues and generate new BC –> survival
- BM-based monoclonal Ab –> identify cell-surface protein (CLUSTER OF DIFFERENTIATION) for precursors –> Fluorescence-Activated Cell Sorter (FACS)
- Different growth factors and TF’s to stimulate colonies –> increase survival and differentiation
Repair/Replacement of Human Tissues
Problems: 1. Difficulty Directing ESC to only 1 pathway; 2. Immune Rejection
> Sol (SCNT/iPS): patient cell and unfertilized donor egg
> Use growth factors to control differentiation path
> Moral embryo treatment: end human suffering, but MEANS is disputed since ESC therapy uses donated embryo and it never enters the uterus (human?)
Reprogram Mature Cells to Pluripotent SC
iPS
iPS: introduce few genes –> PSC
> Expresses Oct4, Sox2, KLF2, and C-Myc (4 TF)
> Skin fibroblast –> retroviral transduction –> selected iPS in normal blastocyst –> crossbreed normal and chimeric mice –> iPS-desired mouse
Reprogramming of Somatic
Patient-specific SC’s that bypass both ethical and practical concerns (SCNT, hES)
> C-Myc overexpression = oncogenic (20% CA)
> C-Myc underexpression = inefficiency and chimeric don’t immediately get CA
Solutions to Abnormal C-Myc Expression
- Insert retroviral LTR –> active promoter/enhancer controls gene –> HIGH proto-oncogene GE/ LOW TSG
- Adenoviral Reprogram: lost after several cell division/not present in genome
- Recombinant proteins –> disease-specific iPS –> study disease mech, screen drugs and new therapies
> hES, iPS-myogenic progenitors restore dystrophin to increase contractility
> Derive phenotypes (DMD) with hiPSC model: different types of mutations identified (reduced fusion competence, etc) –> myogenic specification and myoblast purification form rescued multi-nucleated myotubes –> correct defect
