Ls 3 Ch 18

Front 1

Final Complete Human Genome Sequence

Back 1

Working draft of human genome compiled in 2001 with corrected final version completed in 2003, required 10 years work & at a total cost = ~$3 billion (sequencing cost alone = ~$300 million). The final sequence provides a powerful reference/scaffold for compiling/aligning future human genome sequences.

Front 2

New strategy for sequencing genomes?

Back 2

"Shotgun” (i.e., random) genomic DNA cloning & automated sequencing coupled with computer assembly & alignment - most efficient & cost effective method for genome sequencing (proposed by C. Venter, 1998). Overcame dependence on mapping cloned DNAs which was the bottleneck in early genome sequencing. With shotgun approach, early computer assembly of DNA sequences was rate limiting, not automated DNA sequencing capability.

Front 3

Personal Genome Sequences

Back 3

J. Watson’s personal genome completed in just 3 months at cost of $1 million (presented on two DVDs to Watson, May 31, 2007). Second personal genome sequence (C. Venter) also now completed.
Note: human genomes are ~99.9% identical (i.e., they differ by ~3 million single base pair changes = ~1 bp /1000 bp). Individual genomes also differ by longer DNA insertions/deletions & by changes in copy number -these differences easily account for individual variations of traits in people

Front 4

Future developments in genome sequencing?

Back 4

Continuing advances now make a $5000 genome sequence feasible - ultimate aim is a complete genome sequence for $1000.

Front 5

What do Gene Finder Programs do?

Back 5

programs detect protein-coding gene sequences: look for long (>100 aa) Open Reading Frames (ORF), exons/introns, splice sites, polyA signals
Programs that predict promoters, enhancers & other transcription control

Front 6

Genome Studies
- There are also programs that predict ___, ___ and other ___ __ __

Back 6

Programs that predict promoters, enhancers & other transcription control regions (VISTA, search for clustered known transcription factor motifs)

Front 7

What does BLAST do?

Back 7

comparisons of protein sequences predict relatedness & function
-amino acid searches more efficient than DNA comparisons
-proteins with overall conserved sequences have similar structures & activities
-proteins are organized in domains (discrete functional regions) homologous to related domains in other proteins

Front 8

what is ENCODE?

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ENCODE (Encyclopedia of DNA Elements) next “big biology” project: initiated after human genome finished in 2003, combines computational & experimental strategies to annotate (i.e., define the functions) all expressed sequences in the human genome! ENCODE Analyses of 1% of human genome completed mid-2007.

Front 9

Changes in Gene Number

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Protein-coding gene duplication accounts for increased gene number & biological complexity between yeast (~6000 genes), invertebrates (~15,000 genes) & vertebrates (~25,000 genes). Most vertebrate genes have direct counterparts in invertebrates (many also in yeast). Conclusion: very few “new” protein-coding genes invented in evolution. Gene duplication/loss are important factors contributing to adaptation & evolution

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Gene Mutation

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Changes in protein-coding genes usually generate related proteins with modified functions rather than entirely new activities. Accumulation of separate mutations in duplicated genes can lead to proteins with different activities or functions

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Changes in regulatory DNA sequences or Transcription Factors: Affect expression of a single gene or alter more complex gene

Back 11

Affect expression of a single gene or alter more complex gene expression & control networks (e.g. tissue- or organ-specific, developmental gene programs).

Front 12

Alternative RNA splicing

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Most human protein-coding genes are alternatively-spliced (~70%), this produces >100,000 proteins with altered functions & expands the proteome (i.e., total proteins expressed). Alternative splicing increases with biological complexity.

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Non-protein coding RNA regulation

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Large fraction of all eukaryotic genomes is non-coding DNA (coding DNA = exons) that is transcribed into non-coding RNA. Amount of non-coding DNA & non-coding RNA increases with genome size & biological complexity in eukaryotes. Non-coding RNA likely involved in controlling all biological processes -> novel mechanisms for gene regulation (more next lecture)

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Adaptation by Variation in Gene Copy Number (Duplication)

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Example: The salivary amylase gene (AMY1 ) encodes an enzyme responsible for starch digestion. This gene has undergone duplication in human evolution in adaptation to increasing starch in the diet. Chimps (who eat shoots & leaves) have only 1 copy. Human groups with moderate starch diets have ~5 copies, while humans in modern agricultural societies with high-starch diets have 7-10 copies. Increased amylase gene copies in all humans vs. chimps provides a selective advantage for the digestion of
increased starch in the diet. Even further amylase gene duplications have occurred as an adaptation to diets of very starch-rich foods after the agricultural domestication of crops like maize, rice & wheat ~10,000 years ago (Sci. Am. January, 2009).

Front 15

Humans and Chimps
- how long ago did we diverge?

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~6 million years ago. Chimps are our closest living relatives

Front 16

Humans and Chimps
-How similar is a genomic DNA sequence?

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Genomic DNA sequences of humans & chimps are ~98.8% alike ( ~1.2% single bp differences = ~30 million bp changes out of 3 billion bp total, occur on average ~1/100 bp in the genome

Front 17

Humans and Chimps
-differneces between our genome result from ___ ___ _ with an average rate of ____, that accumulate in genomes at a steady rate over time

Back 17

Such differences result from random genetic mutations (average rate of single bp substitutions = ~1 per 108 bp per generation) that accumulate in genomes at steady rate over time

Front 18

Humans and Chimps
-What does it mean to say that the sequence differences are distributed throughout both genomes?

Back 18

Sequence differences are distributed throughout human & chimp genomes - most have no effect on human or chimp biology because only small fraction of the genomes are protein coding or regulatory sequences

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Humans and Chimps
-How similar are the proteins?

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Majority of human & chimp proteins have essentially identical amino acid sequences (i.e., differ by ~2-3 amino acids) & 29% have identical amino acid sequences - indicates positive selection maintaining common protein functions

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Humans and Chimps
-What is responsible for the larger genomic differences between humans and chimps?

Back 20

Gene duplication/loss is responsible for larger genomic differences between humans & chimps. Their genomes differ ~ 4% in gene number due to lineage-specific gene duplication or loss. Such changes account for significant differences in humans & chimps
ex. salivary amylase gene (AMY1) - adaptation to eat more starch in humans

Front 21

Humans and Chimps
-what is another reason for the differences in genomes?

Back 21

Changes in Regulatory DNA Sequences (transcription control regions) in human v. chimp genes
Example: regulatory region mutations that extend lactase (LCT) gene activity into adulthood -> adult lactose tolerance in humans descended from ancient herders

Front 22

-What did the Comparison of the FOXP2 Gene sequence in humans, chimps and mice reveal?

Back 22

-FOXP2 (715 amino acids) transcription factor known to function in human speech because severe inherited speech defects are associated with point mutations in FOXP2 protein (i.e., mutations predict function).

Front 23

-Human speech is associated with __ ___ FOXP2 amino acid changes (___, ___) which occurred ___ humans and chimps diverged 6 million years ago. Chimps and mice diff by only __ ___ amino acid change (____ vs. ____) after __ ___ years of divergent evolution

Back 23

Human speech is associated with two nonconservative FOXP2 amino acid changes (Asparagine303, Serine325) which occurred after humans & chimps diverged 6 million years ago. Chimps & mice differ by only one nonconservative amino acid change (Asparagine325 v. Alanine325) after 50 million years divergent evolution.

Front 24

FOXP2 ___ ___ is extremely ___ --> predicts essential ___/___ function for other animals besides humans

Back 24

FOXP2 protein sequence is extremely conserved - predicts essential developmental/regulatory function for other animals besides humans

Front 25

-FOXP2 in birds?
-FOXP2 in knockout mice?
-FOXP2 in knock-IN mice?

Back 25

FOXP2 reported to be required for bird songs (complex vocalization like human speech) & FOXP2 KO mice are squeakless. FOXP2 KI mice with the human FOXP2 gene make novel sounds compared to wildtype mice.

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Genome regions that have ___ the __ since humans and chimps diverged give clues to what makes us human

Back 26

changed the most

Front 27

Human genome DNA sequences with the most changes compared to chimp indicates __ of ___ ___ from ___ ___ ___

-These H___ A___ R___ are predicted to have shaped evolutionary changes between humans and chimps

Back 27

-sites of accelerated mutation; strong positive selection
-human accelerated regions

Front 28

Humans Vs. Chimps
-Sites involved in muscular/skeletal development (2)

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MYH16: mutant myosin gene found only in humans (no other primates!) limits jaw development-> smaller jaw & larger human brain size

HAR2: gene regulatory site controlling wrist/thumb fetal development, allowed for increased dexterity for tool making & use

Front 29

Humans Vs. Chimps
-Multiple Loci Involved in Brain Development?

Back 29

-ASPM, MCPH1, MCPH1 & CENPJ: four protein coding genes known to control brain size because genetic mutations cause microcephaly in humans
-HAR1 encodes short non-coding RNA that differs in 18/118 bases in humans vs. chimps (i.e., highest sequence variation in human vs. chimp) - known to function in human fetal neuron formation during development of cerebral cortex at 2-5 months in human embryos

Front 30

Humans Vs. Chimps
Other HAR sites that do not encode protein or RNA
> ___ identified, most predicted to control ___ of ___ ___

Back 30

2000, transcription, nearby genes

Front 31

-How long ago did we diverge from neanderthals?
-Tell me more dumb shit about neanderthals!

Back 31

-H. Neanderthalensis & H. sapiens lines diverged ~350,000 yrs ago in Africa
-H. Neanderthalensis: archaic humans, robust bodies, big-game hunters, migrated out of Africa into Europe & much of Asia ~200,00 yrs ago, died out ~28,000 yrs ago (based on archeological sites), cause of extinction not known
-H. sapiens: ancestors to modern humans , gracile bodies, sophisticated tool makers & creative artists, earliest fossil remains in Africa ~200,000 yrs old, migrated from Africa ~70,000 yrs ago & spread across the world (including the Americas by 15-20,000 yrs ago), arrived in Asia & Europe ~30-40,000 yrs ago, co-existed thousands of years with Neanderthals

Front 32

Neanderthal Genome Project
-What did they use to sequence the genome?
- What was critical in doing the experiment?
-MOrdern humans and neanderthal genomes estimated to be ___ alike?
- mitochondrial dna suggests?
-Neanderthal FOXP2 is reported to be ___ to modern human gene

Back 32

Whole genome now sequenced in rough draft (2009) using multiple DNA samples extracted from ~40,000 yrs old fossil bones from two Neanderthal females from Europe (critical to avoid sample contamination with modern human DNA!)
Findings to date:
1. Modern human & Neanderthal genomes estimated to be ~99.5% alike
(our individual human genome sequences are ~99.9% identical)
2. mitochondrial DNA sequences suggest that Neanderthals & H. Sapiens may
not have interbred
3. Neanderthal FOXP2 gene reported to be identical to modern human gene
(talking cavemen?) Human form of FOXP2 appeared >350,000 years ago!

Front 33

Purebred dogs are the result of centuries of __ ___ ___ Experiments by Humans.
-All modern dogs are thought to be evolved from an ancestor of ___ __ ___ ~ ____ years ago
- ALl dogs belong to a single ___

Back 33

highly selective genetic experiments
-chinese gray wolf, ~15,000 years ago
- single species

Front 34

>____ breeds of modern purebred dogs, produced by ___ ___ often in only a few 100 years
- Dogs of a __ __ are more alike genetically than humans
Purebred dogs often are susceptible to particulare __ __ that affect only one or a few breeds
- Genomic sequence comparisons between different purebred dog genomes can more easily identify __ __ involved in complex genetic disorders than __ __ in ___
- such studies have already begun to define genetic origins of different dog __, ___ and ___

Back 34

- multiple genes
- comparative studies in humans
-features, diseases, and behavior

Front 35

-Small size in ALl dogs results from a __ ___
-___ dogs have largest size range among land animals
-All small dog breeds <20lbs have a __ ___ ___ mutation that suppresses ___ production
-___ deficiency is known to cause ___ in humans and KO mice
-This mutation may have been present in the small wolves that became domesticated WITH humans ___ years ago
- This mutaiton has been maintained to present day by __ __ for small dog breeds

Back 35

-Single mutation
-Domestic
-single regulatory region mutation, supresses IGF1 (insulin growth factor 1) production
-IGF1 Deficiency is known to cause dawrfism in humans and ko mice
-15,000 years ago
- human selection

Front 36

Gene for Human ___ identified based on discovery in canine ____
-rare disorder in __ ___
discoevered to be due to mutation in __-_-___
-now known that most human ___ due to __ ___
-____ now recongized to be important regulator of many critical acitvities including __ __, __, __, in addition to sleep

Back 36

-Narcolepsy X2
-doberman pinschers
-hypocretin-2-receptor
-human narcolepsy due to hypocretin deficiency
-hypocretin, metabolic rate, mood, appetite

Front 37

-Only ___% of the human genome codes for proteins (___)
-___% of the human genome is transcribed into ___ to ___ (primary transcripts). Introns make up __% of __ __ and are ___ out in mRNA processing
-___% of the human genome is __-___ DNA located either in ___ regions between genes (___) or in ___ (___)
- ___% of human genome is transcibed into __-___ ___ (___% introns,___% from integenic regions)
-Human "transcriptome" is composed of ___ more ___-___ ___ than ___-___ ___ ____
-

Back 37

Only ~1.5% of the human genome codes for proteins (exons)
~30% of the human genome is transcribed into precursors to mRNA (primary transcripts). Introns make up ~95% of primary transcripts & are spliced out in mRNA processing.
~93% of the human genome is non-coding DNA located either in intergenic regions between genes (~65%) or in introns (~28%).
~60% (more in some estimates) of human genome is transcribed into non-coding RNA (~28% in introns, ~30% from intergenic regions). Human “transcriptome” is composed of ~40X more non-coding RNA than protein-coding mRNA sequences.

Front 38

Why is most of the human genome regarded as dark matter

Back 38

Most of the human genome (other higher eukaryotic genomes too) long regarded as “Dark Matter” - DNA sequences with no known function, transcribed into RNA of unknown function

Front 39

RNA Interference (RNAi)/RNA silencing

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Non-coding RNAs play a major role in controlliong gene expression and geome stability

Front 40

Genome size in all eukaryotes is directly correlated with ___ of the genome transcripted into ___-___ ___. The greater biological complexity of higher eukaryotes due in part to __ ___ __ controlled by __-___ ___

Back 40

-fraction, non-coding RNA, expanded regulatory circuits, non-coding RNA

Front 41

>50% of the human genome is different types of ___ __ __, that are dispersed throughout the genome, located in __ and ___ regions
-

Back 41

-repeated DNA sequences, introns, and intergenic
-

Front 42

Members of the different families of repeated sequences (ex. ___, ___, __ repeats), have similar but not identical __ ___

Back 42

(LINEs, SINEs, Alu repeates), DNA sequences

Front 43

Transposons
-make up how much of the human genome
-current hypothesis of them?
-its movement does what?

Back 43

Transposons make up ~10% of the human genome - likely remnants from past infections by DNA viruses or retroviruses - usually stably-maintained in the genome, can express non-coding RNA. Movement of transposons can disrupt genes -> genetic disorders (e.g., Factor VIII deficiency in Hemophilia A)

Front 44

Pseudogenes?

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Human genome also contains 10 - 20,000 pseudogenes (highly-mutated, non-functonal relics of genes) - almost as many pseudogenes as protein-coding genes, now estimated that at least 20% are transcribed into non-coding RNA

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Most of the HUman Genome is ___ __ and other oddities

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Most of the Human Genome (Other Higher Eukaryotic Genomes too) is Repeated Sequences & Other Oddities

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The INtrons of most human genomes contain large numbers of __ __ and ___ __
-Recent results indicate that 80% of human genes have ___ (__ __ __ __), ___ (___-INEs) and other types of repeated sequences inserted in their introns.
-most human genes contain __ ___ too.
- repeated sequences often exceed the number of __ in many human genes

Back 46

-Repeated Sequences, Transpoable Elements
-LINEs (Long Interspersed Nuclear Elements), SINEs
-Transpoable elements
-exons (ex. human growth hormone)

Front 47

Non-Coding RNA is ideal for __ ___ ___ specified by DNA and RNA (because?)

Back 47

-regulating cellular processes
- base pairing allows specific "zip code" recognition

Front 48

RNAi likely evolved as __ __ against __ __ __---> double stranded RNA

Back 48

RNAi likely evolved as cell defense against RNA virus infections -> double-stranded RNA (note: anti-viral cytokine, interferon-, is induced by cellular anti-viral miRNAs that are made in response to infection) - some viruses make RNAi to combat the anti-viral responses of infected cells

Front 49

RNAi functions in all __ __ in eukaryotic cells and organisms
(D.A.E.SCP.S.PMT)

Back 49

Now well established that RNAi functions in all major processes in eukaryotic cells & organisms (e.g., development, apoptosis, embryogenesis & stem cell production, silencing & preventing movement of transposons)

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examples of RNAi control now known?

Back 50

-inhibition of translation, RNA degradation, gene silencing via chromatin/epigenetic changes, changes in alternative RNA splicing) - more examples continue to be discovered

Front 51

5. discrepancy in regulatory non-coding RNA sizes and types?
6. two well studied RNAi types? they are processed from different types of __ _, both are incorporated into ___, inhibit __ via several mechanisms
7. now known that small non-coding RNAs also activate ___ and sitmulate ___ via mechanisms now being studied

Back 51

5. Some known regulatory non-coding RNAs are large transcripts (Xist =
10,000 nt), but most are small (21 - 25 nt long) single-stranded RNAs
6. Two well studied classes: microRNA (miRNA) & short interfering RNA
(siRNA) are processed from different types of RNA precursors, both are incorporated into RISC, inhibit translation via several mechanisms
7. Now known that small non-coding RNAs also activate transcription & stimulate translation via mechanisms that are now being actively studied

Front 52

miRNAs are processed from ___ ___ with characteristic ___-shaped ___ ___ that predict their targets

Back 52

RNA precursors, hairpin-shaped secondary structures

Front 53

miRNAs are processed from long nuclear RNAs that contain hair-pin loops by two ___ ___ steps:
1 ___-miRNA (___ ___) --> ___-miRNA (with __ ___)
2. ___-miRNA --> mature __ ___ miRNA containing __ ___ ___ to the target(s) of ___ ___-___ miRNA in ___

Back 53

miRNAs are processed from long nuclear RNAs that contain hair-pin
loops by two RNAse cleavage steps:
1. pri-miRNA (primary miRNA) ->
pre-miRNA (with stem loop)
2. Pre-miRNA -> mature double- stranded miRNA containing core sequences complementary to the target(s) of activated single-stranded miRNA in RISC

Front 54

Two ___ ___ enzymes (specific for ___-___ RNA) involved:
1. D__:
2.D__
-Specificity of both enzymes based on __ ___ rather than ___

Back 54

Two RNAse III enzymes (i.e., specific for double-stranded RNA) involved:
1. Drosha: nuclear enzyme required
specifically for miRNA processing
2. Dicer: cytoplasmic enzyme, used
in all RNAi processing
Specificity of both enzymes based on
RNA structure rather than sequence

Front 55

pre-mrna structures

Back 55

pre-miRNA structures: single-stranded 21-23 nt miRNA sequences that base pair to target mRNA(s) can be derived from one or both pre-miRNA strands (red & blue)

Front 56

miRNAs are processed from __-___ that are transcribed by ___ ___ __, as well as from ___, ___, ___ of some ___-____

Back 56

miRNA are processed from pri-miRNA that are transcribed by RNA polymerase II, as well as from introns, exons, 3’UT of some pre-mRNA

Front 57

miRNA Processing: pri-miRNA cleavage by ___ and ___
- ___ complex with ___ (___ in flies) makes two cutes to release ____ long __-___ conaining a __-__ bp base-paired __ __ and the single-stranded __ ___ from nuclear pri-miRNA
-___-cleaved pre-miRNA then exported to cytoplasm and undergoes ___ cleavage ---> ___-___ bp double-stranded miRNA with _ ___ ___ at 3' End

Back 57

Drosha complex with DGCR8 (Pasha in flies) makes two cuts to release ~65-70 nt long pre-miRNA containing a 21-23 bp base-paired upper stem (with some mismatched bases) & the single-stranded terminal loop from nuclear pri-miRNA
Drosha-cleaved pre-miRNA then exported to cytoplasm & undergoes Dicer cleavage -> 21-23 bp double-stranded miRNA with 2 unpaired bases at 3’ end

Front 58

SiRNA processing by Dicer Cleavage
- Double-stranded forms of siRNA are also generated by __ from larger double-stranded ___ ___ in the ___ (ex.?)
-___ is a nuclear enzyme and not involved in ___ cleavage

Back 58

Double-stranded forms of siRNAs are also generated by Dicer from larger double-stranded precursor RNAs in the cytoplasm (e.g., made by infecting RNA viruses, or from complementary sense/antisense transcripts, inverted repeated sequence transcripts, transposons, exogenous double-stranded RNAs transfected into cells)
Drosha is a nuclear enzyme & not involved in siRNA cleavage

Front 59

Dicer has how many functional domains?

Back 59

3

Front 60

Functional Domains of Dicer (hatchet-shaped)
- two __ __ domains (blades) that cleave RNA connected via a __ __ to the __ domain (handle) that contains a __ __ that positions the __ end of double-stranded RNAs ~_ bp from the __ ___ sites.

Back 60

Dicer is “hatchet-shaped” protein composed of three functional domains; two RNAse III domains that cleave RNA (the blades) connected via a linker region to the PAZ domain (the handle) that contains a binding pocket that positions the 3’ end of double-stranded RNAs ~22 bp from the two dicer cleavage sites.

Front 61

Variation in the sizes of ___ domains in different ___ produce Dicer cleavage products of __-__ bp. Recall that Dicer cleavage generates _ ___ ___ at the __ end of the double stranded product

Back 61

Variations in the sizes of PAZ domains in different species produce Dicer cleavage products of 21-25 bp. Recall that Dicer cleavage generates 2 unpaired bases at the 3’ end of the double-stranded product

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RISC =

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RNA induced Silencing Complex

Front 63

Dicer-cleaved double-stranded ___ or ___ is incorporated into a __ __ protein complex, one strand is ___ or __, leaving a single-stranded "___" RNA that __ __ to __ ___

Back 63

Dicer-cleaved double-stranded miRNA or
siRNA incorporated into a cytoplasmic RISC
protein complex, one strand is removed or
degraded, leaving a single-stranded “guide”
RNA that base pairs to target mRNAs

Front 64

Guide siRNA or miRNA base-pairing specifies __ ___ of target mRNA
-RISC proteins from ___ family either cleave target mRNA (___ activity) or repress ___ (without ___ acitvity)

Back 64

Guide siRNA or miRNA base-pairing specifies
RISC recognition of target mRNA - RISC
proteins from Argonaute Family either cleave
target mRNA (argonautes with slicer activity)
or repress translation (those without slicer
activity)

Front 65

Three general mechanisms of RNAi
inhibition of eukarotic gene expression

Back 65

1. endonucleolytic mRNA cleavage
2. translation inhibition
3. Chromatin remodeling -> inhibition
of transcription in the nucleus

Front 66

Small Regulatory RNAs also activate ___ and stimulate ___

Back 66

Small regulatory RNAs also activate
transcription & stimulate translation

Front 67

Single-stranded “guide” miRNA or siRNA in mature RISC base-pairs to target mRNA -> two outcomes:
1. ___ ___, carried out by Argonaute protein with ___ ___ activity in RISC
2. ___ of __ __, RISC association with ___ _ bodies (___-___ sites for __ turnover, contain __ for __-___ and __-___ of mRNA exonucleases) --> ___ of mRNA

Back 67

1. mRNA cleavage, carried out by Argonaute protein with slicer
endonuclease activity in RISC
2. Inhibition of protein synthesis,
RISC association with cytoplasmic P bodies (RNA-processing sites for mRNA turnover, contain enzymes for de-capping & de-adenylation of mRNA,exonucleases) -> degradation of mRNA

Front 68

How is the RNAi mechanism used for translation control determined?

Back 68

Choice of RNAi mechanism used for translation control is determined by extent of miRNA or siRNA base-pairing to target mRNA(s)

Front 69

Guide miRNAs or siRNA only specify the ___ ___(s); ___ family proteins in ___ carry out ____ cleavage or inhibition of ___/_ ___ entry

Back 69

Guide miRNA or siRNA only specify the target mRNA(s), Argonaute family proteins in RISC carry out endonucleolytic cleavage or inhibition of translation/P body entry

Front 70

Recognition of Target mRNA: ___ __ with miRNA or SiRNA
1. Imperfect Base Pairing
2. Perfect Base Pairing

Back 70

Base Pairing
1. --> translation inhibition, entry into P bodies (this may require binding of several RISC to mRNA)
2. --> endonucleolytic mRNA cleavage and rapid degradation

Front 71

where is the RNAse "Slice Cleavage site on Argonaute Structure?

Back 71

in the middle of Guide RNA/Target mRNA duplex

Front 72

miRNA regulation of alternative splicing
- Example: PTB is a ___ ___ ___ that controls alternative splicing in many genes via PTB bindint to __ splice sites in ___-__ --> ___ skipping or use of alternative __ splice site
-miRNA (miR-1333) is induced in developing ___ and ___ PTB ____ --> changes patterns of ___ __ ___ and expression of different ___ of multiple proteins for ___ cell functions
-Conclusion: miRNAs control the ___ __ that control expression of __ __ or networks of __ ___

Back 72

-Example: PTB is a master regulatory splicing factor that controls alternative splicing in many genes via PTB binding to 3’ splice sites in
pre-mRNA -> exon skipping or use of alternative 3’ splice sites
- miRNA (miR-133) is induced in developing myoblasts & inhibits PTB translation -> changes patterns of alternative RNA splicing & expression of different isoforms of multiple proteins for muscle cell functions
- Conclusion: miRNAs control the master regulators that control
expression of multiple genes or networks of gene expression