Eukaryotic Gene Regulation

Agenda

-Attendance

-Activities:

-LKP1 Protein Questions

-Cell Identity Questions

-Eve expression

-Exit Ticket

LKP1 Protein Background Information

•You are interested in understanding the
gene regulation of Lkp1, a protein that is
normally produced in liver and kidney
cells in mice. Interestingly, you find that
the LKP1 gene is not expressed in heart
cells.

You isolate the DNA upstream of the LKP1
gene, place it upstream of the gene for
green fluorescent protein (GFP), and
insert this entire piece of recombinant
DNA into mice. You find GFP expressed in
liver and kidney cells but not in heart
cells, an expression pattern similar to the
normal expression of the LKP1 gene.

LKP1 Protein Experiments

●Further experiments demonstrate
that three regions in the promoter,
labeled A, B, and C, contribute to
this expression pattern.

●Assume that a single and unique
transcription factor binds each site
such that protein X binds to site A,
protein Y binds to site B, and
protein Z binds to site C.

LKP1 Protein Experiments

●You want to determine which
region is responsible for
tissue-specific expression and
create mutations in the
promoter to determine the
function of each of these
regions.

●In Figure 8-16, if the site is
missing, it is mutated so that it
cannot bind its corresponding
transcription factor.

LKP1 Protein Experiments

●Experiment 1 is the positive
control, demonstrating that the
region of DNA upstream of the
gene for GFP results in a
pattern of expression that we
normally find for the LKP1
gene.

●Experiment 2 shows what
happens when the sites for
binding factors X, Y, and Z are
removed.

Cell Identity

Using only three
transcription regulators.
Each of these hypothetical
cell types (A-H) express
many different genes, as
dictated by the combination
of transcription regulators
that each cell type produces
and defines their cell
identity.

Drosophila
melanogaster

Cell Differentiation and identity

•Differentiation is regulated
by combinatorial control or
accumulation of unique TFs
at enhancer elements
•Transcription Factors then
interact with Mediator to
turn on or off gene
transcription

Eve expression (bands above) specifies 7
different body regions in the growing embryo

Eve gene 7 regulatory regions

Eveexpression in stripe 2 is
turned on because in this
region the repressors Giant
(Gt), Kruppel (Kr) are not
expressed, and the activator
Hunchback (Hb) is expressed.

Exit Ticket

For Midterm 3, how do you feel you did?

Did it go better or worse than previous exams?