app of tr mice

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Applications«.

� To understand Physiology & Development«Use of Transgenic Mice for Understanding the Physiology of Insulin-Like Growth Factors

expression of both IGF-I and IGF-II essential to normal inutero growth of the fetus.

IGF-II required for normal placental growth.

IGF-I necessary for normal in utero maturation andpostnatal growth.

study of type 1 IGF receptor (IGF 1R) knockout mice

indicate that

IGF 1R mediates most IGF-I and IGF-II growth-promoting actions.

� An Irreplaceable Tool for the Study of Mammalian Development and

Biology



� 1982: The first visible phenotype was shown by Dr. R. Palmiter

and colleagues in mice overexpressing rat growth hormone.

� A photograph of a GIANT TRANSGENIC MOUSE was on the

cover of Nature.

�Figure 3 Promoter function seen in transgenic mice. (A) Recombinant

plasmid containing rat growth hormone structural gene, mousemetallothionein regulatory region, and bacterial plasmid pBR322. The

plasmid, pMGH, was injected into the mouse oocytes. A mouse derived

from the eggs injected with pMGH (left) and a normal littermate (right).

(From Palmiter et al. 1982, photograph courtesy of R. L. Brinster.)

The first transgenic animals were mice created by Rudolf Jaenisch in

1974.

95 per cent of all existing transgenic animals are mice.



Human disease models«Alzheimer disease



Disease models for«.� Amyotrophic lateral sclerosis (ALS).

� Huntington disease.

� Arthritis.

� Muscular dystrophy.

� Tumorigenesis.

� Hypertension.

� Neurodegenerative disorders.

� Endocrinological dysfunction.

� Coronary disease.



Gene Regulation Studies«

� To identify promoter regulatory sequences«Studies of the genetic elements that control«

tissue specific and temporal gene expression:

� Heterologous promoters of varying lengths

� Site and strength of transgene expression.

� Gene Reporters in vivo«

-gal, CAT, GFP and Luciferase can be used to assess

the promoter specificity.



� In vivo phenotyping:transgenes fused to luciferase are

used to study gene expressionin a living mouse.

� Companies such as Xenogen

have developed biophotonic

imaging technology that allows

the study of gene expression in

a whole mouse during

physiological challenge.

� Using this model, it is possible

to assay:

� Site of expression

� Intensity

� Modulation

- during development-in response to stimuli, bacterial

challenge, drug challenge, etc.



To study Conditional Gene Expression«

� Useful in situations where it may not be desirable to

have constitutive gene overexpression.� Gene toxicity

� Developmental studies

� Modulation of a disease process

Inducible transgene expression

Tetracycline-regulated gene expression

Cre-Lox tissue specific expression

Conditional gene deletion



Tetracycline-dependent transactivation«

� Tg1

= Tetracycline-dependent transactivator protein ³tTA´ (tet repressor) fused to thetranscriptional activation domain of the HSVprotein VP16.

� Tg 2 = Transgene of interest under transcriptional control of a minimal promoter fused to tet operator from the E. coli Tn10transposon.

� Bitransgenic mouse = Tg1 x Tg 2

� Temporal control of rTA activity, whichstimulates transgene transcription from Tetop is

regulated by administration of tetracycline.



To study Reduced gene

expression«

� RNAi knock-down

� Traditional gene knock-out mice are timeconsuming,and expensive to make.

± Transgenic RNAi knock-down provides an

opportunity to study reduced gen expressionin a shorter time frame.



� Transgenic mice are being developed for use in testing

the safety of vaccines before they are used onhumans.

For Eg,Transgenic mice are being used to test the safety

of the polio vaccine.

� If successful and found to be reliable, they could replacethe use of monkeys to test the safety of batches of the

vaccine.

� humouse

� Antibody production«� Knock out mice«.

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