Growth hormones, examples, mechanisms, steps involved, RDNA technology, Uses

1. GROWTH HORMONES
M.Meenakshi,
Assistant Professor,
Department of
Microbiology, Sri
Ramakrishna College of
Arts and Science for
Women, Coimbatore

2. GROWTH HORMONES
Growth hormone is a peptide hormone that stimulates growth,
development and regeneration. This peptide hormone is made up of 191
amino acids that form a long, single-chain polypeptide. Growth hormone is
synthesized in the somatotropic cells, which are found in the anterior
pituitary gland. These cells are also responsible for storing and releasing
the hormone.

3. EXAMPLES

4. GROWTH HORMONE

5. GROWTH HORMONE
Human growth hormone (hGH) is a polypeptide of
approximately 22,000 daltons in size that is synthesized in
the pituitary. Mature hGH has been produced in
Escherichia coli bacteria using recombinant DNA
technology.

6. TYPES OF GROWTH HORMONES
 Somatotropin is the other name for growth hormone , which is
produced naturally in animals.
 Somatropin is the synthetic form of growth hormone that is
synthesized using recombinant DNA technologies. It is also
referred to under the brand name Humatrope.

7. IMPORTANCE OF GROWTH HORMONES
Human growth hormone (HGH) is an important hormone produced by
your pituitary gland.
Also known as growth hormone (GH), it plays a key role in growth, body
composition, cell repair, and metabolism).
HGH also boosts muscle growth, strength, and exercise performance,
while helping you recover from injury and disease. Low HGH levels may
decrease your quality of life, increase your risk of disease, and make you
gain fat .
Optimal levels are especially important during weight loss, injury recovery,
and athletic training

8. PRODUCTION OF HUMAN GROWTH HORMONE
(HGH) BY RECOMBINANT DNATECHNOLOGY
The gene for human growth hormone (hGH) is
isolated from human pituitary gland.
Insertion of whole hGH gene into plasmid vector
and cloning into E.coli results into production of
biologically inactive hormone because bacteria can
translate the region of gene that are not translated
in human thereby producing a prehormone
containing an extra 26 aminoacids which might be
difficult to remove.
Hence the segment of gene that codes for the first
24 aminoacids of hormone is constructed chemically
from blocks of nucleotide.

9. STEPS INVOLVED
Step I: Chemical synthesis of gene for first 24 aminoacids:
From the known aminoacids sequence of hGH, gene for first 24 aminoacids are constructed
chemically.These genes are constructed in three small fragments and then they are joined by
T4 DNA ligase to get whole gene for first 24 aminoacids.
Step II: Isolation of mRNA for hGH
In this step mRNA for hGH is isolated from human pituitary gland tissue.
Step III: Reverse transcription
Using reverse transcriptase enzyme complimentary DNA (cDNA) is synthesized from mRNA.
The cDNA obtained by reverse transcription process, is the gene for hGH.
The full gene is cut with restriction endonuclease enzyme to remove first 24 gene.

10. STEPS INVOLVED….
Step IV: Joining of synthetic gene and cDNA
In this step synthetic gene (gene for first 24 aminoacids) and cDNA are joined in order to obtain full gene
with its own initiation codon (AUG).T4 DNA ligase join these genes.
StepV: selection of suitable vector and recombination:
Expression vector phGH407 derived from plasmid vector PBR322 is used as carrier vector.
HGH gene is ligated into a restriction site just downstream of Lac; promotor/operator region of the
expression vector.
StepVI: selection and recombination into suitable host cell
E. coli is used as suitable host cell.
The recombinant expression vector is then transformed into E.coli.
The recombinant E. coli then starts producing hGH.
The recombinant E. coli are isolated from the culture and mass production by fermentation technology to
obtain hGH.

11. USE OF RECOMBINANT HUMAN GROWTH
HORMONE (HGH)
Treatment of children suffering from growth deficiency
Treat the patient withTumer’s syndrome and chronic renal insufficiency
To treat patient with renal carcinoma
Bovine somatotropin hormone is used to increases milk production in lactating
cows and also to increase body mass of cattles.
Growth hormone deficiency (GHD) is more likely to affect children rather than
adults and is a symptom of several genetic diseases such as Prader-Willi syndrome
andTurner Syndrome. GHD is also more likely in children with cleft lips or palates.
Infection, head injuries, and radiation treatment may lead to acquired GHD.
Naturally occurring growth hormone is also known as somatotropin