Growth hormones

human Growth hormones is polypeptide produced by pituitary gland. Recombinant human growth hormones are widely used for the dwarfism treatment.

1. human Growth hormones Gunasheela.N 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 DNA technology 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 amino acids) and cDNA are joined in order to obtain full gene with its own initiation codon (AUG). T4 DNA ligase join these genes. Step V: 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. Step VI: 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 with Tumer’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 and Turner 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