Molecular Biology & Medicine

1. Molecular Biology & Medicine

2. Figure 16.13 a bacterial expression vector produces lots of theprotein encoded by a cloned gene

3. strategy for the production of a therapeutic protein Figure 16.14

4. Gleevec, designed atom by atom, is a treatment for CMLp. 339

5. Medical Problems Accessible to Molecular Biology • “One Gene - One Disease” • diseases due to single polypeptides • enzymes of phenylalanine metabolism • alkaptonuria • phenylketonuria (PKU)

6. two defects in phenylalanine catabolism result in different heritable diseasesFigure 17.1

7. Medical Problems Accessible to Molecular Biology • “One Gene - One Disease” • diseases due to single polypeptides • hemoglobin - a carrier protein • sickle cell disease • hemoglobin C disease • hemoglobin E disease

8. Figure 17.2

9. Figure 17.3

10. Medical Problems Accessible to Molecular Biology • “One Gene - One Disease” • diseases due to single polypeptides • membrane proteins - receptors & transporters • familial hypercholesterolemia • cystic fibrosis

11. Medical Problems Accessible to Molecular Biology • “One Gene - One Disease” • diseases due to single polypeptides • structural proteins • Duchenne muscular dystrophy • cells lack dystrophin • hemophilia • blood lacks coagulation protein

12. Medical Problems Accessible to Molecular Biology • “One Gene - One Disease” • diseases due to single polypeptides • misfolded protein • Transmissible spongiform encephalopathies, prion diseases • Scrapie, “mad cow”, Kruetzfeld-Jacob, kuru • transmitted by a protein

13. Figure 17.4 • normal • misfolded

14. Medical Problems Accessible to Molecular Biology • molecular analysis requires isolation of the affected gene(s) • human genomic libraries can be screened with sequence-specific probes • deduced from protein sequence • from mRNA • from other species • identified by a “positional” clue

15. sequences derived from genes or linked to genes can be used to isolate the genesFigure 17.6

16. RFLPs serve as natural genetic markers that can be linked to genesFigure 17.7

17. Heritable Diseases Arise by Mutation • mutations result from a variety of causes • point mutations may be spontaneous or induced • 5-methylcytosine => thymine mutations 5-mCAA or 5-mCAG =>TAA or TAG glutamine => stop 5-mCGA=>TGA arginine => stop

18. the uracil repair system does not recognize a 5-MeC=>T mutationFigure 17.8

19. Heritable Diseases Arise by Mutation • mutations result from a variety of causes • point mutations may be spontaneous or induced • silent - no disease • missense - disease possible • nonsense - disease probable

20. Heritable Diseases Arise by Mutation • mutations result from a variety of causes • large-scale deletion may remove • part of a gene • all of a gene • several neighboring genes • inversion or translocation may • interrupt a gene • create a new gene

21. a hybrid enzyme: part bcr (chr 22) andpart abl(chr 9) an active protein Kinase p. 339

22. Heritable Diseases Arise by Mutation • mutations result from a variety of causes • expanding triplet repeats may cause progressive heritable diseases • Fragile-X syndrome • ~30 CGG repeats - normal • 50-200 repeats - “premutated” • 200-1300 repeats - cytosine methylation, gene inactivation, mental retardation

23. FMR1 promoter regionFigure 17.9 18-162 bp 165-600 bp 600-6000 bp

24. Fragile-X at metaphaseFigure 17.5

25. Heritable Diseases Arise by Mutation • mutations result from a variety of causes • expanding triplet repeats may cause progressive heritable diseases • Fragile-X syndrome - CGG repeats • Myotonic dystrophy - CTG repeats • Huntington’s disease - CAG repeats • > 9 others, so far… • … or not

26. Molecular Diagnosis: Before the Disease • genetically characterized diseases can be detected by various tests • phenotypic screens • PKU preliminary screen

27. the heel-stick testidentifies infants for more testingFigure 17.10

28. possible PKU bacteria that require phe grow on PKU blood, don’t on normal Blood Figure 17.10

29. detection of sickle cell allele by RFLP with a specific restriction enzymeFigure 17.11 MstII recognizes …CCTNAGG… The sickle cell allele has …CCTGTGG…

30. Molecular Diagnosis: Before the Disease • genetically characterized diseases can be detected by various tests • phenotypic screens • genotypic screens • identification of known disease-causing alleles • allele-specific RFLPs • allele-specific hybridization

31. detection of sickle cell allele by allele-specific hybridizationFigure 17.12

32. Cancer - A Disease of Genetic Changes • cancer cells differ from normal cells • division without normal signals to divide • division in spite normal signals not to divide

33. Cancer - A Disease of Genetic Changes • tumor types differ • benign • slow-growing, localized, like source tissue • malignant • dedifferentiated cells

34. Figure 17.13

35. Cancer - A Disease of Genetic Changes • tumor types differ • benign • slow-growing, localized, like source tissue • malignant • dedifferentiated cells • metastatic • express digestive enzymes • fail to make cell adhesion proteins • cause vascularization

36. Cancer - A Disease of Genetic Changes • tumor types differ • different tissues • carcinomas: epithelial (lung, breast, colon, liver) • sarcomas: deep tissues (bone, blood vessels, muscle) • leukemias, lymphomas: blood stem cells

37. Viral agents in cancerTable 17.1

38. Cancer - A Disease of Genetic Changes • varied causes • viruses (~15%) • combined with specific mutations • most cancers (~85%) begin with somatic mutations • dividing cells are most susceptible to mutational consequences

39. mutations in dividing cells produce mutant cell populationsFigure 17.14

40. Cancer - A Disease of Genetic Changes • two types of genes can lead to cancer • proto-oncogenes • normally stimulate cell division • growth factors • growth factor receptors • signal transduction components • transcription factors • usually dominant mutations

41. proto-oncogenes normally stimulate cell divisionFigure 17.15

42. Cancer - A Disease of Genetic Changes • two types of genes can lead to cancer • tumor-suppressor genes • normally regulate cell division • cell-adhesion proteins • DNA repair proteins • cell cycle control proteins • generally recessive mutations

43. Figure 17.17

44. tumor-suppressor mutations are recessiveFigure 17.16

45. Cancer - A Disease of Genetic Changes • metastatic cancers involve the accumulation of many defects

46. five mutations of tumor suppressor genes or proto-oncogeneslead to polyp, benign tumor, class II & III adenomas, malignant tumor & metastatic cancer Figure 17.18 -TS APC -TS p53 +OG ras +telomerase, -adhesion, etc. -TS DCC

47. cytotoxictreatments can be used to control the spread of cancer Figure 17.19

48. Treatment of Genetic Diseases • modify the phenotype • restrict toxic substrates - PKU • metabolic inhibition - block cholesterol synthesis • kill targeted cells - treat cancer with chemicals that kill fast-growing cells • administer missing protein - insulin, clotting factor

49. example of ex vivogene therapyFigure 17.20

50. Treatment of Genetic Diseases • Gene Therapy • ex vivo • remove cells from patient • repair defect in cells • return cells to patient but • returned cells eventually die, so • altered stem cells may serve as a permanent source of new cells