Concatemeric RNA molecules, compositions, and methods and uses thereof

1. A concatemeric RNA molecule, comprising at least a first and a second repeat units, each of the first and the second repeat units including:

a first segment having a first nucleotide sequence;

a second segment having a second nucleotide sequence, complementary to the first nucleotide sequence; and

a connecting segment covalently attached to the second segment,

wherein the first segment and the second segment of at least one of the first or the second repeat units are not covalently attached.

2. A concatemeric RNA molecule, comprising at least a first and a second repeat units, each of the first and the second repeat units including:

a first segment having a first nucleotide sequence;

a second segment having a second nucleotide sequence, complementary to the first nucleotide sequence; and

a connecting segment covalently attached to the second segment,

wherein at least one of the first or the second repeat units further includes a loop segment having a loop nucleotide sequence, the loop segment being covalently attached to the first and the second segments,

wherein the loop nucleotide sequence includes at least one enzyme-specific nucleotide sequence; said enzyme-specific nucleotide sequence is excluded from the connecting segment.

3. The concatemeric RNA molecule of claim 2 , wherein the first segment, the second segment, and the loop segment of at least one of the first or the second repeat units form a hairpin loop structure by non-covalent complementary nucleotide pairing of the first nucleotide sequence and the second nucleotide sequence.

4. The concatemeric RNA molecule of claim 2 , wherein the enzyme is selected from the group consisting of RNAse T1, RNAse T2, RNase U2, RNase A, RNase H, and ribozyme.

5. The concatemeric RNA molecule of claim 2 , wherein the enzyme-specific nucleotide sequence is a self-cleaving ribozyme sequence.

6. The concatemeric RNA molecule of claim 1 , wherein each connecting segment contains 4 nucleotides to 20 nucleotides.

7. The concatemeric RNA molecule of claim 6 , wherein the connecting segment contains 6 nucleotides or 12 nucleotides.

8. The concatemeric RNA molecule of claim 2 , wherein the loop segment contains 4 nucleotides to 20 nucleotides.

9. The concatemeric RNA molecule of claim 8 , wherein the loop segment contains 6 nucleotides or 12 nucleotides.

10. The concatemeric RNA molecule of claim 2 , wherein the first and second segment form a double stranded stem segment comprising anti-sense and sense strands containing 19 nucleotides to 50 nucleotides.

11. The concatemeric RNA molecule of claim 2 , wherein the first and second segment comprise a silencing sequence.

12. The concatemeric RNA molecule of claim 11 , wherein the silencing sequence comprises an RNAi target sequence.

13. The concatemeric RNA molecule of claim 12 , wherein the RNAi target sequence silences a human or non-human gene.

14. A pharmaceutical composition comprising the concatemeric RNA molecule of claim 2 .

15. A particle comprising the concatemeric RNA molecule of Claim 2 .

16. A method for generating a concatemeric RNA molecule comprising:

(a) providing a DNA template;

(b) transcribing said DNA template by rolling circle transcription (RCT) or rolling circle amplification (RCA) under appropriate conditions to yield a plurality of concatemeric RNA molecules;

wherein the RNA molecule comprises at least a first and a second repeat units,

each of the first and the second repeat units including:

a first segment having a first nucleotide sequence;

a second segment having a second nucleotide sequence, complementary to the first nucleotide sequence;

a connecting segment covalently attached to the second segment, wherein the connecting segment of the first repeat unit is covalently attached to the first segment of the second repeat unit; and

a loop segment having a loop nucleotide sequence, the loop segment being covalently attached to the first and the second segments, wherein the loop nucleotide sequence includes at least one enzyme-specific nucleotide sequence; said enzyme-specific nucleotide sequence is excluded from the connecting segment and

(c) isolating the plurality of concatemeric RNA molecules.

17. The method of claim 16 , wherein the DNA template comprises a dumbbell DNA template.

18. The method of claim 16 , wherein the DNA template comprises a DNA molecule comprising a stem region, a first loop region, and a second loop region.

19. The method of claim 18 , wherein the stem region of said DNA template comprises a double stranded DNA molecule contains 19 nucleotides to 50 nucleotides.

20. The method of claim 19 , wherein the stem region of said DNA template comprises contains 25 nucleotides.

21. The method of claim 16 , wherein the DNA template comprises a silencing sequence.

22. The method of claim 18 , wherein the first and second loop region contains 4 nucleotides to 20 nucleotides.

23. The method of claim 22 , wherein the first loop region of said DNA template contains 6 nucleotides and the second loop region contains 12 nucleotides.

24. The method of claim 22 , wherein the first loop region of said DNA template contains 12 nucleotides and the second loop region contains 12 nucleotides.

25. The method of claim 22 , wherein the first loop region of said DNA template comprises a nucleotide sequence having at least one Cytosine nucleotide.

26. The method of claim 25 , wherein the first loop region of said DNA template comprises a nucleotide sequence having all Cytosine nucleotides.

27. The method of claim 25 , wherein the first loop region of said DNA template comprises a nucleotide sequence having no Cytosine nucleotides.

28. The method of claim 22 , wherein the second loop region of said DNA template comprises a nucleotide sequence having at least one Cytosine nucleotide.

29. The method of claim 28 , wherein the second loop region of said DNA template comprises a nucleotide sequence having all Cytosine nucleotides.

30. The method of claim 28 , wherein the second loop region of said DNA template comprises a nucleotide sequence having no Cytosine nucleotides.

31. The method of claim 25 , wherein the first loop region of said DNA template comprises a Cytosine nucleotide at positions 1, 5, and 6 from the 5′ end of the first loop region.

32. The method of claim 25 , wherein the first loop region of said DNA template comprises a Cytosine nucleotide at position 4 from the 5′ end of the first loop region.

33. The method of claim 16 , further comprising a step (d), wherein the step (d) comprises contacting the isolated concatemeric RNA molecules of step (c) to at least one enzyme.

34. The method of claim 33 , wherein the at least one enzyme is selected from the group consisting of RNAse T1, RNAse T2, RNase U2, RNase A, RNase H, and ribozyme.

35. The method of claim 16 , wherein step (b) further includes contacting the DNA template by an RNA polymerase.

36. The method of claim 35 , wherein the RNA polymerase is selected from T7 bacteriophage, phage T3, or phage SP6.

37. A method of gene silencing comprising administering to a subject in need thereof a therapeutically effective amount of the RNA molecule of claim 1 or claim 2 .

38. The concatemeric RNA molecule of claim 1 , wherein the first and second segment form a double stranded stem segment comprising anti-sense and sense strands containing 19 nucleotides to 50 nucleotides.

39. The concatemeric RNA molecule of claim 1 , wherein the first and second segment comprise a silencing sequence.

40. The concatemeric RNA molecule of claim 39 , wherein the silencing sequence comprises an RNAi target sequence.

41. The concatemeric RNA molecule of claim 40 , wherein the RNAi target sequence silences a human or non-human gene.

42. A pharmaceutical composition comprising the concatemeric RNA molecule of claim 1 .

43. A particle comprising the concatemeric RNA molecule of claim 1 .

44. The concatemeric RNA molecule of claim 40 , wherein the RNAi target sequence silences a non-human gene.