Triptolide increases transcript and protein levels of survival motor neurons in human SMA fibroblasts and improves survival in SMA-like mice.
OBJECTIVE
Spinal muscular atrophy (SMA) is a progressive neuromuscular disease. Since disease severity is related to the amount of survival motor neuron (SMN) protein, up-regulated functional SMN protein levels from the SMN2 gene are considered a major SMA drug-discovery strategy. In this study, we investigated the possible effects of triptolide, a diterpene triepoxide purified from Tripterygium wilfordii Hook. F., as a new compound for increasing SMN protein.


METHODS
The effects and mechanisms of triptolide on the production of SMA protein were determined by cell-based assays using the motor neuronal cell line NSC34 and skin fibroblasts from SMA patients. Wild-type (Smn(+/+) SMN2(-/-) , C57BL/6) and SMA-like (Smn(-/-) SMN2) mice were injected with triptolide (0.01 or 0.1 mg·kg(-1) ·day(-1) , i.p.) and their survival rate and level of change in SMN protein in neurons and muscle tissue measured.


RESULTS
In NSC34 cells and human SMA fibroblasts, pM concentrations of triptolide significantly increased SMN protein expression and the levels of SMN complex component (Gemin2 and Gemin3). In human SMA fibroblasts, triptolide increased SMN-containing nuclear gems and the ratio of full-length transcripts (FL-SMN2) to SMN2 transcripts lacking exon 7 (SMN2Δ7). Furthermore, in SMA-like mice, triptolide significantly increased SMN protein levels in the brain, spinal cord and gastrocnemius muscle. Furthermore, triptolide treatment increased survival and reduced weight loss in SMA-like mice.


CONCLUSIONS
Triptolide enhanced SMN protein production by promoting SMN2 activation, exon 7 inclusion and increasing nuclear gems, and increased survival in SMA mice, which suggests triptolide might be a potential candidate for SMA therapy.
Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Ya-Yun
YY
Hsu
Yuh-Jyh
YJ
Jong
Hsin-Hung
HH
Tsai
Yu-Ting
YT
Tseng
Li-Mei
LM
An
Yi-Ching
YC
Lo
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004195:Disease Models, Animal; D004224:Diterpenes / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004852:Epoxy Compounds / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D055531:Gemini of Coiled Bodies / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D053208:Kaplan-Meier Estimate; D051379:Mice; D018345:Mice, Knockout; D015394:Molecular Structure; D009046:Motor Neurons / Q000187:drug effects* / Q000378:metabolism; D009134:Muscular Atrophy, Spinal / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D010616:Phenanthrenes / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D060888:Real-Time Polymerase Chain Reaction; D055540:Survival of Motor Neuron 2 Protein / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*; D029757:Tripterygium / Q000737:chemistry; D015854:Up-Regulation
D004224:Diterpenes; D004852:Epoxy Compounds; D018696:Neuroprotective Agents; D010616:Phenanthrenes; D055540:Survival of Motor Neuron 2 Protein; C001899:triptolide