Diverse small-molecule modulators of SMN expression found by high-throughput compound screening: early leads towards a therapeutic for spinal muscular atrophy.
We have exploited the existence of a second copy of the human SMN gene (SMN2) to develop a high-throughput screening strategy to identify potential small molecule therapeutics for the genetic disease spinal muscular atrophy (SMA), which is caused by the loss of the SMN1 gene. Our screening process was designed to identify synthetic compounds that increase the total amount of full-length SMN messenger RNA and protein arising from the SMN2 gene, thereby suppressing the deleterious effects of losing SMN1. A cell-based bioassay was generated that detects SMN2 promoter activity, on which greater than 550,000 compounds was tested. This resulted in the identification of 17 distinct compounds with confirmed biological activity on the cellular primary assay, belonging to nine different structural families. Six of the nine scaffolds were chosen on the basis of their drug-like features to be tested for their ability to modulate SMN gene expression in SMA patient-derived fibroblasts. Five of the six compound classes altered SMN mRNA levels or mRNA splicing patterns in SMA patient-derived fibroblasts. Two of the compound classes, a quinazoline compound series and an indole compound, also increased SMN protein levels and nuclear gem/Cajal body numbers in patient-derived cells. In addition, these two distinct scaffolds showed additive effects when used in combination, suggesting that they may act on different molecular targets. The work described here has provided the foundation for a successful medicinal chemistry effort to further advance these compounds as potential small molecule therapeutics for SMA.
Jarecki
Jill
J
Vertex Pharmaceuticals, Inc., San Diego, CA 92121, USA. jill@fsma.org
Chen
Xiaocun
X
Bernardino
Alexandra
A
Coovert
Daniel D
DD
Whitney
Michael
M
Burghes
Arthur
A
Stack
Jeffrey
J
Pollok
Brian A
BA
D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D020541:Coiled Bodies / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D017931:DNA Primers; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007150:Immunohistochemistry; D009134:Muscular Atrophy, Spinal / Q000188:drug therapy / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein
D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; C526477:SMN2 protein, human; D055533:Survival of Motor Neuron 1 Protein; D055540:Survival of Motor Neuron 2 Protein