SALL4 mediates teratogenicity as a thalidomide-dependent cereblon substrate

Abstract

Targeted protein degradation via small-molecule modulation of cereblon offers vast potential for the development of new therapeutics. Cereblon-binding therapeutics carry the safety risks of thalidomide, which caused an epidemic of severe birth defects characterized by forelimb shortening or phocomelia. Here we show that thalidomide is not teratogenic in transgenic mice expressing human cereblon, indicating that binding to cereblon is not sufficient to cause birth defects. Instead, we identify SALL4 as a thalidomide-dependent cereblon neosubstrate. Human mutations in SALL4 cause Duane-radial ray, IVIC, and acro-renal-ocular syndromes with overlapping clinical presentations to thalidomide embryopathy, including phocomelia. SALL4 is degraded in rabbits but not in resistant organisms such as mice because of SALL4 sequence variations. This work expands the scope of cereblon neosubstrate activity within the formerly 'undruggable' C2H2 zinc finger family and offers a path toward safer therapeutics through an improved understanding of the molecular basis of thalidomide-induced teratogenicity.

Manumycin Polyketides Act as Molecular Glues Between UBR7 and P53 to Impair Breast Cancer Pathogenicity

“…Cell survival and proliferation studies were performed using Hoechst 33342 dye (Invitrogen) as described previously 2,15,24 . Briefly, 231MFP cells were seeded at 20,000 (proliferation) or 40,000 (survival) cells/well, respectively, in serum-containing (proliferation) or serum-free (survival) media in 96-well plates and allowed to adhere overnight.…”

“…IsoTOP-ABPP studies were done as previously reported 2,15,24 . 231MFP cells were treated with DMSO vehicle or 10 μM of Asukamycin for 3 h. Cells were then harvested and lysed by probe sonication in PBS and protein concentrations were determined by bicinchoninic acid (BCA) assay (Pierce).…”

“…Thalidomide binds to the E3 ligase cereblon to form a new protein interface that recruits neo-substrates such as SALL4 or Ikaros transcription factors for ubiquitination and degradation [13][14][15][16] . Paradoxically, degradation of the former leads to teratogenic effects while degradation of the latter is a proven chemotherapeutic strategy 7,9,17 .…”

Proteolysis‐targeting chimeras in drug development: A safety perspective

“…For example, the identification of SALL4 has remained elusive for many years until the correct biological system expressing that protein was utilized. Additionally, optimal cellular systems must be chosen for profiling against other reported off targets of CRBN warheads, such as IKZF1 and IKZF3 as mentioned earlier(Donovan et al, 2018;Matyskiela et al, 2018) as well as p63(Asatsuma- Okumura et al, 2019).Following identification of off-target proteins that are degraded by the PROTAC, it is necessary to investigate the safety risks of these undesired effects through understanding the function of the degraded proteins and the physiological consequences of reducing their levels in different tissues. This can be a formidable task, especially when the function of the degraded protein has not been characterized.…”

Structural basis of recruitment of RBM39 to DCAF15 by a sulfonamide molecular glue E7820

“…The mechanism of action of SPLAMs is analogous to that of immunomodulatory drugs (IMiDs), such as thalidomide, lenalidomide, and pomalidomide. IMiDs bind to another adaptor protein for Cul4, cereblon, and alter its substrate selectivity to recruit, ubiquitinate, and degrade proteins including IKZF1, IKZF3, CK1a, GSPT1, and SALL4 (Ito et al 2010;Kronke et al 2014;Lu et al 2014;Fischer et al 2014;Petzold et al 2016;Matyskiela et al 2016;Matyskiela et al 2018). The degrons on the neo-substrates lack a consensus primary sequence but share a common motif, an extended b-hairpin motif (Petzold et al 2016;Matyskiela et al 2016).…”