Project description:Disruption of circadian rhythms increases the risk of several types of cancer. Mammalian cryptochromes (CRY1 and CRY2) are circadian transcriptional repressors that are related to DNA repair enzymes. While CRYs lack DNA repair activity, they modulate the transcriptional response to DNA damage, and CRY2 can promote SCFFBXL3-mediated ubiquitination of c-MYC and other targets. Here, we characterize five mutations in CRY2 observed in human cancers in The Cancer Genome Atlas. We demonstrate that two orthologous mutations of mouse CRY2 (D325H and S510L) accelerate the growth of primary mouse fibroblasts expressing high levels of c-MYC. Neither mutant affects steady state levels of overexpressed c-MYC, and they have divergent impacts on circadian rhythms and on the ability of CRY2 to interact with SCFFBXL3. Unexpectedly, stable expression of either CRY2 D325H or of CRY2 S510L robustly suppresses P53 target gene expression, suggesting that this is the primary mechanism by which they influence cell growth.
Project description:The functional consequences of cancer-associated missense mutations are unclear for majority of proteins, here we interrogated cancer mutation databases and identified recurrently mutated positions at structural contact interface of DNA-binding domains of SOX and POU family transcription factors. We used conversion of mouse embryonic fibroblasts (MEFs) to induced pluripotent stem cells (iPSCs) as a functional read out. In this study we identified several gain-of-function mutations that enhance cellular pluripotency reprogramming by SOX2 and OCT4. Wild type SOX17 does not support pluripotency reprogramming while recurrent missense mutation SOX17-V118M converts SOX17 into a pluripotency inducer, viability of cancer cells and provides protein stability. Here, we conclude that mutational profile of SOX and OCT family factors in cancer association can give direction to design high-performance reprogramming factors.
Project description:Cryptochromes are blue-light receptors in plants and animals. Homodimers are the physiologically active form of plant cryptochromes that mediates blue light regulation of gene expression and photomorphogenesis, but how light regulates the photoreceptor activation and inactivation remains unclear. We identified an Arabidopsis protein BIC1 (Blue-light Inhibitor of Cryptochromes 1) that inhibits all photoreactions of plant cryptochrome 2 (CRY2) examined, allowing direct tests of the photoactivation and inactivation mechanisms of CRY2. We found that blue light stimulates homodimerization of CRY2, whereas BIC1 binds to CRY2 to suppress CRY2 dimerization and the interaction of CRY2 with its signaling partners. We further show that cryptochromes and phytochromes mediate light induction of BIC1 transcription, evoking the negative feedback circuitry to control homeostasis of the active cryptochromes under the broad spectra of solar radiation in nature.
Project description:CRY2 expression was silenced in MCF7 cells using siRNA oligos, in order to examine the impact of CRY2 knockdown on carcinogenic processes. CRY2 was ~3-fold down-regulated in both replicates, relative to negative control.
Project description:OBJECTIVES: Abnormal chondrocyte gene expression promotes osteoarthritis (OA) pathogenesis. RNA-sequencing revealed that circadian rhythm pathway and expression of core clock protein cryptochrome 2 (Cry2) are dysregulated in human OA cartilage. Here we determined expression patterns and function Cry1 and Cry2. METHODS: Cry mRNA and protein expression was analyzed in normal and OA human and mouse cartilage. Mice with deletion of Cry1 or Cry2 were analyzed for severity of experimental OA and to determine genes and pathways that are regulated by CRY. RESULTS: In human OA cartilage, CRY2 but not CRY1 staining and mRNA expression was significantly decreased. Cry2 was also suppressed in mice with surgical or aging-related OA. Cry2 KO but not Cry1 KO mice with experimental OA showed significantly increased severity of histopathological changes in cartilage, subchondral bone and synovium. In OA chondrocytes, the levels of Cry1 and Cry2 and the amplitude of circadian fluctuation were significantly lower. RNA-seq on knee articular cartilage of wild-type and Cry2 KO mice identified 53 differentially expressed genes, including known CRY2 target circadian genes Nr1d1, Nr1d2, Dbp and Tef. Pathway analysis indicated that circadian rhythm and extracellular matrix remodeling were dysregulated in Cry2 KO mice. CONCLUSIONS: These results show an active role of the circadian clock in general, and of CRY2 in particular, in maintaining ECM homeostasis in cartilage. This cell autonomous network of circadian rhythm genes is disrupted in OA chondrocytes. Targeting CRY2 has potential to correct abnormal gene expression patterns and reduce the severity of OA.
Project description:Skeletal muscle has remarkable capacity to regenerate upon injury due to the presence of satellite cells. The maintenance and function of satellite cells are regulated by circadian clock. Cryptocrhome 2 (CRY2) is a key component of the circadian clock and its role in skeletal muscle regeneration remains controversial. Here, we report that CRY2 is down-regulated during muscle regeneration. Using the satellite cell specific CRY2 knockout mice (CRY2scko), we show that deletion of CRY2 enhances muscle regeneration. Single myofiber analysis showed that deletion of CRY2 enhances satellite cell self-renewal. In the absence of CRY2, the ERK1/2 and JNK1/2 signaling pathways become activated, which phosphorylates the transcription factor ETS1, which in turn binds to the promoter of PAX7 to induce its transcription. CRY2 deficient myoblasts survived better in ischemic muscle. Deletion of CRY2 also alleviated myopathy in mdx mice. Therefore, CRY2 plays an essential role in regulating satellite cell function and skeletal muscle regeneration.
Project description:Missense mutations account for nearly 50% of pathogenic mutations in human genetic diseases, most lack effective treatments. Gene therapies, CRISPR-based gene editing, and RNA therapies including transfer RNA (tRNA) modalities are common strategies for potential treatments of genetic diseases. However, reported tRNA therapies are for nonsense mutations, how tRNAs can be engineered to correct missense mutations have not been explored. Here, we describe missense correcting tRNAs (mc-tRNAs) as a potential therapeutic modality for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs that are charged with one amino acid and read codons of another amino acid in translation in human cells. We first developed a series of fluorescence protein (FP)-based reporters that indicate successful correction of missense mutations via restoration of fluorescence signals. We engineered mc-tRNAs that effectively corrected Serine and Arginine missense mutations in the reporters and confirmed the amino acid substitution by protein mass spectrometry and mc-tRNA expression by tRNA sequencing. We examined the transcriptome response to the expression of mc-tRNAs and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an Arg-tRNAGln(CUG) mc-tRNA to rescue the autolytic activity of a pathogenic CAPN3 Arg-to-Gln mutant involved in limb-girdle muscular dystrophy type 2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
Project description:Missense mutations account for nearly 50% of pathogenic mutations in human genetic diseases, most lack effective treatments. Gene therapies, CRISPR-based gene editing, and RNA therapies including transfer RNA (tRNA) modalities are common strategies for potential treatments of genetic diseases. However, reported tRNA therapies are for nonsense mutations, how tRNAs can be engineered to correct missense mutations have not been explored. Here, we describe missense correcting tRNAs (mc-tRNAs) as a potential therapeutic modality for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs that are charged with one amino acid and read codons of another amino acid in translation in human cells. We first developed a series of fluorescence protein (FP)-based reporters that indicate successful correction of missense mutations via restoration of fluorescence signals. We engineered mc-tRNAs that effectively corrected Serine and Arginine missense mutations in the reporters and confirmed the amino acid substitution by protein mass spectrometry and mc-tRNA expression by tRNA sequencing. We examined the transcriptome response to the expression of mc-tRNAs and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an Arg-tRNAGln(CUG) mc-tRNA to rescue the autolytic activity of a pathogenic CAPN3 Arg-to-Gln mutant involved in limb-girdle muscular dystrophy type 2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.