Publications

Many alleles of human disease genes have mutations within splicing consensus sequences that activate cryptic splice sites. In Caenorhabditis elegans, the unc-73(e936) allele has a G-to-U mutation at the first base of the intron downstream of exon 15, which results in an uncoordinated phenotype. This mutation triggers cryptic splicing at the -1 and +23 positions and retains some residual splicing at the mutated wild-type (wt) position. We previously demonstrated that a mutation in sup-39, a U1 snRNA gene, suppresses e936 by increasing splicing at the wt splice site. We report here the results of a suppressor screen in which we identify three proteins that function in cryptic splice site choice. Loss-of-function mutations in the nonessential splicing factor smu-2 suppress e936 uncoordination through changes in splicing. SMU-2 binds SMU-1, and smu-1(RNAi) also leads to suppression of e936. A dominant mutation in the conserved C-terminal domain of the C. elegans homolog of the human tri-snRNP 27K protein, which we have named SNRP-27, suppresses e936 uncoordination through changes in splicing. We propose that SMU-2, SMU-1, and SNRP-27 contribute to the fidelity of splice site choice after the initial identification of 5' splice sites by U1 snRNP.

Recently in Nature, Furuyama et al. (2019) provide evidence for lineage plasticity in the human endocrine pancreas, demonstrating that α cells derived from adult human pancreatic islets can be reprogrammed to become glucose-responsive, insulin-secreting β-like cells that are capable of reversing diabetes in mouse models.

The mucopolysaccharidoses (MPS) are a common cause of carpal tunnel syndrome (CTS) in children and adolescents. As the MPS diseases are progressive in nature, it is essential that CTS in these children is readily diagnosed and treated, before damage to the median nerve becomes irreversible. Currently, no standards for diagnosing and treating CTS associated with MPS exist. Proper diagnosis of CTS generally involves the assessment of clinical signs and symptoms, in combination with nerve conduction studies. As the clinical signs and symptoms of CTS described for adults are often absent in children with MPS, early diagnosis of CTS in these children requires recognition of subtle findings such as decreased sweating, nocturnal waking, gnawing of hands, and manual clumsiness. Sensory tests could also be useful for detecting early CTS when the integrity of the nerve is still relatively intact. Nerve conduction velocities, which are the gold standard for diagnosing CTS, can be difficult to perform in patients with MPS and should be adapted to the patients' clinical characteristics such as their abnormally small hands and young age. Ongoing monitoring for CTS is indicated for all MPS patients, including those treated with hematopoietic stem cell transplantation or enzyme replacement therapy.