Reciprocal regulation of hnRNP C and CELF2 through translation and transcription tunes splicing activity in T cells.

RNA binding proteins (RBPs) frequently regulate the expression of other RBPs in mammalian cells. Such cross-regulation has been proposed to be important to control networks of coordinated gene expression; however, much remains to be understood about how such networks of cross-regulation are established and what the functional consequence is of coordinated or reciprocal expression of RBPs. Here we demonstrate that the RBPs CELF2 and hnRNP C regulate the expression of each other, such that depletion of one results in reduced expression of the other. Specifically, we show that loss of hnRNP C reduces the transcription of CELF2 mRNA, while loss of CELF2 results in decreased efficiency of hnRNP C translation. We further demonstrate that this reciprocal regulation serves to fine tune the splicing patterns of many downstream target genes. Together, this work reveals new activities of hnRNP C and CELF2, provides insight into a previously unrecognized gene regulatory network, and demonstrates how cross-regulation of RBPs functions to shape the cellular transcriptome.

RNA-binding protein CELF6 is cell cycle regulated and controls cancer cell proliferation by stabilizing p21.

CELF6, a member of the CELF family of RNA-binding proteins, regulates muscle-specific alternative splicing and contributes to the pathogenesis of myotonic dystrophy (DM), however the role of CELF6 in cancer cell proliferation is less appreciated. Here, we show that the expression of CELF6 is cell cycle regulated. The cell cycle-dependent expression of CELF6 is mediated through the ubiquitin-proteasome pathway, SCF-ß-TrCP recognizes a nonphospho motif in CELF6 and regulates its proteasomal degradation. Overexpression or depletion of CELF6 modulates p21 gene expression. CELF6 binds to the 3'UTR of p21 transcript and increases its mRNA stability. Depletion of CELF6 promotes cell cycle progression, cell proliferation and colony formation whereas overexpression of CELF6 induces G1 phase arrest. The effect of CELF6 on cell proliferation is p53 and/or p21 dependent. Collectively, these data demonstrate that CELF6 might be a potential tumor suppressor, CELF6 regulates cell proliferation and cell cycle progression via modulating p21 stability.

Alternative RNA splicing associated with axon regeneration after rat peripheral nerve injury.

The intrinsic axon regeneration capacity is crucial for peripheral nerve regeneration after injury. Identifying key molecules involved in this process makes great contribution to the investigation of peripheral nerve injury repair. Alternative splicing (AS) is an important regulation mode of eukaryotic gene expression, which has been widely studied both in physiological and pathological processes. However, less is known about the role of AS in peripheral nerve regeneration. In this work, to identify the AS events associated with axon regeneration capacity, we analyzed the AS events during sciatic nerve injury repair by RNA sequencing (RNA-Seq) and replicate multivariate analysis of transcript splicing (rMATS). The differential AS events were underwent gene ontology enrichment and pathway analyses. Moreover, we identified a significantly increased AS event of neuronal cell adhesion molecule Nrcam (Nrcam-S), and demonstrated down-regulation of Nrcam-S by specific siRNAs inhibited axon regeneration of Dorsal Root Ganglion (DRG) neurons after sciatic nerve injury in vitro and in vivo. Additionally, we found expression levels of RNA binding proteins (RBPs) CUGBP Elav-like family member 3 (CELF3) and RNA binding protein fox-1 homolog 2 (Rbfox2) were markedly increased after sciatic nerve injury. Our data may serve as a resource useful for further understanding how AS contributes to molecular regulations in DRG during sciatic nerve regeneration.