bDuring adipocyte differentiation, significant alternative splicing changes occur in association with the adipogenic process. However, little is known about roles played by splicing factors in this process. We observed that mice deficient for the splicing factor SRSF10 exhibit severely impaired development of subcutaneous white adipose tissue (WAT) as a result of defects in adipogenic differentiation. To identify splicing events responsible for this, transcriptome sequencing (RNA-seq) analysis was performed using embryonic fibroblast cells. Several SRSF10-affected splicing events that are implicated in adipogenesis have been identified. Notably, lipin1, known as an important regulator during adipogenesis, was further investigated. While lipin1 is mainly involved in lipogenesis, its alternatively spliced isoform lipin1␣, generated through the skipping of exon 7, is primarily required for initial adipocyte differentiation. Skipping of exon 7 is controlled by an SRSF10-regulated cis element located in the constitutive exon 8. The activity of this element depends on the binding of SRSF10 and correlates with the relative abundance of lipin1␣ mRNA. 〈 series of experiments demonstrated that SRSF10 controls the production of lipin1␣ and thus promotes adipocyte differentiation. Indeed, lipin1␣ expression could rescue SRSF10-mediated adipogenic defects. Taken together, our results identify SRSF10 as an essential regulator for adipocyte differentiation and also provide new insights into splicing control by SRSF10 in lipin1 pre-mRNA splicing.
Dysregulated alternative splicing events have been implicated in many types of cancer, but the underlying molecular mechanisms remain unclear. Here, we observe that the splicing factor SRSF1 regulates DBF4B exon6 splicing by specifically binding and promoting its inclusion. Knockdown of the exon6-containing isoform (DBF4B-FL) significantly inhibits the tumorigenic potential of colon cancer cells in vitro and in mice, and SRSF1 inactivation phenocopies DBF4B-FL depletion. DBF4B-FL and SRSF1 are required for cancer cell proliferation and for the maintenance of genomic stability. Overexpression of DBF4B-FL can protect against DNA damage induced by SRSF1 knockdown and rescues growth defects in SRSF1-depleted cells. Increased DBF4B exon6 inclusion parallels SRSF1 upregulation in clinical colorectal cancer samples. Taken together, our findings identify SRSF1 as a key regulator of DBF4B pre-mRNA splicing dysregulation in colon cancer, with possible clinical implications as candidate prognostic factors in cancer patients.
Cancer‐associated cachexia (CAC) is a devastating syndrome characterized by progressive losses of adipose tissue and skeletal muscle. CAC‐related adipose tissue loss (CAL) occurs early and is associated with a shorter survival time. To explore potential regulatory long noncoding RNAs (lncRNAs) of CAL, RNA microarrays were used to analyze the transcriptomes of white adipose tissue from CAC mice vs. control mice. A set of differentially expressed lncRNAs was identified, and among them was CAAlnc1, which suppressed adipogenesis of C3H10 cells as demonstrated by gain‐of‐function and loss‐of‐function experiments. RNA immunoprecipitation and pull‐down assays revealed Hu antigen R (HuR) was an important binding partner of CAAlnc1. The interaction between CAAlnc1 and HuR blocked the binding of HuR to adipogenic transcription factor mRNAs and further downregulated the expression of these transcription factors. This study generated a list of CAL‐related lncRNAs and provided details of a functional lncRNA which may play an important role in CAL.
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