Transcripts of unknown function in multiple-signaling pathways involved in human stem cell differentiation.

Area of Science:

• Molecular Biology
• Stem Cell Biology
• Genomics

Background:

• Mammalian transcriptomes contain numerous transcripts of unknown function (TUFs).
• Many TUFs are hypothesized to be non-coding RNAs involved in vital cellular processes.
• The functional roles of most TUFs remain largely uncharacterized.

Purpose of the Study:

• To identify and characterize novel functional TUFs.
• To investigate TUFs regulated during human mesenchymal stem cell (hMSC) differentiation.
• To understand the molecular mechanisms underlying TUF function.

Main Methods:

• Screening of TUFs expressed during hMSC differentiation.
• Analysis of transcriptional kinetics during adipogenesis and osteogenesis.
• Structural and comparative genomic characterization of identified TUFs.
• Investigating transcriptional regulation by Wnt and protein kinase A (PKA) signaling pathways.

Main Results:

• Six novel TUFs, termed transcripts related to hMSC differentiation (TMDs), were identified.
• TMDs exhibited distinct expression patterns during hMSC adipogenesis and osteogenesis.
• Structural analysis suggested diverse biological activities, including long non-coding RNA, microRNA host gene, and small protein gene functions.
• Most TMDs were transcriptionally regulated by Wnt and PKA signaling pathways.

Conclusions:

• The identified TMDs represent a new repertoire of functional non-coding RNAs and a novel small protein gene.
• TMDs are dynamically regulated during hMSC differentiation by key signaling pathways.
• This study suggests that many uncharacterized TUFs likely play crucial roles in fundamental cellular functions.