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Identification, expression and characterization of rat isoforms of the serum response factor (SRF) coactivator MKL1

Mitsuru Ishikawa1, Jun Shiota, Yuta Ishibashi

  • 1Laboratory of Molecular Neurobiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.

FEBS Open Bio
|November 20, 2013
PubMed

Insights

Researchers identified three rat MKL1 transcripts, including a novel MELODY variant. These MKL1 isoforms differentially regulate serum response factor (SRF)-mediated transcription, potentially fine-tuning gene expression during brain development.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • Developmental Biology

Background:

  • Megakaryoblastic leukemia 1 (MKL1) is a key coactivator of the serum response factor (SRF).
  • Understanding MKL1 transcript diversity and function is crucial for deciphering gene regulation.
  • Previous studies focused on mouse MKL1, leaving rat homologues less explored.

Purpose of the Study:

  • To identify and characterize rat MKL1 transcripts.
  • To investigate the differential expression patterns of rat MKL1 isoforms.
  • To determine the functional impact of MKL1 isoforms on SRF-mediated transcription.

Main Methods:

  • Identification of rat MKL1 transcripts using molecular cloning techniques.
  • Quantitative analysis of MKL1 transcript expression across various rat tissues and during brain development.
  • Reporter assays to assess the effect of MKL1 isoforms on SRF and CREB activity.

Main Results:

  • Three rat MKL1 transcripts were identified: FLMKL1, BSAC, and a novel transcript, MELODY.
  • Rat MKL1 transcripts showed differential expression in tissues, with highest levels in testis and brain.
  • FLMKL1 encodes two isoforms (differing in RPEL motifs) that, along with BSAC and MELODY, enhanced SRF-mediated transcription but not CREB-mediated transcription.

Conclusions:

  • Rat MKL1 exhibits transcript diversity with distinct expression profiles.
  • Different MKL1 isoforms modulate SRF activity, suggesting a role in fine-tuning gene expression.
  • These findings provide insights into the regulatory mechanisms of SRF during development, particularly in the brain.
Keywords:
Alternative promoterBSAC, basic, SAP, and coiled-coil domainsDAPI, 4′, 6-diamidino-2-phenylindoleGFP, green fluorescent proteinMAL, megakaryocytic acute leukemiaMELODY, MKL1-elongated derivative of yieldMKL1, megakaryoblastic leukemia 1Megakaryoblastic leukemiaRPEL, arginine proline XXX glutamate leucineSRF, serum response factorSerum response factorTranscriptTranscriptional coactivator

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