Function of E-protein dimers expressed in catfish lymphocytes.
E-proteins are essential class I bHLH transcription factors that play a role in lymphocyte development. In catfish lymphocytes the predominant E-proteins expressed are CFEB (a homologue of HEB) and E2A1, which both strongly drive transcription. In this study the role of homodimerization versus heterodimerization in the function of these catfish E-proteins was addressed through the use of expression constructs encoding forced dimers. Constructs expressing homo- and heterodimers were transfected into catfish B cells and shown to drive transcription from the catfish IGH enhancer. Expression from an artificial promoter containing a trimer of muE5 motifs clearly demonstrated that the homodimer of E2A1 drove transcription more strongly (by a factor of 10-25) than the CFEB homodimer in catfish B and T cells, while the heterodimer showed intermediate levels of transcriptional activation. Both CFEB1 and E2A1 proteins dimerized in vitro, and the heterodimer CFEB1-E2A1 was shown to bind the canonical muE5 motif.
Hikima
Jun-ichi
J
Medical University of South Carolina, Marine Biomedicine and Environmental Sciences Center, Charleston, SC 29425, USA.
Lennard Richard
Mara L
ML
Wilson
Melanie R
MR
Miller
Norman W
NW
Warr
Gregory W
GW
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D002397:Catfishes / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D019281:Dimerization; D029941:Fish Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D013601:T-Lymphocytes / Q000378:metabolism*
D051792:Basic Helix-Loop-Helix Proteins; D029941:Fish Proteins