Expression and synthesis of alternatively spliced variants of Dp71 in adult human brain

Transcripts encoding the 70-75 kDa C-terminal protein product of the dystro phin gene (Dp71) are alternatively spliced to generate multiple protein pro ducts in a number of adult human tissues. In this report, reverse transcrip tase-polymerase chain reaction was used to clone and characterize a subpopu lation of truncated Dp71 transcripts in adult human brain tissue which did not contain exons 71-74, resulting in an in-frame deletion of 330 bp encodi ng the syntrophin-binding domain. These truncated Dp71 transcripts are also alternatively spliced for exon 78, Immunoblot analysis, using dystrophin-s pecific C-terminal antibodies directed against epitopes in either exon 77 ( MANDRA1), or 78 (1461), identified full-length dystrophin, Dp140 and Dp71, in total protein lysates from adult human brain tissue. In addition, a mino r immunoreactive protein of approximately 58 kDa was also identified (desig nated Dp71 Delta(110)). The observation that a monoclonal antibody directed against epitopes within exons 73-74 (MANEX7374A) failed to detect this 58 kDa protein provides definitive evidence that Dp71 Delta(110) is derived fr om Dp71 transcripts deleted for the syntrophin-binding domain. These result s, as well as previous findings, demonstrate that alternative splicing of D p71 in the human brain generates a variety of mRNA transcripts encoding dis tinct protein variants of Dp71, and further supports the use of exon-specif ic antibodies in characterizing these variants. The presence of these Dp71 protein variants in brain tissue points to their interaction with various c ellular proteins and their involvement in different cellular functions. (C) 2000 Elsevier Science B.V. All rights reserved.