DEVELOPMENTAL-CHANGES IN EXPRESSION OF MYOTONIC-DYSTROPHY PROTEIN-KINASE IN THE RAT CENTRAL-NERVOUS-SYSTEM

Myotonic dystrophy protein kinase (DMPK) is the protein product of the genetic locus associated with myotonic dystrophy, in which alteration s of muscle excitability, cardiac conduction defects, mental retardati on, and cognitive deficiencies are inherited as an autosomal dominant trait. DMPK belongs to a novel protein serine/threonine kinase family, but its regulation and physiological functions have not been specifie d. In a first step toward understanding the functions of DMPK in the c entral nervous system, we have characterized its localization and deve lopmental pattern of expression in rat brain and spinal cord by using a monospecific rabbit antiserum produced against bacterially expressed DMPK. Expression of DMPK begins after birth and increases gradually t o peak at postnatal day 21 with antibody labeling of neuronal cell typ es in many regions. After postnatal day 21 and proceeding to the adult , the pattern of expression becomes more restricted, with localization to certain regions or cell groups in the central nervous system. Elec tron microscopy reveals localization within adult spinal motor neurons to the endoplasmic reticulum and dendritic microtubules. The adult lo calizations suggest that DMPK may function in membrane trafficking and secretion within neurons associated with cognition, memory, and motor control. (C) 1998 Wiley-Liss, Inc.