TY - JOUR T1 - Phosphodiesterase I, A Novel Adhesion Molecule and/or Cytokine Involved in Oligodendrocyte Function JF - The Journal of Neuroscience JO - J. Neurosci. SP - 9095 LP - 9103 DO - 10.1523/JNEUROSCI.17-23-09095.1997 VL - 17 IS - 23 AU - Babette Fuss AU - Hiroko Baba AU - Tom Phan AU - Vincent K. Tuohy AU - Wendy B. Macklin Y1 - 1997/12/01 UR - http://www.jneurosci.org/content/17/23/9095.abstract N2 - One of the more complex developmental processes occurring postnatally in the CNS is the formation of the myelin sheath by oligodendrocytes. To examine the molecular events that take place during myelination, we isolated oligodendrocyte-derived cDNA clones, one of which (p421.HB) represents a putative alternatively spliced isoform of rat brain-specific phosphodiesterase I (PD-Iα) and a species homolog of the human cytokine autotaxin. Analysis of the structural composition of the p421.HB/PD-Iα protein suggests a transmembrane-bound ectoenzyme, which, in addition to the phosphodiesterase-active site contains presumed cell recognition and Ca2+-binding domains. Consequently, it may be involved in extracellular signaling events. Expression of p421.HB/PD-Iα is enriched in brain and spinal cord, where its mRNA can be detected in oligodendrocytes and in cells of the choroid plexus. Expression in the brain increases during development with an intermediate peak of expression around the time of active myelination and maximal expression in the adult. We have identified four presumably alternatively spliced isoforms, two of which appear to be CNS-specific. Decreased levels of p421.HB/PD-Iα mRNA in the dysmyelinating mouse mutant jimpy, but notshiverer, suggest a role for p421.HB/PD-Iα during active myelination and/or late stages of oligodendrocyte differentiation. Furthermore, p421.HB/PD-Iα mRNA levels were reduced in the CNS at onset of clinical symptoms in experimental autoimmune encephalomyelitis. These data together implicate the importance of p421.HB/PD-Iα in oligodendrocyte function, possibly through cell–cell and/or cell–extracellular matrix recognition. ER -