The need for a consensus on the locution "central nuclei" in striated muscle myopathies

Abstract

"Central nuclei" and "centrally located nuclei" are both widely used expressions to describe the nuclear positioning in skeletal muscle fibers during embryogenesis or muscle regeneration, as opposed to the definitive, subsarcolemmal (i.e., peripheral) nuclear position in adult muscle fibers. The two expressions are mutually exclusive in major databases of scientific literature and authors from different research groups seem to opt for one or the other stochastically, though are consistent with their choice over time. This poses a problem, since a search for one or the other set of keywords retrieves different subsets of articles, limiting the bibliography available. Defining nuclear position is very important in pathology, since many muscle disorders share the mispositioning of nuclei in the muscle fibers (Romero and Bitoun, 2011). In healthy conditions myonuclei are spaced in the periphery of the muscle fibers in such a way that the distance between them is maximized, while they are often found in the center of the myofibers in pathological conditions (recently reviewed by Folker and Baylies, 2013). This phenomenon makes nuclear positioning a common morphological marker for myopathies and the expressions used to describe it are widely used in basic research as well as in diagnosis. Therefore, the issue of using the expression "central" rather than "centrally located nuclei" is not limited to basic research in myology and can affect translational medicine and clinical practice as well, going far beyond a simple matter of semantics. We think there is an urgent need to establish an agreement on the term used in myopathy research as well as in clinical guidelines, "central nuclei" being our favorite choice. This article means to bring this issue to the attention of the scientific community of myologists, including health care professionals. Below, we discuss in detail the two options and justify our proposal.