Subcellular localization and function of 2LIM proteins in plants and humans.

In their recent review article published in Planta, Srivastava and Verma (2017) comprehensively summarise 25 years of research on plant LIM proteins, with a focus on their biological functions and potential for translational applications in crop improvement. The present commentary extends the discussion on the subcellular localization of two-LIM domain proteins (2LIMs), with the objective to further delineate the key questions that need to be answered, as well as the hurdles that investigators may have to overcome. The 2LIMs belong to a unique LIM protein subfamily which is found in both plants and vertebrates. In the latter, they are referred to as cysteine-rich proteins or CRPs (Weiskirchen and Gunther 2003). In addition to their similar structural organization and dual cytoplasmic and nuclear distribution, 2LIMs and CRPs share common functionalities, such as the capacity to crosslink actin filaments (AFs) (Hoffmann et al. 2014b, 2016; Tran et al. 2005), and to regulate gene transcription (Chang et al. 2003, 2007; Kawaoka et al. 2000; Moes et al. 2013). Accordingly, we also draw attention to those studies on CRPs relevant to the question of 2LIM nuclear-cytoplasmic partitioning.