Open AccessTroponin-I localizes selected apico-basal cell polarity signals
Author(s) -
Sergio CasasTintó,
Alberto Ferrús
Publication year - 2019
Publication title -
journal of cell science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.384
H-Index - 278
eISSN - 1477-9137
pISSN - 0021-9533
DOI - 10.1242/jcs.225243
Subject(s) - biology , polarity (international relations) , basal (medicine) , microbiology and biotechnology , cell , biophysics , biochemistry , endocrinology , insulin
Beyond its role in muscle contraction, Drosophila Troponin I (TnI) is expressed in epithelial cells where it controls proliferation. TnI traffics between nucleus and cytoplasm through a sumoylation-dependent mechanism. We address here the TnI role in the cytoplasm. TnI accumulates apically in epidermal cells and neuroblasts. TnI co-immunoprecipitates with Par-3/Bazooka and Disc large (Dlg), two apico-basal polarity components. By contrast, Scribbled is not altered by TnI depletion. In neuroblasts, TnI contributes to the polar localization of Miranda while non-polar Dlg is not affected. Vertebrate PI3K contributes to apico-basal polarity of epithelia but Drosophila PI3K depletion alters neither apical TnI or Par3/Bazooka, nor basal Dlg. Nevertheless, overexpressing PI3K prevents TnI depletion defects. TnI loss-of-function disrupts cytoskeletal β-Catenin, E-Cadherin and γ-Tubulin localization, along with γH2Av revealed DNA damage. The TnI-dependent apoptosis is suppressible upregulating Sparc or downregulating Dronc. Rescue from apoptosis by p35 does not prevent DNA damage demonstrating that both features are mechanistically independent. Thus, TnI binds certain apico-basal polarity signals in a cell type dependent context, and it unveils a hereto unsuspected diversity of mechanisms to allocate cell polarity factors.