TCTEX1D4, a novel protein phosphatase 1 interactor: connecting the phosphatase to the microtubule network
Luís Korrodi-Gregório,
Sandra I. Vieira,
Sara L. C. Esteves,
Joana V. Silva,
Maria João Freitas,
Ann-Kristin Brauns,
Georg Luers,
Joana Abrantes,
Pedro J. Esteves,
Odete A. B. da Cruz e Silva,
Margarida Fardilha,
Edgar F. da Cruz e Silva
Affiliations
Luís Korrodi-Gregório
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Sandra I. Vieira
Laboratory of Neurosciences, Centre for Cell Biology, Health Sciences Department and Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Sara L. C. Esteves
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Joana V. Silva
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Maria João Freitas
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Ann-Kristin Brauns
Department of Anatomy and Experimental Morphology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
Georg Luers
Department of Anatomy and Experimental Morphology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
Joana Abrantes
CIBIO-UP, Centro de Investigação em Biodiversidade e Recursos Genéticos – Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, número 7, 4485-661 Vairão, Portugal
Pedro J. Esteves
CIBIO-UP, Centro de Investigação em Biodiversidade e Recursos Genéticos – Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, número 7, 4485-661 Vairão, Portugal
Odete A. B. da Cruz e Silva
Laboratory of Neurosciences, Centre for Cell Biology, Health Sciences Department and Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Margarida Fardilha
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department and Health Sciences Department, University of Aveiro, 3810-193 Aveiro, Portugal
Edgar F. da Cruz e Silva
Laboratory of Signal Transduction, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
Summary Reversible phosphorylation plays an important role as a mechanism of intracellular control in eukaryotes. PPP1, a major eukaryotic Ser/Thr-protein phosphatase, acquires its specificity by interacting with different protein regulators, also known as PPP1 interacting proteins (PIPs). In the present work we characterized a physiologically relevant PIP in testis. Using a yeast two-hybrid screen with a human testis cDNA library, we identified a novel PIP of PPP1CC2 isoform, the T-complex testis expressed protein 1 domain containing 4 (TCTEX1D4) that has recently been described as a Tctex1 dynein light chain family member. The overlay assays confirm that TCTEX1D4 interacts with the different spliced isoforms of PPP1CC. Also, the binding domain occurs in the N-terminus, where a consensus PPP1 binding motif (PPP1BM) RVSF is present. The distribution of TCTEX1D4 in testis suggests its involvement in distinct functions, such as TGFβ signaling at the blood–testis barrier and acrosome cap formation. Immunofluorescence in human ejaculated sperm shows that TCTEX1D4 is present in the flagellum and in the acrosome region of the head. Moreover, TCTEX1D4 and PPP1 co-localize in the microtubule organizing center (MTOC) and microtubules in cell cultures. Importantly, the TCTEX1D4 PPP1BM seems to be relevant for complex formation, for PPP1 retention in the MTOC and movement along microtubules. These novel results open new avenues to possible roles of this dynein, together with PPP1. In essence TCTEX1D4/PPP1C complex appears to be involved in microtubule dynamics, sperm motility, acrosome reaction and in the regulation of the blood–testis barrier.
