PINCH1 regulates cell-matrix and cell-cell adhesions, cell polarity and cell survival during the peri-implantation stage

Abstract

PINCH1 is composed of 5 LIM domains, binds integrin-linked kinase (ILK) and locates to integrin-mediated adhesion sites. In order to investigate PINCH1 function we generated mice and embryonic stem (ES) cell-derived embryoid bodies (EBs) lacking the PINCH1 gene. Similar to mice lacking β1 integrin or Ilk, loss of PINCH1 arrested development at the peri-implantation stage. In contrast to β1 integrin or Ilk mutants, however, disruption of the PINCH1 gene produced implantation chambers with visible cell clumps even at embryonic day 9.5. In order to define the phenotype leading to the peri-implantation lethality we made PINCH1-null EBs and found similar but also additional defects not observed in β1 integrin or Ilk mutant EBs. The similarities included abnormal epiblast polarity, impaired cavitation and detachment of endoderm and epiblast from basement membranes. Additional defects, which were not observed in β1 integrin- or ILK-deficient mice or EBs, included abnormal cell-cell adhesion of endoderm and epiblast as well as the presence of apoptotic cells in the endodermal cell layer. Although ILK and PINCH1 were shown to be involved in the phosphorylation of serine-473 of PKB/Akt, immunostaining with specific antibodies revealed no apparent alteration of PKB/Akt phosphorylation in PINCH1-deficient EBs. Altogether these data demonstrate an important role of PINCH1 for integrin function, actin organization, cell-cell adhesion and endodermal cell survival during the implanting of mouse embryos.

Molecular dissection of the ILK-PINCH-parvin triad reveals a fundamental role for the ILK kinase domain in the late stages of focal-adhesion maturation

“…2A). In agreement with previous reports, ILK or PINCH1 deletion was accompanied by a trans-downregulation of PINCH1 and ILK, respectively (Fukuda et al, 2003;Li et al, 2005;Stanchi et al, 2005).…”

A critical role for Ras Suppressor-1 (RSU-1) revealed when PINCH-Integrin-linked Kinase (ILK) binding is disrupted

“…The Pinch null mouse survives slightly longer (E6.5-E7.5) than the Ilk null mouse (E5.5-E6.5). Furthermore, Pinch null embryoid bodies display additional defects in cell-cell adhesion of the endoderm and the epiblast and contain apoptotic cells within the endodermal layer that are not seen in embryoid bodies derived from Ilk null embryos (Sakai et al, 2003;Li et al, 2005). Genetic studies in Drosophila also support the view that ILK and PINCH, though performing many common functions, have some unique and independent roles.…”

“…In the mouse, targeted gene disruption of either Pinch or Ilk results in embryonic lethality at the peri-implantation stage. Embryoid bodies derived from Pinch and Ilk null embryos display abnormal epiblast polarity, impaired cavitation, and detachment of the endoderm and epiblast from the basement membrane (Sakai et al, 2003;Li et al, 2005).…”

Basement Membranes: Cell Scaffoldings and Signaling Platforms

“…These findings suggested the existence of compensatory integrin/dystroglycan/ECM mechanisms for epiblast development . Mediators of polarization downstream of the basement membrane were found to include integrin-linked kinase, PINCH-1, Rac1 and Cdc42 and kindlin-2 (Sakai et al 2003;Li et al 2005a;Wu et al 2007;Montanez et al 2008;He et al 2010). …”