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Analysis of Protein-protein Interactions and Co-localization Between Components of Gap, Tight, and Adherens Junctions in Murine Mammary Glands
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Isoform-specific function of calpains in cell adhesion disruption: studies in postlactational mammary gland and

Lucía Rodríguez-Fernández1, Iván Ferrer-Vicens2, Concha García2

  • 1Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Valencia, Avda. Blasco Ibañez, 15, Valencia 46010, Spain Fundación Investigación Hospital Clínico - INCLIVA, Avda. Blasco Ibañez, 15, Valencia 46010, Spain.

The Biochemical Journal
|July 13, 2016
PubMed

Insights

Calpains (CAPNs), calcium-dependent proteases, cleave adhesion proteins during mammary gland involution and breast cancer. CAPN2 interacts with E-cadherin in mammary glands, while CAPN1 drives cell migration in breast cancer, highlighting isoform-specific roles.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Cleavage of cell adhesion proteins is crucial for physiological processes like mammary gland involution and pathological conditions such as breast cancer metastasis.
  • Intracellular calcium-dependent proteases, known as calpains (CAPNs), are implicated in cleaving these adhesion proteins.

Purpose of the Study:

  • To investigate and compare the isoform-specific functions of calpain-1 (CAPN1) and calpain-2 (CAPN2) in disrupting cell adhesion.
  • To elucidate the roles of CAPN1 and CAPN2 in both physiological mammary gland involution and pathological breast cancer contexts.

Main Methods:

  • Western blot analysis to detect cleavage of adhesion proteins (E-cadherin, β-catenin, p-120, talin-1).
  • In vitro assays using mammary gland explants.
  • Proximity ligation assay to analyze in vivo protein interactions.
  • Calpain inhibitor administration.
  • Isoform-specific knockdown of CAPN1 and CAPN2 in breast cancer cell lines.
  • Subcellular localization studies (immunofluorescence, nuclear fractionation).

Main Results:

  • Both CAPN1 and CAPN2 cleaved adhesion proteins in vitro and in vivo during mammary gland involution.
  • CAPN2 localized with E-cadherin at cell junctions during lactation and its interaction increased during involution, with inhibition preventing E-cadherin cleavage.
  • In breast cancer cells, CAPN2 was nuclear, while CAPN1 mediated adhesion protein cleavage and cell migration, irrespective of tumor subtype.
  • Isoform-specific expression and activity of CAPNs varied with breast cancer subtype.

Conclusions:

  • The subcellular distribution of CAPN1 and CAPN2 dictates their substrate recognition and isoform-specific functions in cell adhesion disruption.
  • CAPN2 plays a physiological role in mammary gland involution by interacting with E-cadherin at cell junctions.
  • CAPN1 is the primary mediator of adhesion protein cleavage and cell migration in breast cancer, independent of tumor subtype, suggesting distinct roles in physiological and pathological contexts.
Keywords:
E-cadherin-cleavagecalpainscell adhesioncell migrationmammary gland involutionsubcellular distribution

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