Dissection of Nidogen function in Drosophila reveals tissue-specific mechanisms of basement membrane assembly

PLoS Genet. 2018 Sep 27;14(9):e1007483. doi: 10.1371/journal.pgen.1007483. eCollection 2018 Sep.

Abstract

Basement membranes (BMs) are thin sheet-like specialized extracellular matrices found at the basal surface of epithelia and endothelial tissues. They have been conserved across evolution and are required for proper tissue growth, organization, differentiation and maintenance. The major constituents of BMs are two independent networks of Laminin and Type IV Collagen in addition to the proteoglycan Perlecan and the glycoprotein Nidogen/entactin (Ndg). The ability of Ndg to bind in vitro Collagen IV and Laminin, both with key functions during embryogenesis, anticipated an essential role for Ndg in morphogenesis linking the Laminin and Collagen IV networks. This was supported by results from cultured embryonic tissue experiments. However, the fact that elimination of Ndg in C. elegans and mice did not affect survival strongly questioned this proposed linking role. Here, we have isolated mutations in the only Ndg gene present in Drosophila. We find that while, similar to C.elegans and mice, Ndg is not essential for overall organogenesis or viability, it is required for appropriate fertility. We also find, alike in mice, tissue-specific requirements of Ndg for proper assembly and maintenance of certain BMs, namely those of the adipose tissue and flight muscles. In addition, we have performed a thorough functional analysis of the different Ndg domains in vivo. Our results support an essential requirement of the G3 domain for Ndg function and unravel a new key role for the Rod domain in regulating Ndg incorporation into BMs. Furthermore, uncoupling of the Laminin and Collagen IV networks is clearly observed in the larval adipose tissue in the absence of Ndg, indeed supporting a linking role. In light of our findings, we propose that BM assembly and/or maintenance is tissue-specific, which could explain the diverse requirements of a ubiquitous conserved BM component like Nidogen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / cytology
  • Adipose Tissue / metabolism
  • Animals
  • Animals, Genetically Modified
  • Basement Membrane / physiology*
  • Drosophila / physiology*
  • Drosophila Proteins / physiology*
  • Female
  • Fertility / physiology
  • Male
  • Membrane Glycoproteins / physiology*
  • Muscles / cytology
  • Muscles / metabolism
  • Mutation
  • Organ Specificity / physiology
  • Organogenesis / physiology
  • Protein Domains / physiology

Substances

  • Drosophila Proteins
  • Membrane Glycoproteins
  • nidogen

Grants and funding

This work was supported by the Ministerio Español de Ciencia y Tecnología (grant number BFU2016-80797 to MDM-B) and by the NSFC (grants number 31771600 and 31371459 to JCP-P). BJS-S was supported by a FPI studentship from the MCYT. The institutional support from the Junta de Andalucía to the CABD is acknowledged. The funders had no role in study, design, data collection and analysis, decision to publish, or preparation of the manuscript.