Extracellular Matrix Protein Signatures of the Outer and Inner Zones of the Rat Adrenal Cortex

This study analyzes
the extracellular matrix (ECM) signatures of
the outer (OF = capsule + subcapsular + zona glomerulosa cells) and
inner fractions (IF = zona fasciculata cells) of the rat adrenal cortex,
which comprise two distinct microenvironment niches. Proteomic profiles
of decellularized OF and IF samples, male and female rats, identified
252 proteins, with 32 classified as ECM-component and ECM-related.
Among these, 25 proteins were differentially regulated: 17 more abundant
in OF, including Col1a1, Col1a2, Col6a1, Col6a2, Col6a3, Col12a1,
Col14a1, Lama5, Lamb2, Lamc1, Eln, Emilin, Fbln5, Fbn1, Fbn2, Nid1,
and Ltbp4, and eight more abundant in IF, including Col4a1, Col4a2,
Lama2, Lama4, Lamb1, Fn1, Hspg2, and Ecm1. Eln, Tnc, and Nid2 were
abundant in the female OF, while Lama2, Lama5, Lamb2, and Lamc1 were
more abundant in the male IF. The complex protein signature of the
OF suggests areas of tissue stress, stiffness, and regulatory proteins
for growth factor signaling. The higher concentrations of Col4a1 and
Col4a2 and their role in steroidogenesis should be further investigated
in IF. These findings could significantly enhance our understanding
of adrenal cortex functionality and its implications for human health
and disease. Key findings were validated, and data are available in
ProteomeXchange (PXD046828).