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Updated: May 27, 2026
Induction of Nephrotic Syndrome in Mice by Retrobulbar Injection of Doxorubicin and Prevention of Volume Retention by Sustained Release Aprotinin
Published on: May 6, 2018
Doxorubicin-induced glomerulosclerosis with proteinuria in GFP-GABARAP transgenic mice
Miyuki Takagi-Akiba1, Katsuhiko Asanuma, Isei Tanida
1Div. of Nephrology, Dept. of Internal Medicine, Juntendo Univ., Hongo, Bunkyo-ku, Tokyo, Japan.
Abstract:
Autophagy is a process of cellular degradation, and its dysfunction elicits many pathological symptoms. However, the contribution of autophagy to kidney glomerular function has not been fully clarified. We previously reported that LC3, a promising executor of autophagy, played an important role in recovery from podocyte damage in an experimental nephrosis model (Asanuma K, Tanida I, Shirato I, Ueno T, Takahara H, Nishitani T, Kominami E, Tomino Y. FASEB J 17: 1165-1167, 2003). γ-Aminobutyric acid A receptor-associated protein (GABARAP), has recently been characterized as another homolog of LC3, although its precise role in autophagy remains unclear. We recently generated green fluorescent protein (GFP)-GABARAP transgenic mice, in which GFP-GABARAP is abundantly expressed in glomerular podocytes. We found that the transgenic mice showed no obvious phenotype, and podocytes isolated from these mice manifested autophagic activity almost equivalent to that of wild-type mice when measured in vitro. Surprisingly, a single injection of doxorubicin caused a greater increase in proteinuria and sclerotic glomeruli in transgenic mice compared with wild-type mice. Under these conditions, neither GFP-GABARAP nor endogenous GABARAP appeared to be recruited to autophagosomes, and both remained in the cytosol. Moreover, the cytosolic GFP-GABARAP was significantly colocalized with p62 to form aggregates. These results indicate that the GFP-GABARAP/p62 complex is responsible for impairment of glomerular function and that it retards recovery from the effects of doxorubicin.
Insights
Green fluorescent protein-gamma-aminobutyric acid A receptor-associated protein (GFP-GABARAP) transgenic mice showed worsened kidney damage after doxorubicin treatment. The GFP-GABARAP/p62 complex impairs glomerular function and delays recovery.
Area of Science:
- Cell Biology
- Nephrology
- Molecular Biology
Background:
- Autophagy, a cellular degradation process, is crucial for maintaining cellular homeostasis, but its role in kidney glomerular function remains unclear.
- Dysfunctional autophagy is linked to various pathological conditions.
- LC3, an autophagy executor, has shown importance in podocyte damage recovery.
Purpose of the Study:
- To investigate the role of gamma-aminobutyric acid A receptor-associated protein (GABARAP), an LC3 homolog, in kidney glomerular function.
- To determine the impact of GABARAP overexpression in podocytes on kidney response to doxorubicin-induced injury.
Main Methods:
- Generation of green fluorescent protein (GFP)-GABARAP transgenic mice with abundant GFP-GABARAP expression in glomerular podocytes.
- In vitro assessment of autophagic activity in isolated podocytes.
- Administration of a single doxorubicin injection to transgenic and wild-type mice to evaluate kidney damage, proteinuria, and glomerular sclerosis.
- Immunofluorescence and biochemical analyses to assess GABARAP localization and colocalization with p62.
Main Results:
- Transgenic mice exhibited no apparent phenotype or altered in vitro autophagic activity compared to wild-type mice.
- Doxorubicin treatment led to significantly increased proteinuria and glomerular sclerosis in transgenic mice versus wild-type controls.
- Neither GFP-GABARAP nor endogenous GABARAP were recruited to autophagosomes post-doxorubicin; they remained in the cytosol.
- Cytosolic GFP-GABARAP colocalized with p62, forming aggregates.
Conclusions:
- Overexpression of GFP-GABARAP in podocytes does not affect basal autophagic activity but exacerbates doxorubicin-induced kidney injury.
- The formation of a GFP-GABARAP/p62 complex in the cytosol, rather than recruitment to autophagosomes, is associated with impaired glomerular function.
- This complex appears to hinder recovery from doxorubicin-induced podocyte damage, highlighting a novel mechanism of kidney dysfunction.
