Divergent regulation of lncRNA expression by ischemia in adult and aging mice

Abstract

Elderly patients have increased susceptibility to acute kidney injury (AKI). Long noncoding RNAs (lncRNA) are key regulators of cellular processes, and have been implicated in both aging and AKI. Our aim was to study the effects of aging and ischemia-reperfusion injury (IRI) on the renal expression of lncRNAs. Adult and old (10- and 26-30-month-old) C57BL/6 N mice were subjected to unilateral IRI followed by 7 days of reperfusion. Renal expression of 90 lncRNAs and mRNA expression of injury, regeneration, and fibrosis markers was measured by qPCR in the injured and contralateral control kidneys. Tubular injury, regeneration, and fibrosis were assessed by histology. Urinary lipocalin-2 excretion was increased in old mice prior to IRI, but plasma urea was similar. In the control kidneys of old mice tubular cell necrosis and apoptosis, mRNA expression of kidney injury molecule-1, fibronectin-1, p16, and p21 was elevated. IRI increased plasma urea concentration only in old mice, but injury, regeneration, and fibrosis scores and their mRNA markers were similar in both age groups. AK082072 and Y lncRNAs were upregulated, while H19 and RepA transcript were downregulated in the control kidneys of old mice. IRI upregulated Miat, Igf2as, SNHG5, SNHG6, RNCR3, Malat1, Air, Linc1633, and Neat1 v1, while downregulated Linc1242. LncRNAs H19, AK082072, RepA transcript, and Six3os were influenced by both aging and IRI. Our results indicate that both aging and IRI alter renal lncRNA expression suggesting that lncRNAs have a versatile and complex role in aging and kidney injury. An Ingenuity Pathway Analysis highlighted that the most downregulated H19 may be linked to aging/senescence through p53.

Keywords: Acute kidney injury; Ischemia–reperfusion injury; lncRNA.

Fig. 1

The effects of aging and ischemia on renal morphology and function

Fig. 2

LncRNA profiling in the kidneys. Adult (age: 10 months) and old (age: 26–30 months) mice subjected to unilateral renal ischemia–reperfusion injury (IRI). Contralateral right kidneys served as controls (CTR). (A) Heat map of significantly changed lncRNAs (Rm, right kidney from adult mice; Ro, right kidney from old mice; Lm, left kidney from adult mice; Lo, left kidney from old mice). The effects of age (B, C) in the control (B) and in the IRI (C) kidneys. The effects of IRI (D, E) in the kidneys of adult (D) and of old (E) mice. (B–E): horizontal lines mark p = 0.05; vertical lines mark FC = 2x. One-way ANOVA

Fig. 3

Renal expression of lncRNAs altered by IRI and/or aging. (A) Y RNAs, (B) Six3os, (C) AK082072, (D) H19, (E) RepA transcript, (F) linc1242, (G) Linc1633, (H) SNHG5, (I) Neat1 v1, (J) RNCR3, (K) AK028326 (Miat), (L) Igf2as, (M) Air, (N) Malat1, (O) SNHG6, (P) linc1610-(med), (Q) Adapt33. Adult (age: 10 months) Adapt33 and old (age: 26–30 months) mice subjected to unilateral renal ischemia–reperfusion injury (IRI). Contralateral right kidneys served as controls (CTR). LncRNA expression was normalized to GAPDH. Two-way ANOVA; ns, not significant; *p < 0.05, **p < 0.01, ***p < 0.001 (Tukey’s multiple comparisons test)

Fig. 4

IPA analysis supports the potential functional connection between significantly influenced lncRNAs and aging (A) and senescence (B) in control (non-ischemic) kidneys. miR-124a-1gh: Rncr3, 5430416N02Rik: Adapt33, Gm17750: AK082072

Fig. 5

IPA analysis supports the potential functional connection between significantly influenced lncRNAs and senescence in injured vs. control kidneys in adult (A) and old (B) mice. miR-124a-1gh: Rncr3, 5430416N02Rik: Adapt33, Gm17750: AK082072