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Skeletal muscle is the largest organ in the human body by mass, making up approximately 40 % of total body weight. Furthermore, it accounts for the majority of insulin-stimulated glucose uptake and is also highly involved in lipid metabolism. Lipids can accumulate in muscle through different distinct depots: as intramyocellular lipids (IMCL), stored as triglyceride-containing droplets within muscle cells and as intermuscular adipose tissue (IMAT), located between muscle fiber bundles beneath the deep muscle fascia. The muscular fat depots have been positively correlated with an increased body fat content in obesity, just like subcutaneous and visceral adipose tissue (SAT and VAT, respectively). IMCL, IMAT, VAT and SAT have additionally been linked to insulin resistance and type 2 diabetes mellitus (T2D).

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AMPK inhibition and elevated angiogenin are associated with tRNA fragmentation in the male germline exposed to a high-fat diet

Eunbi Lee, Seo Yoon Choi, Seungmin Song, Anders M. Lindroth, Yoon Jung Park

AMPK inhibition and elevated angiogenin are associated with tRNA fragmentation in the male germline exposed to a high-fat diet

The existence of an inherent rewiring of metabolic regulation has been demonstrated through studies of obese mice that are fed a normal diet and produce offspring with metabolic disorders. tRNA-derived fragments (tRFs) have been suggested as a potential mediator of this inheritance. To explore a mechanism underlying metabolic stress-induced tRNA fragmentation, we examined the effects of a HFD on tRFs in sperm. Small RNA sequencing on sperm revealed that HFD-induced metabolic changes affect the tRF profiles, showing a trend of decreased 5′-derived tRFs and increased 3′-derived tRFs, suggesting a shift in tRNA cleavage patterns under HFD feeding. In conjunction with the alteration of tRFs, the expression of Ang, which encodes the ribonuclease angiogenin, was significantly increased in the testis. Transcriptome and metabolome analyses indicated that AMPK-mTOR signaling pathway was the possible mediator of these effects, with decreased AMPK activity and increased mTOR activity confirmed at the protein level in the testis. Moreover, in vitro experiments showed that AMPK inhibition led to increased angiogenin expression level and alterations in tRF profile. In vitro angiogenin induction experiments, designed to mimic HFD conditions, produced changes in tRF profiles similar to those observed in HFD-fed mice, although the resulting tRF profiles did not completely recapitulate the in vivo HFD-induced profiles. Our findings suggest that HFD-induced metabolic stress inhibits AMPK during spermatogenesis, leading to increased Ang expression and altered tRF remodeling.

Articles in Press

AMPK inhibition and elevated angiogenin are associated with tRNA fragmentation in the male germline exposed to a high-fat diet

Eunbi Lee, Seo Yoon Choi, Seungmin Song, Anders M. Lindroth, Yoon Jung Park

AMPK inhibition and elevated angiogenin are associated with tRNA fragmentation in the male germline exposed to a high-fat diet

The existence of an inherent rewiring of metabolic regulation has been demonstrated through studies of obese mice that are fed a normal diet and produce offspring with metabolic disorders. tRNA-derived fragments (tRFs) have been suggested as a potential mediator of this inheritance. To explore a mechanism underlying metabolic stress-induced tRNA fragmentation, we examined the effects of a HFD on tRFs in sperm. Small RNA sequencing on sperm revealed that HFD-induced metabolic changes affect the tRF profiles, showing a trend of decreased 5′-derived tRFs and increased 3′-derived tRFs, suggesting a shift in tRNA cleavage patterns under HFD feeding. In conjunction with the alteration of tRFs, the expression of Ang, which encodes the ribonuclease angiogenin, was significantly increased in the testis. Transcriptome and metabolome analyses indicated that AMPK-mTOR signaling pathway was the possible mediator of these effects, with decreased AMPK activity and increased mTOR activity confirmed at the protein level in the testis. Moreover, in vitro experiments showed that AMPK inhibition led to increased angiogenin expression level and alterations in tRF profile. In vitro angiogenin induction experiments, designed to mimic HFD conditions, produced changes in tRF profiles similar to those observed in HFD-fed mice, although the resulting tRF profiles did not completely recapitulate the in vivo HFD-induced profiles. Our findings suggest that HFD-induced metabolic stress inhibits AMPK during spermatogenesis, leading to increased Ang expression and altered tRF remodeling.

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13th
Helmholtz Diabetes Conference 
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