Increased nuclear permeability is a driver for age-related motoneuron loss

Systemic Inflammation in Sarcopenia Alter Functional Capacity in Thai Community-dwelling Older People: A Preliminary Observational Study

BACKGROUND

Sarcopenia is linked to the loss of muscle mass in older adults, leading to impaired functional capacity and quality of life. In addition, this finding was recognized as an agerelated chronic inflammatory process. We aimed to determine the relationship between sarcopenia, functional capacity, and inflammatory biomarkers and subsequent prediction of inflammatory biomarkers in older adults.

METHODS

A total of 126 women and men aged ≥ 60 years were enrolled. Participants were required to complete a handgrip dynamometer, 6-meter walk test, and bioimpedance analysis. Diagnosis was based on the definition of sarcopenia from the Asian Working Group for Sarcopenia 2019. Prior to performing a 6-minute walking test (i.e., functional capacity testing), blood samples were drawn for a C-reactive protein (CRP) test.

RESULTS

A total of 12.70% were categorized as having sarcopenia. Significant differences in CRP and functional capacity between the sarcopenia and non-sarcopenia groups were found (p <.05). Older people with high CRP levels had significantly reduced functional capacity and slow gait speed.

CONCLUSIONS

Poor functional capacity was associated with increased CRP levels, which might be due to the development of age-related inflammation. Older patients with sarcopenia may be at higher risk for functional decline.

Age-dependent changes in nuclear-cytoplasmic signaling in skeletal muscle

Mechanical forces are conducted through myofibers and into nuclei to regulate muscle development, hypertrophy, and homeostasis. We hypothesized that nuclei in aged muscle have changes in the nuclear envelope and associated proteins, resulting in altered markers of mechano-signaling.

METHODS

YAP/TAZ protein expression and gene expression of downstream targets, Ankrd1 and Cyr61, were evaluated as mechanotransduction indicators. Expression of proteins in the nuclear lamina and the nuclear pore complex (NPC) were assessed, and nuclear morphology was characterized by electron microscopy. Nuclear envelope permeability was assessed by uptake of 70 kDa fluorescent dextran.

RESULTS

Nuclear changes with aging included a relative decrease of lamin β1 and Nup107, and a relative increase in Nup93, which could underlie the aberrant nuclear morphology, increased nuclear leakiness, and elevated YAP/TAZ signaling.

CONCLUSION

Aged muscles have hyperactive nuclear-cytoplasmic signaling, indicative of altered nuclear mechanotransduction. These data highlight a possible role for the nucleus in aging-related aberrant mechano-sensing.