Nucleophagy at a glance

Abstract

Under certain circumstances, the removal of damaged or non-essential parts of the nucleus, or even an entire nucleus, is crucial in order to promote cell longevity and enable proper function. A selective form of autophagy, known as nucleophagy, can be used to accomplish the degradation of nucleusderived material. In this Cell Science at a Glance article and the accompanying poster, we summarize the similarities and differences between the divergent modes of nucleophagy that have been described to date, emphasizing, where possible, the molecular mechanism, the membrane interactions and rearrangements, and the nature of the nucleus-derived material that is degraded. In turn, we will consider nucleophagy processes in the lower eukaryotes, the budding yeast Saccharomyces cerevisiae, filamentous fungi Aspergillus and Magnaporthe oryzae and the ciliated protozoan Tetrahymena thermophila, and finally in mammalian cells. We will also briefly discuss the emerging links between nucleophagy and human disease.

Cachexia in chronic obstructive pulmonary disease: new insights and therapeutic perspective

“…A possible alteration in apoptosis in the muscle of COPD patients remains inconclusive due to the lack of studies and the use of different markers. Furthermore, the possible role of apoptotic signalling in the skeletal muscle atrophy remains obscure,75 and multinucleated muscle fibres may utilize other mechanisms for selective myonuclear loss, such as autophagy 76…”

Carbon and nitrogen depletion-induced nucleophagy and selective autophagic sequestration of a whole nucleus in multinucleate cells of the filamentous fungus <i>Aspergillus oryzae</i>

“…For example, the autophagic degradation of peroxisomes and mitochondria is referred as to pexophagy and mitophagy, respectively (Kanki and Klionsky, 2010;Manjithaya et al, 2010). More recently, nucleophagy has been described as one type of selective autophagy to degrade nucleus-derived materials in several organisms, such as mammals, budding yeast, ciliated protozoan and filamentous fungi (Mijaljica and Devenish, 2013).…”

“…In addition, it has been reported that autophagy is involved in the elimination of micronuclei (Rello-Varona et al, 2012), which are formed by mitotic abnormalities when exposed to genotoxic agents (Erenpreisa et al, 2012). In these cases, nucleophagy involves the degradation of abnormal nuclear structures, which are sequestered into the autophagosome in a manner termed macroautophagy (Mijaljica and Devenish, 2013).…”

“…In the budding yeast Saccharomyces cerevisiae, nucleophagy is induced by nitrogen starvation (Mijaljica and Devenish, 2013;Mochida et al, 2015). Three modes of typical nucleophagy have been reported: piecemeal microautophagy of the nucleus (PMN) (Roberts et al, 2003), late nucleophagy (LN) (Mijaljica et al, 2012), and Atg39-dependent nucleophagy (Mochida et al, 2015).…”

Eating the ER and the nucleus for survival under starvation conditions

“…Atg39 homologs are not found in higher eukaryotes, but autophagy of the nucleus has been observed in mammals and other organisms. 9 Atg39 counterparts may act to execute nucleophagy in these organisms.…”