Many organisms can pause their growth cycle to enter a stationary phase (SP). The mechanisms governing SP entry in protozoans are not currently well known, with most studies carried out in yeast. However, a more complete understanding of the mechanisms behind SP entry could aid our understanding of protozoan infections, including malaria and cell cycle irregularities in cancer biology. Various kinases are known to play a role in SP entry in both bacteria and yeast. Protein kinase C (PKC) regulates cell proliferation in different contexts in both cancer cells and in yeast, but whether it has a role in instigating SP entry is unknown. In this study (Umachandran et al., 2022), the authors use the unicellular eukaryote Dictyostelium discoideum to investigate the role of the PKC ortholog pkcA in SP entry. The authors show that pkcA– cells have early-onset SP, which is reached at a lower cell density compared to wild-type Ax2 cells, under shaking conditions. By measuring polyphosphate (polyP) levels of Ax2 and pkcA– cells, the authors find that pkcA– cells produce excess polyP, leading to increased levels of extracellular polyP and contributing to their early entry into SP. Furthermore, rates of pinocytosis and exocytosis are lower and higher, respectively, in pkcA– cells compared to wild-type, resulting in starvation-like conditions normally associated with high cell density. Together, these findings suggest that reduced PkcA levels trigger SP because cells cannot acquire or retain nutrients efficiently, therefore mimicking the conditions of actual starvation.
PKC ortholog regulates stationary phase onset in Dictyostelium
PKC ortholog regulates stationary phase onset in Dictyostelium. J Cell Sci 1 May 2022; 135 (9): e135_e0902. doi:
Download citation file:
Advertisement
Cited by
Reasons to submit to Journal of Cell Science

There are many benefits to publishing in Journal of Cell Science - read more about why you should choose JCS or visit our submission page now.
Call for papers: Cell and Tissue Polarity
-PolarityCFP.png?versionId=5161)
We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
The Forest of Biologists

The Forest of Biologists is a biodiversity initiative created by The Company of Biologists, with support from the Woodland Trust. For every Research and Review article published in Journal of Cell Science a native tree is planted in a UK forest. In addition to this we are protecting and restoring ancient woodland and are dedicating these trees to our peer reviewers. Visit our virtual forest to learn more.
Propose a new Workshop for 2025

Do you have an idea for a Workshop? We are now accepting proposals for our 2025 Biologists Workshops programme. As the scientific organiser, your involvement will be focused on the science. We'll take care of all the logistics. In 2025 we'll continue our efforts to diversify our Workshop programme and will be reserving one of our Workshops for an application from a Global South (GS) country to host an event overseas.
FocalPlane Image Competition 2023

FocalPlane’s 2023 image competition is underway, in celebration of the community site’s third birthday. Click here for submission details and information on how to showcase your favourite image.