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J Biol Chem. 2019 Jun 21;294(25):9873-9887. doi: 10.1074/jbc.RA118.004445. Epub 2019 May 10.

Heat shock protein DNAJA1 stabilizes PIWI proteins to support regeneration and homeostasis of planarian Schmidtea mediterranea.

Author information

1
From the Shanghai Institute of Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China.
2
the CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China, and.
3
From the Shanghai Institute of Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China, haifan.lin@yale.edu.
4
the Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut 06511.
5
the CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China, and qjing@sibs.ac.cn.

Abstract

PIWI proteins are key regulators of germline and somatic stem cells throughout different evolutionary lineages. However, how PIWI proteins themselves are regulated remains largely unknown. To identify candidate proteins that interact with PIWI proteins and regulate their stability, here we established a yeast two-hybrid (Y2H) assay in the planarian species Schmidtea mediterranea We show that DNAJA1, a heat shock protein 40 family member, interacts with the PIWI protein SMEDWI-2, as validated by the Y2H screen and co-immunoprecipitation assays. We found that DNAJA1 is enriched in planarian adult stem cells, the nervous system, and intestinal tissues. DNAJA1-knockdown abolished planarian regeneration and homeostasis, compromised stem cell maintenance and PIWI-interacting RNA (piRNA) biogenesis, and deregulated SMEDWI-1/2 target genes. Mechanistically, we observed that DNAJA1 is required for the stability of SMEDWI-1 and SMEDWI-2 proteins. Furthermore, we noted that human DNAJA1 binds to Piwi-like RNA-mediated gene silencing 1 (PIWIL1) and is required for PIWIL1 stability in human gastric cancer cells. In summary, our results reveal not only an evolutionarily conserved functional link between PIWI and DNAJA1 that is essential for PIWI protein stability and piRNA biogenesis, but also an important role of DNAJA1 in the control of proteins involved in stem cell regulation.

KEYWORDS:

Argonaute; DNAJA1; PIWI proteins; PIWI-interacting RNA (piRNA); chaperone; heat shock protein (HSP); heat shock protein 40 (Hsp40); neoblast; planarian; regeneration; stem cells

PMID:
31076507
PMCID:
PMC6597837
[Available on 2020-06-21]
DOI:
10.1074/jbc.RA118.004445

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