identification-intracellular-signaling-events-induced-viable-cells

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Cells dying by apoptosis, also referred to as regulated cell death, acquire multiple new activities that enable them to influence the function of adjacent ...

University of Illinois at Chicago

Jesse Brown Veterans Affairs Medical Center

Myelin repair is inhibited in multiple sclerosis (MS), ultimately leading to axonal damage and disability. We aimed to understand the transcriptional mechanisms of regeneration in primary human oligodendrocyte cultures isolated from white matter of medically intractable epilepsy patients. Cultures at isolation contained 84% mature oligodendrocytes and 16% oligodendrocyte progenitor cells (OPC). The two populations showed a protracted regeneration of membranes expressing myelin proteins after 2-3 weeks in culture, and were kept long-term to study membranes maintenance. We profiled by quantitative PCR (qPCR) the sequential mRNA expression of transcription factors Olig1, Olig2, Nkx2.2, Sox10, PPARδ, PPARγ, cyclic nucleotide phosphodiesterase (CNP), myelin basic protein (MBP), myelin-associated glycoprotein (MAG) and myelin oligodendrocyte glycoprotein (MOG). In summary, Olig1 was not expressed in freshly isolated oligodendrocytes, but was expressed from the beginning of process extension until membranes maintenance. In contrast, Olig2 expression was restricted to isolation and during membranes production. We show for the first time PPARδ expression and absence of PPARγ in human oligodendrocytes. Nkx2.2, Sox10, PPARδ, CNP, MBP and MOG messengers were expressed at any time, while MAG messenger was expressed at mature stage only. Myelin proteins CNP, MBP, MAG, and MOG were confirmed by immunocytochemistry. Our findings point to different roles of Olig1 and Olig2 in regeneration of cultured adult human oligodendrocytes. Noticeably, the transcriptional profiles found in cultured neonatal rodent OPC are different. More studies are necessary to elucidate myelin repair in the adult human brain.

Olig1 is expressed in human oligodendrocytes during maturation and regeneration.

This study has established the presence of IgM against S-nitrosylated proteins in cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients using S-nitrosocysteine epitope (anti-SNOcys) as previously shown in serum. Anti-SNOcys IgM increased significantly in CSF during relapsing-remitting MS compared to milder neurological conditions. Evidence from albumin, IgG and IgM suggest that the production of anti-SNOcys IgM is intrathecal rather than the result of ingress from serum. Two correlations during relapse: between CSF level of anti-SNOcys IgM and time elapsed since relapse onset; and between CSF and serum anti-SNOcys IgM levels, suggest that this antibody may have potential as a biomarker.

IgM to S-nitrosylated protein is found intrathecally in relapsing-remitting multiple sclerosis.

Regenerative mechanisms after surgical injury have been studied in many organs but not in the kidney. Studying surgical injury may provide new insights into mechanisms of kidney regeneration. In rodent models, extrarenal tissues adhere to surgical kidney wound and interfere with healing. We hypothesized that this can be prevented by wrapping injured kidney in a plastic pouch. Adult rats tolerated 5/6 nephrectomy with pouch application well. Histological analysis demonstrates that application of the pouch effectively prevented formation of adhesions and induced characteristic wound healing manifested by formation of granulation tissue. Additionally, selected tubules of the wounded kidney extended into the granulation tissue forming branching tubular epithelial outgrowths (TEOs) without terminal differentiation. Tubular regeneration outside of renal parenchyma was not previously observed, and suggests previously unrecognized capacity for regeneration. Our model provides a novel approach to study kidney wound healing.

A novel model of surgical injury in adult rat kidney: a "pouch model".

Apoptosis plays an indispensable role in the maintenance and development of tissues. We have shown that receptor-mediated recognition of apoptotic target cells by viable kidney proximal tubular epithelial cells (PTECs) inhibits the proliferation and survival of PTECs. Here, we examined the effect of apoptotic targets on PTEC cell growth (cell size during G1 phase of the cell cycle). Using a cell culture model, we show that apoptotic cells potently activate AMP-activated protein kinase (AMPK), a highly sensitive sensor of intracellular energy stores. AMPK activation leads to decreased activity of its downstream target, ribosomal protein p70 S6 kinase (p70S6K), and concomitant inhibition of cell growth. Importantly, these events occur without detectable change in intracellular levels of AMP, ADP, or ATP. Inhibition of AMPK, either pharmacologically by compound C or molecularly by shRNA, diminishes the effects of apoptotic targets and largely restores p70S6K activity and cell size to normal levels. Apoptotic targets also inhibit Akt, a second signaling pathway regulating cell growth. Expression of a constitutively active Akt construct partially relieved cell growth inhibition but was less effective than inhibition of AMPK. Inhibition of cell growth by apoptotic targets is dependent on physical interaction between apoptotic targets and PTECs but independent of phagocytosis. We conclude that receptor-mediated recognition of apoptotic targets mimics the effects of intracellular energy depletion, activating AMPK and inhibiting cell growth. By acting as sentinels of environmental change, apoptotic death may enable nearby viable cells, especially nonmigratory epithelial cells, to monitor and adapt to local stresses.

Article	Year
Olig1 is expressed in human oligodendrocytes during maturation and regeneration. Glia\| PubMed ID: 21446039	2011
IgM to S-nitrosylated protein is found intrathecally in relapsing-remitting multiple sclerosis. Journal of neuroimmunology\| PubMed ID: 23351705	2013
A novel model of surgical injury in adult rat kidney: a "pouch model". Scientific reports\| PubMed ID: 24100472	2013
Apoptotic cells activate AMP-activated protein kinase (AMPK) and inhibit epithelial cell growth without change in intracellular energy stores. The Journal of biological chemistry\| PubMed ID: 26183782	2015

Snezana Vujicic

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