RNA-binding proteins tristetraprolin and human antigen R are novel modulators of podocyte injury in diabetic kidney disease

Identification of RNA-binding protein genes associated with renal rejection and graft survival

Rejection is one of the major factors affecting the long-term prognosis of kidney transplantation, and timely recognition and aggressive treatment of rejection is essential to prevent disease progression. RBPs are proteins that bind to RNA to form ribonucleoprotein complexes, thereby affecting RNA stability, processing, splicing, localization, transport, and translation, which play a key role in post-transcriptional gene regulation. However, their role in renal transplant rejection and long-term graft survival is unclear. The aim of this study was to comprehensively analyze the expression of RPBs in renal rejection and use it to construct a robust prediction strategy for long-term graft survival. The microarray expression profiles used in this study were obtained from GEO database. In this study, a total of eight hub RBPs were identified, all of which were upregulated in renal rejection samples. Based on these RBPs, the renal rejection samples could be categorized into two different clusters (cluster A and cluster B). Inflammatory activation in cluster B and functional enrichment analysis showed a strong association with rejection-related pathways. The diagnostic prediction model had a high diagnostic accuracy for T cell mediated rejection (TCMR) in renal grafts (area under the curve = 0.86). The prognostic prediction model effectively predicts the prognosis and survival of renal grafts (p < .001) and applies to both rejection and non-rejection situations. Finally, we validated the expression of hub genes, and patient prognosis in clinical samples, respectively, and the results were consistent with the above analysis.

LncRNA AA465934 Improves Podocyte Injury by Promoting Tristetraprolin-Mediated HMGB1 DownRegulation in Diabetic Nephropathy

Although LncRNA AA465934 expression is reduced in high glucose (HG)-treated podocytes, its role in HG-mediated podocyte injury and diabetic nephropathy (DN) remains unknown. Herein, we investigated the role of AA465934 in HG-mediated podocyte injury and DN using a spontaneous type II diabetic nephropathy (T2DN) model. The model was created by injecting AA465934 overexpressed adeno-associated virus (AAV) or control into mice. The levels of renal function, proteinuria, renal structural lesions, and podocyte apoptosis were then examined. Furthermore, AA465934 and autophagy levels, as well as tristetraprolin (TTP) and high mobility group box 1 (HMGB1) expression changes were detected. We also observed podocyte injury and the binding ability of TTP to E3 ligase proviral insertion in murine lymphomas 2 (PIM2), AA465934, or HMGB1. According to the results, AA465934 improved DN progression and podocyte damage in T2DN mice. In addition, AA465934 bound to TTP and inhibited its degradation by blocking TTP-PIM2 binding. Notably, TTP knock-down blocked the ameliorating effects of AA465934 and TTP bound HMGB1 mRNA, reducing its expression. Overexpression of HMGB1 inhibited the ability of AA465934 and TTP to improve podocyte injury. Furthermore, AA465934 bound TTP, inhibiting TTP-PIM2 binding, thereby suppressing TTP degradation, downregulating HMGB1, and reversing autophagy downregulation, ultimately alleviating HG-mediated podocyte injury and DN. Based on these findings, we deduced that the AA465934/TTP/HMGB1/autophagy axis could be a therapeutic avenue for managing podocyte injury and DN.

GSK3β: A ray of hope for the treatment of diabetic kidney disease

Diabetic kidney disease (DKD), a major microvascular complication of diabetes, is characterized by its complex pathogenesis, high risk of chronic renal failure, and lack of effective diagnosis and treatment methods. GSK3β (glycogen synthase kinase 3β), a highly conserved threonine/serine kinase, was found to activate glycogen synthase. As a key molecule of the glucose metabolism pathway, GSK3β participates in a variety of cellular activities and plays a pivotal role in multiple diseases. However, these effects are not only mediated by affecting glucose metabolism. This review elaborates on the role of GSK3β in DKD and its damage mechanism in different intrinsic renal cells. GSK3β is also a biomarker indicating the progression of DKD. Finally, the protective effects of GSK3β inhibitors on DKD are also discussed.

The intellectual base and global trends in inflammation of diabetic kidney disease: a bibliometric analysis

Diabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). The literature on DKD inflammation research has experienced substantial growth. However, there is a lack of bibliometric analyses. This study aimed to examine the existing research on inflammation in DKD by analyzing articles published in the Web of Science Core Collection (WOSCC) over the past 30 years. We conducted a visualization analysis using several software, including CiteSpace and VOSviewer. We found that the literature on inflammation research in DKD has experienced substantial growth, indicating a rising interest in this developing area of study. In this field, Navarro-Gonzalez, JF is the most frequently cited author, Kidney International is the most frequently cited journal, China had the highest number of publications in the field of DKD inflammation, and Monash University emerged as the institution with the most published research. The research area on inflammation in DKD primarily centers around the investigation of 'Glycation end-products', 'chronic kidney disease', and 'diabetic nephropathy'. The emerging research trends in this field will focus on the 'Gut microbiota', 'NLRP3 inflammasome', 'autophagy', 'pyroptosis', 'sglt2 inhibitor', and 'therapeutic target'. Future research on DKD may focus on further exploring the inflammatory response, identifying specific therapeutic targets, studying biomarkers, investigating stem cell therapy and tissue engineering, and exploring gene therapy and gene editing. In summary, this study examines the main areas of study, frontiers, and trends in DKD inflammation, which have significant implications for future research.

RNA-binding proteins in metabolic-associated fatty liver disease (MAFLD): From mechanism to therapy

Metabolic-associated fatty liver disease (MAFLD) is the most common chronic liver disease globally and seriously increases the public health burden, affecting approximately one quarter of the world population. Recently, RNA binding proteins (RBPs)-related pathogenesis of MAFLD has received increasing attention. RBPs, vividly called the gate keepers of MAFLD, play an important role in the development of MAFLD through transcription regulation, alternative splicing, alternative polyadenylation, stability and subcellular localization. In this review, we describe the mechanisms of different RBPs in the occurrence and development of MAFLD, as well as list some drugs that can improve MAFLD by targeting RBPs. Considering the important role of RBPs in the development of MAFLD, elucidating the RNA regulatory networks involved in RBPs will facilitate the design of new drugs and biomarkers discovery.

Long non-coding RNA DLX6-AS1 is the key mediator of glomerular podocyte injury and albuminuria in diabetic nephropathy by targeting the miR-346/GSK-3β signaling pathway

Progressive albuminuria is the primary clinical symptom of diabetic nephropathy (DN), leading to a gradual decline in kidney function. DLX6-AS1 was the first reported long non-coding RNA (lncRNA) to participate in organogenesis and play crucial roles in the brain or neural cell development. Herein, we investigated the DLX6-AS1 (Dlx6-os1 in mice) role in DN pathogenesis. We found that DLX6-AS1 expression in DN patients correlated with the extent of albuminuria. Dlx6-os1 overexpression induced cellular damage and inflammatory responses in cultured podocytes through miR-346-mediated regulation of the GSK-3β pathway. In various established diabetic and newly developed knockout mouse models, Dlx6-os1 knockdown/knockout significantly reduced podocyte injury and albuminuria. The Dlx6-os1 effects were remarkably modulated by miR-346 mimics or mutants and significantly diminished in podocyte-specific GSK-3β-knockout mice. Thus, DLX6-AS1 (Dlx6-os1) promotes DN development by accelerating podocyte injury and inflammation through the upregulation of the GSK-3β pathway, providing a novel molecular target for DN therapy.

The association of RNA-binding protein Human antigen R with kidney clinicopathologic features and renal outcomes in patients with diabetic nephropathy

AIMS

RNA-binding protein Human antigen R (HuR) is closely related to diabetic nephropathy (DN) pathogenesis. However, the capacity of histological HuR level as a biomarker for DN progression remains unclear.

METHODS

A total of 147 patients with type 2 diabetes mellitus who had biopsy-proven DN were enrolled. Renal outcomes were defined by doubling serum creatinine level or progression to end-stage renal disease (ESRD). A nomogram was built to predict renal outcomes based on Cox proportional hazards regression.

RESULTS

The median follow-up period was 31 months, during which 71 (48.30 %) patients confronted DN progression. Pearson's correlation indicated that histological HuR increased along with DN pathological class rising (r = 0.776, p < 0.001). Notably, multivariate Cox regression analysis showed that elevated HuR was associated with a greater risk of DN progression (HR 2.431, 95 %CI: 1.275-4.634, p = 0.007) beyond 6 months after renal biopsy. Patients in the higher HuR expression group had lower cumulative renal survival rates beyond the first 6 months. Simultaneously, a well-performed nomogram including HuR classification, was developed to predict the individual progression risk (C-index 0.828).

CONCLUSIONS

Our findings demonstrated that the histologic HuR expression was an independent risk factor for kidney progression beyond 6 months after renal biopsy in DN.

Post-transcriptional control by RNA-binding proteins in diabetes and its related complications

Diabetes mellitus (DM) is a fast-growing chronic metabolic disorder that leads to significant health, social, and economic problems worldwide. Chronic hyperglycemia caused by DM leads to multiple devastating complications, including macrovascular complications and microvascular complications, such as diabetic cardiovascular disease, diabetic nephropathy, diabetic neuropathy, and diabetic retinopathy. Numerous studies provide growing evidence that aberrant expression of and mutations in RNA-binding proteins (RBPs) genes are linked to the pathogenesis of diabetes and associated complications. RBPs are involved in RNA processing and metabolism by directing a variety of post-transcriptional events, such as alternative splicing, stability, localization, and translation, all of which have a significant impact on RNA fate, altering their function. Here, we purposed to summarize the current progression and underlying regulatory mechanisms of RBPs in the progression of diabetes and its complications. We expected that this review will open the door for RBPs and their RNA networks as novel therapeutic targets for diabetes and its related complications.

HuR as a molecular target for cancer therapeutics and immune-related disorders

The control of eukaryotic gene expression occurs at multiple levels, from transcription to messenger RNA processing, transport, localization, turnover, and translation. RNA-binding proteins control gene expression and are involved in different stages of mRNA processing, including splicing, maturation, turnover, and translation. A ubiquitously expressed RBP Human antigen R is engaged in the RNA processes mentioned above but, most importantly, controls mRNA stability and turnover. Dysregulation of HuR is linked to many diseases, including cancer and other immune-related disorders. HuR targets mRNAs containing AU-rich elements at their 3'untranslated region, which encodes proteins involved in cell growth, proliferation, tumor formation, angiogenesis, immune evasion, inflammation, invasion, and metastasis. HuR overexpression has been reported in many tumor types, which led to a poor prognosis for patients. Hence, HuR is considered an appealing drug target for cancer treatment. Therefore, multiple attempts have been made to identify small molecule inhibitors for blocking HuR functions. This article reviews the current prospects of drugs that target HuR in numerous cancer types, their mode of action, and off-target effects. Furthermore, we will summarize drugs that interfered with HuR-RNA interactions and established themselves as novel therapeutics. We will also highlight the significance of HuR overexpression in multiple cancers and discuss its role in immune functions. This review provides evidence of a new era of HuR-targeted small molecules that can be used for cancer therapeutics either as a monotherapy or in combination with other cancer treatment modalities.

Advances in The Study of RNA-binding Proteins in Diabetic Complications

Background

It has been reported that diabetes mellitus affects 435 million people globally as a primary health care problem. Despite many therapies available, many diabetes remains uncontrolled, giving rise to irreversible diabetic complications that pose significant risks to patients’ wellbeing and survival.

Scope of Review

In recent years, as much effort is put into elucidating the posttranscriptional gene regulation network of diabetes and diabetic complications; RNA binding proteins (RBPs) are found to be vital. RBPs regulate gene expression through various post-transcriptional mechanisms, including alternative splicing, RNA export, messenger RNA translation, RNA degradation, and RNA stabilization.

Major Conclusions

Here, we summarized recent studies on the roles and mechanisms of RBPs in mediating abnormal gene expression in diabetes and its complications. Moreover, we discussed the potential and theoretical basis of RBPs to treat diabetes and its complications.

• Mechanisms of action of RBPs involved in diabetic complications are summarized and elucidated.

• We discuss the theoretical basis and potential of RBPs for the treatment of diabetes and its complications.

• We summarize the possible effective drugs for diabetes based on RBPs promoting the development of future therapeutic drugs.

RNA-binding proteins in diabetic microangiopathy

BACKGROUND

As the most common complication of diabetes, the diabetic microangiopathy characterizes diabetic retinopathy (DR) and nephropathy (DN). Diabetic microangiopathy has always been a serious clinical problem. A wide variety of nucleic acid interacting factors called the RNA binding proteins (RBPS) take part in several crucial cellular processes.

METHODS

Over the past decade, studies have shown that RBPs have crucial part in both malignant tumors and diabetes, especially in diabetic microangiopathy. This review examined the research history of RBPS in DR and DN.

RESULTS

We reviewed the literature and found that RBPS is potentially useful as therapeutic targets, diagnostic markers, or predict disease progression.

CONCLUSION

HuR acts as a vital therapeutic targeting protein in diabetic microangiopathy. IGF2BP2, P311, TTP, YBX1, and MBNL1 have a potential role in the treatment of DN.

RNA-binding proteins and their role in kidney disease

RNA-binding proteins (RBPs) are of fundamental importance for post-transcriptional gene regulation and protein synthesis. They are required for pre-mRNA processing and for RNA transport, degradation and translation into protein, and can regulate every step in the life cycle of their RNA targets. In addition, RBP function can be modulated by RNA binding. RBPs also participate in the formation of ribonucleoprotein complexes that build up macromolecular machineries such as the ribosome and spliceosome. Although most research has focused on mRNA-binding proteins, non-coding RNAs are also regulated and sequestered by RBPs. Functional defects and changes in the expression levels of RBPs have been implicated in numerous diseases, including neurological disorders, muscular atrophy and cancers. RBPs also contribute to a wide spectrum of kidney disorders. For example, human antigen R has been reported to have a renoprotective function in acute kidney injury (AKI) but might also contribute to the development of glomerulosclerosis, tubulointerstitial fibrosis and diabetic kidney disease (DKD), loss of bicaudal C is associated with cystic kidney diseases and Y-box binding protein 1 has been implicated in the pathogenesis of AKI, DKD and glomerular disorders. Increasing data suggest that the modulation of RBPs and their interactions with RNA targets could be promising therapeutic strategies for kidney diseases.

Six Decades of History of Hypertension Research at the University of Toledo: Highlighting Pioneering Contributions in Biochemistry, Genetics, and Host-Microbiota Interactions

PURPOSE OF REVIEW

The study aims to capture the history and lineage of hypertension researchers from the University of Toledo in Ohio and showcase their collective scientific contributions dating from their initial discoveries of the physiology of adrenal and renal systems and genetics regulating blood pressure (BP) to its more contemporary contributions including microbiota and metabolomic links to BP regulation.

RECENT FINDINGS

The University of Toledo College of Medicine and Life Sciences (UTCOMLS), previously known as the Medical College of Ohio, has contributed significantly to our understanding of the etiology of hypertension. Two of the scientists, Patrick Mulrow and John Rapp from UTCOMLS, have been recognized with the highest honor, the Excellence in Hypertension award from the American Heart Association for their pioneering work on the physiology and genetics of hypertension, respectively. More recently, Bina Joe has continued their legacy in the basic sciences by uncovering previously unknown novel links between microbiota and metabolites to the etiology of hypertension, work that has been recognized by the American Heart Association with multiple awards. On the clinical research front, Christopher Cooper and colleagues lead the CORAL trials and contributed importantly to the investigations on renal artery stenosis treatment paradigms. Hypertension research at this institution has not only provided these pioneering insights, but also grown careers of scientists as leaders in academia as University Presidents and Deans of Medical Schools. Through the last decade, the university has expanded its commitment to Hypertension research as evident through the development of the Center for Hypertension and Precision Medicine led by Bina Joe as its founding Director. Hypertension being the top risk factor for cardiovascular diseases, which is the leading cause of human mortality, is an important area of research in multiple international universities. The UTCOMLS is one such university which, for the last 6 decades, has made significant contributions to our current understanding of hypertension. This review is a synthesis of this rich history. Additionally, it also serves as a collection of audio archives by more recent faculty who are also prominent leaders in the field of hypertension research, including John Rapp, Bina Joe, and Christopher Cooper, which are cataloged at Interviews .

A global analysis on the differential regulation of RNA binding proteins (RBPs) by TNF–α as potential modulators of metabolic syndromes

Metabolic syndrome (MetS) is associated with a group of conditions, which enhances the risk of diabetes, heart diseases and stroke in the affected individuals. Earlier reports from our lab have shown that Tumor necrosis factor-α (TNF-α) significantly modulates the expression of 56 genes at the alternative splicing level which are involved in various signaling and metabolic pathways (MetS genes) connected to MetS. These MetS genes were predicted to interact with various RNA-binding proteins (RBPs) when exposed to TNF-α, resulting changes in their alternative splicing patterns. Here we are presenting data of an RNA-Seq analysis, which identified 1218 unique, and significantly regulated genes by TNF-α, 15% of which are RBPs . Among the 1218 genes, 204 genes have been identified as MetS genes by the ingenuity pathway analysis, and 10% of the MetS genes are found as RBPs. Our results also show that TNF-α changes the phosphorylation status of certain RBPs such as SR proteins, crucial players in alternative splicing, possibly via changing the activation status of certain upstream signaling molecules which also act as upstream kinases for these proteins. Taken together, these findings suggest that TNF-α influences the regulation of the RBPs at the various levels for their expression, which may lead to the alteration of the splicing pattern of the MetS genes. MetS genes acting as RBPs and are modulated by TNF-α, predict the existence of highly interconnected mechanisms which require further analysis to understand their dual roles on the onset of these diseases.

Long Noncoding RNA ENSG00000254693 Promotes Diabetic Kidney Disease via Interacting with HuR

Diabetic kidney disease (DKD) is one of the most common complications of diabetes mellitus (DM), without suitable therapies, causing end-stage renal diseases (ESRDs) ultimately. Moreover, there is increasing evidence demonstrating that long noncoding RNAs (lncRNAs) play crucial roles in the development of DKD. Our RNA sequencing data revealed a large group of differentially expressed lncRNAs in renal tissues of DKD, of which lncRNA ENSG00000254693 (lncRNA 254693 for short) changed drastically. In this study, we found that the expression of lncRNA 254693 was increased in both DKD patients and high-glucose-induced human podocytes. 5'/3'RACE and Northern blot assays were used to find the full length of lncRNA ENSG00000254693 which is 558 nucleotides and nonisoform that existed in human podocyte. Downregulation of lncRNA 254693 remarkably reversed the elevation of inflammation, apoptosis, and podocyte injury caused by high glucose. Then, we did bioinformatics analysis via RBPDB and found that lncRNA 254693 can combine with HuR, a RNA binding protein. Meanwhile, immunofluorescence and in situ hybridization double staining was used to prove the existence of colocalization between them. Intriguingly, lncRNA 254693 knockdown decreased HuR levels, while HuR knockdown also decreased the level of lncRNA 254693 and its stability. After this, RNA immunoprecipitation assay results confirmed the binding association between them again. In addition, we found that HuR was increased in high glucose-induced podocytes, and the silence of HuR could alleviate podocyte injury, inflammation, and apoptosis. These results together suggested a novel feedback regulation between lncRNA 254693 and HuR which could involve in podocyte injury and may serve as a predicted target for DKD therapies.

Trimethylamine-N-Oxide Aggravates Kidney Injury via Activation of p38/MAPK Signaling and Upregulation of HuR

BACKGROUND

Trimethylamine-N-oxide (TMAO) is an intestinal metabolic toxin, which is produced by gut flora via metabolizing high-choline foods. TMAO is known to increase the risk of atherosclerosis and cardiovascular events in chronic kidney disease (CKD) patients.

OBJECTIVES

The objective of this study was to explore the role and mechanism of TMAO aggravating kidney injury.

METHOD

We used the five-sixths nephrectomy (5/6 Nx)-induced CKD rats to investigate whether TMAO could aggravate kidney damage and its possible mechanisms. Six weeks after the operation, the two groups of 5/6 Nx rats were subjected to intraperitoneal injection with 2.5% glucose peritoneal dialysis fluid (2.5% PDF) and 2.5% PDF plus TMAO 20 mg/kg/day.

RESULTS

In this study, we provided evidence showing TMAO significantly aggravated renal failure as well as inflammatory cell infiltration and in five-sixths nephrectomy-induced CKD rats. We found that TMAO could upregulate inflammatory factors including MCP-1, TNF-α, IL-6, IL-1β, and IL-18 by activating p38 phosphorylation and upregulation of human antigen R. TMAO could aggravate oxidative stress by upregulating NOX4 and downregulating SOD. The result also confirmed that TMAO promoted NLRP3 inflammasome formation as well as cleaved caspase-1 and IL-1β activation in the kidney tissue.

CONCLUSIONS

Taken together, the present study validates TMAO as a pro-inflammatory factor that causes renal inflammatory injury and renal function impairment. Inhibition of TMAO synthesis or promoting its clearance may be a potential therapeutic approach of CKD in the future.

IL-6/STAT3 signaling activation exacerbates high fructose-induced podocyte hypertrophy by ketohexokinase-A-mediated tristetraprolin down-regulation

Glomerular hypertrophy is a crucial factor of severe podocyte damage and proteinuria. Our previous study showed that high fructose induced podocyte injury. The current study aimed to explore a novel molecular mechanism underlying podocyte hypertrophy induced by high fructose. Here we demonstrated for the first time that high fructose significantly initiated the hypertrophy in rat glomeruli and differentiated human podocytes (HPCs). Consistently, it induced inflammatory response with the down-regulation of anti-inflammatory factor zinc-finger protein tristetraprolin (TTP) and the activation of interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling in these animal and cell models. Subsequently, high-expression of microRNA-92a-3p (miR-92a-3p) and its target protein cyclin-dependent kinase inhibitor p57 (P57) down-regulation, representing abnormal proliferation and apoptosis, were observed in vivo and in vitro. Moreover, high fructose increased ketohexokinase-A (KHK-A) expression in rat glomeruli and differentiated HPCs. Exogenous IL-6 stimulation up-regulated IL-6/STAT3 signaling and miR-92a-3p, reduced P57 expression and promoted podocyte proliferation, apoptosis and hypertrophy in vitro. The data from anti-inflammatory agent maslinic acid treatment or TTP siRNA transfection showed that high fructose may decrease TTP to activate IL-6/STAT3 signaling in podocyte overproliferation and apoptosis, causing podocyte hypertrophy. Whereas, KHK-A siRNA transfection remarkably restored high fructose-induced TTP down-regulation, IL-6/STAT3 signaling activation, podocyte overproliferation, apoptosis and hypertrophy in differentiated HPCs. Taken together, these results suggested that high fructose possibly increased KHK-A expression to down-regulate TTP, subsequently activated IL-6/STAT3 signaling to interfere with podocyte proliferation and apoptosis by up-regulating miR-92a-3p to suppress P57 expression, causing podocyte hypertrophy. Therefore, the inactivation of IL-6/STAT3 to relieve podocyte hypertrophy mediated by inhibiting KHK-A to increase TTP may be a novel strategy for high fructose diet-associated podocyte injury and proteinuria.

Global analysis of RNA-protein interactions in TNF-α induced alternative splicing in metabolic disorders

In this report, using the database of RNA-binding protein specificities (RBPDB) and our previously published RNA-seq data, we analyzed the interactions between RNA and RNA-binding proteins to decipher the role of alternative splicing in metabolic disorders induced by TNF-α. We identified 13 395 unique RNA-RBP interactions, including 385 unique RNA motifs and 35 RBPs, some of which (including MBNL-1 and 3, ZFP36, ZRANB2, and SNRPA) are transcriptionally regulated by TNF-α. In addition to some previously reported RBPs, such as RBMX and HuR/ELAVL1, we found a few novel RBPs, such as ZRANB2 and SNRPA, to be involved in the regulation of metabolic syndrome-associated genes that contain an enrichment of tetrameric RNA sequences (AUUU). Taken together, this study paves the way for novel RNA-protein interaction-based therapeutics for treating metabolic syndromes.

Cataloguing the phosphorylation sites of tristetraprolin (TTP): Functional implications for inflammatory diseases

Tristetraprolin (TTP) is a destabilizing mRNA binding protein known to regulate gene expression of a wide variety of targets, including those that control inflammation. TTP expression, regulation and function is controlled by phosphorylation. While the importance of key serine (S) sites (S⁵² and S¹⁷⁸ in mice and S¹⁸⁶ in humans) has been recognized, other sites on the hyperphosphorylated TTP protein have more recently emerged as playing an important role in regulating cellular signalling and downstream functions of TTP. In order to propel investigation of TTP and fully exploit its potential as a drug target in inflammatory disease, this review will catalogue TTP phosphorylation sites in both the murine and human TTP protein, the known and unknown roles and functions of these sites, the kinases and phosphatases that act upon TTP and overview methodological approaches to increase our knowledge of this important protein regulated by phosphorylation.