P57Kip2 and Beckwith-Wiedemann Syndrome Tim Lockney P57Kip2 and Beckwith-Wiedemann Syndrome

What is p57? Alias: CDKN1C 316 Amino Acids long Localized in the Nucleus Important during development Localized to Chromosome 11p15.5 Matsuoka et al.

What type of protein is p57? CDK-inhibitor p21 Family ? ? Cip/Kip = CDK interacting protein/Kinase inhibitory protein Has an NLS in the CDKi domain. Siblings include p21 and p27 QT domain function is yet to be elucidated, More complex structure suggests more roles. The Cip/Kip proteins are intrinsically unstructured, adopting specific tertiary conformations only after binding to other Proteins This conformational flexibility suggests that phosphorylation events and protein-protein interactions may modify the folding of the CKIs, thereby modulating their ability to inhibit cyclin-CDK complexes. Likewise, it may explain why CKIs are capable of interacting with a wide diversity of proteins to regulate various cellular functions. Duronio, B. http://www.getreligion.org/wp-content/photos/Face_of_RPI___question_mark.gif

p57 Function Negative regulator of cell cycle Tumor Suppressor! Penultimately: CDK inhibitor Ultimately a Tumor Suppressor Specifically the G1-> S transition. Mainprize, T.G. et al. http://www.genome.jp/dbget-bin/show_pathway?hsa04110+1028

p57 Function Also involved in differentiation Can act as a transcription factor MyoD keeps myocyte a myocyte The N-terminal cyclin-CDK binding region of p57 can interact with MyoD, protecting MyoD from degradation and thus promoting transactivation of muscle-specific genes Besson, A. et al.

p57 Function Summary Tumor Suppressor Over expression = G1 arrest Can bind to Proliferating Cell Nuclear Antigen (PCNA), a DNA polymerase Sigma processivity factor, via its C terminus (aa 143–160), thereby blocking processive DNA synthesis Differentiation Also involved in cytoskeletal dynamics and apoptosis, but involvement remains unclear. So, as you can see, These proteins turn out to be MULTIFACETED Segue into BWS

What is Beckwith-Wiedemann Syndrome? 1-13,000 or 1-15,000 http://beckwith-wiedemannsyndrome.org/graphics/uploadfile/1276/dia_0025a_.jpg COHEN JR., M.M. Om-fowl-o-seal

BWS Tumors Zhang, P. et al. Larger kidney = more cells = more likelihood of cancer in absolute terms. Cohen Jr., M.M. http://images.google.com/imgres?imgurl=http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/9056.jpg&imgrefurl=http://www.nlm.nih.gov/medlineplus/ency/imagepages/9056.htm&h=320&w=400&sz=11&hl=en&start=1&um=1&tbnid=9gfxNPL-LdXZGM:&tbnh=99&tbnw=124&prev=/images%3Fq%3Dwilm%2527s%2Btumor%26um%3D1%26hl%3Den%26safe%3Doff%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN

Connecting BWS with p57 Knockout mice Mainprize, T.G. et al.   none of the p57 knockouts lived past 2 weeks, and most died shortly after birth. had BIRTH DEFECTS. SHOW that MIDDLE IS HAPLOINSUFFICIENT!! What Are the Birth defects? Segue into next slide Zhang, P. et al. Zhang, P. et al.

Knockout Mice Continued Similarities http://ez-host.org/graphics/uploadfile/1276/omphalocele_.jpg Zhang, P. et al.

How does p57 cause BWS? Imprinting: complex genetics “A process that causes genes to be expressed according to their parental origin,” Affects ~1000 human genes The ones important for development p57 is an imprinted gene. P57 is not the only culprit, BWS is a pleiotropic diseases Genomic imprinting is defined as an epigenetic modification of a gene or the chromosome Typically, imprinting results in monoallelic expression, The cdkn1c gene is also an imprinted gene with preferred expression of the maternal allele (Matsuoka et al., 1996), which is recognized as a general mechanism to regulate embryonic growth (Andrews et al., 2007). Importantly, p57 is the only CKI to be required for embryonic development, as most mice lacking the cdkn1c gene have multiple developmental abnormalities and die at birth Some expression ~5% from paternal allele - Andrew Feinberg – Imprinting of a Genomic Domain of llp15 and Loss of Imprinting in Cancer: An Introduction

How does imprinting work? Methylation Histone Acetylation (chromatin modeling) The cdkn1c gene is also an imprinted gene with preferred expression of the maternal allele (Matsuoka et al., 1996), which is recognized as a general mechanism to regulate embryonic growth (Andrews et al., 2007). Importantly, p57 is the only CKI to be required for embryonic development, as most mice lacking the cdkn1c gene have multiple developmental abnormalities and die at birth http://genome.wellcome.ac.uk/assets/GEN10000675.jpg

Imprinting and BWS Normally Maternal p57 is expressed Methylation is the main control Methylation is green light Uses methyl binding transcription factors Many have normal karyotype, leads scientist to believe that LOI is the cause. Disruption of monoallelic expression. LOI = cancer/bws HETEROZYGOUS MICE THAT inherited a mutant allele from the mother manifested with almost identical developmental anomolies as the homozygous knockout mice, demonstrating that the locus is imprinted.

LOI LOI can occur via LOH LOM Or even a bad gene White oval is unmethylated, black oval is methylated. Bad genes, can be deletions or even point mutations. LOSS OF METHYLATION IS THE MOST COMMON CAUSE OF BWS ~50% Chromosomes in the egg conserve histones whereas histones are replaced by protamines in sperm HETEROZYGOUS MICE THAT inherited a mutant allele from the mother manifested with almost identical developmental anomolies as the homozygous knockout mice, demonstrating that the locus is imprinted. K. Higashimoto et al. Izuho Hatada et al.

MENTION TEST TUBE BABIES! Tx’s? Intravenous solutions for hypoglycemia This is why I’m hot. MENTION TEST TUBE BABIES! Tx’s? Intravenous solutions for hypoglycemia Toungue resection Cancer treatment Hatada I. et al.

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